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Discussion Starter · #1 ·
I finally had a chance to type up this post....

Prior to Super Lap Battle I revamped my car so that it can be 100% for the competition. On the list was to revise front aero, rebuild/Balance Motons, and most importantly repair/reinforce my subframe + bushings.

I got a care package from TMS which included, monoball bushings for the control arm, solid subframe and diff bushings. I quickly went to work and tore the car apart, I dropped the complete rear end to find a pretty severely cracked subframe.

My subframe has been cracked for about a year now and I've been keeping a close eye on it, however it is more severe than I had expected since I could only see a small portion of the crack I wasn't expecting it to be as bad as it is.

Seeing that my car is a 95% track car I wanted to really reinforce the factory subframe, I made custom subframe mounting plates that are a little thicker than ones that you can get on the market. Upon removal of the chassis undercoating we found very light hairline cracks on the crease of the chassis as well as each mounting point on the rear subframe mounts. From there we welded all the cracks and extra welds around the mounting points to prevent further failure later down the line. We also drilled extra holes in the reinforcement plates around the mounting points to spot weld for more penetration between the plate and the chassis.

In between welding/cooling periods we were installing all the bushings we received from TMS. Pressing the subframe bushings in/out was quite a pain, however we shoved all the bushings into the freezer which helped but 1/2 way through you can see the bushing heat up and it would get more and more difficult as you get to the end.

I also did other top secret mods but that info will be released later on. :shifty:

On completion of everything the car felt awesome! I swear the car actually rides better than it did w/ the oem bushings. It could be a combination of the custom work I did along with the monoball bushings for the control arm, the monoball bushing would give the rear spring a more consistent spring rate since it removes the flex from the inner bushing.

Photos:

Cracks!!!



Starting the repair/extra welds



After repair/extra welds



Thicker plates, extra spot welds to the chassis from the reinforcement plate



TMS Goodies



TMS Subframe bushings installed



TMS Monoball bushings



TMS Diff bushings
 

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Discussion Starter · #3 ·

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What symptoms did you notice with the subframe cracks when driving the car hard?
 

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Discussion Starter · #7 ·
What symptoms did you notice with the subframe cracks when driving the car hard?
There aren't really symptoms that you can feel, its more of popping/creaking noises from the crack metal when the chassis flexs. Majority of the time its when you go in/out of driveways at an angle.
 

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Great thread, still seems crappy that the BMW sub-frame program had such an early end date....Did you even try for a BMW fix?
 

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My SF is cracked too.. nowhere near that bad.. i wont be going this car but i will be installing the TMS re-enforcement kit..kinda worried once the rear end is out the cracks will be worse.. but either way its fixable.. i cant feel or hear the affects of the cracked subframe.. so im hoping for the best.

OP, my car is my DD is there any need to buy anymore then the re-enforcement kit? bushings anything like that..
 

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There aren't really symptoms that you can feel, its more of popping/creaking noises from the crack metal when the chassis flexs. Majority of the time its when you go in/out of driveways at an angle.
So even when driving hard you wouldn't notice any difference in handling? The car still drives stable and predictable?
 

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Discussion Starter · #13 ·
My SF is cracked too.. nowhere near that bad.. i wont be going this car but i will be installing the TMS re-enforcement kit..kinda worried once the rear end is out the cracks will be worse.. but either way its fixable.. i cant feel or hear the affects of the cracked subframe.. so im hoping for the best.

OP, my car is my DD is there any need to buy anymore then the re-enforcement kit? bushings anything like that..
I would put in new OEM bushings at the least since the subframe is already out of the car.

So even when driving hard you wouldn't notice any difference in handling? The car still drives stable and predictable?
Not really, but with the fresh subframe/bushings the car does feel amazing now though.
 
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