What is the advantage of rear turbo trailing arms

[edbaus]

I have a racer that currently uses non-turbo rear trailing arms. I am considering going to turbo trailing arms. What is the advantage of the turbo arms over what I have other than wheel offest.

Thanks

Ed

[Chuck Moreland]

Turbo trailing arms have a more agressive camber curve. As the suspension compresses, the wheel gains negative camber at a faster rate that more closely approaches ideal.

This was first introduced on the 73 RS, then later used on all the turbo cars.

The net result is a more optimal tire contact patch.

[Steve@Rennsport]

Don't forget that 930 trailing arms are dimensionally different as well as attached in a different position on the torsion bar tube than 911 ones.

Thats why the camber curves are not the same as a 911,....

[edbaus]

Interesting. Had not known that. What about weight. How much weight will I pick up with them.

Thanks

Ed

[pmajka]

have 4 bearings vs narrowbody carrera 2 bearings.
Mo is bedda. stronga. lastin longa.

[Jack Olsen]

They have better anti-squat geometry, too.

Don't they need different mounting points? Or is that only the case if you modify the stock mounting point with the Smart Racing camber boxes?

They are also very expensive, which might be a factor with a race car, where getting replacements on short notice might be trickier when one gets bent.

[Grady Clay]

Ed,

It is generally not practical to retrofit Turbo trailing arms
because of the mounting issues. Either the torsion bar
tube must be replaced or the trailing arm mounts fabricated.
That said, it can be done but is expensive.

The arm is considerably heavier than the Alu 911 version.
Not so much from the casting but more from the massive
rear wheel bearings and stub axle assembly. It uses two
large (and adjustable) tapered roller bearings spaced farther
apart than the 4-point 911 bearing. The half-shaft is
correspondingly shorter.
"
"
© Dr, Ing. h.c. F. Porsche A.G.

"
"
© Dr, Ing. h.c. F. Porsche A.G.


Also the front suspension is relocated in the chassis.
The M491 uses all these pieces.

Many racers use the Turbo configuration (if class legal)
because of the dramatic increase in strength.

Best,
Grady

[Steve@Rennsport]

Originally posted by Jack Olsen
They have better anti-squat geometry, too.

Don't they need different mounting points? Or is that only the case if you modify the stock mounting point with the Smart Racing camber boxes?

They are also very expensive, which might be a factor with a race car, where getting replacements on short notice might be trickier when one gets bent.

Yep, and that comes from the raised pickup points,...

Indeed, they do require different mounting points due to being slightly shorter than 911 ones. One can install the 930 torsion bar tube as Grady illustrated or weld in the Smart Racing camber boxes in the proper location; we've done both.

Expensive? Oh yes, but they are just the ticket for high-HP race cars,....

[edbaus]

Hi,

I already have the smart racing boxes for the regular arms. I do understand that I need to cut these out and weld in the camber boxes for the 930 arms using 911 torsion tube. That is not a problem.

I have been running very large rubber on a fairly high Hp car and I think I am coming to the limit of the stock arms.

Ed

[john walker's workshop]

i'm doing turbo rear suspension on a G50 car. and the smart camber boxes for turbo arms are not made to fit the G50 pickup points, so i had to cut, heat, beat the pieces, but they came around.