How important are subframe reinforcements?

[zellamay]

I didn't mess with fender liners. I don't remember any reason to do that. I used the scissor jack to help with handling the subframe. I didn't disconnect any brake lines.

[325bob]

I've been axing my coupe for 40k and haven't seen any weld problems yet, very aggressive driving with big ,275/295 stickies on the back?, I did do a kluge fix on my subframe mounts years back, just screwed some big lag screws into the rubber mounts, eliminating the flex that may cause the problems being seen.I've been racing Bimmers for 25 yrs., I only seem to hurt motor/tranny mounts, and my clutch is going at 130 K, still fine for daily use, but slips in 2nd at full chat.
.

[Tigershark48]

Would it be possible for you to show a picture of your lag bolt reinforcement?

Thanks.

[Badger56]

The R.F. kit or equivalent (if there is one) is the way to go. Solve the real problem, not just the symptoms.

[325bob]

Would it be possible for you to show a picture of your lag bolt reinforcement?

Thanks.

I'm not to techie savvy, but you would just see the heads of the bolts seated on the bushings, not pretty or expensive, but very easy and fast, another kluge method is to drill out the rubber and fill area with JB-Weld,I also filled the support rubber in my csb with silicone to lessen strain on it.

[bionicbelly]

My coupe had 155k when I wrecked it. I had the car since 90k. I installed poly rsfb's as soon as I got the car. Ran countless autocrosses (>90), and ~40 track days/time trials with it. Not a single popped spotweld, and the diff mount was fine. Some cars need it, some don't. Keep an eye on it, if you start to see issues, get it done ASAP. If you don't, have fun! (poly RSFB's highly recommended)

[Tigershark48]

Bionic,

That’s a good testimonial. Which brand poly rsfb did you use?

[bionicbelly]

Started with powerflex, then went to condor speedshop's delrin. Powerflex is good for the street/auto-x/track days. No extra noise, smooth ride, etc. Once you bolt on the Hoosiers though, you can feel the poly squishing around, and delrin is what you need.

[Randy Forbes]

I didn't always work off a lift.

Most of the work was done with the rear tires on a couple of 6 x 6s (about 2' long) I trust pressure treated wood more than any jack-stand.



In order to swap s/f bushes, I had to resort to jack-stands.