LP2a SAR restoration

[Andrew Rowe]

I just use 10mm nitrite rubber. The local gasket guy does it with his CAD program using a thermal knife cutter, but you can also water jet the rubber out for a reasonable job as well. I believe it is only there for a water proof seal for the grease.

[Lynn Eades]

Andrew, that sounds like a good way to do it. I'll keep that in mind for the next one (maybe in my next life )

[Phillip]

Rubber

Mine were so hard I thought they were Bakelite but closer examination shows them to be, yes - petrified rubber.

We only have one firm in town that offer CAD cutting, I'll have to see if they can cut rubber, then I'll have to find some nitrile rubber sheet.

Another option may be a seal, is there any sideways force on the seal?

[Lynn Eades]

Yes there is quite a reasonable lateral pressure. The seal surface (pin collars) is grooved and the compressed seal is forced into the grooves under compression. The seal twists in itself as the suspension arm rotates, effectively no movement at the mating points. So, no, not a conventional seal. Find someone with a water cutter.

[Phillip]

Thanks, can anyone give me the accurate measurements for the new seal seals, I assume mine are a little compressed and if made to the same size would not seal.

[Lynn Eades]

I have one here that is 12mm thick. I suspect it is compressed to 11mm. It may be less.
There is a lip in one end of the bore (i.d.) measuring about 29mm, however the rest of the bore is approximately 31mm. i.d.
The lip is approximately 1mm wide.
It has a Patent no. (pat. no.) 360168 moulded into the side.
The o.d. is about 49.5mm but is scalloped (sp?) in the center (about 46.5mm. o.d. at center)
I'd ignore the lip and the scollap and as Andrew said have some cut from a piece of Nitrile (11mm is about the same as 7/16")
I had a box of NOS Aussie ones. If you dropped them on the floor they would break like glass.
When you install the shaft and collar, you will compress the two seals to get the bolt through. It would be good to do this with the bogie arm pointing at its normal working angle.
I hope that helps.

[Andrew Rowe]

Measure the width of the Bogie fork and then measure your gap between the suspension unit and divide x 2 to get the thickness of the seal. All the lips, etc in the original are there to over complicate a rather simple application. Do not make the seals too thick as you will swear a lot trying to get the fork in the housing, without wrecking the new seals. You may find different measurements for different housings, and you only need 1 mm or 2 mm compression on the rubber seals to work, and inside dia. is only a snug fit for the dia. of the shaft that goes through the fork. Cheers Andrew.