coilover chassis stress question

[Shuie]

Does going to coilovers eliminate the torsion tube as a major stress point of the chassis? If I discovered some rust in my torsion tube, would going to coil overs transfer most of the stress away from the torsion tube area and to the shock towers? Are shock tower re-enforcements necessary on a street car?

TIA

[ZCAT3]

Sherman - I am in no way an expert on this, but have been through these issues myself. I converted my 930 to coil overs several years back and did all the work myself. I did quite a bit of research as well before deciding to do this. Depending on who you ask, some "experts" will tell you to reinforce the rear towers, some will say don't worry if it is only a street car. I ran for almost 3 years without reinforcements, inclduing some track time, and see no negative impact. That said, I recently had the engine and transmission out and chose to do some minor reinforcement. I just reinforced each side of the shock tower based on a picutre TRE sent me (you should be able to find it here by searching on RSR shock reinforcement). I was planning on seam welding the shock tower caps as well, but mine were evidently done at the factory (this may be different on earlier cars). As for relieving stress from the torsion tube, most of the stress is moved away and into the shock towers. That said, there is still some weight there. If there was rust to the outside of the torsion tube that would still worry me. If it is toward the center I would be less concerned.

Hopefully some real experts will chime in for you.

[Shuie]

Thanks Bill!

The rust I found is on the drivers side above the fuel pump bracket, literally right next to the longitudinal. Its not bad, but I have a set of coilovers that are ready to be installed and I was curious about how much of the stress would be transferred away from the torsion tube if I used them instead of t-bars.

Any of you suspension gurus have any thoughts on this?

[Shaun @ Tru6]

Sherman, I am in NO WAY an engineer or anything even close, but I think it would be worthwhile to cut the bar out and put a buttress or 2 from the longitudinal to the backseat vertical.

since my track car didn't sell, that's what I'll be doing next winter and putting coilovers in.

[rjay]

I too am no expert. I would think that it would depend somewhat on the spring and shock rates chosen as to the absolute necessity to reinforce. I track my car, so I had mine done. OTOH, the street isn't without peril. Who knows what havoc a good sized pothole might cause. Equally, one would supect that there still is some reasonable stress generated in the that area from the spring plates. A third thought is that the tube is a piece of the chassis and if compromised it's probably not a good thing under any circumstance. I would think if you're going in there anyway, you probably shoud try to have it cleaned up, it aint going to get any better by ignoring it.

[mmastro]

Aren't the rear trailing arm pick-ups tied into the torsion tube also? Would this be a problem?...I can't picture it all in my mind right now, but Before you install your coil-overs you shou get the tube fixed/reinforced. My 0.02...

I had an RSR gusset kit welded into the rear corners of my engine compartment and then had shock tower reinforcments fab'd and welded in too. My car is on the street ~80% of the time.

[POKDUB]

I think you need to also keep the torsion bars in situ as extra support.
Coilovers will add stress to parts it should not.