Can someone explain this process for any 81SC. Thanks - happy new year.

 

The short answer is taking the car to a professional to have the susspension sorted so that the car has equal weight on each wheel. This may mean adjusting torsion bars, torsion plates, front ride height adjustment screw, trailing arms.

Hope this helps.
Cheers
Mark

 

What should this procedure cost - how many hours of labor Etc. Thanks

 

Mark and others are right on the money. If you really want to know, surf the Grassroots Motorsports Web site. There is an article on corner balancing that explains it fully. Also read How To Make Your Car Handle by Fred Puhn. Also note that this is all labor, figure 4 to 6 hours at the going rate. Also be advised with a lower car, you may want to install a Bump Steer kit that moves the steering rack to accomodate the new suspension geometry. And while you are at it, consider installing Turbo Tie rod ends, about $150 a kit. The Bump Steer shims are pretty cheap too.

Surf over to http://www.rennsport.com There is a pretty comprehensive selection of material for you to bone up on. And as always, read the Rennlist Technical Archives: There is great stuff in there.

One other thing, and you can be quite arrogant about this, the SC and Carrera cars through 1989 were fully adjustable, front and rear through the torsion bars. This is not the case with the 993 and 996 cars. Adjustment of these cars for corner balancing is limited, the front end only on the 993, and I believe the same on the 996. If one wants the flexibility that you have with the SC abd Carrera through 89, you have to install new coil overs and sway bars that go with the coil overs. This is about $3,000, before labor, add in another $1,000. So go ahead and feel superior....but not that superior. The 993 and 996 cars have 100+ more HP, power steering, ABS 5, 6 speed transmissions: That's enough of a trade off...as ususal, I digress. I think I'll go out and fire up the 993 and make an early AM coffee run!

 

I'm sure I'll get some negative feedback on this one but here goes:
My feeling on the subject of corner balancing an SC is that unless you are willing to change out the torsion bars and add adjustable anti-roll bars you just don't have any adjustablity with stock equipment. You can't change the torsion rate, only the ride height, the stock torsion bars were calculated to match the front to rear weight differences by the factory. Unless you change the weight distribution of the vehicle the balance should be ideal. Adding adjustable sway bars and new torsion bars would give you more of a track ride with the ability to adjust oversteer and understeer, while limiting nose dive and squat, but the torsion bars should be chosen carefully, with matching sway bars, based on the corner weights. I suggest a four wheel alignment from a reputable shop experienced with track set-ups and ride height,on PORSCHES, I'm sure someone on this board can recommend one in your area.

 

I get my car Corner balanced at EPE in Natick, Mass. Jerry is a first rate mechanic and they do this on a regular basis. I own and '87 Carrera which is tracked frequently. I would highly recommend this if you plan on DE'ing the car.

James

 

Can you tell me what it cost to corner balance your car?? Thanks

 

Grand Prix White, I'll let you know in a few days. The last car I had done at EPE they replaced a bunch of other stuff. I'm having my '87 done tomorrow so I'll let you know.

Cheers, James

 

Cost should be around $200 - $250. That is not only cornerbalancing, but setting ride height and wheel alignment. It is all done together.

As far as cornerbalancing a 911SC, I don't see why that can't be done w/o changing out torsion bars and swaybars. The purpose of corner balancing is indeed to achieve the weight ratios recommended by the factory. The problem with USA cars is their ride height is higher than optimum. Once you lower the car, the weight balances (front/rear and left/right) change, so the car needs to be rebalanced.

No doubt, stiffer torsion bars and bigger swaybars will provide better handling, but the size of these bars will not change the range of adjustment. The balance of the car will certainly will change with the change in torsion bar diameter. I agree torsion bars and swaybars need to be carefully matched, but that is an issue that goes beyond just car balance.

I think the stock 911SC with a good alignment, ride height, and corner balance is a wonderful handling car. I would track it stock before changing a thing. Once you start changing torsion bars and swaybars, it is quite possible to end up with something that handles no better than stock.

Once the 964s came out, their coil over design provided a much greater range of adjustment an also made the job easier.

Mike Piera wrote a good article describing his method of alignment and cornerbalancing. You can find that Here

Here is a link to a downloadable worksheet for cornerbalancing. Use it for Mike's examples and I think you'll get the math. you can find that There

 

JBH, thanks for your reply - My car has adjustable swaybars and has been lowered and bumpsteered all prior to my ownership.
I want to start with a proper "baseline" of middle of the road settings and see how it works. Making certain alignment and corner weights are accurate. I agree - that a stock car is a wonderful thing and most of the time you go backwards b4 you go forwards!! However since my car has all the goodies it should work nicely when properly set up. I don't feel the handeling is as good as it should be, hence my topic for this board. Thanks for you reply.

 

Here's a link regarding corner balancing, of course you will feel rather dizzy after reading it. LOL
http://pantheon.yale.edu/~kgibble/bm...balancing.html

 

Howard, Wow, what an article! Iam going to print it and see if I can cipher the code inwhich it is written. Looks like english- but can't be sure. (great info - thanks)

 

GPW911, My car, corner balanced and aligned was 240 at EPE, Hope this helps.

James

 

James, thanks for your reply, I am going to do it in the spring. the car is under wraps for the winter. Best wishes.