Torsion Bar Tube Corrosion/Repair

[chris_seven]

We are seeing an increasing number of SC's with badly corroded torsion bar tubes.



The corrosion is close to the end of the tube and is associated with the bushing fitted to the spring plate.

As the bush deteriorates water enters the gap and corrodes the surface of the tube and the 'end stop' which locates the end of the bush and creates some radial expansion of the rubber.

Once the tube is in this condition fitting a new bushing onto the spring plate will help but as the end location isn't present the bush will not expand and the fit will still be poor.

I am not sure that even a hard bush will locate very well and some remedial work must be needed.

Is there a 'standard' fix? or do I need to make a small pressing and a suitable bush?

[chris_seven]

It seems as if this may not be a problem in better climates than the UK but we need to solve the problem on two or three cars.

We have made the pressings that fit into the torsion bar tubes and the new bushes that are needed.

These pressings convert the end of the tube to the same dimensions as the 1965 to 1967 Torsion Bar Tube ends so it can be used with the smaller inner bush that Porsche still sell or with the UHMWPE1000 Polymer bushes we have made for competition cars.




The Rings fits on a spigot machined into the bush and acts as a tolerance ring between the bush and spring plate.

I will post a final photograph when we have them fitted and welded in place.

[Fishcop]

Very savvy solution!

I've seen 'some' rust in the TBs over here in the Antipodeans, but it's mainly in the tube itself where I presume temperature change condensation pools water at all the low points (and then it's not normally a problem unless you're near the sea).

[chris_seven]

Fitted and welded in place and bush installed - needs a good clean and some stone chip and then paint.

We will probably Waxoyl inside the tube.

[micheloaks]

Chris great solution. Can you post pics of fitting the cup, prior to fitting the bush?

I assume the cup is located true by pushing it into the cup and then welding the outer edge, though what occurs if the cup is if significantly compromised?

With the polymer bush replacement, while selected to provide accurate geometry, what of noise transmission over extended use. Road car versus track car?

Also is the third layer of metal, between the inner outer longitudinals welded originally to the cup?

Regards Michel

[lrodri64]

Hi Chris.
Do you have a kit for sale?
I need to repair both sides on my 67.
Thanks