Trailing Arm/ Rear Subframe Reinforcement Question

[88Sedan]

With regard to trailing arm/ subframe reinforcement I understand what the pieces welded in are supposed to do with one exception. Specifically I am wondering about the pieces that triangulate the subframe where the trailing arm bushings mount.

I would have thought some flexibility in those tabs is a design feature so that it tightens up onto the bushing sleeve properly during torquing. Does that part of the rear subframe ever even get damaged outside of accidents?

Essentially my concern is that after these pieces are welded in that it would no longer properly squeeze the bushing. I am NOT adding toe/camber adjustment because for my desired ride height it really isn't worth the hassle/expense. I would also have to drive far for an alignment shop that would agree to deal with that.

I am building my car so that the chassis is ready if I ever 24V swap it. I already reinforced the front subframe and the rear is torn apart now for full rebuild.

[digger]

The longitudinal tabs are already in effect gusseted by the lateral piece (connecting the two tabs) that forms a C-channel in plan view and realistically i don't think these significantly affect/stiffen the longitudinal tabs to the point the pin wont get clamped (welding the adjusters which thickens this area does not stop the clamping action). i also think it is not necessary for these gussets for most applications.

[88Sedan]

I agree. In that case I may as well use them since I will have other things to weld too. Thanks.

[moatilliatta]

Maybe weld up the reinforcement with the bushing in. It is not there to flex for clearance.

[hasa]

That's serious reinforcement!

[zaq123]

I really believe Z3 trailing arm OEM design is all most e30s really needs. Designed for S50 so should be able to handle some abuse, the same for the subframe design. You know how trailing arms become destoyed the most? By someone changing bushings watching YouTube videos that tell you to use threaded rod to work one bushing again another. The trailing arm can not take that abuse and will deform. Z3 one obviously stronger due to the brace but I'd still won't use that method.

Z3 OEM arm

[E30SPDFRK]

On some toe adjusters, the range of adjustment is so much that you will need to cut the front of the C channel out for trailing arm clearance. This is when you'll want to add the reinforcement gussets. They aren't needed otherwise.