Worried with those subframe stories

[Alx]

Hello,

I hope everyone is doing well.

A lot of those subframe stories have made me quite worried.

It sometimes even makes consider selling my CSL.

The BMW "specialists" in my area have never heard of it - just like the guys in Munich actually...

I have heard that BMW doesn't recommend the foam injections anymore.

Some say that this procedure was just supposed to delay the problem in order to pass the 10-year goodwill repair, but that it does not solve the problem.

My car gets regularly checked (at each inspection), but I am wondering if I could do any preventive work.

It seems that the cars are harder to repair once the foam has been injected.

Thank you for your advice and kind regards,
Alex

http://i19.photobucket.com/albums/b183/M_Alx/7D34AEE5-0C35-4C5F-AE61-F2B011764499-260-00000014A8F89558_zpsa83b6ce8.jpg

[Monkey]

Hello,

I hope everyone is doing well.

A lot of those subframe stories have made me quite worried.

It sometimes even makes consider selling my CSL.

The BMW "specialists" in my area have never heard of it - just like the guys in Munich actually...

I have heard that BMW doesn't recommend the foam injections anymore.

Some say that this procedure was just supposed to delay the problem in order to pass the 10-year goodwill repair, but that it does not solve the problem.

My car gets regularly checked (at each inspection), but I am wondering if I could do any preventive work.

It seems that the cars are harder to repair once the foam has been injected.

Thank you for your advice and kind regards,
Alex

http://i19.photobucket.com/albums/b183/M_Alx/7D34AEE5-0C35-4C5F-AE61-F2B011764499-260-00000014A8F89558_zpsa83b6ce8.jpg

Hi Alex,

You could get the aftermarket reinforcement plate kit fitted as a precautionary measure. It's quite expensive though, around £1000 for us to do it. I would say though, if yours has not cracked by now, there's a good chance it wont.
I have seen them crack in 3 different places, so make sure you get it checked thoroughly by someone who is familiar with the issue.
If you need to know which areas to check, let me know and I will take some photos of a car at work and upload them on here.

[Alx]

Hi Alex,

You could get the aftermarket reinforcement plate kit fitted as a precautionary measure. It's quite expensive though, around £1000 for us to do it. I would say though, if yours has not cracked by now, there's a good chance it wont.
I have seen them crack in 3 different places, so make sure you get it checked thoroughly by someone who is familiar with the issue.
If you need to know which areas to check, let me know and I will take some photos of a car at work and upload them on here.

Hi James,

Many thanks for your precious advice.

If you were not that far from where I live, I would have taken my car to you.

I am sure there are some detailled pictures on where to look for the cracks, but if you don't mind, I would be grateful if you posted some.

The guys here in Geneva don't really seem aware of the issue.

I often drive the car without the radio on and I'm always trying to listen to any suspicious noises. It seems fine so far...

I'll pray that it doesn't hapen to mine as I am not too keen on the foam injection.

Again, many thanks for your help.

Kind regards,
Alex

[LeinsCSL]

Alex, I went with both the reinforcement plates and the foam injection as a purely precationary measure. With no cracks found and the 10 year period from BMW running out I decided it was worth doing for my peace of mind, as my CSL is a keeper long-term I think

[Alx]

Alex, I went with both the reinforcement plates and the foam injection as a purely precationary measure. With no cracks found and the 10 year period from BMW running out I decided it was worth doing for my peace of mind, as my CSL is a keeper long-term I think

Hi Leins,

I remember talking to you about this at the bar of the hotel in Munich.

The ideal would be to find a competent garage to do it either here in Switzerland or even in Germany.

Many thanks,
Alex

[LeinsCSL]

Can't advise on Germany I'm afraid, but I'd be very surprised if there aren't some good indepedent garages there who have done a few CSLs before. There must surely be a demand for it I would have thought?

[Alx]

There might be some specialists, but the BMW dealers in my area don't really put me in confidence when it's something other than their regular business.

[pinkpanther008]

There might be some specialists, but the BMW dealers in my area don't really put me in confidence when it's something other than their regular business.


Alx,

Have you tried writing to BMW Switzerland to ask about the well known rear floor issue? THey might help you remind your dealer of the fault and assist you getting it rectified or inspected properly?

Good Luck
PP

[alexk]

Alx,

Have you tried writing to BMW Switzerland to ask about the well known rear floor issue? THey might help you remind your dealer of the fault and assist you getting it rectified or inspected properly?

Good Luck
PP

As per BMW Switzerland...
- There was never ever a problem with the subframe of the E46 M3 and E46 M3 CSL.
- There was never a CSL in the world that has been repaired.
- If your BMW was ever on a track (even for BMW driver training), whatever warranty you had (even if the car is 1 month old) it gets terminated immediately.

PS: here we have 3 years factory warranty and then you are on your own ;)

[shimmy]

i guess they have decided that the chance a legal case succeeding is very low so are denying it all.

have you tried the BmW techical repair paperwork that is issued to solve the problem

[Alx]

As AlexK says, they have never heard of it here.

The technical papers state models until February 2000 if I remember correctly, so they will just ignore it.

I have been put in contact with a guy that owns a small garage who is a BMW specialist (and a big CSL fan).

He did mention that it was quite a rare problem. He has client who owns a CSL with 40'000 km of hard track driving and the car is flawless.

He said that as a preventive work, we could install PowerFlex bushes.

He did not mention the foam injections though.

I might take my car there for the next service.

Thank you again,

Alex

[shimmy]

As AlexK says, they have never heard of it here.

The technical papers state models until February 2000 if I remember correctly, so they will just ignore it.

I have been put in contact with a guy that owns a small garage who is a BMW specialist (and a big CSL fan).

He did mention that it was quite a rare problem. He has client who owns a CSL with 40'000 km of hard track driving and the car is flawless.

He said that as a preventive work, we could install PowerFlex bushes.

He did not mention the foam injections though.

I might take my car there for the next service.

Thank you again,

Alex

alx

sounds like that guy doesnt understand either

[Alx]

Thank you Shimmy.

So the best thing would be the foam injection + the reinforcement kit like this http://www.turnermotorsport.com/p-91-e46-rear-chassissubframe-reinforcement-kit.aspx ?

[JBird]

Hi Alex (OP Alex that is)

Where abouts are you? Before you go ahead with the plate kit, I would wait for the photos from Monkey, and have the floor thoroughly checked by someone who knows what to look for. The cracks on the LH tend to be more visible, you can get a small camera in through stabiliser bar bracket to take a photo. Those on the RHS (for me at least) were not visible till the floor was removed. You need to get in there with a probe camera to have a chance of seeing them, and the the wax and dirt on the surface would have to be cleaned off. I just put some updated info on my repair here (http://www.cslregister.com/forum/showthread.php?p=158597&posted=1#post158597).

You are right that there appears to be less acknowledgement of the problem in other countries compared to the UK. When I was trying to get my (UK) CSL done in Germany I asked at M directly (through some friends that work there) if they could recommend a Garage in sthn Germany experienced with the repair. To my surprise they claimed that the cracks never happen on any late model E46s/M3s, only on the very early 98/99 std E46s. I laughed and explained that every second car with an SMG in having the floor replaced, to which they were sceptical. I really wonder how many of the goodwill claim statistics filter through to the engineers responsible for issuing the repair guidelines, and if (as you hinted at) it is still the correct repair method long term. i.e., is a replaced-and-foam-filled-floor only going to crack again in a few years?

If you read German M3 forums it seems some people have had the repair done by BMW under goodwill / kulanz. When asking in Switzerland, try to differentiate between body warranty and goodwill. AFAIK goodwill is 10yrs worldwide, and that is how everyone gets the repair done. The 3yr factory warranty you mention should be irrelevant. I don't think anyone in the UK ever had more that a 3yr base warranty without paying for it. There is a 6 or 12 years on body corrosion depending on if it is an 03 or 04 car. Many 03 models have been repaired under goodwill between 6 and 10 years age for example. I suspect you need to push harder / ask the right person. Print out the repair guidelines (https://docs.google.com/file/d/0B818hrBYPkZBSTRVQXpwNlJYVlE/edit?pli=1), and go to a bodyshop with pics of the damage. Obviously remove any go faster bits, and you never went on track if asked!

Anyway, if you manage to find cracks, and are considering trying to get it fixed in Germany feel free to PM me for some garages. I did quite a bit of enquiring before ultimately getting it done in the UK.

[JBird]

alx

sounds like that guy doesnt understand either

Agreed. I don't think poweflex bushes will help, and I am sceptical of the reinforcement kit, certainly not without the foam injection.

I honestly think a car that has only been on track will be less likely to have a cracked floor than a car that has been only on the road. To me it's the cold low rev changes typical of everyday driving that send a jolt through the drive line that loads the 3 diff bushes to the limit of their progression which in turn loads the subframe bushes and floor. Well, that and sharp bumps like those from potholes. Maybe the problem is more known in the UK because the roads are so unbelievably shit? The high rev changes that you can achieve on track tend to be crisp and smooth. Anyway, I digress, thoughts are irrelevant, BMW want to hear that it hasn't been on track, so that's what you tell em.

[Alx]

Hi JBird,

Many thanks for your precious help.

I live in Geneva in Switzerland.

I don't think I will do anything before the spring.

My car had an Oilservice in July of this year at my local BMW garage and the guys inspected the chassis. Apparently no cracks were found.

It's not that I totally trust them, but I'm a bit relieved.

I am hesitating on doing the preventive work (foam only?) or leave it as it is and have it checked at each service.

Thank you again!
Alex

[JBird]

Ok Alx, but be wary of the 10yrs goodwill, just in case that is possible to make use of in Switzerland.

I'd still go to an indy sooner rather than later and get your car on a ramp and look for yourself. Good vid here from Reddish motorsport describing how to identify the initial cracks. For the LHS you can even see it with the car on a normal jack and the LH wheel off. Really need to know where to look though.

http://www.youtube.com/watch?v=HaTYBaMpUtE

[mattCSLnut]

i guess they have decided that the chance a legal case succeeding is very low so are denying it all.

You'd be surprised how close U are to the truth :whistle:

[Alx]

Ok Alx, but be wary of the 10yrs goodwill, just in case that is possible to make use of in Switzerland.

I'd still go to an indy sooner rather than later and get your car on a ramp and look for yourself. Good vid here from Reddish motorsport describing how to identify the initial cracks. For the LHS you can even see it with the car on a normal jack and the LH wheel off. Really need to know where to look though.

http://www.youtube.com/watch?v=HaTYBaMpUtE

Thank you JBird.

I took my car to a body shop earlier this year to repaint the wheels and the front bumper and I also asked him to check the chassis.

He told me that it was fine.

My car is from July 2003, so it's out of the 10 years goodwill anyway.

Cheers,
Alex

[alexk]

There is no 10yr goodwill in Switzerland...

[Monkey]

'You are right that there appears to be less acknowledgement of the problem in other countries compared to the UK'

Probably because our roads are so crap!

I've heard a few people mention recently that they think its the bushes that are causing the cracks. That could be true of the crack at the front right rear subframe bush, but what about the cracked seam in the lower inner arch? Or the floor pan at the front of the spare wheel well area? I dont think so personally.

I've used both the Turner motorsport repair kit, & the Reddish Motorsport kit. Reddish one a lot better. There is also the option of cutting open the chassis inside the car, just behind the rear seats. The spot welds are then visible which split, so these are welded. Unfortunately you do end up with a couple of welded plates in the boot, only visible if you lift the carpet.

Sorry Alex, been very busy today and not had an M3 in. I may have some endoscope shots saved at work, I'll see if I can find them tomorrow.

[Alx]

Hi James,

No problem, thank you again for your help! :)

I'm not really in a hurry, I was just wondering what I could do as a preventive work as this spoils the pleasure of ownership a bit.

So before I make an irreparable mistake, like selling the CSL during the winter, I was wondering what I could do.

Kind regards,
Alex

[The Gorilla]

Hi,

Quote- '''You are right that there appears to be less acknowledgement of the problem in other countries compared to the UK'

Perculiar statement given that it was a
Multipile Class Action by owners in the
States that kicked this all off.

The problem is a piss poor design made worse
by the fact that even the BMW remeadies are
aimed at recitfying the symptoms not the
cause.

I would not be at all surprised to see some
of the BMW ''fixes'' starting to unravel in
a few more years, maybe sooner.

The 10 year window has fuck all to do with fixing it,
its BMW's way of saying, your car, your fucking problem,
were now all done on that.

Who ever thought that mounting a load bearing
torque absorbing rear subframe, itself subjected
to high loads and lateral forces, on four mount
points all on the same plane without any chassis dowels
into the securing bushes was a clever design, should never be allowed
to design anything again, but to compound the issue by
elongating one of the bush holes to facilatate
subframe fixing, instead of moving complant bushes,
to facilitate bolt fixing and assist with absorbing
load, they should be shot.

Christ even Merc 190's have chassis dowels fitting into the
rear subframe bush to prevent 'sawing' stresses ripping
at the mount points and surrounding sheet etc.
All the laod and movement is absorbed by the bush,
the bush wear out and are replaced, BUT the mounting
points never move !!!
They were designed in 1983 and BMW has just
started to emulate that design in the E90 series etc.

As for ripping out distorted boot floors and re-welding
in new ones, well ye olde Roost monster will be having
a field day, even more so with anything synthetic filling
the boot floor skin voids, as any fucking retard knows
that when a cold surface, the boot floor skin meets a warm surface,
the expoxy filler or whatever, then hey presto, its called condensation and
guess what its water, and water on internally welded metal makes for
a loverly feeding ground for the Roost monster.

And they reckon I am on drugs, fuck me, well at least mine
in part are working some.

The fact remains the E46 Rear subframe fixing design
is kinder garten design at its very worst, its nothing to
do with the boot floor not being strong enough, or
to many launches in this gear or that gear, its the
very basic fact that any rear subframe should have
securing dowels as part of the chassis that fit into the
bushes on the subframe, or the back rear Bushes should
have been on a different plane to the front ones in
the very least, to counter any subframe movement which ideally should
be absorbed by the bush not by the the 4 H/T bolts ripping
at the sheet metal ala the BMW design, made worse
by the elongated hole.

But hey as the AD says ''Joy''.

Regards,

The Gorilla.

[Mike R]

Danny,
Do you know if the replacement floor sections have been redesigned with the dowels, or are they the exact same?

Looking at the photos of the new section that Mark posted up, I am unsure of the differences?

http://img.photobucket.com/albums/0703/MikeR/CSL%20stuff/Subframe09_zps0a299803.jpg (http://smg.photobucket.com/user/MikeR/media/CSL%20stuff/Subframe09_zps0a299803.jpg.html)

[Neil M]

Hi,

Quote- '''You are right that there appears to be less acknowledgement of the problem in other countries compared to the UK'

Perculiar statement given that it was a
Multipile Class Action by owners in the
States that kicked this all off.

The problem is a piss poor design made worse
by the fact that even the BMW remeadies are
aimed at recitfying the symptoms not the
cause.

I would not be at all surprised to see some
of the BMW ''fixes'' starting to unravel in
a few more years, maybe sooner.

The 10 year window has fuck all to do with fixing it,
its BMW's way of saying, your car, your fucking problem,
were now all done on that.

Who ever thought that mounting a load bearing
torque absorbing rear subframe, itself subjected
to high loads and lateral forces, on four mount
points all on the same plane without any chassis dowels
into the securing bushes was a clever design, should never be allowed
to design anything again, but to compound the issue by
elongating one of the bush holes to facilatate
subframe fixing, instead of moving complant bushes,
to facilitate bolt fixing and assist with absorbing
load, they should be shot.

Regards,

The Gorilla.

Bang On, 100% Nail on the head - an inherent design fault with the E46 chassis!
This should have been rectified before continuing production as it was known to exist before 2003.
Yet production remained unchanged, except for the CSL where if anything the likelihood of the defect occurring was enhanced. :(
The term 'Professional Negligence' springs to mind! :whistle:

[rstoughy]

So now that mine is cracked and sitting in my garage while I decide the best route for repair what's the thoughts?
I'm totally in agreement that the new floor fix and resin injection will come back in years to bite in one way or another.

Would there Be a way to tie these mounts into some sort of rear strut brace to spread the load a little?

Concern would be loosing all the boot space in place of steel tubes as for me part of the CSL's appeal is that it has a usuable boot (in the dry obviously) :whistle:
From the rear struts forward would be ok though.

Then there is the repair plates. Again its into welding and heat, condensation, internal corrosion etc etc and at the end of the day will this actually stop it happening again or will it just rip out a bigger chunk of metal?

I think the load / movement needs to be absorbed and spread through the car rather than just the boot floor. Just a case of how?

I'm in a position now to try and only want to be doing this once.
Discussions and opinions please?

[Mike R]

So now that mine is cracked and sitting in my garage while I decide the best route for repair what's the thoughts?
I'm totally in agreement that the new floor fix and resin injection will come back in years to bite in one way or another.

Would there Be a way to tie these mounts into some sort of rear strut brace to spread the load a little?

Concern would be loosing all the boot space in place of steel tubes as for me part of the CSL's appeal is that it has a usuable boot (in the dry obviously) :whistle:
From the rear struts forward would be ok though.

Then there is the repair plates. Again its into welding and heat, condensation, internal corrosion etc etc and at the end of the day will this actually stop it happening again or will it just rip out a bigger chunk of metal?

I think the load / movement needs to be absorbed and spread through the car rather than just the boot floor. Just a case of how?

I'm in a position now to try and only want to be doing this once.
Discussions and opinions please?


I saw some pictures of the result of the strengthening, where it just did as you said and ripped even more of the floor apart, but I can't remember where I saw them. It was shocking how bad it was though :smt120 !

[JBird]

Given that we are where we are, i.e., love theses cars but the feckers keep cracking, and that BMW offer a "fix" that we either; can get but are sceptical of, don't want, or, as in the Swiss guys situation, can't get, what does someone like Alx do?

Is a reinforcement plate such as the Reddish kit a bearable (no pun intended) comprimise? I'd have thought yes, but only with a structural foam intection to distrubute the load more softly through the plates into the body. Structural foam in itself is a good idea, the sandwich structure formed offers excelent properties, but only an option if it lasts and does not promote corrosion. When used in OEM design from the onset, the car body gets properly dipped in for corrosion protection, something we don't have the benifit of.


As for ripping out distorted boot floors and re-welding in new ones, well ye olde Roost monster will be having a field day, even more so with anything synthetic filling the boot floor skin voids, as any fucking retard knows that when a cold surface, the boot floor skin meets a warm surface, expoxy filler or whatever, then hey presto, its called condensation and guess what its water, and water on internally welded metal makes for a loverly feeding ground for the Roost monster.

Is the foam itself going lead to that more corrosion? Maybe a little, but i'd have thought the main issue is the new welds them self / areas of the body where the original factory protection coat has been disturbed. i.e, foam or no foam, condensation will eventually get in an rust will start. If so, is enough being done in either the BMW cut-out-your floor method, or Reddish reinforcement plate method to corrosion protect welds / exposed metal on both sides of the weld?

Those who have had the BMW goodwill fix do have a life time guarentee, but I think we'd rather not ever have to use it.

[Alx]

Hi,

I finally had aome information from my local BMW garage.

Thet say that they can do the foam injection as a prevention, but they can't garantee that the cracks will not appear.

The thing is I don't really trust them...

[JBird]

In that case alex, i'd also not trust their insp where they sait it wasn't cracked. If your going to get it foam filled, get a second opinion first. Foam filling a cracked floor then trying to fix / patch cracks afterwards would be a disaster. Best, check yourself. I was told mine was fine, then Gareth found a crack in 10 sec. Need to knowcwhere to look.

[Mike R]

This may help you locate them - here are photos of the cracks on my car that Gareth took for the warranty work to be done.

FYI mine was checked as follows:
November 2012:
No cracks

June 2013:
No cracks

September 2013:
http://img.photobucket.com/albums/0703/MikeR/CSL%20stuff/Subframecracks01_zps5a848233.jpg (http://smg.photobucket.com/user/MikeR/media/CSL%20stuff/Subframecracks01_zps5a848233.jpg.html)

http://img.photobucket.com/albums/0703/MikeR/CSL%20stuff/Subframecracks02_zpsf1ab8a40.jpg (http://smg.photobucket.com/user/MikeR/media/CSL%20stuff/Subframecracks02_zpsf1ab8a40.jpg.html)

[Alx]

Yes, I agree with you JBird.

I'm quite upset with BMW at the moment...

On top of their recent ugly designs and turbo-engine philosopy, they handled this problem quite badly.

I'm sometines leaning to sell my beloved CSL I confess...

[Alx]

Wow, that's impressive!

Thank you for the pictures Mike!

[DuncanR]

Call them cracks !! Check these out on a car thats been driven by Miss Daisy all her life !

[DuncanR]

few more..

[DuncanR]

Final one

[DuncanR]

BMW are having a fookin laugh saying that this doesnt happen and denying it in Germany ..then coming up with Technical Bulletins and stupid crazy foam fixes ... I may write a letter to them and say Im going to drive around in it until the floor gives way and kills me !:hahaha: ... then I will sue them :thumbs:

[Neil M]

BMW are having a fookin laugh saying that this doesnt happen and denying it in Germany ..then coming up with Technical Bulletins and stupid crazy foam fixes ... I may write a letter to them and say Im going to drive around in it until the floor gives way and kills me !:hahaha: ... then I will sue them :thumbs:

There speaks a man on a mission :hahaha:

They can't deny that the problem exists as they issued a worldwide memo to all Dealerships in 2003, advising them of what would be required to undertake their preferred fix eg. Plates and 2 pack Poly?Filler! :(

[LeinsCSL]

There speaks a man on a mission :hahaha:

They can't deny that the problem exists as they issued a worldwide memo to all Dealerships in 2003, advising them of what would be required to undertake their preferred fix eg. Plates and 2 pack Poly?Filler! :(

Did BMW suggest plates in the memo? My understanding is that the BMW fix is to replace the floor, and the option of the epoxy resin injection on one side

I've heard that the new floor they put in is the same as the original E46 M3 convertible one which is stronger. No idea if this is true though...

[alexk]

I've heard that the new floor they put in is the same as the original E46 M3 convertible one which is stronger. No idea if this is true though...

There is only one part number for M3 E46s.
http://mfans2.com/parts/catalog/41117000246/

[MCSL]

So is it possible for a 'replacement' floor to again.... crack?

[Monkey]

Danny,
Do you know if the replacement floor sections have been redesigned with the dowels, or are they the exact same?

Looking at the photos of the new section that Mark posted up, I am unsure of the differences?

http://img.photobucket.com/albums/0703/MikeR/CSL%20stuff/Subframe09_zps0a299803.jpg (http://smg.photobucket.com/user/MikeR/media/CSL%20stuff/Subframe09_zps0a299803.jpg.html)

The new boot floors are exactly the same. Gorilla, we have seen 2 replacement boot floors fail again within a 3 year period of the repair.

[shane@mbtech]

Just go full weld in cage. Job done.

[JBird]

The new boot floors are exactly the same. Gorilla, we have seen 2 replacement boot floors fail again within a 3 year period of the repair.

With the foam fill?

[mick csl]

when i bought my csl I also concerned about the subframe stories.
My csl with 45k miles had no cracks, but let them welt preventive the reinforcement kit on the car.
when i read the horror stories on the web every e46 M3/M3 CSL will get it at some time of its life.
(I paid 1000 euro for the job with new subframe bushes, PSG Geel M specialist in belgium:notworthy:)

(Sorry for the bad english:wink:)

[mattCSLnut]

BMW are having a fookin laugh saying that this doesnt happen and denying it in Germany ..then coming up with Technical Bulletins and stupid crazy foam fixes ... I may write a letter to them and say Im going to drive around in it until the floor gives way and kills me !:hahaha: ... then I will sue them :thumbs:

That could work :thumbs: BTW good to see you back on here matey :beer:

[JBird]

I would be interested to hear if any forum members who had a proper floor replacement and foam fill early on have carried out a detailed inspection since. Any signs of cracks or corrosion? I remember some ppl geting it done back in 09 - cant find the post though...only about 200 subframe threads! General search of tinternet doesn't find anything either - good sign i guess.

we have seen 2 replacement boot floors fail again within a 3 year period of the repair.
Monkey, do you recall the root cause of the second time round failures you saw, corroded welds poping, or genuine cracks in foam filled floors?

I'm quite upset with BMW at the moment... On top of their recent ugly designs and turbo-engine philosopy, they handled this Problem quite badly

:hahaha::hahaha::hahaha: cheer up Alex, all the more reason to get the CSL sorted and hold onto it. Just incase you havn't seen it, clearly plenty of others who share your opinion mate....

http://www.youtube.com/watch?v=ZtenM2hFTgE&feature=youtube_gdata_player

[Alx]

Haha, this one is a classic JBird. :)

It makes me laugh every time - thank you.

Like you, I'm interested to know if any car has failed after having the foam injections.

Thank you again everyone!

[The Gorilla]

Hi,

MikeR- no, they replace with more or less the
same panel etc, nothing is done with regard
to addressing the main cause, as its
a design flaw.

Go to any Chassis engineer worth his salt
tell him you have a triple layer sheet floor
section with two vertical folds and that the
fixing point for the subframe bolts are
spot welded in with top and bottom
flanges.

Then tell him that the subframe mounts via
4 H/T bolts all in the same plane to a flat
'seat' section and there are no Chassis
dowels for bush location.

Mention that one Bush has an elongated hole
in the alloy insert for subframe fitting,
and that under ''clamp'' the bushes are
no more than 60nm.

Then tell him you going to inject foam
or whatever to stiffen the the 3 layer
honeycoombe sheet, as the torque loads
from the diff, which is mounted solely on
the subframe, and the lateral G loads
into the bushes via the rear wheels,
CSL on Type R can pull close to
1.2/1.5 lateral G in some corners, are
ripping the mounts and causing sheet metal
fatigue and cracks.

A good one would ask what medication your
on and a poor one would tell you that
''it'' migh work, not sure but he available
if your require his services.

As a tail note when BMW developed the
M3 GTR, one of my favorite Race cars
of all time, one of the first things to go
was the E46 rear subframe.


Regards,

The Gorilla.

[alexk]

Danny the solution is very simple in my opinion.
We need to get an E46 M3 GTR chassis. :notworthy:

[The Gorilla]

Hi Alex,

I agree with that for sure.

Regards,

The Gorilla.

[The Gorilla]

Hi,

Alex, no ''Bushes'' to worry about either !!!!

Regards,

The Gorilla

[Alx]

I would say though, if yours has not cracked by now, there's a good chance it wont.

Thank you again James, that's good to read.

My car has currently 60'000 km, but with all those horror stories, I'm not sure it will not break one day.

@The Gorilla: That would be a nice solution!

I'm wondering if any car had cracks even after the foam injection.

I won't do anything before the spring anyway.

[MCSL]

Does anyone know how long warranty BMW give on the replacement floor?

[Steve B]

I had mine done at BMW Hitchin bodyshop and they had a guy from France bring his car over for a goodwill replacement....


Steve

[Monkey]

I would be interested to hear if any forum members who had a proper floor replacement and foam fill early on have carried out a detailed inspection since. Any signs of cracks or corrosion? I remember some ppl geting it done back in 09 - cant find the post though...only about 200 subframe threads! General search of tinternet doesn't find anything either - good sign i guess.


Monkey, do you recall the root cause of the second time round failures you saw, corroded welds poping, or genuine cracks in foam filled floors?



:hahaha::hahaha::hahaha: cheer up Alex, all the more reason to get the CSL sorted and hold onto it. Just incase you havn't seen it, clearly plenty of others who share your opinion mate....

http://www.youtube.com/watch?v=ZtenM2hFTgE&feature=youtube_gdata_player

Genuine cracks:( I think I'm right in saying one of them had the foam fill, not sure on the other one. It may just be isolated cases, potentially down to human error in the fitting process. Time will tell if this will happen more frequently.

[Monkey]

Does anyone know how long warranty BMW give on the replacement floor?

I would have to double check, but 99% certain its 3 years.

[JBird]

Does anyone know how long warranty BMW give on the replacement floor?

The warranty on the workmanship is lifetime, if you keep up annual inspections at the bodyshop that did the repair (insp should be free). If you don't manage the inspections it reduces to 5 years. This only applies to the owner of the car at the time of the repair. This is what I was told at the Woodstock bodyshop where i had mine done. I believe this is std for all UK BMW bodyshops. Exactly what "workmanship" entails i dont know. If the fucker starts corroding, i'd argue it wasn't done properly, but BMW always seem to have a get out clause with corrosion. Certificate looks like this. On the reverse side is where you log the inspections.

http://i928.photobucket.com/albums/ad130/JBirdCSL/Cert2_zpsd83171f2.jpg

http://i928.photobucket.com/albums/ad130/JBirdCSL/Conditions2_zps736cab2b.jpg

[JBird]

Take back what I said about the corrosion....turns out its 12 years.

...although, it sounds a bit grey, 12 yrs on the new floor, or 12 years since the car was first registered? Sounds more like the latter which doesn't help much. I guess it means 04 cars that have had new floors have their inherent cover till 2016, but 03 cars (which had just 6 years corrosion warranty originally) have no corrosion cover on the new floor. Gee, BMW thought that one thorough well. Hopefully common sense would prevail and we would still be looked after if they all start rusting.

http://i928.photobucket.com/albums/ad130/JBirdCSL/Corrosion_zpsd1f595e8.jpg

[MCSL]

I would have to double check, but 99% certain its 3 years.

Cheers.

[MCSL]

Take back what I said about the corrosion....turns out its 12 years.

...although, it sounds a bit grey, 12 yrs on the new floor, or 12 years since the car was first registered? Sounds more like the latter which doesn't help much. I guess it means 04 cars that have had new floors have their inherent cover till 2016, but 03 cars (which had just 6 years corrosion warranty originally) have no corrosion cover on the new floor. Gee, BMW thought that one thorough well. Hopefully common sense would prevail and we would still be looked after if they all start rusting.

http://i928.photobucket.com/albums/ad130/JBirdCSL/Corrosion_zpsd1f595e8.jpg


Cheers. I hope it does have at least a 3 yr warranty...

[shane@mbtech]

If the repair was carried out under warranty foc then the repair itself carries no warranty, other than quality of work. If it's an inherent fault which they are aware of and they are aware, as they repaired it for said fault. Then if they refuse take it to court, as it's obviously a design flaw. They can't have it both ways surely?

By fixing it originally they accept there is a flaw, so how can they then decide to fob you off.

It's not a corrosion warranty repair in reality, it's a repair because of a design flaw.

[Alx]

Hello everyone!

First, I wish you a happy new year to you and your relatives!

Like AlexK, after inquiring with BMW Switzerland, I had a reply stating that the problem does not exist and that the subframe cracks and TIS number that I mentionned do not reflect the reality of the situation...

This is very frustrating and I confess that I am quite upset with BMW despite being a fan for more than 30 years and having driven their cars for about 18 years. :moan::mad:

I sometimes consider selling the CSL and look for a Porsche or a Ferrari. ...unless I decide to do the foam injections myself.

Cheers everyone,
Alex

[LeinsCSL]

It's very annoying when BMW carry on like this Alex. However, don't let it put you off what is a great car!

So if you're still in love with your CSL, my advice would be to get it sorted yourself so you shouldn't have the worry going forward. I believe if you do decide to sell it on down the line then the preventative work should make it even easier to find a buyer. Even though BMW in Switzerland won't acknowledge the issue, a lot of buyers probably now do!

[Alx]

It's very annoying when BMW carry on like this Alex. However, don't let it put you off what is a great car!

So if you're still in love with your CSL, my advice would be to get it sorted yourself so you shouldn't have the worry going forward. I believe if you do decide to sell it on down the line then the preventative work should make it even easier to find a buyer. Even though BMW in Switzerland won't acknowledge the issue, a lot of buyers probably now do!

Hi Leins,

Thank you for your kind words.

Not only am I still in love with my CSL, I also find this community great and helpful.

I just don't recognise myself in BMWs nowadays.

They have become poseur machines with ugly designs and emotionless engines. I feel a bit like Alfa Romeo fans in the 80's...

I would also fancy a Ferrari F355 or a Porsche 993 and these issues just make me want to make the move.

Regards,
Alex

[LeinsCSL]

Yep that happens me in the winter too. I've been obsessed with early 3.3 930 Turbos for at least a week now!

[The Gorilla]

Hi,

I was under the impression that the work
relating to the ''design flaw'' was / is being
carried out as act of ''Goodwill'' and that
BMW introduced a self imposed deadline
for their own Good will gesture in this instance.

I would have thought that an act of ''Goodwil''l
is just that, and it comes with no future
liability, either implied or otherwise.
No further Warranty on what is undertaken
as it was not done under Warranty or as a Model recall.

ie ] What you get is what you got.

So until a Court Case ensues whereby its Ruled
that the design is flawed and BMW are responsible
then that is it.
[Very Costly to prove even given the evidence to date]

Hence why I think BMW CH are saying basically
''Fuck Off'' as there is no official Euro Warranty Recall
or Model Recall for E46 Rear Subframe mounts.

The opportunity to bring BMW to the table has
somewhat been missed in that some owners in mainland
Europe should have brought/sent there car[s] to
the UK for repair, which really would have focused
BMW on the matter to hand, especially given
the fact that BMW UK had been sanctioned to
undertake ''goodwill'' repairs on a issue that
other BMW Franchises deny the existance of.

Nothing like European ''Corporate Contridiction'' for
getting the Brussels Quango's all fucked up, even
better when it involves one of the inner circle.

Regards,

The Gorilla.

[AlexGTT]

Just go full weld in cage. Job done.

Shane, I think even with a full cage, long term the problem would still be there.

There's only one solution and as my car doesn't yet have cracks but is beyond the 10 years "goodwill" that seems available from BMW. Having said that, I wouldn't let BMW loose on my car with foam or a replacement floor.

So, I'm going to remove the sub frame, access the bush mounting points, fabricate dowels as Gorilla has mentioned to bridge the floor skins. With welded in dowels, studs fixed and passing though the dowels for bush mounting. A lot of work but I believe the only solution, keeping some sort of originality to the visible floor. Rust prevention will be the concern.

[The Gorilla]

Hi,

AlexGTT- I think you could achieve the
same results with less work.

On a Car that has not suffered any metal
fatigue then a 12.9 HT Bolt that has a fixing
point on the top when bolted up from underneath
[ie welded plate recessed into the boot floor]
would act as the dowel, then an alloy collar
fitted over the bolt that sits into the correct
sized recess in the subframe bush when tightened
up could act as the dowel peg.

The existing boot floor fixing point is 'spot' welded at the bottom
skin and then the metal tube extends upto the upper
skin with another flange, where its spot welded
to the upper skin.

The tube is to accommodate bolt length.

So by continuing the hole thru into the upper boot
floor skin you can weld in a fixing point below the
boot skin and cover with an access plate etc.

Nice thick plate welded at the top would allow the bolt to be fitted
from below as norma,l and then fit a large M12 flange bolt
tightened from the top, with or without access plate [if recessed]


Its basically what Merc did on the 190 etc, but there
access plates on the upper boot skin are tack
welded on, and sealed, more to stop condensation
causing corrosion.

This would give you a HT 12.9 Bolt fixed at top
and bottom with a alloy collar fitted over to
create the dowel/peg for the recess into the
alloy centre of the subframe bush.

Shear factor on a m12 12.9 bolt is way
above any lateral forces or spot loads
that the CSL will ever generate.

Could either make own subframe rear bushes with
shore 90 or 95 poly, [or delrin ?] and then have inserts made
to suit the new dowels/pegs, or if there is enough
meat on the std E46 bush insert, re-drill them and
use them for a little compliance on a Road / Track car.

I spent a long time fucking around under the
E46 CSL rear boot area cut much away and learnt that
BMW basically got it wrong and the design is
flawed regarding rear subframe mounts.

Given that the standard look was lost long ago
I have gone a different route to that above, but its a gamble,
so time will tell if the Primate's thinking outside the
box, is in the pound seats or not as the case may be.
When its finished and works will give the SP
and few pics.

Regards,

The Gorilla.

[Alx]

Hi Gorilla,

That looks interesting.

Any pictures of this modification?

I am quite frustrated at the moment.

I think I'll end up doing the foam injections myself or just selling the car...

[alexk]

Alex dont be so frustrated.

Just drive the bloody thing and enjoy it.
Life is short.

[Alx]

Alex dont be so frustrated.

Just drive the bloody thing and enjoy it.
Life is short.
True... :beer:

[The Gorilla]

Hi,

Alx- I do not have pics of what I am
suggesting only the direction I have
gone, which is far away from stock/std.

There are several ways the rear subframe
/ subframe mounts can be altered, without
taking out the boot floor section which
BMW seemed to favour.

Its the rear mounting points where all the
issues first stem from, as the front [rearsubframe] mounts
are weled into the 'monocouque beam section'
fabricated into the shell.
Its the same section where the seat belts are
fixed to on the strap bottoms etc, and where
BMW welded in massive 'damping plate' for the
diff etc.

I will see if I can take a picture or two,
as the direction I have gone does now allow
better visual of the existing rear subframe mounts
which I am no longer using.

Regards,

The Gorilla

[AlexGTT]

Hi,

AlexGTT- I think you could achieve the
same results with less work.

On a Car that has not suffered any metal
fatigue then a 12.9 HT Bolt that has a fixing
point on the top when bolted up from underneath
[ie welded plate recessed into the boot floor]
would act as the dowel, then an alloy collar
fitted over the bolt that sits into the correct
sized recess in the subframe bush when tightened
up could act as the dowel peg.

The existing boot floor fixing point is 'spot' welded at the bottom
skin and then the metal tube extends upto the upper
skin with another flange, where its spot welded
to the upper skin.

The tube is to accommodate bolt length.

So by continuing the hole thru into the upper boot
floor skin you can weld in a fixing point below the
boot skin and cover with an access plate etc.

Nice thick plate welded at the top would allow the bolt to be fitted
from below as norma,l and then fit a large M12 flange bolt
tightened from the top, with or without access plate [if recessed]


Its basically what Merc did on the 190 etc, but there
access plates on the upper boot skin are tack
welded on, and sealed, more to stop condensation
causing corrosion.

This would give you a HT 12.9 Bolt fixed at top
and bottom with a alloy collar fitted over to
create the dowel/peg for the recess into the
alloy centre of the subframe bush.

Shear factor on a m12 12.9 bolt is way
above any lateral forces or spot loads
that the CSL will ever generate.

Could either make own subframe rear bushes with
shore 90 or 95 poly, [or delrin ?] and then have inserts made
to suit the new dowels/pegs, or if there is enough
meat on the std E46 bush insert, re-drill them and
use them for a little compliance on a Road / Track car.

I spent a long time fucking around under the
E46 CSL rear boot area cut much away and learnt that
BMW basically got it wrong and the design is
flawed regarding rear subframe mounts.

Given that the standard look was lost long ago
I have gone a different route to that above, but its a gamble,
so time will tell if the Primate's thinking outside the
box, is in the pound seats or not as the case may be.
When its finished and works will give the SP
and few pics.

Regards,

The Gorilla.

Thanks Gorilla, I'm liking the sound of that. Anything to make the fix easier! I'll post pics, whatever the solution.

Hi Gorilla,

That looks interesting.

Any pictures of this modification?

I am quite frustrated at the moment.

I think I'll end up doing the foam injections myself or just selling the car...

Alx, don't just throw the foam in. I'm convinced, as others, this is a bad idea.

[Rick H]

I have to admit to not fully understanding the proposed solution - but two things to be aware of are local bearing failure (i.e. tearing of thin steel around the bolt) and block shear failure if the bolt is close to an unstiffened edge (think pages in a ring binder). These two modes of failure should be greater than the shear capacity of the M12 bolt to allow it to reach full capacity. Welded-in bosses will help this - but only locally, they may just transfer the problem elsewhere, it's difficult to judge without seeing a sketch.

[shane@mbtech]

Plate, weld, tie cage in. Should do the trick.

After that I will do probably 3k per year if that. Should suffice for me.

It's funny how some go and some don't. Alex you must have put in a fair few ring laps in yours and lots of trackdays too, but yours is ok. My old Csl was hammered around tracks, it had a track life before I got it, I could tell. But my boot floor was fine.

I like to get going fast and stay going fast.

My theory is it's the traffic light Grand Prix session launches which do the damage. That coupled with poor design obviously.

[Alx]

Alx, don't just throw the foam in. I'm convinced, as others, this is a bad idea.
Thanks for the advice Alex.

Some have said that the foam just postpones the problem, but I don't really know what to believe anymore.

As some suggested, I will just go and drive the car - we only live once! ;)

[The Gorilla]

Hi,

Here are the pics taken which show
the metal tube that is welded in to
the bottom of the boot floor where the
subframe bushes sits against and the
middle section of the 3 sheet layers.

Centre picture shows it the best.

The bolt that aligns with the std subframe tube was my
''guide' bolt for welding on my plates with
dowels as I used the original subframe
bolts as my template for setting up the
way I have now done the rear subframe and
suspension etc.

As I said before its a work in progress and
a radical move away from the std set up,
but the issues reagrding the std subframe
fixings are illuustrated and can be rectified
without ripping out the boot floor even if
the sheet metal has suffered fatigue etc.

The main reason that the metal fatigues
and tears is that the subframe bolt thru the std
bush is only fixed at the bottom of the
tube it screws into, and thus when the
subframe moves around [sawing action]
due to the elongated hole in the bush for
subframe fitting, the sawing action tears
and rips at the bolt fixing which
in turn loads up and splits the surrounding sheet.

If the subframe bolt was also fixed at the top, then
the bolt would be unable to move around
like it does and hence the subframe bush
would do its job correctly, and absorb the
load and lateral forces etc.

As I mentioned by recessing the top skin
and welding in a plate, then fitting a longer
bolt and having a flange nut tightened also
from above the whole tube bolt arrangem,ent
would have to bend [shear] before any deflection
was absorbed into boot floor skin to start the
tears etc.

As you can see I have gone in a totally different
direction and now have all four subframe bushes
with 'dowels' which fit inside the subframe bush
inserts, M12 HT bolts with clamps across the
bushes, and then hold it all in place.

Ripping out the boot floor skins is counter productive
as its not the floor skins which are the issue, its
the design of the mounts and how the subframe
bolts fix a flat bush without dowel.

The foam is really a nonsense, in that its not
the floor skin sheet metal that is the issue.

Regards,

The Gorilla.

[Alx]

That's very interesting!

Thank you for taking your time to explain and to take the pictures.

[Rick H]

Hi again - bending and shear are two different failures - shear is a slicing action of two parallel planes (scissor blades shear paper) whereas bending is caused by eccentricity of the load from fixity (diving board) resulting in a tension tear/compression ripple in the bolt - assuming it is held fast enough to allow generation of full fixity that it. You dont want ANY bending on an M12 bolt (f=m/z - and z is tiny cos all the material's in the middle of the cross-section), any bending will crucify the bolt - even worse for a fully-threaded bolt (thread right to underside of head). Combined shear and tension is about 1.45 unity from memory.

There is double shear (two shear planes on the bolt) - if that can be generated up to full capacity that may help - the bolt would need to be fixed both sides of the component to generate that.

Again, I can't tell from the pics how the bolt will be loaded so the above may not be relevant.

[The Gorilla]

Hi,

Yes, Bending and Shear are two different
load / Stress factors, but the 'bolt head' that holds
the subframe to its fixing point is approx 60mm
down from where the bolt is secured [depth of subframe bush]

The original bolt is not held at the top but only
by a threaded section in the tube just above the
surface of the lower skin where the bush/subframe is clamped
up to.

Hence when the subframe starts moving around [vibration initially]
via lateral forces due to the elongation in the
bush alloy insert, this then side ways motion is what is
causing the bolt/fixing to start tearing via a pivoting pendulum
motion at the sheet metal, which over time induces the
stress cracks.

Hence, one force shear, when transmitted via
the pivoting penduliam actions of the bolt is then causing
tear, ie the sheet fatigue.

If the main subframe fixing Bolts were fixed at the top also
and the bolt had a alloy over tube acting as the dowel, then the
shear load on its own is unable move the bolt which is then
not only secured in two places, top and bottom, to prevent
pivotal pendulum type movement but it also has a much
larger surface of clamp which also assist in deflecting load
forces via the alloy spacer around the bolt, being absorbed
correctly into the bush.

The combnation of these additional factors would
mean that the M12 H/T bolt is then performing in
true shear loads only, and any load deflection would
then be loaded into the alloy 'dowel' and absorbed
by the bush as it was originally designed to do.

Its almost be almost identical to what Mercedes did on the
190 rear subframe and while many Merc 190 rear
subframe bushes have been replaced [proves it works well]
I have never herad of or seen a Merc 190 subframe ripping
out its subframe chassis mounts or cause any metal
fatigue or tears other than age corrosion.

Regards,

The Gorilla.

[AlexGTT]

Plate, weld, tie cage in. Should do the trick.

After that I will do probably 3k per year if that. Should suffice for me.

It's funny how some go and some don't. Alex you must have put in a fair few ring laps in yours and lots of trackdays too, but yours is ok. My old Csl was hammered around tracks, it had a track life before I got it, I could tell. But my boot floor was fine.

I like to get going fast and stay going fast.

My theory is it's the traffic light Grand Prix session launches which do the damage. That coupled with poor design obviously.

Shane, it does appear to be totally random. Mine has done upwards of 15 trips to Ring and average 5-6 TD's a year since I've owned it. With me it's gone from mid 20k miles to high 70k. No cracks and it's constantly inspected.

Thanks for the advice Alex.

Some have said that the foam just postpones the problem, but I don't really know what to believe anymore.

As some suggested, I will just go and drive the car - we only live once! ;)

That's the spirit Alx. :smokin:

Thanks Gorilla, good pics.

[NZ_M3]

Personally I feel the official epoxy fix is sound. It has been used in the past by OEM manufacturers for frame strengthening (Ford, Audi to name a few), in addition it was an official fix for F3 for suspension pickup points. The product is designed specifically just for this purpose (cavity filling, bonding of two plane surfaces and structural strengthening for increased crash rating).

I have the epoxy injected in my car as a preventative (no cracks) and I can tell you for a fact that the difference in rigidity was immediate and noticeable post epoxy.

Even if it isn't a full fix it doesn't bother me ... nothing lasts forever. Plus so long as you don't do the front points you can still put a cage in with subframe pick up (so when mine cracks I'll either cage it or part it out).

The epoxy used has the following technical specs for those more technically minded:


Compressive strength: 15–20 MPa
E-Modulus: 700
±50 MPa

Poisson’s ratio: 0,22–0,26
Volume change: 0–30 % (depending on the curing conditions/volume/geometry)
Water absorption: < 0,5 % weight gain
Test conditions: 24 hours at 98 % humidity and 40
°C

In service temperature rang -40
°C to 90°C

Short exposure (up to 1h): 110°C


And if you are in further doubt about the epoxy ... consider this. We have a factory E46 320i WTCC car here locally that was raced extensively (and did many sprint and 6 hour endurance races regularly). The floor finally gave up (and believe it or not only when the car was in NZ not when it raced in Germany) as the cage in those never tied the rear subframe into the roll cage ... a new floor was welded in and the official epoxy injected. It still races today and as far as I am aware the new floor is sound with no cracks.

As for talks about moisture and rust from the epoxy ... seriously learn a bit of chemistry people. If that was the case then expect all our carbon roof ridges to all rust to nothingness soon - the roof is bonded to bare metal with guess what ... Epoxy!!!

[The Gorilla]

Hi,

Quote[ ''As for talks about moisture and rust from the epoxy ... seriously learn a bit of chemistry people. If that was the case then expect all our carbon roof ridges to all rust to nothingness soon - the roof is bonded to bare metal with guess what ... Epoxy!!!

The steel lip that the roof is bonded to is not only
painted but it has been sprayed with hot galv prior to paint.

Further when the roof is bonded there is
no void between the steel lip and the carbon
edge, hence no moisture can form via condensation.

That is why the factory Carbon roofs have 4 large fixing bolts
that are tightened after the resin is applied to the
lip, so as the pull the roof down evenly and remove any
voids, and also as a secondary fixing.

If you have ever taken one off then you would know this,
its not a bare unpainted lip as you suggest, its exactly
the same paint process as the rest of the A/B/C pillars
and shell for that fact..

However if you belive that an external resin injection
into a void that does not fully seal up that void [boot floor skins] and
has been previously welded will not cause condensation
on the inner sections which will cause roost then you've
not seen inside many chassis sections.

Its nothing to do with chemistry, its the plan fact that your
unable to correctly treat welded surfaces inside voids
such as chassis or multi layer skin areas.

Regards,

The Gorilla.

[NZ_M3]

The steel lip that the roof is bonded to is not only
painted but it has been sprayed with hot galv prior to paint.

Further when the roof is bonded there is
no void between the steel lip and the carbon
edge, hence no moisture can form via condensation.

The surface is in primer I know, but it isn't anything special - but there are tiny little spacers bonded on the bottom of the carbon roof to space the roof correctly for the epoxy to cure and bond at its optimal engineering strength thickness - but you'd know that if you've taken one off before.


That is why the factory Carbon roofs have 4 large fixing bolts
that are tightened after the resin is applied to the
lip, so as the pull the roof down evenly and remove any
voids, and also as a secondary fixing.

If you've seen one you'd know that the factory roof jig has 4 suction cups to hold the carbon roof skin and "six" clamping points (2 on front windscreen and 2 on rear and one on each side) - not sure where you are getting the fixing bolts from. Your roof must be special.


However if you belive that an external resin injection
into a void that does not fully seal up that void [boot floor skins] and
has been previously welded will not cause condensation
on the inner sections which will cause roost then you've
not seen inside many chassis sections.

Right and an unrepaired M3 CSL that lives in good old UK and used during winter has no rust on it at all .... please give me a break ... all cars made during that period by BMW will rust regardless of the treatment. I've seen plenty of UK imported low mileage CSLs (and E46s) to know you live in fairy land where no rust will ever form on BMW cars.

You'd also know that the two rear mounting points has sufficient access points from both the bottom and top for rust proofing to the applied after welding. (I concur much harder with the front points - hence why no epoxy is recommended to be injected in those areas)

I will however concede that when you weld plates to such thin gauge sheet metal, you've sufficiently changed the property of it that no matter how many layers of sealant or primer you slap on there it'll rust eventually.

I however don't agree that the epoxy somehow accelerates that process any quicker or how a car without any repair welds but with just epoxy injection will now rust faster than a car without the epoxy injection.

[JBird]

I also stand by the epoxy fill as the most sensible solution. I've seen profesional FEM studies and crash tests done on dual skin B pillars with and without structural foam bridging the skins. The epoxy structure was nothing short of amazing, and retained adhesion, keeping the skins at an even gap from one and other as the structure was loaded to failure. The OEM in question ended up using this to get 5 star NCAP rating in side impact. (it was some time ago, when this was a big deal to have). This gives me confidence that the epoxy injection in out floors will remain strongly bonded for the life of the car, genlty distrubuting all those axial and sheer lug loads evenly into the two skins over a much larger area than any mechanical bolt / dowel solution ever will.

My only concern is corrosion, but only from the point of view that we have to rely on a BMW bodyshop taking due car in sealing all bare metal from welds etc adequatly, which as Tom said, is in theory possible. If they havn't, well that sux but there is a lifetime warranty on workmanship.

[monkeycsl]

I can't think where I saw the thread but someone I think in America was using a bonding non weld technique to fix reinforced plates to boot floor so no issue with rust on inner skin of cavity.
This seems a very good idea as these epoxy glue chemical weld systems are really strong,what do you think guys.