Front Torsion Bar Replacement for Daily Driver 81 SC

[81 SC Ray]

Hi All,


I am planning on going with 21 MM torsion bars because I use the car as a daily driver and need to keep the ride a little plush so I don't tear up the car. The roads are not good in the Norfolk, VA, area and I cringe at some of the bumps the car has to absorb. My question is - any real difference between solid and hollow torsion bars - is it worth the extra money?? Also, if any of you have changed these yourselves - any tips - keep in mind that I am only doing the fronts. The backs are still in good shape.

Thanks!!

[Rusty Heap]

just doing the fronts is a waste of time and money........put together the whole package front and rears at the same time, and get your front struts revalved and NO it won't be a harsh ride.

mine, 22 / 28's revalved struts for a little softer compression on the strut and a stiffer rebound (send them to RENNSPORT) so the suspension takes a set in the corners or over a bump but doesn't rebound.

you need to do the whole package otherwise the car will be mish-mashed and not tuned.

Just my 3 cents worth.

[Jeff Higgins]

If you are only doing the fronts, it would be better to stay with the stock diameter. Making a drastic change in spring rate on only one end of the car will upset the balance of the car, turning it into an ill handling little beast.

On top of that, changing torsion bars will require you also revalve the struts on the front and the shocks on the back. Increasing spring rate without also increasing damping will have a negative affect on handling as well. The car will be what we call "oversprung", or "underdamped" - pick your term; they mean the same thing.

The idea is to maintain a balance between spring and damping rates, and a balance between the front and rear of the car. Replacing front torsion bars only, with no other changes, will ruin both.

[OldTee]

Good reading on this, and other, subjects in "Porsche 911 Performance Handbook" by Bruce Anderson. Can be purchased from our host here on Pelican.

[81 SC Ray]

Hi,

Thanks for replying. More clarity is needed. I had a shop put in all new bushings and a turbo tie rod kit after I bought the car 3 months ago. He told me the car was in great shape and rust free, except for the front torsion bars. They were pitted and rusted. He cleaned them up and put them back in - I wish he had called me - I would have had new ones put in. Anyway, I do not want to put in 22's - I want to put in 18's to maintain proper spring rates for this daily driver. I cannot find a source for 18's. The smallest I can find - Pelican Parts / ********** are 22's. Any advice - thanks.

Ray

[moneymanager]

If not rusted, torsion bars will last nearly forever. Just get some used ones. Look for a nice set here. They turn up all the time.

[911st]

If he cleaned them up to inhibit further corrosion and redid the bushings so the bars do not come in contact with there tubes, I would not worry about it.

There are a lot of good used take outs if you want them.

Ride quality is probably mostly related to your tire and shock choice and bushings to a lesser degree.

If you go up from 19mm to 21mm considering that your sway bars add to your spring rates, this will increase your front spring rate about 39%. Remember your tires are part of the spring rate to so it would probably feel like less than that.

Making the front stiff relative to the rear would increase the stick in the back and to a lesser deg alow for the front to push. However, in a full on corner you are probably on three wheels any way so stiffening up the front relative to the rear is probably not as big a deal as one might at first think. Stiffening up the rear relative to the front after a point can increase the potential for a 911 to over-steer and spin.

I am not an expert on this.

Good luck.