SWB Spring Plates

[chris_seven]

As the MSA Technical Regs specifically outlaw Adjustable Spring Plates for SWB Rally Cars in the UK and my local FIA Scrutineer is unhappy with them for Period F Appendix K cars I need to source several spring plates to replace parts that are badly corroded.

Evwen the splined tubes are in poor condition on some of the old plates that I have and I am sure I am not alone.

They are listed by Porsche as 'discontinued'

Does anyone know anyone who is re-manufacturing these parts or do I have to make a batch?

[304065]

Chris, I've never seen these remanufactured. Mostly they get scrapped in favor of adjustables.

Nor would cutting down a pair of LWB plates be a great solution either-- the camber eccentric hole in the LWB plates is precisely at the tip of the parabolic cutout in the plate.

As in this example of a man who made a pair of adjustable SWB from LWB.



I suppose you could weld up the hole and then contour the surface, but I would be worried about cracks, particularly for rally use.

There are doubtless decent sets to be had, but shipping to UK could be cost prohibitive.

I have been resetting ride height lately on '065 and have it down to about 45 minutes from jack to final torque.

One thing that would be useful as a tool for resetting ride height would be a 44 spline ring with a flat piece of steel welded to it, onto which an iPhone or other electronic level-measuring instrument can rest.

This would allow one to make more controlled changes to the inner spline position by precisely measuring the number of splines moved (using 9 degree increments).

While the same manipulation is possible using the spring plate itself, it's pretty large, and when attempting to withdraw the inboard end of the bar, often times the outer end slips free.

A simple splined ring with a bar tangent would allow a repeatable reference vs. horizontal.

[chris_seven]

If I could use the adjustable plates life would be much easier but they will not even permit adjustable plates that have been welded solid.

Many of the 40+ year old plates on European cars are in a very poor condiciton and have almost corroded all the way through and just look terribel.

Making the plate rom a weldable High Stength Steel is quite straightforward and cutting the internal spline is easy and quite cost effective at around $10 a tube.

The cost issue may be swaging down the tube ends to allow the spline to be formed.

I will look at the cost of making the tubes.

Making the setting fixture you described would be relatively straightforward.

I just bought a batch of Digital Inclinometers to make Camber Gauges so we would fix them to a tangential plate without too much trouble.

[chris_seven]

I have priced up making 20 pairs and they come out at around $250 per pair.

I need about 5 pair so I plan to order the material this week and draw them up in the next two- three weeks.

They will be correct to the standard 65-67 Spring plates and we can bond bushes on if needed - I don't think they were bonded on the early cars.

The ends will be correctly swaged and splined and fitted with a dished core plug.

We will use a modern high strength steel for the plates and Zinc plate and yellow passivate or E Coat in Black.

[304065]

Chris,

I don't think the bushes were bonded either, just slipped on. Many make the mistake of greasing the bushing or the cover, but in fact the suspension compliance comes from the flexion of the rubber, not from motion of the rubber against the torsion tube or the cover, or against the splined tube. Where motion occurs the bushing rapidly wears away.

Chuck Moreland of Elephant Racing suggests the use of alphacyanoacrylate ("Krazy") glue. When I questioned Chuck on this point he said, "If I had found something that worked any better, I would use it instead." I think the bond comes from friction between rubber and metal, not from the adhesive, in any case.

Good luck and looking forward to photos of the prototype.

[chris_seven]

John,

I agree and have been speaking with 3M Technical Department and they have a rubber bonding agent which works well if you use a suitable primer and we may try this method for the later 69 plates.

I don't plan to bond the SWB Plates.

I checked with Porsche and the 69 type plate is listed as 'Out of Stock' with no planned delivery date.

The last time they were available the price was about $500 each + 20% sales tax

The only plate that is currently available with bushes is about $550.00 each + sales tax.

We see quite a few cars where the plates can't be re-used due to corrosion and I think it is worth making a few extra plates as the swaged tubes are common, and the laser cuts are easy.

I will post photos as soon as possible.

[chris_seven]

Tubes have been cut to length and are being swaged this week and will be splied next week.

The plates will be cut by the end of the weeks so we should have SWB plates ready by the end of the month.