This is the Upgrade and Modification page for the Porsche 968 Project

Rear Suspension

Preparation work

I purchased a used set of torsion mounts, and arms from eBay, so I could do the required drilling and machine on the set, before disassembling the car.  There is a good few hours to remove the old rubber bushings from the arms.  Messy and smelling when you have to heat and peel the vulcanized rubber off of the torsion arm tube.  The big advantage is being to do this work over a period of time, as I did, prior to taking your car apart.  It also will allow me to remove the whole suspension and return it to stock, if I choice.

Before

Jack Stands are behind the wheel wells, the jack in view is only as a safety backup.  Never work under a car with just jacks!  I removed the side sills, which made working on the rear suspension much easier.

Disassembly

Once you get the shock loosened, and the torsion bar is at full droop.  Mark the line of the arm onto the banana arm. Note on my car the eccentric is set to the lowest position.

I used a scissor jack under the hub to lower the axles.  The banana arm is unbolted, and the shock is removed.  The suspension is at full droop, and the banana arm is marked.

 

Torsion arm is removed.  Getting the mount past the inner stand mount requires dropping the suspension quite a ways. (Removing the inner lift point makes the job very easy.  I noticed many of the full race cars don't have this lift point) Also, note that the brake line as been released from its clip, and the inside a-arm mount as been unbolted (Not visible). The cross arm is resting on the exhaust.

Installation Begins

Using a sanding drum on a drill, cleanup all the burrs from inside the cross arm, and wet down the Polybronze bushing and press in.  If the mount is smooth inside, this can be hard pressed in by hand.  Once it is fully mounted, you will need to drill a hole for the Grease fitting.  The directions I received for Elephant Racing Polybronze stated to drill a 1/16" hole.  That is fine for the pilot hole, but will require a larger hole before you can tap the M5 thread for the grease fitting.  Lube it heavily with a synthetic grease before you slide in the torsion arm.

The torsion bar and arm is installed.  The alignment was set to have full droop here with the eccentric set to center.  This lined up with where I had lined with the eccentric at full low.  This gave me a fairly good baseline for a 330mm rear ride height.  This is was one inner tooth, as I recall.

Note: Don't make the same mistake I did here.  Make sure you install the inside torsion arm bolt before you install, else you will need to pull it back out to install.

 

Assembled, and all the bolt I've painted to confirm torque, and to check if they loosen!

The Rear Shock Installation.  The top rubber bushing has a flashing on it from the factory.  You make the surface flush with the steel inner bushing, else it will stick when you attempt to install in on the the top slot of the shock housing. 

 

Note the sway bar is still out of the car.

Alignment

Needless to say, after disassembly and installation, the alignment was WAY OFF.  After spending a few hours with Chris at EuroTire, the alignment was spot where I wanted it.

Chris setting up up for the alignment

Nearly there with me in the car.  Goal alignment was:

Front Camber -2.0

Caster 2.5+

Front Toe - Minimal

Rear Camber -1.6

Rear Toe 0.06

 

Corner Balance

Here is the rough cut at the balance.  2887lb wet with stock interior, Momo Seats, stock battery, floor mats and a roll bar with harnesses.  1/4 tank of gas.  Better than expected.  That puts it at 3040lb with driver.  Chris had to careful go back and forth between alignment and corner balance to get to the ultimate goal.

Final results with Driver

Some room to handle the smaller battery (-15lb) , passenger side harness (+8lb), and more then a 1/4 tank of gas!

 

 

 

 

Finished State, before alignment

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