Need less squat
 

Hi everyone,
I need a little advice on suspension.

I have a '75 911S with a 930 engine. The car weighs in at 2260 lbs, and has 7x16Fuchs all around. I currently have Bilstein HDs and a 19/26 torsion bar setup. I also have stock swaybars front and rear.

While it's a blast to drive, it squats down so low under acceleration that it's in danger of scraping its muffler tip. I have height set at Anderson's.

So, what should I do to get a bit less squat, without stiffening the rear too much? I don't want a bunch of added oversteer. I already have a lot of that. :D

I thought about raising rear height 1/2" to see what happens handling-wise. Is this a reasonable first approach? I'm open to changing suspension components.

Thanks!

I have Bilstein performance shocks in the rear and it squats a bit. I'm very close to getting those adjustable spring plates since I need to change some 25 year old bushings anyway. Car is lowered.

A 930 engine is pretty heavy. You could probably go to 28mm torsion bars in the rear (maybe 21's in front?)

One other note is if I do the work of the adjustable spring plates then I'm putting 26 or 27mm torsion bars in the rear.
I believe mine are 24s and 25years old!! and yours are 23s so that will solve some squat as well.

edit: Guess I should read - you already got bigger bars!!

Raising the rear a bit will help, either w/ a t-bar adjustment or taller tires. Best would still be heavier bars f/r and adjustable sways for final tune.

Someone on another board put coil helpers on the rear

You either need shocks or springs. New shocks are easier so go with that first. You don't have to buy race shocks. Since the '84-'89 930 engine weighs up to 40 lbs. more than your original 2.7, you may have the wrong springs. Good luck.

Springs????? Must be a special build. :)

bigger torsion bars and bilstein sports.

Sorry about saying springs. It's hard to refer to torsion bars when you've learned about spring rates all your life. so if he installed a lighter engine can you go with smaller torsion bars or add weight?

Larger torsion bars helped mine to reduce the swatting (28mm).

Noel

Torsion bars are springs.

Pissy today. I'm gonna clear out until things are back to normal.

BTW, I read the original post very carefully and he said he didn't want to stiffen the rear more than necessary and avoid oversteer. With that, I vote for raising the car a little. With the Bilstein HDs, I bet the next and only practical move would be a bgiger bar. So raise first. It's cheap.

If your car was in our shop, I'd install 22mm and 29mm torsion bars.

Thats a very balanced package and with the right shocks (sport rears), the squat problem will be aleviated without making the car oversteer too much.

I had a 2500-pound car that I ran 21/30 t-bars on, without handling craziness. Bruce Anderson acknowledges guys who run significantly higher rear spring rates than he recommends in his book -- and you've got (probably) a pretty scary f/r weight bias.

You need the shorter turbo rear banana arms and rewelded pickup points.
And then turbo brakes and and and.......

Jack, you're right that it has a scary weight bias right now. I'm keeping it off the track until can I get flares and wider rubber in the rear...some day. But it is a ton of fun as a street car when driven carefully. :)

Coil helpers sound expensive, and I'm not up to changing the pickup points right now. Shocks and torsion bars would be doable for me as I've done this work on my Carrera before. It also sounds like no one thinks rasing the rear a bit is necessarily a bad idea...

So keeping in mind this is a street car right now, 22/29 or 21/30 plus Bilstein Sports in back would be appropriate, and not too firm? The ride is fairly firm already with the 19/26 bars, given the light weight.

I think you "feel" more firmness from bigger sway bars say 22/22 than torsion bars. But I know my 19/24s need to go to at least 22/27 maybe 22/29 and the sways probably 22/22 from 20/18.
With the adjustable spring plates.

no useful technical content within my post
 

Yeah... Clouds do that to me. ;)

Thanks ts. Sounds like I should keep the swaybars I have and focus on t-bars and shocks. I guess the swaybars are just along for the ride in straight-line acceleration anyway. The amount of corner role it has is not bad (at least with the amount of grip I have with the current skinny tires). It's really just the squat that's a problem. Braking dive does not seem too bad either.

I must have lucked out in the PO lottery - my '75 has the adjustable plates already, and I've been fiddling with height and alignment. I had to reindex a couple times to get to Anderson's spec anyway, though. Oh well.

Thanks for the replies everyone. I appreciate your advice.
Colin