sub-frame mount re-enforcement

[CHIF8008]

so i have a new e30 that im gonna be installing a weld in camber /toe kit and full poly bush. set with the 12mm sub frame risers. as far as i have heard it will work but it is a tight fit. (please correct me if i am wrong)

now, as i have all this torn apart i have decided that i want to re-enforce the car where the sub-frame mounts up. i have seen others peoples car have the sheet metal fail and id rather not risk it. id imagine that with stiffer bushings and a stiff suspension setup it would really be putting stress on where they mount up. i know plenty of people run without modification, but im not to easy on my cars.

question is, have any of you done this? and what would you recommend? i don't necessarily wanna add plate on the underside as that would reduce how far up my sub-frame will be raised. im looking for max camber correction as i have the car pretty much on the floor. but i figure that when people buy that extra plate for the rear shock towers and that is considered suitable with it just on the top- that i can add plate from the inside of the car.

should it just be a plate welded around with a hole cutout that is closely matched to the bolt opening, or should i have the bolt actually grab onto the plate? only problem i see with the later it that i will probably need longer bolts :/ not necessarily a prob, but i want it to work right.

thoughts? still have to pull this car apart to get a better pic and take measurements, but just throwing it out there. thanks for any input you guys have.
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[jlevie]

The only failures I've seen there involved rust damage. I wouldn't bother.

If you are installing camber/toe adjusters, there's is no reason to use the 12mm riser bushings.

[Earendil]

To add to what the SpecE30 god has said, I don't know of any PRO-3 guys that have done this, and I'd be surprised if its legal since they call out pretty specifically what can be reinforced. You should be just fine, as no one is as rough on the subframe as the racers are :)

[CHIF8008]

The only failures I've seen there involved rust damage. I wouldn't bother.

If you are installing camber/toe adjusters, there's is no reason to use the 12mm riser bushings.

i fail to see why it is pointless to run both? more correction is more correction- so either way its a benefit. adjusters allow to get both sides to a matched camber and toe spec, as the raised sub-frame helps add a degree or so of camber correction + changes roll center and ground clearance for me, thus allowing the exhaust that dips under the sub-frame to have a bit more breathing room.

[CHIF8008]

To add to what the SpecE30 god has said, I don't know of any PRO-3 guys that have done this, and I'd be surprised if its legal since they call out pretty specifically what can be reinforced. You should be just fine, as no one is as rough on the subframe as the racers are :)

The PRO-3 cars drive on a pretty smooth track, but being full time DD as well we have hard dips, transitions, and random pot holes that wanna sneak up on you. id say suspension wise- a street car's suspension gets more of a hard hitting beating than the race cars.


Sure the pro-3 cars get thrown into corner more constantly but that's more of stress on the shock towers + trailing arms mounts as onto the sub-frame. it may see abuse, but not as rough as the street tends to offer to a vehicle. There are some pretty bad roads that are considered safe for the public.

or am i way over thinking it? just saying that if stock e30's get the front strut towers to move over 20+ years of driving- i would think that the metal for the sub-frame mounts have gotten softer and more playable as well (especially on a lowered vehicle) shoot everything gets more stress put on it when something is lowered.

[Holland]

If you are installing camber/toe adjusters, there's is no reason to use the 12mm riser bushings.

The entire point of the risers is to compensate. If you have adjustability in the first place then risers are moot and your driveline will be off anyhow.

IE posi lock adjusters won't clear with 12mm risers either.

[CHIF8008]

Going to be running the Dungeon Motorsport adjusters. Had them on my previous car and they held up fine.

[AndrewBird]

The spacers are pointless because the weld on adjusters will provide enough adjustment to dial the camber back.

The rear subframe holes inside the car are actually raised slightly. There is a dimple the bolt sits on so the bolt head doesn't sit flat against the rest of the sheet metal. You could get plate that is the same thickness and weld it on so that the bolt would sit flat on the plate without needing longer bolts.

[CHIF8008]

The weld on adjusters did NOT provide enough adjustment at max positive camber on my current e30. still have negative 3+ (the kit will only correct 1.25 degrees at max fyi and for anyone looking into this style of camber correction) so, i find it very logical to use the sub-frame risers AND the weld in kit to compound the amount of camber correction. maybe you don't realize how low i was running. static.




i have noticed the 'bung" and was planning to just have the plate sit flush with it. seems like the simplest and easiest way to do it.

[Earendil]

Just...wow.

[CHIF8008]

I can put the rear on the floor as well. I have since raised her up, but i believe this is how a coil-over should work. all the way down is actually ALL the way down. nuff said.

running about:

much more manageable and very DDable

[CHIF8008]

mount failure that gave me the idea to re-enforce:

[CHIF8008]

also this guys as well, but his actually had the sheet metal fail on the bottom side.





just food for thought.

[SLEEPYDUB]

Im very interested in this as well. I believe my subframe may be shifting around and id like to reinforce anything I can in the rearend.

Im making about 600hp, so for me, there is a need. AND its a drift car, so it gets pretty abused...

[Cletonius]

Did they say what kind of stuff they were doing when those subframe mounts failed? Looks like street usage to me