Need help choosing T-bar size.

[jpahemi]

Hi guys:
I'm in the process of rebuilding my suspension and I'm having a problem with choosing the rear size. The shocks are Bilstein Sport with 225/112 front valving (stock) and the rear shocks are 315/159 (bounce/rebound). The front T-bars will be 21mm and the rears were going to be 28mm.
Well, after getting off the phone with Jack French of Bilstein, he recomended 30 mm; stating the 28's would be over powered by the Sport valving. I never imagined going to 30's for my car (it's not a total track car), but this recomendation comes from a very experienced individual. He ended by stating the car would make a good track candidate, but not a quite a race car.
Could those who have been down this road, please give me advice on this decision.
BTW, the car's weight didn't seem to be of any real concern to Jack. The car weighs @ 2500 lbs. and has OEM style sway bars in 22/21 mm size.
TIA,
j.p.

Ps. The car will see some track work, but not exclusively. I've also read that some people have experienced cracking in the spring plate carrier area when using 30 mm and larger bars; definately don't want to have this problem.

T-bar spec's
Sander 21 mm have 145 lb/in rate.

28's have 350 lb/in rate.
Not sure what the 30's are (400+ lb/in would be my guess).

[911pcars]

Sounds fine for a track car.

Sounds aggressive for a street car.

If it's more street than track, I'd scale back on the Bilsteins and go with the 21/28s.

Check the archives also.

Sherwood

[jpahemi]

Thanks Sherwood, that's what I was thinking, but Jack was quite adamant regarding the 28 not being up to the sport valving.
j.p.

[dd74]

Jack told me the same as you, J.P. Although I've also heard Sports can support 30mm bars before needing to be revalved. I would say it's a subjective call up to the point where one's doing serious track work.

[jpahemi]

dd:
What did you end up with? I think the 30's are a tad big for me; although I've never driven a car with 30's.
j.p.

[dd74]

Originally posted by jpahemi
dd:
What did you end up with? I think the 30's are a tad big for me; although I've never driven a car with 30's.
j.p.

I ended up not putting torsion bars. I have stock up front and 26s in the rear - a setup from four years ago. My car weighs under 2300# and sees more street time than track, so the ride is good enough. I did, however, install Bilstein Sport shocks all around, which was a factory option back in the SC days.

I've driven a big torsion-bar car (22/30) with relatively the same weight as mine - and could tell no difference in ride stability or sway while cornering.

For my money, I'd hold off on the torsion bars and install sport shocks first. When you install torsions, you're going to probably need a four-wheel alignment, then you'll want to corner balance the car, and before you know so, you've spent $1K. Just do the shocks, see how well you drive with that, then, as you gain more confidence, think about torsion bars.

[jpahemi]

Ten years ago I replaced the A-arms and with the "while your in there" mentality, I installed HD inserts in the front and sport shocks in the rear. I also installed T-bars 22/28 Sway-Away. Now the bushings are deformed on both the A-arms and the spring plates, so I'm leaning towards replacing the Sway-Away with the Sander bars; I've heard the quality is better.
j.p.
Ps. HD or Rallye weres the only options when I first did this, so that's how I ended up with HD's

[dd74]

Well, it sounds like you need bushings, and that your car can stand sport shocks. Your torsion bars seem fine - 22/28 is a preferred setup for an agressively-driven SC.