cracked subframe

[Malcolm D]

Hi, been a member for a few years but tend to view and not post. However could do with any help/advice. Car is with Chandlers at present for service etc and they have identified a small crack on each side of the subframe. I have the BMW Insured warranty but they will not approve the repair or make a contribution based on age of vehicle, seem pretty adamant about it as well. Car has full BMW service history etc.

I seem to remember seeing post about a number of cars where this repair was covered, but i'm guessing its all moved on and is no longer covered?

Thanks in advance for any help.

[Malcolm D]

Hi, Just been reading the thread of Calcifer, think I have my answer!

[Calcifer]

Sorry to hear that, it's a shame they won't cover a design flaw.

[MisterCorn]

If car manufacturers started covering design flaws for ever and a day they would all be out of business by now. Hope it doesn't cost you too much to get it sorted out.

MC

[shawn 968cs]

I had the same, makes the warranty a bit useless when you are paying the full amount like me.
I must adjust my policy the main mechanicals / drivetrain only

[Calcifer]

If car manufacturers started covering design flaws for ever and a day they would all be out of business by now. Hope it doesn't cost you too much to get it sorted out.

MC

Such as?

Having owned a number of cars. I haven't experienced a major failure as this in the CSL EXCEPT for in my M Coupe. Also BMW!

If a car has been under dealer servicing and upkeep and everything was carried out on schedule by way of maintenance then surely something significant as this ought to be rectified by them.

[JBird]

Yep, as mentioned in the other thread, 10 yr goodwill has unfortunatly come to an end.

Got me wondering if the BMW Insured Warranty that many people have might cover it (I guess it wasn't really a consideration till now as the goodwill was available). The comprehensive policy wording says it covers all "mechanical and electrical" exept for ... [long exclusion list]. In the exlusion list "bodywork" is mentioned.

Personally I would not call an integral part of the chassis like the floorpan in question, "bodywork". Bodywork to me is fenders, bumpers etc. (As an engineer, I would argue the chassis just a large part of the suspension!) So it is a bit grey. The policy clearly covers driveline, and the mounting of the rear driveline to the chassis is the cause of the issue. Conclusion, grey as hell.

If you can't get them to cover it, must you repair it yourself to pass the MOT?

[select]

First of all, you guys in the UK should be happy that you have the option to have a bmw warranty for an car as old as the CSL. In germany they offeryou nothing. Except if you buy a used car from them.. but then its only 2 years and not transferable, so pretty much different story.



If you can't get them to cover it, must you repair it yourself to pass the MOT?


I'd venture and say its definitely a MOT failure.. if its spotted. The issue is, it won't be spotted from the MOT guy unless the whole boot floor is coming apart already.

[JBird]

I should add that I was reading an actual print version of policy book from 2008. It lists bodywork as exception idem that is not covered. The BMW Insured Warranty website actually does not.

[Malcolm D]

Yep, as mentioned in the other thread, 10 yr goodwill has unfortunatly come to an end.

Got me wondering if the BMW Insured Warranty that many people have might cover it (I guess it wasn't really a consideration till now as the goodwill was available). The comprehensive policy wording says it covers all "mechanical and electrical" exept for ... [long exclusion list]. In the exlusion list "bodywork" is mentioned.

Personally I would not call an integral part of the chassis like the floorpan in question, "bodywork". Bodywork to me is fenders, bumpers etc. (As an engineer, I would argue the chassis just a large part of the suspension!) So it is a bit grey. The policy clearly covers driveline, and the mounting of the rear driveline to the chassis is the cause of the issue. Conclusion, grey as hell.

If you can't get them to cover it, must you repair it yourself to pass the MOT? Yep that's correct, ironically its BMW who have failed it for MOT, so they knew what to look for. But BMW Insured Warranty wont entertain it, not even a contribution towards repair. Just waiting on quote to see how much!

[estoril]

You're better off with a 3rd party repair anyway as all BMW did was replace the cracked floor with another one and fill part of the void (not all of it) with resin. 2nd failures have been seen but are rare, also, the resin is flammable so another repair then becomes far more difficult. 3rd party repair with strengthening plates is (IMO) far better in the long run.

[MisterCorn]

Such as?

Having owned a number of cars. I haven't experienced a major failure as this in the CSL EXCEPT for in my M Coupe. Also BMW!

If a car has been under dealer servicing and upkeep and everything was carried out on schedule by way of maintenance then surely something significant as this ought to be rectified by them.

How about bore scoring and IMS bearing failure in the Porsche M96 engine, Big end bearings wearing out in short order and throttle actuator failures in the V8 M3 engines, EGR issues on Range Rover diesels. These are just off the top of my head, I'm sure there are countless others. All affecting cars under 10 years old, all potentially very expensive, not covered by the manufacturer.

MC

[Chad]

You're better off with a 3rd party repair anyway as all BMW did was replace the cracked floor with another one and fill part of the void (not all of it) with resin. 2nd failures have been seen but are rare, also, the resin is flammable so another repair then becomes far more difficult. 3rd party repair with strengthening plates is (IMO) far better in the long run.

Yes definitely do fail again after a new floor panel,as our other csl did as stated on another post, but to be Fair to BMW it's a fair size panel that's replaced inc other panels where required, I personally saw work that was done, practically take rear end out of car, not just a couple of lines of weld and a couple of plates, saying this second repair done by BMW on this car was only welded, will have to wait to see how that pans out. :whistle:

[GregorFuk]

Get your car to Redish, they will fix it once and for all.

[Malcolm D]

Get your car to Redish, they will fix it once and for all.
Redish are not taking any bookings as they are fully booked out till November:hahaha:

[Chad]

Redish are not taking any bookings as they are fully booked out till November:hahaha:

Personally I don't see how a couple of plates welded over already damaged/cracked subframe panel,can be better than a full new thicker floor panel, personally trust BMW technology over a couple of aftermarket plates welded in, But anything is better than subframe dropping off.:thumbs:

[JBird]

I agree. Reddish seem like a good bunch, but welding plates over the top is bit mickey mouse. If the BMW resin injection is done to a high standard it should give a softer load distrubution and be better in theory. There is a reason why it is 2-3x more expensive than the plate method (other than usual BMW rip off rates).

[estoril]

I agree. Reddish seem like a good bunch, but welding plates over the top is bit mickey mouse. If the BMW resin injection is done to a high standard it should give a softer load distrubution and be better in theory. There is a reason why it is 2-3x more expensive than the plate method (other than usual BMW rip off rates).

The resin is done as well as the plates, or at least it was in my case, and across the entire floor. BMW only do the resin on the weak side unless you push them to do both.

[JBird]

BMW only do the resin on the weak side unless you push them to do both.

You got me worried for a second, but looks like they did both.

[select]

When i had mine done by a shop who specializes in this repair (pretty much like redish) they advised the following. They also have patented their plates so im guessing they know their stuff.

Mine had a small crack on the right hand side which "they all have" they welded the plates on and they advised to replace the subframe bushings with stiffer ones, because according to them, the rear axle transfers the force onto the subframe but the rubber bushings designed to damp the force is too soft which allows the subframe to flex which it wasn't built for and therefore starts to crack.

FYI that is the same that BMW did on the e92 M3 GTS, the used solid subframe bushings instead of rubber ones. And the M4 doesn't have subframe bushings at all, as far as i know.

[Gazza]

How do you check for these cracks/where to look ?

[select]

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

[Chad]

https://www.youtube.com/watch?v=HaTYBaMpUtE. I'd be embarrassed to call that my undercarriage, needs a bloody gud scrub ,mother would be ashamed.:gayfight:

[GregorFuk]

Personally I don't see how a couple of plates welded over already damaged/cracked subframe panel,can be better than a full new thicker floor panel, personally trust BMW technology over a couple of aftermarket plates welded in, But anything is better than subframe dropping off.:thumbs:

Redish drill stop any cracks, weld them up and then install their strengthing plates. Once they have done that they inject the BMW resin. It's a proper job.

There is nothing 'new, improved or thicker' about the panel BMW weld in when they do a full repair. It's the exact same pressing. There is a thread on here that has pictures which shows no difference.

[Jon8710]

How about bore scoring and IMS bearing failure in the Porsche M96 engine, Big end bearings wearing out in short order and throttle actuator failures in the V8 M3 engines, EGR issues on Range Rover diesels. These are just off the top of my head, I'm sure there are countless others. All affecting cars under 10 years old, all potentially very expensive, not covered by the manufacturer.

MC

I've got a 996 C4S and a CSL so im proper F**ked !!!!

[Gazza]

How do you check for these cracks/where to look ?


Thanks for the video, hopefully mine is ok as it had a check-up at Elms just before I bought it.

[MisterCorn]

I've got a 996 C4S and a CSL so im proper F**ked !!!!

I have a 996 C2, CSL and a Range Rover, I like living on the edge :bigcry:

MC

[Monkey]

Thanks for the video, hopefully mine is ok as it had a check-up at Elms just before I bought it.

If you're ever down Brighton way just pop into see me and I'll check it free or charge for you:thumbs:

[Gazza]

If you're ever down Brighton way just pop into see me and I'll check it free or charge for you:thumbs:


Thanks for that :thumbs:

[nigt3]

It amazing me that some people think the BMW repair is a better option than welding in plates and stop drilling the cracks. BMW put the same Sh1te back in that broke in the 1st place, and as what's happening in the op's case in should just about last 10years so they don't really give a sh1t after that!! Also some of the people who work at BMW main dealers I would'nt let work on my kids push bike never mind a csl.
OP take it to Redish or there's others who can fix it properly (there's more options than just plates)

[Trawler]

It amazing me that some people think the BMW repair is a better option than welding in plates and stop drilling the cracks. BMW put the same Sh1te back in that broke in the 1st place, and as what's happening in the op's case in should just about last 10years so they don't really give a sh1t after that!! Also some of the people who work at BMW main dealers I would'nt let work on my kids push bike never mind a csl.
OP take it to Redish or there's others who can fix it properly (there's more options than just plates)

If I remember correctly NZ_M3 a few years back posted a good write up why plates do not work. The foam injection was also discussed.

[Chad]

Personally with high expectations regarding service histories etc on the Csl, buyers would expect repairs to be done buy BMW, any other repairs could possibly knock valves, But nothing wrong with useing polyfilla :thumbs:

[GregorFuk]

Personally with high expectations regarding service histories etc on the Csl, buyers would expect repairs to be done buy BMW, any other repairs could possibly knock valves, But nothing wrong with useing polyfilla :thumbs:

Great to have faith in BMW.

[Mike R]

It amazing me that some people think the BMW repair is a better option than welding in plates and stop drilling the cracks. BMW put the same Sh1te back in that broke in the 1st place, and as what's happening in the op's case in should just about last 10years so they don't really give a sh1t after that!! Also some of the people who work at BMW main dealers I would'nt let work on my kids push bike never mind a csl.
OP take it to Redish or there's others who can fix it properly (there's more options than just plates)

The BMW repair IS better than the welding of plates (IF the injection of the resin isn't carried out as well)....

If you look at any repair that has been done with just plates and you understood why it cracked in the first place, you would also understand why just welding plates on is even more of a disaster than the original problem....

[Chad]

Great to have faith in BMW.

BMW are good for somethings. If csl wasn't what it is ,and just a £7k e46 m3 I'd have no problems with tin foil and polyfilla repair, as I do 99 percent of my own maintenance anyway :thumbs:

[GregorFuk]

BMW are good for somethings. If csl wasn't what it is ,and just a £7k e46 m3 I'd have no problems with tin foil and polyfilla repair, as I do 99 percent of my own maintenance anyway :thumbs:


A little harsh

https://youtu.be/09mqQRcAPds

[select]

The BMW repair IS better than the welding of plates (IF the injection of the resin isn't carried out as well)....

If you look at any repair that has been done with just plates and you understood why it cracked in the first place, you would also understand why just welding plates on is even more of a disaster than the original problem....

How come? As said earlier, BMW just replaces the cracked subframe with a new one while the issue remains. Its a fact that new cracks developed after BMW replaced the subframe. On the other hand i have not seen one subframe fail after its been reinforced with good plates and got uprated bushings.

I would like to hear your opinion on what you think is the issue, why the subframe cracks.

[Chad]

For a bit of fun let's put it to a vote. BMW new floor pan. Verses welding plates. My vote goes to BMW fix. But I'm not against welding plates for cheaper fix. :thumbs:

[select]

My Point is, a new floor pan from BMW is no fix at all.

[Trawler]

If anyone is interested

http://www.cslregister.com/forum/showthread.php?t=11573&highlight=Coke&page=4

[select]

Yes, thats exactly what happens if you stay with stock bushings.

To use his analogy.

Using the BMW repair = Simply Replacing the coke can with a new one., it just delays the "cracking process" which will inevitably happen.

The point is, to drill and weld the cracks that are there and they will be on nearly all csl with 60.000 miles. Even 316i have this problem, so its not only affecting cars which are driven hard. And reinforce the structure with the plates, whichs point is, to distribute the induced load via a bigger area. But the key thing is, to replace the squishy stock bushings with delrin or even solid ones, to stop the load from even ocurring. Like BMW did with from factory with M3 GTS and F8X M4.

See this video of an Camaro, which has the same issues.
https://www.youtube.com/watch?v=6yOz--DIuIc

[Mike R]

My Point is, a new floor pan from BMW is no fix at all.

YES IT IS. BMW don't just replace the floor plan, do your research :blalalala:.

If you JUST weld plates to the "coke can" floor plan (as you have pointed out) - it WILL just crack around the welds of the plates and rip out the ENTIRE floor section around the plates :bigcry:.

The BMW repair replaces the entire floor section with a new item, but the key part to their repair is to fill the void with a special resin that links the two floor parts together to create a honey-comb effect (which makes the boot floor and sub frame mount much stronger than the sum of their parts - in the same way it does for composite sheets).

The main problem is the holes for the subframe bolts are just too big and allow a yawing motion that causes the cracks. Spoon actually do some "Rigid Collars" for the E46 M3 that effectively plug the holes and allow the precise location of the bolts which will prevent the yawing motion. I don't really understand why more people haven't fitted these.

Here is a video that shows them on another car, but the principle is the same :) :
https://www.youtube.com/watch?v=zWyUD6UXfog

I would hasten to add that MOST legitimate repairers understand this and weld the plates in conjunction with the resin injection. If they do NOT, then walk away!

[select]

I know they inject foam too. Funny enough they didnt until they were faced with lawsuits they started to inject foam.

Still its a Bandaid.. as it doesnt fix the issue. It merely strengthens the chassis to be able to withstand it. For what amount of time? Nobody knows, i decided for myself that i didnt want my csl to be a testbed for BMW, so i used what is proven to fix the issue.

Regarding the rigid collars i think i have read about that solution in the past.
But its not very widespread this.

[MisterCorn]

Yes, thats exactly what happens if you stay with stock bushings.

To use his analogy.

Using the BMW repair = Simply Replacing the coke can with a new one., it just delays the "cracking process" which will inevitably happen.

The point is, to drill and weld the cracks that are there and they will be on nearly all csl with 60.000 miles. Even 316i have this problem, so its not only affecting cars which are driven hard. And reinforce the structure with the plates, whichs point is, to distribute the induced load via a bigger area. But the key thing is, to replace the squishy stock bushings with delrin or even solid ones, to stop the load from even ocurring. Like BMW did with from factory with M3 GTS and F8X M4.

See this video of an Camaro, which has the same issues.
https://www.youtube.com/watch?v=6yOz--DIuIc

I would have assumed that the bolts provided a clamping force, and that the subframe was held in place by this force. Is this suggesting that there is actual yaw movement on the subframe when it is mounted in the car? Seems unlikely to me. I have read about these for the NSX but the word from those that know was that they were not needed and that the hole sizes were like they are for production tolerances.

MC

[Mike R]

I know they inject foam too. Funny enough they didnt until they were faced with lawsuits they started to inject foam.

Still its a Bandaid.. as it doesnt fix the issue. It merely strengthens the chassis to be able to withstand it. For what amount of time? Nobody knows, i decided for myself that i didnt want my csl to be a testbed for BMW, so i used what is proven to fix the issue.

Regarding the rigid collars i think i have read about that solution in the past.
But its not very widespread this.

The correct permanent fix would be the BMW repair and the installation of the Rigid Collars.

Welding of plates will NOT fix the issue any more than doing just the BMW repair, it is the exact same band-aid. The yawing motion of the bolts (more prevalent in SMG equipped cars due to the shockloading the automated gear changes in the faster modes transfer to the diff and hence the subframe mounts) is the issue and so you have to remove this. Obviously anything else that helps lesson this movement is going to increase the amount of time it takes to re-occur, but not prevent it (so still a band-aid).

[MisterCorn]

Unless somebody can provide evidence that a correctly torque subframe bolt is not stopping the subframe from moving, and that the subframe is held in place by the bolts being effectively used as dowels rather than clamps then I'm afraid I'm calling bullsh!t on the collars.

MC

[select]

Welding of plates will NOT fix the issue any more than doing just the BMW repair, it is the exact same band-aid.

Could you please stop suggesting that i ever said that plates only will fix it? I didn't, i said plates are for restrengthening the chassis, incase its been cracked, to former levels and the real fix to the issue are the solid bushings.


The yawing motion of the bolts (more prevalent in SMG equipped cars due to the shockloading the automated gear changes in the faster modes transfer to the diff and hence the subframe mounts) is the issue and so you have to remove this.

If you believe that some magical foam is able to stop any force induced by the brutal transmission shifts into the chassis, that is fine. I do not, or better said.. i don't trust that it will withstand this over time. Its a gamble... and if it fails its game over, because you will never get the foam out and any welding with the foam in place on the subframe is a serious fire hazard.


Obviously anything else that helps lesson this movement is going to increase the amount of time it takes to re-occur, but not prevent it (so still a band-aid).

Yes, but that is exactly what solid subframe bushings do. They tie the rear axle carrier to the subframe.. so there is ZERO movement. Thats the definition of solid.

Just look at what BMW did for the E92 M3. It has rubber subframe bushings from factory, just like the E46 M3. What have they done on the GTS? They used solid bushings.


@MisterCorn I don't know if the stock bushings allow YAW(Vertical) movement of the carrier but i don't think so. But its not the big problem for the subframe, its the lateral movement that the sheet metal can't handle.


Unless somebody can provide evidence that a correctly torque subframe bolt is not stopping the subframe from moving, and that the subframe is held in place by the bolts being effectively used as dowels rather than clamps then I'm afraid I'm calling bullsh!t on the collars.

I think thats the big question mark on these things, and probably the reason they are not very commonly known.

[Mike R]

Unless somebody can provide evidence that a correctly torque subframe bolt is not stopping the subframe from moving, and that the subframe is held in place by the bolts being effectively used as dowels rather than clamps then I'm afraid I'm calling bullsh!t on the collars.

MC

The subframe isn't moving, but because the bolt has so much tolerance, it allows the subframe and floor-pan to flex as one piece.

This yawing motion causes the cracking. By joining the two pieces together and fitting the collars, you eliminate the ability of the floor to flex.

Tom did a great analogy with a Coke can. Drink the contents and then drill a hole through it and stick a bolt through the hole and then try moving it, you will see how badly it flexes the two separate pieces (that's our standard floor pan :bigcry:). Now fill the can with resin and try the experiment - it makes it much more rigid and less prone to flex - that's the BMW repair.

Do the same with just a washer either side and see what happens (that is the equivalent of just welding plates on without the resin). All it does is move the fracture point from around the hole to around the washer (plates).

Fitting more rigid bushes isn't going to stop the (E46) floor-pan from flexing...

[MisterCorn]

I understand the coke can analogy, it is the collars which I can't see how they fit in to the equation. Whether the collars are in place or not, when the subframe is bolted on to the car there is no relative movement between the subframe and the chassis, the clamping forces of the bots see to this. I can see that the collars would allow a more precise initial alignment of the subframe on the chassis by taking out the slop in the holes, but once it is clamped together I can't see how it has any impact at all. Sure the chassis around the mounting can and does flex, but I can't see any way in which the collars would affect this.

For the coke can analogy would it not be like drilling a more snug hole in the can so that the bolt can be fitted more accurately in the first place?

I really feel like I am fundamentally missing the point of what the collars are supposed to do here, I'm not being deliberately thick, honest!!

MC

[Alx]

Another question would be:

Has any subframe cracked after the foam injections? (Even if it was still the standard subframe)

[Mike R]

I understand the coke can analogy, it is the collars which I can't see how they fit in to the equation. Whether the collars are in place or not, when the subframe is bolted on to the car there is no relative movement between the subframe and the chassis, the clamping forces of the bots see to this. I can see that the collars would allow a more precise initial alignment of the subframe on the chassis by taking out the slop in the holes, but once it is clamped together I can't see how it has any impact at all. Sure the chassis around the mounting can and does flex, but I can't see any way in which the collars would affect this.

For the coke can analogy would it not be like drilling a more snug hole in the can so that the bolt can be fitted more accurately in the first place?

I really feel like I am fundamentally missing the point of what the collars are supposed to do here, I'm not being deliberately thick, honest!!

MC

I just feel the collars do a belt and braces job. I have them on my S2000 and noticed an immediate improvement, so will be fitting them to the CSL as well.

I just think the elimination of any movement in this area is going to improve things and off the improvements that are stated in the above clip regarding geometry.

At the end of the day it is your car, but for the sake of £200 fitted, it seems a bit of a no-brainer to me (even if it only gives the geometry improvements) :).

[select]

@Alx
Yes, unfortunately m3forum.net is currently offline, else i could give you the link.


Fitting more rigid bushes isn't going to stop the (E46) floor-pan from flexing...

I am sure you can back up your claims? Every E46 that races in VLN uses plates and solid bushings. And they never had any issues again, despite hammering the car for 24h on the Nordschleife.

Mike, why did you chose to largely ignore my post?

[Mike R]

Another question would be:

Has any subframe cracked after the foam injections? (Even if it was still the standard subframe)

Given that the original cracks took 10 years (one week before the warranty expired) and 50k miles to manifest themselves (on my car), I would guess that we have to wait even longer (as this is "supposed" to be a fix) before we know if it is truly the cure BMW state it is.

Come back to this thread in another 12 years time to see :bigcry::blalalala:;)

[Alx]

:hahaha:Given that the original cracks took 10 years (one week before the warranty expired) and 50k miles to manifest themselves (on my car), I would guess that we have to wait even longer (as this is "supposed" to be a fix) before we know if it is truly the cure BMW state it is.

Come back to this thread in another 12 years time to see :bigcry::blalalala:;)

[Mike R]

@Alx
Yes, unfortunately m3forum.net is currently offline, else i could give you the link.


I am sure you can back up your claims? Every E46 that races in VLN uses plates and solid bushings. And they never had any issues again, despite hammering the car for 24h on the Nordschleife.

Mike, why did you chose to largely ignore my post?

They are not road cars, they have fully welded cages that greatly change the strength of the car (subframe is often bolted into the cage in the boot) and they also don't do the big miles that road cars do. In addition, very few are SMG (which seem to be the worst suffers of subframe failure).

I personally think that a lot of this cumulative damage occurs in the lower gears (when you feel the diff thump in S6 going from 1st to 2nd and 2nd to 3rd). Race cars don't do this very often either, once they are away from the line the lower gears are used infrequently.

Like I said, it's your car, you do what you like :blalalala:.

[select]

Given that the original cracks took 10 years (one week before the warranty expired) and 50k miles to manifest themselves (on my car):bigcry::blalalala:;)

In case of CSLs.. you might have to wait another 12 years. But luckily there are regular E46's which get driven alot more.

First time BMW acknowledged that there is an issue with the subframe was in 2004. Click me. (https://translate.google.de/translate?sl=de&tl=en&js=y&prev=_t&hl=de&ie=UTF-8&u=http%3A%2F%2Fwww.auto-motor-und-sport.de%2Fnews%2Fbmw-probleme-mit-der-hinterachse-688441.html&edit-text=)

And that is in Germany, where Manufacturers only acknowledge faults if they have to. I.E. the federal car agency is pushing them to start working on a fix or else they will force them to a recall.

[select]

Mike, surely its my car i can do what i like. But when someone asks for advice and you are spreading false claims, i feel the urge to voice my opinion.

If you have cracks then get them drilled and welded up and reinforce the structure with plates. Also replace bushings with stiffer ones, preferably solids. Thats exactly what BMW did on the E92 GTS and F8X M3/M4.
They didnt choose to inject foam...:whistle:

You can also inject the foam if you feel the need to, and that is the big plus.. you can always go back and foam it. But vice versa? Good Luck.
However there is no need for the foam once you've done the above.



Contrary to what mike said, there are documented examples that only doing the Foam Injection isn't enough. Thats a fact.



Every E46 thats used as trackcar/racecar on the Nürburgring and elsewhere (and that not only includes professional teams with a full cage) uses plates & solid bushings. Without any issue, since years.



Be aware of the fact that any welding on the rear of your car will be difficult if not impossible with the foam injected. Because it will melt and catch fire.



I think everybody now can make himself an opinion on the matter. I however will rest my case.

[Mike R]

Mike, surely its my car i can do what i like. But when someone asks for advice and you are spreading false claims, i feel the urge to voice my opinion.

If you have cracks then get them drilled and welded up and reinforce the structure with plates. Also replace bushings with stiffer ones, preferably solids. Thats exactly what BMW did on the E92 GTS and F8X M3/M4.
They didnt choose to inject foam...:whistle:

You can also inject the foam if you feel the need to, and that is the big plus.. you can always go back and foam it. But vice versa? Good Luck.
However there is no need for the foam once you've done the above.



Contrary to what mike said, there are documented examples that only doing the Foam Injection isn't enough. Thats a fact.



Every E46 thats used as trackcar/racecar on the Nürburgring and elsewhere (and that not only includes professional teams with a full cage) uses plates & solid bushings. Without any issue, since years.



Be aware of the fact that any welding on the rear of your car will be difficult if not impossible with the foam injected. Because it will melt and catch fire.



I think everybody now can make himself an opinion on the matter. I however will rest my case.


You can't compare the floor plan of a different car which has obviously had changes made based on the issues they had with the earlier model :clown:.

Or are you trying to say that following the millions BMW had to pay out on the issues with the E46, they decided to use the exact same design for subsequent models :bigcry: :blalalala: :hahaha: ?

Just reinforcing the sub-frame structure with plates is NOT a cure for the E46, hence why I am pulling you up on it. You only have to search Google for images of people in the USA who have done JUST that, to see the catastophic damage that then does to the floor pan, where the plates and all are ripped from the floor pan. There is little point in welding something of greater thickness to something that is paper thin (an exaggeration, but you get the point), you just move the failure point further out.

Obviously the best solution would be a much stronger floor plan (which was done on subsequent models). However, that isn't financially viable on an out-going model, so BMW came up with a "best fix" that will (hopefully) last a lot longer than the original arrangement. From an engineering and design point of view, it is certainly several times stronger than welding plates to an already weak structure :whistle:.

Which is why all of the (well known) companies in the UK do the welding of the plates in CONJUNCTION with the resin injection, it's just a cheaper way of doing the same repair without having to unpick all the spot welds and completely replace the floor plan with a new item (which is what BMW do).

[Chad]

Another question would be:

Has any subframe cracked after the foam injections? (Even if it was still the standard subframe) yes my lad csl did. But then so did his cylinder head, then so did his engine, so on and so on, BMW then refused to fit another new floor, just welded it , but then he does rag the thing to death ,all good fun that's what they were made for ,:thumbs: ps from memory first boot we had done on his car was about 2010,

[JBird]

I don't buy the talk of solid bushings for a second. Ill try to explain why:

First of all terminology. Subframes do not crack, boot floor skins do. Below is a picture of the E46 rear end.

The OEM subframe bushings are there to isolate/soften/dampen the subframe movement/loads. Subframe loads are arise from road reaction forces & movements which pass through the tires, into the rim, into the upright, along suspension arms, into the (small & quite hard) suspension arm bushings, into the subframe, into the (large & soft) subframe bushings, then finally from the aluminum bushing core into the boot floor via the central bushing bolt/pin). Additional subframe loads arise from the diff/driveline - torque, likely to be higher in an SMG equipped car such as the CSL.

You can not avoid suspension & driveline loads, so you must 1) reduce peak load with a bushing, 2) ensure the floor is strong & rigid enough to dissipate the bushing pin load (on a road car, BMW foam resin injection).

By installing solid bushes, you will amplify the peak load that the boot floor sees, by, thumb in the wind, about 3x. Solid Bushes make sense for a track car with proper braced mounting points - e.g., M3 GTR or e46 track slag modified in a similar way, where a stiff, almost rigid rear end is wanted, and thing like a cage and bracing are viable.

Regarding plates VS OEM repair, we can probably argue all day long if 'Plates + Drilled cracks + Foam Injection' is as good as 'BMW new Floor + Foam Injection'. Probably if done properly they will be similar in how long they hold. Certaily, plates with no foam injection makes zero sense.

Personally, I think the plates are a mess, and there is that much welding involved the chance of a bad weld that causes a stress raisers and eventual cracking at the edge of the plates is high.

I would lean out the window and say a properly carried out BMW repair foam injection repair with OEM bushings will not crack again. All depends how well it is done.

[s1csl]

Hope you get it sorted Malcom, as said there are a few options open to you but if you go for the plates I would stay away from the resin, Regards

[Malcolm D]

Hope you get it sorted Malcom, as said there are a few options open to you but if you go for the plates I would stay away from the resin, Regards
Hi John, I've viewed all the comments generated on here (thanks everyone) and think its safe to say there is not one right or wrong way of dealing with it. So, trying to strike a balance of best route versus costs. Somewhat disappointed with the response or lack of it from BMW UK Customer Services who have not even bothered to call me back, but guess that's the way it is sometimes!

[Chad]

Would be interesting to know how many uk csl boot floors have failed, and then repaired by BMW goodwill, Both our cars were done on goodwill, from memory repairs were done when cars had covered 50k miles " approx " so that's Two. Any body else ???

[estoril]

They refused to do mine about 2.5 years ago despite proving that the fault existed 5 years prior to that (the car had been stored for 5 years).

[Chad]

They refused to do mine about 2.5 years ago despite proving that the fault existed 5 years prior to that (the car had been stored for 5 years).

Looks like if you rag um, they crack. if you put them in storage they crack, or if you use them like a old get like me,they crack. But if you have no service history like me or extended warranty bmw will fix them for free. :blalalala: I would imagine BMW are glad to see the back of um

[JBird]

Would be interesting to know how many uk csl boot floors have failed, and then repaired by BMW goodwill, Both our cars were done on goodwill, from memory repairs were done when cars had covered 50k miles " approx " so that's Two. Any body else ???

There was a poll on another thread somehere - back in the period when most cars were getting close to 10yrs and this was a hot topic.

[Chad]

There was a poll on another thread somehere - back in the period when most cars were getting close to 10yrs and this was a hot topic.

Must have a read back , But I guess it's just as relevant now as ever, as there are over 20 csl's up for sale at the moment, many claiming to be low mileage at crazy money , possibly never needed to have been repaired , possibly an higher mileage car with repairs already done , could be a better buy if your not in it for investment,and it's a car you have always wanted, and actually want to use :thumbs:

[Brendanmck]

A year ago I decided to refurbish the rear underside of my car as it had started to look a bit sorry. So as the rear subframe was coming down anyway I decided that I was going to fit the reddish plates whether my racp was cracked or not. Turned out when we cleaned it all up we found one small crack starting to appear at the front right mounting location also a few spot welds were showing signs they were parting again the left side inner arch was showing a slight part in the seam also. So it was in better condition than you could be led to believe. Basically you really need to drop the subframe out clean the whole area up access The condition then decided your course of action. You really don't need to spend a fortune fixing this issue my whole fix came to about £3000 but that included
1. The complete fitting of the reddish plates all the welding of the affected areas all rust removal then por15 .seam sealer etch primer and painting
2.all rear parts blasted and powder coated. We hand painted the diff housing and drive shafts
3.replaced rear brake lines and all the carriers for them and fuel lines.
4.replaced diff/trailing arms/subframe bushes with power flex items
5.new hubs brake shields and rear shocks including top mounts
6.new hand brake shoes and cables .
7.all fluids(diff/brakes) and gaskets.
End result was excellent and money well spent.

[Alx]

I also asked some questions about this some time ago:
http://www.cslregister.com/forum/showthread.php?t=11428

[0-60Motorsports]

Reddish can sort this out for you and also get the vince bar. Check on m3forums for his contact.

[CSLSEM3]

Reddish can sort this out for you and also get the vince bar. Check on m3forums for his contact.

http://www.m3forum.net/m3forum/showthread.php?t=582641

[Alx]

Reddish can sort this out for you and also get the vince bar. Check on m3forums for his contact.
The Vice bar seems an interesting option.

Would it need to be done with reinforcing plates? And resin as well?

Also how much does it cost and were do you buy it?

Does Redish provide it as well?

Kind regards,
Alex

[JamesR]

The Vice bar seems an interesting option.

Would it need to be done with reinforcing plates? And resin as well?

Also how much does it cost and were do you buy it?

Does Redish provide it as well?

Kind regards,
Alex

Hi Alx,

We (Redish) can help you with this if needed.

If going for the VinceBar, it's also worth improving the structural mounting points (under the car) of the Rear Axle Carrier Panel.

I'm not sure of the exact price of the VinceBar as it's an American product but he's on m3forum.net, as Ejaz just mentioned.

Over the past 6 years repairing E46 RACP's we've completed 8x CSL's (and approx 140x standard M3's).

The other thing to look out for is the internal cavity mount spotweld and cracks which are becoming more common.
These are even harder to diagnose, and go on to repair, than the underside of the RACPanel as they are hidden in cavities only accessible inside the car.
Check out this 49k 2004 M3 from last week:

https://youtu.be/5DkWHgtMlIc

If you need any help or have any questions just let us know and we'll be more than happy to help.

Best regards,
James Redish

[Alx]

Hi Alx,

We (Redish) can help you with this if needed.

If going for the VinceBar, it's also worth improving the structural mounting points (under the car) of the Rear Axle Carrier Panel.

I'm not sure of the exact price of the VinceBar as it's an American product but he's on m3forum.net, as Ejaz just mentioned.

Over the past 6 years repairing E46 RACP's we've completed 8x CSL's (and approx 140x standard M3's).

The other thing to look out for is the internal cavity mount spotweld and cracks which are becoming more common.
These are even harder to diagnose, and go on to repair, than the underside of the RACPanel as they are hidden in cavities only accessible inside the car.
Check out this 49k 2004 M3 from last week:

https://youtu.be/5DkWHgtMlIc

If you need any help or have any questions just let us know and we'll be more than happy to help.

Best regards,
James Redish

Thank you for your advice, James.

As I said before, if you were not this far from Switzerland, I would already have taken my CSL to Redish.

Maybe we will find a solution in the future? ;-)

My independent mechanic is quite familiar with the CSLs and he regularly checks the car.

His advice is to reinforce it, but only once the cracks appear.

Very few cars seem to suffer from this here apparently. Maybe this is due to the roads or to the fact that we are too far from the racetracks...

I will keep following this thread with great interest.

Kind regards,
Alex

[Alx]

Interesting read:

https://drivetribe.com/p/Pl7K58qaTcOyY3cDgHPu-Q?iid=BhwtPI6xQmCiMZQjWh-Sdg

[select]

@Alex
Plates + Stiffer Bushings is everything you need. Forget the vincebar, its way over the top and intrusive. I personally wouldn't consider buying any car with such an invasive install done.
I would die a little inside if i knew that a CSL was ruined with this. :bigcry:

If you are thinking about going to these lengths, at this point just get a half cage tied to the struts installed.

Thanks to James Redish for dropping by, i think we all can learn alot from you in this department. :thumbs:

[Monkey]

I have to admite that Vicebar looks way ott. Each to their own I guess, but as Select said its incredibly invasive.

Alx, If your car does not currently have a crack you may consider injecting the resin as a preventative measure.

[Alx]

I have to admite that Vicebar looks way ott. Each to their own I guess, but as Select said its incredibly invasive.

Alx, If your car does not currently have a crack you may consider injecting the resin as a preventative measure.

I considered the resin, bit I didn't find anyone in my area that does it.

BMW says that they don't do it anymore.

I also read that it makes it difficult to weld afterwards as the resin is inflammable.

[Chad]

I considered the resin, bit I didn't find anyone in my area that does it.

BMW says that they don't do it anymore.

I also read that it makes it difficult to weld afterwards as the resin is inflammable.
My sons had his welded up by BMW with the resin in, BMW wouldn't redo the full panel again, foc :whistle: Will have to see how this pans out.

[select]

BMW says that they don't do it anymore.


Interesting..did you ask what is their way to resolve the issue? Im guessing they would just replace the Bootfloor for the thousandth time? I might just ask my dealer what they advise, just out of curiousity.


I also read that it makes it difficult to weld afterwards as the resin is inflammable.

Yes, that is correct it will melt and eventually catch fire. I'll have a look, as far as i know BMW released a bulletin regarding that concern.

[Alx]

Interesting..did you ask what is their way to resolve the issue? Im guessing they would just replace the Bootfloor for the thousandth time? I might just ask my dealer what they advise, just out of curiousity.


I guess they would wait for it to break and then replace the entire floor.

The local BMW garage is not very keen on "old" BMWs.

They are too busy working on the Active Tourers...

[CSLSEM3]

I'd be happy to help any cslregister folks with parts from the left side of the pond if needed.

MJ