For the rear trailing arm is there a more stout bushing to replace it with to give some added strength?

Any info on this weak point of the chassis would be helpful.

Thanks

 

You can install a monoball which are readily available from ERP

 

Has anyone done the Euro RS mod, as using a thicker washer to lock the bushing from flexing? I've locked in the pet5 but I haven't found the part. Does anyone know the dimensions of the washer?

 

Just to make sure we are all talking about the same thing. I'm talking about where the trailing arm attached to the body. I've heard there is a solid mount, but I'm guessing that's pretty harsh for all but strictly track....anyone do a urethane or other type of material?

havent heard about the Euro RS mod....anyone do that?

 

I'm aware of three options when it comes to the replacing the rear trailing arm bushing:
1) Stock trailing arm
2) Carrera RS trailing arm
3) ERP monoball

Stock trailing arm is designed with the Weissach axle effect, to add toe when cornering or under braking. The Carrera RS trailing arm has stiffer rubber/washer to limit the Weissach axle effect. ERP monoball is a metal-to-metal monoball, and eliminates the Weissach axle effect. Note the bushings do not have Porsche replacement parts - if you want the Carrera RS bushing, you buy it already mounted in the trailing arm. Installation of the ERP monoball, however, can be made into your existing trailing arm.

There's a cross section diagram of the RS bushing in the original 'Lightweight Confusion' article in Panorama and Up-Fixin, however, the pictures seem to have been omitted from the web-based versions. The article, which is well worth the read, sans pictures, is at http://www.carreracupusa.org under articles.

 

Anyone do any of the above mods?

opinions and comments?

 

I have ERP monoballs installed front and rear, with ERP spring plates in the rear too. In the back, for street use, I can say that I don't notice any difference from the stock setup (note, I didn't install them to benefit street usage). Where I noticed monoballs was on the front. Porsche designed forward/backward compliance into the front a-arms, which the monoballs eliminate, making turn-in much crisper. Using the Cup Car steering bushings (harder rubber) helps with steering crispness, too (the difference, however, is not as dramatic as Turbo tie rods on the 89 and earlier 911's).

If you go with the ERP monoballs on the back, be aware that they are not sealed units. They may not last 10 (an arbitrary number just for discussion) years due to dust and grit being able to get into the monoballs. You could seal them yourself - one suggestion was to use the plastic/rubber gook that tool handles can be dipped with.

For a street-driven 964, using rear monoballs may not be the best choice for two reasons: first, you may not want to eliminate the stabilizing toe-in that Porsche designed into the semi-trailing arm suspension, and second, durability longer term may not match the stock Porsche solution. If I wanted a better rear trailling arm bushing solution than stock for a street driven application, I'd recommend the Carrera RS trailing arms, which is 964.331.021.70 (left) and 964.331.022.70 (right). If you need more camber, the Carrera RS spring plates would do that, which are 964.331.059.80 (left) and 964.331.060.80 (right). RS spring plates also require a different eccentric bolt, 964.331.137.80.