claykos

I have a 1974 911 GT-type race car and I am considering doing the 993 rear suspension swap. The car has a 993 widebody, and about 350 rwhp. It currently has ERP 935 front and rear suspension (with 930 trailing arms) that is pretty well optimized. The car works very well and is very fast but there's always more right?

There are a couple of threads in the archives on this site and pelican that I have read where various claims are made regarding X seconds per lap improvement, etc.

Basically, I am looking for someone with first hand experience before and after this modification. Was the car faster? What did it do better? What did it do worse?

Thanks in advance,
Clay

JoeMag

I believe pete dawe has the jig's etc to do this conversion. may want to give him a ring. he's on east side of PA.

http://www.dawesmotorsports.com/

claykos

I have talked to a few companies that do it, and they are more than willing to tell me what a HUGE different it makes :-).

I'm looking for an unbiased opinion from someone who actually has it on their own car...

Geoffrey

I think you'll want to think this through very carefully. The 5 link 993 suspension was Porsches first attempt at this type of suspension and requires careful setup to minimize the bump steer it introduces. There are many shops that don't understand how it works, and don't take the time to do the engineering to set it up properly. In stock form, it does not hold alignment as well as what you currently have, so it will require more maintenance. What you have now will be better than a poorly setup and maintained 993 suspension.

M758

Clay,
Have you tried to contact Chris Cervelli? He is another 993 expert.

claykos

That is sort of my thinking. I have a degree in mechanical engineering and I will model the whole thing in WinGEO before doing it. I would also do all monoballs/rod ends, etc. I am a firm believer in anecdotal evidence (from someone not trying to sell me something) - so that is what I am after.

My initial thoughts are the multi-link is potentially more stable mid corner and for high speed sweepers, but is harder to set up right and might not have as much forward bite coming off the slow stuff.

claykos

I've talked to Chris about it. He doesn't have any experience with it in an early car, but thinks it's potentially faster than a real 993 because you can raise the whole cradle up in the car and get the car really low without screwing up the roll centers and camber control.

M758

sounds like a fun project.

race911

Matt Lowrance out of Sporthaus in Reno did Hank Watts car like that (w/ 993 turbo engine) about 7-8 years ago. Matt has built many successful torsion bar chassis cars for guys in Northern California (Masuo Robinson's probably being the fastest). He also campaigned IMSA as a privateer in the '90's.

JWERION

Clay,
I did this in my car (78 SC tub) and there was a significant improvement, I first tried the 996 rear suspension but it just won't fit into the older style tubs. If you do then you will also need to use all the ERP adjustable links and replace all of the factory units. Also you do need a shop that kows how to adjust and setup the suspension particularly the kinmatic toe as this requires a special tool that can be purchased from autometrics. http://www.autometricsmotorsports.co.../ktt/index.htm
The car handled much better and provided a great sense of confidence in the car.
It was however very expensive and I would get a firm price from someone who has done it before. I had 3R automotive do mine and they are tops when comes to building race cars (world challenge GT champions last two years), but this was the first time they had done it and it cost more than I care to divulge.