The Stovebolt Site Forums The Shop Area Engine Shop Knee Shocks-Single Action Rebuild

Is it possible to rebuild the original single action knee shocks from a 39 Chevy 1/2 ton? If so, does anyone know of a supplier for the parts? Thanks!

Yes, you can rebuild them...get a copy of Hemmings Motor News, you'll find parts suppliers there...I think the Filling Station in
Oregon carries the parts...

apple hydraulics in new york also rebuilds, and sell kits I believe

I took all 4 of mine apart and cleaned them. They work fine now. Aside from making new gaskets for the cover there is nothing inside the shock that will require a rebuild

Kip, I was under the impression that these type of shocks have some really tough springs inside them and can be dangerous to take apart? My Dad has a '40 Special Deluxe and the rear shocks need attention and I've been unsure of taking on the project myself. Please offer a few pointers on how you did yours if you could.
Thanks
Don

Hi Don:

I should have taken some photos of these things while they were apart but unfortunately did not. Maybe someone here can supply some.

There is a fairly powerful spring in there but I did not have a problem with it as the spring was almost fully extended by the time the screws were out of the cap. On the first one I took half of the screws out and replaced them with longer ones to be sure the cap would not fly off. On the others I just clamped them in the vice and held the lever to slightly compress the spring while removing the screws from the cap. I used the same procedure when re-assembling.

There is also another smaller spring (for the check valve) under the small screwed in refill cap but it is fully extended before the cap is free of the threads.

Really, all there is inside is a piston with a built in check valve, a large spring, and the secondary ball check and spring under the refill cap, As far as I could determine if the shock body is not leaking from the bushing where the lever is attached all it will need is cleaning, Be sure you watch how the check valves came apart. Installed wrong and the shock will not work. Also do not refill right to the brim as the oil will expand slightly when hot. I used break fluid, but I’m sure you can find lots of opinions there.