KeithC2Turto

Do the 935 style rear trailing arms increase the camber curve of the rear suspention on a normal 911.

I am thinking that if the forwared link is mounted higher it might.

Might also exadurate toe??

Also, would moving the inside arm atachment point down also increase the camber curve on top of adding neg camber?

What other issues might come with these?

911ST

KeithC2Turto

Steve Weiner-Rennsport Systems

Keith,

You've asked (perhaps unwittingly) a rather complex question that contains a LOT of variables.

There is a big difference between the 930 (cast) & 935 (fabricated aluminum) trailing arms. Both were shorter which increased camber change through the suspension's arc.

935's had height-adjustable mounts in most cases to permit adjustments in camber and roll center heights. The camber curves would depend on ride height as much as trailing arm position. Toe changes and compensation were done with the rod ends at the spring plates.

Its difficult to answer your questions without knowing precisely what you have and what you are trying to do,....

KeithC2Turto

Steve, Thank you for responding.

I am wondering if on a 3.2 911, if one goes to coil overs and uses the 935 style spring plate or trailing arms where the hing point can be rased or lowered, if doing so can benifit the rear camber curve.

If so, would one go higher than the CL of where the torsion bar was? How much of a change do you think this might make.

The best.

Steve Weiner-Rennsport Systems

Hi Keith,

The reason for the differences in trailing arm mounts has to do with getting a better camber curve for wide tires at low ride heights. Don't forget, all that design work occurred when bias-ply tires were the only choice,.....

Depending on the details of your car, one could install camberboxes on the torsion bar tube and 930 trailing arms to get a better camber curve for racing and some anti-dive, to boot. The 930 arms are shorter and angled differently than SC/Carrera ones so the latter ones won't work the same way.

935 trailing arms are deathly expensive and very difficult to find
so I'd be using 930 ones and mount them in the same place as the 930 using Camberboxes. 935 spring plates will be needed, depending on ride height (the biggest variable).

Don't overlook reinforcing the rear shock console and adding a full cage to the car if you replace the t-bars with coilovers.

KeithC2Turto

Thank you much Steve!

Mahler9th

An interesting question...

A lot of 911-based race cars have 930 trailing arms and Hamlin pivot boxes... these are also sold for the SC-style alu trailing arms. SmartRacing Products sells these.

Of course, what something is worth depends on what you compare it to. For example, many of the front-running cars in our (PRC) races have plain SC trailing arms and factory spring plates. Mine is a good example. A lot of us run bias ply slicks. In my car's case, the geometry benefits of the 930 parts and pivots are known, but I cannnot justify the $$ as they would not make me a second or more faster...

One thing about 911s is that they have been raced for a long time, and while there are occasional advancements with new products, most basics have been covered as far as set up and so on...

In our area here in NorCal, there are still a lot of people around that we part of various 911 and 935 racing efforts, so we are extra fortunate in terms of depth of expertise and resources.

rusnak

I think 930 trailing arms and camber boxes would be the wise choice vs 935. You get a clean and simple mounting point for 930 brakes as well as the anti-dive geometry. I also agree that using your existing 911 trailing arms is probably even wiser unless you like spending money. Besides, I'm waiting until the RSR style brakes are available from Alton and Co.

whalebird

I love it when Steve chimes in. It's a learning experiance every time. In regards to the original post, I performed a similar modification on certain customers car. Never my own. We would lower the inner control arm mount by an inch or so (there was a measurment I don't have in memory, but it wasn't dramatic) and then set the car up based on ride height and corner weights. This is not an obscure procedure and IIRC is touched on in Bruce's 911 Handbook. However the intention was to gain some of the above mentioned benefits. The fabrication was modest and cost was minimal. The owner/drivers claimed improvements and considered it worthwhile.
Your objective may carry further than this minimalist approach. In which case the gurus here will give you good advice
Good luck.