930 trailing arm geometry question

[Tar356]

I'm doing the homework on an upcoming '74 RSR project, and had a question about using the 930 trailing arm.

I want to replicate (as much as reasonably possible) the RSR rear suspension.

I've read alot of the posts/threads here about the subject, but couldn't find a definative answer about the geometry. I keep reading about 930 arms being "wider" than 911 arms. How does the geometry of the 930 arms compare to the original RSR arms.

Is it safe to say that mounting the 930 arm will give me a similar geometry to an RSR? I know there needs to be new mounts fabricated, which leads to question number two: what mounting location would give me the desired results?

Thanks,

Todd

[Steve@Rennsport]

Originally Posted by Tar356

I'm doing the homework on an upcoming '74 RSR project, and had a question about using the 930 trailing arm.

I want to replicate (as much as reasonably possible) the RSR rear suspension.

I've read alot of the posts/threads here about the subject, but couldn't find a definative answer about the geometry. I keep reading about 930 arms being "wider" than 911 arms. How does the geometry of the 930 arms compare to the original RSR arms.

Is it safe to say that mounting the 930 arm will give me a similar geometry to an RSR? I know there needs to be new mounts fabricated, which leads to question number two: what mounting location would give me the desired results?

Thanks,

Todd

Todd:

930 arms, mounted in the proper (930) position on the torsion bar tube, come closest to replicating the RSR geometry as these were designed for more camber gain with big tires.

The 930 arms are wider in the area between the axle flange and where the outer CV attaches with a double wheel bearing set up. Its very robust.

[Tar356]

Thanks for the reply Steve...

You say "come closest to replicating the RSR geometry"....how far off and in what dimension/direction?

Todd

[Steve@Rennsport]

930's had the same basic trailing arm mounts that were 15mm closer to the car's centerline and rearwards about 47mm.

The 930 trailing arm mounts were also raised slightly for additional anti-squat characteristics.

[drb930]

Hey guys, my friend said there was a great article here about turbo trailing arms on early cars.
Anybody have the link to the thread?

Thanks,
Dave