teske

Is there a post or posts on this site that explains how to lower the front and rear suspension on a '78 911SC? If there were good pictures and graphics that would also be helpful!

I have owned this car for 23 years and never like the ride height and now that i am retired i want to lower it!

Thanks in advance!!!

whalebird

You did the right thing comming here and asking first. I think a search would give you more than enough(maybe to much)info. But properly lowering a torsion bar car is an involved process. It is reletivly easy to turn the adjusters on the front t-bars and play with the adjustable spring plates on the rear. However I think lowering the rear typically requires re-indexing the torsion bars and that is something you want to proceed with cation on. There are a number of good sources on the process if you do a search. When you get ready be sure the final result has the proper rake Front-rear. I always dialed in about 1.5degrees measured at the flat area in the door sill. towards the front that is. At the same time it makes a big differance to add the bump-steer extensions at the tie rod ends. When all of this is done, Its real easy to corner weight the car and get a good alighnment at the same time. While your in there.......its always a good idea to do the spring plate bushings. I have used stock replacement and also the Weltmeister eurothane both with good results. I guess I am just saying it is a good time to do turbo tie-rods/ball joints etc. When its all done properly the visual impact is stunning and I think a marginal handling improvement is an understatement. Its easy to do wrong though. I think I have not really helped you though, maybe just complicated things. Sorry but I truly hope you have a great retirement and spending one's time on a 911 can be very gratifying.
Good luck.

teske

Any idea the distance in inches up or down the movement of one spline of the t-bar equates to? How may splines are on the t-bar?

Seems like one would not be able to determine adjusted ride height after the car is disassembelled! So it seems like you need to know the inches you want the car lowered ( keeping the 1.5 deg rake) and how many splines move the car up or down enough to accomplish this.

Seems like this should be done from an origional mark on a spline and the appropriate place on the body to correspond to it, then rotate the bar the correct number of splines to make the proper change in inches.

Hope questions and concerns makes sense!! I am probably confusing myself...but i am looking for details!

Thanks again!

whalebird

You have the right idea. One must determine the final ride hight desired and the move the splines accordingly. The process would involve setting the car on jack stands and mesuring the angle of the spring plate before and then making the adjustments to get a final angle which corresponds to the final ride height. the splines are tricky. There are splines on both ends of the T-bar and they are of different number. So one might advance two splines on the inner part of the bar but retard one spline at the outer end. There are an infinite number of combinations. I refrain from making exact suggestions as they are covered in great detail and I am working from memory here in my office at work. I will do a search on here and see if I can provide a link to a more detailed procedure. I have done this the old fasioned way of using a protractor with a string attached, but had better results by using a digital level that measured degrees. I have even used the unit from a Smart camber camber tool with great results. Once you get the T-bars in the ball park, the final adjustments and corner weights can be dialed in with the adjustable spring plates after the car is assembled and sitting under it's own weight. I did this a bunch in my shop and had all the required equipment that made it consistant and predictable. There are a lot of people here that have had great results in their garage and I don't want to discourage that, but it is nice to find a shop that has corner-scales and experiance with this process to get the final ride and alignment set.

Ed Hughes

The Bentley manual has a chart that shows what each spline does. As Whalebird mentions, there are numerous posts on this subject, no need to post them all again. There's also an Excel spring calculator on Pelican-do a search there using "spring calculator" or similar term.

Plan on a 4 wheel alignment as your camber and toe will change.

Steve Weiner-Rennsport Systems

Be sure and have the car cornerweighted as its lowered before the final alignment for consistent and predictable handling.