Z4M Frame issue... If you track your car look at this thread

[ga41]

http://www.zpost.com/forums/showthread.php?p=9962413

Guys, you might want to have a look at this thread.

So I went to the track on saturday and did about 4 sessions. During my third session I am chasing down this EVOIII with a 11,000rpm built motor. I hear this pop and think "oh no the motor mount bolts have broke again." I pull into the pits have a look over the motor and see that the motor mount is still perfectly in place. Do a quick visual inspection and can't find anything wrong so I head back out. The car no seems to have a touch more over steer then normal. I just chalk it up to the rear tires getting to hot. I normally like a happy rear end so oversteer is nothing new but I still have a slight knocking soundevery once in a while. Car is running fine so I don't think much of it.

Fast forward to last night and I am taking apart the front end the car to remount my front splitter. I notice one of the brackets to the sway bar sagging a bit. Perfect...I just found the knocking sound that I heard yesterday! I go grab a 13mm socket to tighten it up but when I go to tigthen it I notice the the bolt is moving with the bracket and not only that but the entire bar is movining too! Below are pictures of what I found. Both the passenger side studs in the frame that you bolt the sway bar brackets to have ripped right out of the frame! One of the drivers side studs is 90% out and the other has a bad crack around it. Great so this totally ruins my 3rd of July night! I don't know how I am going to fix this yet. As you can see from the pic of the sway bar the studs don't have much surface aream. I am thinking I will just have a shop weld a steal plate to the bottom of the bracket but I gotta talk to some race shops to see if that will work.

Alot of BMW's as of late are having frame issues. The Z8, Z3's, e46s and now the Z4M. I know I do push my car harder then most people but I didn't suspect this being a weak point. If you track you car you should inspect the sway bar frame mounts for cracks so it doesn't get to the point I am at.

 

[mmm-five]

I bet if you take your car back to BMW with a fault like that, they'd realise you'd been tracking it hard and void any warranty you have on EVERY component.

When I was tracking my M5, I was wearing out components at 3-5 times the rate of guys who drove hard but only on the road.

 

[ga41]

Not the point of my post though, it's just something that people who really push their cars should check out every now and then.

 

[Beedub]

ga41 i definatly see what your doing so we can check, i must be of note to you all this guy had insane spring rates, tracked the car heavily and also had beefed up ARBs combine that with a massive 9.5"front wheel and sticky tyres and you have the problem above.....
Its simply overstressed the anchor points and this could and can happen to any modded platform, im on stock suspension but do use the car properly so will keep and eye on these points, i do however feel we have nothing to worry about, ga41 definatly a worthwhile post....

 

[mmm-five]

Not the point of my post though, it's just something that people who really push their cars should check out every now and then.

I understood the point, and was simply trying to support the fact that track use will require more regular checks on the vehicle.

 

[alfamale]

Have a strong plate made of about 5mm with captive nuts welded on the back, you might have to make the holes bigger in the chassis to let the captive nut fit through
It's good practice to drill out the end of the cracks to stop them spreading and give the rest of the torn metal edge a good clean up to remove stress raiser areas. Once it's prepped bolt the plate to the ARB and offer it up to the chassis, make sure it's all in the correct place and tack it to the chassis
Remove the ARB and fully weld, should be good for whatever you throw at it after that.

 

[playalistic]

First thing I would have guessed is he had slick tyres and beefed up ARBs...

 

[ChawenHalo]

ga41 i definatly see what your doing so we can check, i must be of note to you all this guy had insane spring rates, tracked the car heavily and also had beefed up ARBs combine that with a massive 9.5"front wheel and sticky tyres and you have the problem above.....
Its simply overstressed the anchor points and this could and can happen to any modded platform, im on stock suspension but do use the car properly so will keep and eye on these points, i do however feel we have nothing to worry about, ga41 definatly a worthwhile post....

I remember a post about attaching strut braces badly. Does that have anything to do with it? Its just that I was considering those from ACS.

GA41. Thanks for letting us know,preventive medecine the way to go.

 

[ga41]

Not the point of my post though, it's just something that people who really push their cars should check out every now and then.

I understood the point, and was simply trying to support the fact that track use will require more regular checks on the vehicle.

Agreed

I know members here might not have modified their cars to the point of that ZPost member but stuff like that is good to be made known for future reference.

 

[ga41]

ga41 i definatly see what your doing so we can check, i must be of note to you all this guy had insane spring rates, tracked the car heavily and also had beefed up ARBs combine that with a massive 9.5"front wheel and sticky tyres and you have the problem above.....
Its simply overstressed the anchor points and this could and can happen to any modded platform, im on stock suspension but do use the car properly so will keep and eye on these points, i do however feel we have nothing to worry about, ga41 definatly a worthwhile post....

I remember a post about attaching strut braces badly. Does that have anything to do with it? Its just that I was considering those from ACS.

GA41. Thanks for letting us know,preventive medecine the way to go.

The latest posts in that thread mention that reinforcement kits are already available to beef up certain stress points.

 

[ChawenHalo]

Goes to show that if tracking a lot you should get your car prepped by a serious specialist as opposed to DIY unless you really know what you're doing (and we all think its so simple...)