You've probably not seen an E30 suspension failure like this before

[kronus]

Passenger side:





Driver side:




Removed:




Car is a lemons racer, 24v swapped with the Nasieg 5-lug kit and e46 M front rotors, 255 tires. ~10 years, 30 endurance races on the subframe. A third of that with the big brakes and tires.

Our spitball diagnosis is repeated heavy braking work hardened the subframe metal and fractured it into pieces.

The final failure was thankfully smooth and uneventful. Driver pulled off the track in a controlled manner after losing steering. No real warning signs before failure except slightly pulling to the left under braking.

Check your subframes!

[Panici]

I will admit I personally have not seen that failure.

However garagistic's reinforced subframes have a plate welded over that area, so it must be a known issue.

https://www.garagistic.com/products/e30-reinforced-front-subframe?_pos=3&_sid=b8f52557b&_ss=r

[It's Soda Not Pop]

I reinforced my engine mounts and sway bar tabs. I've seen these control arm plates before, but I wasn't sure if that was necessary. At least necessary for what I do with my car. But I might due this mod in the near future for peace of mind.

[redneckvtek]

Yes, On enduro cars or high-grip cars the ball joint pockets pull out. Took about 2 seasons on my chump-e30s with stock brakes - I would not attribute it to the brakes.

Its probably track-dependent and happens faster if the car takes more curb hits

I never understood the subframe "reinforcement" kits that reinforce the engine mount or sway bar mount areas, as I have not seen those issues before.

[Northern]

It's definitely more common for street cars to tear the sway bar tab or engine mount tab off the subframe. Plenty of threads here about those, but I haven't seen this one before.

TBH I thought the reinforcement kits for the inner BJ was just a marketing thing, but I guess not.

[moatilliatta]

Happens on E36 and E46 also.

I like welding a big washer on the top side also around the inner ball joint boss also.

Sounds like the car could use a better inspection between events.

[kronus]

I nut&bolted it before the event and didn't see anything of particular note up there.. definitely didn't look closely enough to note cracks beginning to form. Reasonable ideas regarding spreaders and other reinforcements. I'm wondering what that will end up transferring the load to, though.

I did find an old s14.net thread featuring stories of similar failures. They seemed to have some concern about the metallurgy of the subframe post-reinforcement. The torn-out balljoint failed entirely around the weld, which would have been a harder and more brittle part of the metal than the rest of it. I'm worried that a similar result will occur around the edge of whatever reinforcement finds its way on the replacement for this subframe.

Kind of wondering if going back to non-solid CABs would be a decent compromise.

[kronus]

bonus uneventful failure video: https://www.youtube.com/watch?v=FNOpWFDK-UI

[redneckvtek]

Here is my failure and repair. I was lucky that I caught it (twice) before it actually failed.

Failure:



Drill Stopped and TIG crack


MIG reinforcement welded



Your subframe looks too far gone to repair TBH. I would start fresh and reinforce immediately. It does appear that a decent curb hit is what did it in, but the left side took the hit and both sides failed.
This repair was done in 2017 and 2018 and (knock on wood) has not been an issue since. I race ~ 60 hours per season per car on 245 RS4. Generally at the pointy end of the chump field. Not sure how that compares to your car's use case.


If you don't have the time/equipment to DIY this repair, there is a local shop called Backyard Bavarian that sells complete reinforced front/rear subframes, powder coated and all, for a reasonable price. Facebook/Insta is how to contact or PM me and I can send you his number.

-Chris

[kronus]

I'll post up once we get our reinforcements onto the spare subframe, we should be good to do it in-house. Definitely no intention of reusing our original subframe - the side that cracked instead of ripping out has a lot of stress cracking going all over the place.

Car is a multiple Lemons race winner in the competitive CA field, despite not being supremely fast in a straight line. Reliability and stint length help :)

Interestingly enough, I ran a different E30 in lemons for about a decade, with an M30, stock brakes, 225s, and absolutely no regard for gently easing over curbs. We parted it out recently, the front subframe had no damage at all.

[redneckvtek]

Ok i have a new one for y’all.

any thoughts on the root cause and/or necessary repair/reinforcement?

[e30austin]

woah, i've never seen failures quite like the ones in this thread. i've seen the engine mount tabs rip off, primarily on the M42 and S14 powered cars, and have seen one sway bar mount rip off on an incredibly neglected '87 325i, that i parted out many years ago, but these are genuinely impressive. guess i should inspect the one on my red car, next time i have it on the rack. that car gets driven harder than anything else i've ever owned and, likely, will ever own.

[McGyver]

Are these failures all on extremely stiff suspensions on a track car? I would assume it's just the repeated force of slamming through bumps for hours.

[moatilliatta]

Ok i have a new one for y’all.

any thoughts on the root cause and/or necessary repair/reinforcement?

what subframe bushings you running?

[redneckvtek]

what subframe bushings you running?

Condor