Intrax suspension failure

[TANKSLAPPER]

At the Ring last weekend and my mates intrax rear suspension failed

http://i213.photobucket.com/albums/cc311/IAIN830/IPhone2002.jpg

[Jeff]

Intrax are the ones that use coils on struts at the rear unlike the standard setup which has the springs separate correct?

This therefore doesn't surprise me given the tower isn't necessarily designed for the extra load - as it would have only been designed to hold a shock, not the cars full weight.

My 2 cents. I think others had mentioned their concern over this previously?

[thegingerninja]

These failures are quite common - they can only be used if a full weld-in cage has been fitted to the rear top monuts to take the extra loadings. You have to stick with the seprate spring and damper unit if you want to stay standard. Imagine if it had completely pushed through while mid cornering - major shunt!
Iain - was it Nathans?

[David1972]

It seems like the suspension did not fail, but the top mounting fork punched through the sheet metal of the car. So the car failed :thumbs:not the suspension. I would weld a small strenghtening plate in the car. Or go back to the original spring position. But then you loose the advantages of the coilover system.

[TANKSLAPPER]

Iain - was it Nathans?



Yes, NathanCSL

[TANKSLAPPER]

It seems like the suspension did not fail, but the top mounting fork punched through the sheet metal of the car. So the car failed :thumbs:not the suspension. I would weld a small strenghtening plate in the car. Or go back to the original spring position. But then you loose the advantages of the coilover system.

What, either way you look at it, He walked home LOL

Original position is best with the lower springs taking the load onto the chassis.

Like "thegingerninja" said you need a fully weld cage with strengthening on the turrets for intrax

[NZ_M3]

It seems like the suspension did not fail, but the top mounting fork punched through the sheet metal of the car. So the car failed :thumbs:not the suspension. I would weld a small strenghtening plate in the car. Or go back to the original spring position. But then you loose the advantages of the coilover system.

Actually looks to me that the rear top mount have failed and it's punched through the the sheet metal on the top mount and the rear shock carrier - so it's the suspension that's failed not the car - how can you fail something that wasn't designed to carried such a load in the first place? That's like driving your car into water and saying the car failed.

I've said many times ... those Intrax should not be used without a roll cage - a full rear coilover setup on these cars are just plain stupid without a roll cage or related structural inhancement.

[s.mac]

a full rear coilover setup on these cars are just plain stupid without a roll cage or related structural inhancement.

What make/set up should be looked at then ?

[Thorney]

Whilst its not right to say I told you so it does validate an opinion we have mentioned (and been criticised for) over an over again. Glad to hear he was OK. The chassis was not designed for a rear coil over, period.

We have designed this to address the issue should people not want to go for a full cage (the only alernative if you want to run rear coil overs)

http://www.thorneymotorsport.co.uk/products/images/_MG_0668.jpg

You cant see from this picture but the brace/harness bar has a top plate that fits over the suspension tower and the suspension bolts to it directly. The lower portion bots directly to the chassis floor.

[Thorney]

What make/set up should be looked at then ?

three options:

1. Fit a full cage
2. Fit a rear tower support (as pictured)
3. Run rear spring and strut

We run rear spring and strut on the CSL Cup cars and not much get near them in terms of handling, we run KW 2 way or 3 way race.

[NZ_M3]

Thorney ... may I suggest that perhaps you can come up with a bolt in solution to help prevent the rear subframe mount tear (if that's at all possible) - I think you'll sell thousands of them :hahaha: especially to the Yanks across the pond.

[thegingerninja]

Look at the photo again and read his post - it is a bolt in brace!

[NZ_M3]

Look at the photo again and read his post - it is a bolt in brace!

Read my reply again - I am refering to the rear diff subframe mount not the rear shock mount - 2 different weaknesses in the E46 chassis.

[Thorney]

All of our cages had diff mounts integral as well. Whilst I've heard of numerous suspension tower failures with coil overs I've not heard of any diff mount problems unless you run slicks where the extra lateral grip causes the issue.

[NZ_M3]

All of our cages had diff mounts integral as well. Whilst I've heard of numerous suspension tower failures with coil overs I've not heard of any diff mount problems unless you run slicks where the extra lateral grip causes the issue.

http://www.cslregister.com/forum/showthread.php?t=1543&highlight=subframe

[Thorney]

AH, missed that. Heard of the US ones but was told that was primarily earlier cars and a US issue only (or certainly not as common in Europe for some reason?). Not seen a failure of that kind here yet and we get a few ring, track cars here.

[thegingerninja]

Read my reply again - I am refering to the rear diff subframe mount not the rear shock mount - 2 different weaknesses in the E46 chassis.

Apologies - I'll get my coat...........

[Nords]

Whilst its not right to say I told you so it does validate an opinion we have mentioned (and been criticised for) over an over again. Glad to hear he was OK. The chassis was not designed for a rear coil over, period.

We have designed this to address the issue should people not want to go for a full cage (the only alernative if you want to run rear coil overs)

http://www.thorneymotorsport.co.uk/products/images/_MG_0668.jpg

You cant see from this picture but the brace/harness bar has a top plate that fits over the suspension tower and the suspension bolts to it directly. The lower portion bots directly to the chassis floor.

John, how much and does it need the boot carpet cut about?

Also, roughly how much labour (cost) to take the Intrax off and refit the std stuff?

Cheers...

[Thorney]

We can cut the bootlining so its in flaps so one removed they flap back into place.

About an hour to remove, 2 hours to fit new and 2 hours geo, so all up around £400 or so?

[shimmy]

We can cut the bootlining so its in flaps so one removed they flap back into place.

About an hour to remove, 2 hours to fit new and 2 hours geo, so all up around £400 or so?

John

Does the KW Clubsport need the same thing?

[Ade]

Whilst its not right to say I told you so it does validate an opinion we have mentioned (and been criticised for) over an over again. Glad to hear he was OK. The chassis was not designed for a rear coil over, period.

We have designed this to address the issue should people not want to go for a full cage (the only alernative if you want to run rear coil overs)

http://www.thorneymotorsport.co.uk/products/images/_MG_0668.jpg

You cant see from this picture but the brace/harness bar has a top plate that fits over the suspension tower and the suspension bolts to it directly. The lower portion bots directly to the chassis floor.

John,
I'm sure you've looked into this, but bolting the suspension onto the brace/harness bar then assumes the harness bar top plate was designed to be fully load bearing with the car's weight+ in mind? Excuse me if I'm asking the bleeding obvious!

ps, any chance of those bolts you asked Adam to send over? :beer:

[glendog74]

John

Does the KW Clubsport need the same thing?

I'd be interested to know too.

[Thorney]

No, KW run seperate spring and strut on the back. Even the race suspension runs separate spring and strut.

[Thorney]

John,
I'm sure you've looked into this, but bolting the suspension onto the brace/harness bar then assumes the harness bar top plate was designed to be fully load bearing with the car's weight+ in mind? Excuse me if I'm asking the bleeding obvious!

ps, any chance of those bolts you asked Adam to send over? :beer:


Bleeding obvious.......but bleeding sensible. :)

Yes, the issue is that the chassis is not contructed to take the kind of stress that struts generate, so the bar is designed to strengthen both the supporting area (the top mount itself) via a 5mm thick steel plate that fits around the top of the mount. The suspension then bolts to this plate. However as well as this we use the same system as with cage design, ie you make sure that all areas of the chassis are supported along a minimum of two axixs. With the rear bar we tie in the boot floor to the suspesnion tower to ensure the tower 'shares' its stress along a wider area.

[azrael]

From the picture it looks like you can use this to connect harnesses to also :)

[Nords]

Cheers John, roger on the £400 to swap back to std. How much for the rear suspension 'strut brace' and how much to fit?

[Thorney]

From the picture it looks like you can use this to connect harnesses to also :)

Yep, that was the point. Create something with multi purpose.

[Thorney]

Cheers John, roger on the £400 to swap back to std. How much for the rear suspension 'strut brace' and how much to fit?

We've got 5 in stock. Fitting is about 2 hours (plus harness, another hour say). The bars themselves are £670 complete kit.

[Nords]

Lordy, was planning to swap the Intrax off and get it serviced, see what std suspension is like and then decide whether to stay std and sell the Intrax or refit with that rear bar. I'm wary of the Intrax and the pressure put on the top mounts; that rear bar seems ideal.

Time to start saving I suppose! I have some Shroth (sp?) harnesses already but std CSL seats soooooo a bit arse really!

[Thorney]

We can put a deal together if you like. Issue is that stock CSL seats cant be used with harness's (no cut outs). But we've done a couple of deals:

rear harness/suspension support bar
Schroth harness
Recaro Profi SPG seat (single or pair)

£2k for one seat, £2800 for pair.

You'll get at least £2500 for the standard seats on ebay, we did.

This issue with the rear suspension failing the chassis is that whilst its repairable (and easy to hide, if you're that way inclined) it does mean the chassis warranty has gone.

[The Gorilla]

Hi,

Having read this thread I can't believe that
anybody is running rear coilovers and are not using
the Z3 Rear Turret stiffeners.

They cost about 22.00 pounds for the pair,
and are available from the dealer.

Strange how guys running 600.00 Gaz or Leda
suspension on their E30's use them, yet guys
running CSL's with 2k plus of Intrax do not make
the small Investment.

Even stranger that the suspension selling dealer does not even
recommend them in the first place, and yet knows all
about suspension, most strange.

A cage only resolves the problem if fitted
with top plates, which most of the E46 ones
I have ever seen welded in do not, they are
more often welded to the side of the rear turret
for cross bracing and stiffness.

The coilovers punch through, due to the
suspension drop slowly weaking the metal as the
all the force it taken by the nuts on top
during drop, which after time stresses the
shell metal to the point, that once fatigued,
then on rebound, they will eventually punch
through.

Regards,

The Gorilla.

[shimmy]

2 x Z3 Reinforcement Plates (Part Number 51-71-8-413-35) ???

[kbird]

What is the part number please?

[kbird]

Hi,

Having read this thread I can't believe that
anybody is running rear coilovers and are not using
the Z3 Rear Turret stiffeners.

They cost about 22.00 pounds for the pair,
and are available from the dealer.

Strange how guys running 600.00 Gaz or Leda
suspension on their E30's use them, yet guys
running CSL's with 2k plus of Intrax do not make
the small Investment.

Even stranger that the suspension selling dealer does not even
recommend them in the first place, and yet knows all
about suspension, most strange.

A cage only resolves the problem if fitted
with top plates, which most of the E46 ones
I have ever seen welded in do not, they are
more often welded to the side of the rear turret
for cross bracing and stiffness.

The coilovers punch through, due to the
suspension drop slowly weaking the metal as the
all the force it taken by the nuts on top
during drop, which after time stresses the
shell metal to the point, that once fatigued,
then on rebound, they will eventually punch
through.

Regards,

The Gorilla.

Is this the part number 33 52 1 137 972?

[shimmy]

http://home.comcast.net/~matthew.c.smith/mods/rear_shock_mount/index.htm

found this!

[azrael]

http://home.comcast.net/~matthew.c.smith/mods/rear_shock_mount/index.htm

found this!

Sounds like these are a must! if only a minimum

[kbird]

http://home.comcast.net/~matthew.c.smith/mods/rear_shock_mount/index.htm

found this!

Nice work Shimmy!! Parts ordered, here on Tuesday so I can get them fitted for my Ring/Spa trip this weekend! Cheers

[glendog74]

http://www.turnermotorsport.com/html/subcategory_detail.asp?modelcode=E46&subcat_id=96

http://www.rogueengineering.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=RSM&Category_Code

[azrael]

So whats the general concensus on this then. I've got intrax and turner bush limiter kit. Seems to be a few different options with plates...?

[The Gorilla]

Hi,

A good rear strut brace will also do the same
job as the Z3 reinforcement Rings.

The rear Intrax coilovers on my car are on Hangers,
which are used to run shorter rear springs.

Cage is welded to the side of the turrets, although
if I has specified it, I would have picked up the
rear turret top mount and spread the point load out
away, into the shell and the cage.

Shorter rear spring for Track work is better, although much
harsher and skittish on the road though.

E30 M3 DTM 92 cars ran hangers as well on the rears
for a shorter rear spring, so its not a new idea.


Regards,

The Gorilla.

[kbird]

So whats the general concensus on this then. I've got intrax and turner bush limiter kit. Seems to be a few different options with plates...?

I have fitted the plates as a precaution, have you asked Anthony/Julian what they think?

[NZ_M3]

In my opinion the Z3 reinforcement plates will do bugger all - you are not spreading the load to other parts of the chassis, merely sandwiching the weak ass top shock steel - the failures are in the whole shock tower, not just the mounting points.

[Thorney]

I have to say I agree, the top plates will help for sure and it maybe enough (failures are relatively rare) but BMW state the entire suspension tower must be supported or at least tied into the chassis floor to properly 'fix' the issue, that why we did a lot more on the harness bar (it would be dead easy just to run a bar from one side to the other and knock em out for £150).

[The Gorilla]

Hi,

NZ_M3- Interesting statement you make.

I have never seen a rear BMW Turret damaged
with them fitted but have seen plenty of damaged
ones without them.

Regards,

The Gorilla.

[shane@mbtech]

Hi,

NZ_M3- Interesting statement you make.

I have never seen a rear BMW Turret damaged
with them fitted but have seen plenty of damaged
ones without them.

Regards,

The Gorilla.

Serious question, are you really a gorilla?;)

I think it will certainly help with the problem as where the shock comes through will no longer split.

Was this splitting the only fault with rear coilovers?

Although im only running front coilovers it will be interesting to know for future reference.

Thanks

[The Gorilla]

Hi,

Lawsy- accordingly yes, or so I am told.

The Rear Turret problem as previously explained in
not caused by 'bump' its caused by the 'drop'.

In the drop, the weight of force of the rear suspension
dropping, that's the complete, wheel, hub, brake/disc, trailing arm,
wishbones, and coilover is all transmitted to the two nuts
that hold the rear top mount in place.

This situation is increased when running shorter suspension
than say stock where you encounter rear wheel lift.

By inserting the Z3 Plates, or a rear strut bar, you push
the load across a larger flat surface rather than the the two
small point loads, of the original two nuts.

By spreading the down force load, instead of creating a
load point, the shell metal does not fatigue.

If not running a front strut bar, you should also really run
large custome washers plates in steel or alloy on the front struts
under the top mount locating nuts, as they, to a lesser degree
are incurring the same downward forces.

On bump, the top mount itself from underneath speads
the load across the turret top.

It also helps in spreading load across the turret top into the shell as
opposed creating a small load point.

Better chassis dynamics and so on.

Regards,

The 'Real' Gorilla.

[azrael]

I have fitted the plates as a precaution, have you asked Anthony/Julian what they think?

I've ordered the plates as a precaution too, car going back next week to have the suspension re fettled now its settled

[shimmy]

Fitted mine last week

[Nords]

As mine spends much of it's time on the road, I'm going to swap back to std suspension, have the Intrax serviced and brought up to the new spec (if reqd) and then make a decision about staying on std or refitting.

If I do, then those plates or a Thorney set of bars will be going in...

[NZ_M3]

By inserting the Z3 Plates, or a rear strut bar, you push
the load across a larger flat surface rather than the the two
small point loads, of the original two nuts.


Sorry but I disagree.

The Z3 plate is smaller than the actual top mount flat surface, all it does is sandwich something inherently weak with a smaller mount surface - it doesn't affect or change the strength of the surface you are sandwiching (not when it is actually smaller).

The load is first taken up by the Rear shock rubber mount - that mount spreads the load to the whole shock tower which is inherently weak to take a full coilover in the first place.

I am not saying that it will or won't necessarily develop the failure with the Z3 plate. All I am saying is if you are relying on it as a "fix" ... then you are placing way too much faith in it.

You need to properly spread the load to use a full coilover on these cars - period - just look at the ALMS M3 GTRs - that's exactly what they have done.

If you don't believe, go grab a piece of tissue and place two pieces of cardboard on either side that is slightly smaller but in about the same shape as the tissue paper - put a bolt through it and pull hard - I bet you the tissue paper will still tear - it does nothing to add strength to the inherently weak part. Now try the same experiment but this time spread the load completely - you'll get a different result.

[The Gorilla]

Hi,

NZ_M3- I am no engineer but with the greatest
of respect, I think you have missed the issue.

If it takes 'x' amount of force for a nut to be forced
through a sheet of metal, then by adding a washer
with a far greater diameter than the nut, it will require
a force far greater than 'x' to force the nut through.

The point load had been spread.

The issue is created by load forces down not up.

Regards,

The Gorilla.

[Nords]

http://www.turnermotorsport.com/html/subcategory_detail.asp?modelcode=E46&subcat_id=96

http://www.rogueengineering.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=RSM&Category_Code

Did we decide what the best idea was? The rogue ones look very much like Z3 items however the Turner ones look a little more bespoke?

[shimmy]

I have fitted the z3 ones myself and easy to do

[kbird]

+1

[Dino]

Bit of a thread resurrection but I've recently bought a 3-way Intrax coilover kit for my e36 M3 and stumbled upon this thread when looking for info on the Intrax.

The Z3 plates have been used by the e36 boys for years and I was somewhat suprised that e46 owners hadn't cottoned on to this before '09!

As an aside - John (Thorney) do you make any rear brace kits like that for e36 M3s?

[Thorney]

Ys, we do do an E36 version, looks similar but not got any shots of it sorry.

[funtime]

What a horrible thread to look at for an Intrax owner :bigcry::hahaha:

[AlexGTT]

What a horrible thread to look at for an Intrax owner :bigcry::hahaha:

Not really. You don't know what abuse those cars have seen to cause that type of failure. It's a rare failure.

[funtime]

Not really. You don't know what abuse those cars have seen to cause that type of failure. It's a rare failure.

True! - hopefully 5 up + 1 in the boot and blasting over all the curbs and speedbumps :hahaha:

[AlexGTT]

True! - hopefully 5 up + 1 in the boot and blasting over all the curbs and speedbumps :hahaha:

Like when Shimmy got air over the railway lines in yours?:whistle:;)

Now you opened yourself up for that one!:thumbs::hahaha:

[funtime]

Like when Shimmy got air over the railway lines in yours?:whistle:;)

Now you opened yourself up for that one!:thumbs::hahaha:

fookers :birdman::hahaha: