911 ST suspension homologation

[John Sinclair]

Sorry if this has been discussed before, I did a scan yesterday evening and couldn't find the right info.

I would like to address the handling of my newly acquired 911 T and change the suspension, bushes, torsion bars, etcetera. As I would like to convert the 911 T into an ST I would like to get the right parts instead of fitting some parts for the moment and having to change it in 1-2 years time while building it into a ST.
Does anybody know where I can get the homologation papers for the ST or factory papers that state the specs? I have seen one with 22 mm torsion front and 29 mm at the back, but those were for the later RSR.

What would be the right numbers for the ST for the torsion bars, stabilisers?
Can I get poly bushes on a ST?
Are camber plates allowed on the ST?
Etcetera.

I would appreciate your help.

John

[Paul Schooley]

Does the Factory Sports Purpose manual cover the ST? Hmmmm, John, I think I have that manual hidden somewhere and will have a look. Been a while since I looked thru it.

[John Sinclair]

Thanks Raj, I was hoping you would chime in. I would really appreciate anything you can come up with.

Although the car is from 1971, I would like to convert it to probably one of the last ST versions (1972-1973?), at least regarding the engine, chassis and brakes.

John

[Flunder]

I believe that the FIA regulations allowed owners to choose freely shocks, torsion bars and sway bars to personal preference as long as use of these items did not alter suspension location points or geometry.


A.
The factory Spare Parts List Type 911 S competition type Edition april 70 has this to say:

"All parts for chassis are to be taken from the spare parts catalogue model 69, group 4-7 and RS, with exception of the wheels." (this means the standard street car suspension components).

The same page lists only one spare suspension part:

911.333.052.10 Shock absorber, rear - KONI

B.
The factory Spare Parts list Type 911 S Model 72 competition type mentions nothing is respect of suspension components. This reinforces the impression that the 72 ST - as prepared by the factory - continued to use standard street car suspension. A fellow board member's 72 ST had standard rubber bushed suspension and 15mm sway bars.

As Gib can attest, the Kremer brothers experimented with all sorts of suspension components and were among the first of the Porsche teams to adopt the revolutionary Bilstein gasdruck struts and shocks.


C.
As camber plates change geometry, I think they are dis-allowed for FIA sanctioned historic events in Europe.

The Ginther entry at LeMans 1970 had urethane bushings so I assume that is OK. However, the ST as factory prepped retained its standard rubber bushings.

Gib can elaborate on what suspension components Kremer used to such good effect.

[letsrollbabe]

In his famous 'Porsche 911 Story', Paul Frere states that for the 70 Monte Carol Rally, the factory used 24 mm rear torsion bars and 16 mm rear sways (15 mm fronts) to get more oversteer. He also confirms what Flunder has shown that the stock 'S' T-bars and sway bars were used on competition cars through the D series (71). Larger sway bar sizes were available. Brakes were stock 'S' alum. front, M rear.

Gib