Torsion Bar Sizes

[creator8]

My 72T RS replica came with a track prepped suspension setup. It currently runs with 31mm tubular torsion bar on the rear and a 23mm solid on the front.

This is way too stiff for the street use I plan for this car. Also of note are CF front fenders that trim about 60lbs off the front end. While too stiff I do like the fact the car is neutral handling with a slight tendency to oversteer. Definitely no understeer.

I had a 73S with standard S bars--don't know the sizes. I liked their suppleness but could live with something just a little stiffer.

So my question is what size torsion bars should I go to F&R for street use, particularly given the roads we deal with in the LA area. I want suspension to be supple and to maintain the neutral to oversteer balance too. I'm running 7s and 8s too. What makes do you suggest too.

Any suggestions on who to go to for alignment/corner balancing/ride height. i've used Darren at West End alignment for new cars and he's a genius. I know he does P cars too so would probably choose him first absent of other suggestions.

Thanks for your help.

[Eric911S]

Steve: If it is a street only car use 21mm front and 27mm rear bars. I personally like 22mm and 29mm for cars with 60 series tires and big 3.0 or bigger engines. The seats in the cars makes a big difference as well. The smaller front bars take alot of that front end harshness out. Also the sway bars can give the car a harsh ride if very large. Hope this helps. Thanks Eric

[kenikh]

The smaller front bars take alot of that front end harshness out. Also the sway bars can give the car a harsh ride if very large. Hope this helps. Thanks Eric

My 2000 lb 'S' has what I believe to be 23/28 with the Konis cranked all the way down. It is ROUGH. I will probably go with 21s or 22s next time I do the suspension due to running 50 series tires up front. I'll keep the 28 in the rear even though I am running an ultra light 1R cased 2 liter motor with 55 series tires. I am really starting to believe that ride comfort is mostly determined by the front swaybar and shocks.

[Eric911S]

Hello: Kenik I would put some smaller front torsion bars on your car. I have never installed 23mm front torsion bars on any early car. They are just too large and you get too much front harshness that you can't dial out. It is important on a 911 that the front stays planted. I have a road around here that I use for a test to see how the car handles. On one early 911 I worked on it had 23mm front torsion bars and when it hit this dip it would do a wheelly. The owner said he was having troubles at certain race tracks with front end washing out. A 911 doing wheelies is just not right. I installed some 22mm bars and all was wonderful. Hope this helps you guys. Thanks Eric

[pu911rsr]

So I am curious for a street car that would not see any track use would you increase torsion bar size over stock. I have 73 1/2 T that has factory sways, Bilstiens HD shocks, I intend to have car lowered, if I would ever want to change torsions now would be the time. I already have a race car and a street hot rod so this is a car I just putt around in.
Thanks,
Phil

[kenikh]

Hello: Kenik I would put some smaller front torsion bars on your car. I have never installed 23mm front torsion bars on any early car. They are just too large and you get too much front harshness that you can't dial out. It is important on a 911 that the front stays planted. I have a road around here that I use for a test to see how the car handles. On one early 911 I worked on it had 23mm front torsion bars and when it hit this dip it would do a wheelly. The owner said he was having troubles at certain race tracks with front end washing out. A 911 doing wheelies is just not right. I installed some 22mm bars and all was wonderful. Hope this helps you guys. Thanks Eric

Eric, thanks for validating my thinking. I am definitely going smaller on the front then.

[creator8]

Tony at TLG has recommended 21mm front/26mm rear so I'm going to go with that.

I'm sure on track my current setup is dynamite but I have no plans for track use.

Thanks for the info.

[Eric911S]

Steve: Let me know if you want to sell those old torsion bars. I am building up a 82 SC for a track car and may install a 3.6 993 engine. I could also install the 2.7 twin plug engine or? Too many engines not enough cars. Thanks Eric

[Jeff Higgins]

I'm running 22's and 29's in my '72 T, which weighs in at right about 2300. Sway bars are stock 15mm front and 16mm rear "S", and shocks are Koni Specials set at 3/4 stiff. Tires are 205/50-15. No monoballs or poly-bronze bushings; stock rubber all around.

I think the torsion bar stiffness has relatively the least impact on comfort on the street. Very stiff sway bars and/or hardened pick-up and pivot points (monoballs. poly-bronze bushings) seem to be what really kill the ride quality on a street car. That, and very low profile tires. My current set of 50 series tires are very noticably harsher riding than the previous set of 60 series.

Most folks who ride in, or drive my car are somewhat surprised at how heavy my torsion bars are; their stiffness is not reflected in its ride quality. I have ridden in and driven cars of about the same weight on lighter torsion bars, like 21/26 or 21/27, that have very stiff sway bars in the 19-22mm sizes. They are very noticably "harsher" than my car.

I am very pleased with how my car handles with its heavy torsion bar / light sway bar combination. It's not too harsh on the street and exhibits very predictable, neutral-with-a-touch-of-oversteer handling on the track. I'm a big believer in this kind of set-up, as I feel it allows a little more compliance than the stiff sway bar / moderate torsion bar set-up. Just my opinion, but it works for me, and gives me a wonderfull handling car that is not too harsh for daily street use.

[sithot]

Jashford's PCR car runs a big tubular torsion bar setup with re-valved shocks from Smart Racing.

I rode in it during our Valley Rally and it was quite surprising how compliant it is. It was very comfortable save for the passenger seat whichwas about 4 sizes too small for me.

Of course we have much better roads in the country than you may encounter in the "big city".

Maybe you shoulda' kept the big Benz sedan?

Tom