poppett valves

[groundog]

has anyone re-built the poppett valves on the side of a 5 ton transmission?

 

[M543A2]

I have rebuilt two of them. The rubber seals in them had gotten deformed by the pressure to the point they were leaking. I cleaned out the old rubber seal pads and cut new ones from some conveyor belting I had. The belting has a woven fiber back and a top surface that is a polymer coat of some kind, very tough. It is overall about 3/16 thick. I glued the new seals in place with a good two-part epoxy. The rebuilt valves have been working for over two years now with no problem. I think the belting is enough tougher than the original rubber seals that it will last longer. For my first attempt at rebuilding these, I tried a softer rubber and it did not last long, a month or so.
When I am done with the trucks for the day, I go to the back, remove the glad hand connection cover, and bleed off the air pressure. This relieves the pressure on the valves which helps prolong the life. When the truck is driven or sitting with the trans in neutral, the valve is normally in the position for forward drive, so when parking the truck with the engine shut down for shorter periods than overnight, I put the trans in reverse so the other side of the valve has pressure on it. In this way, the forward direction poppet of the valve that sees pressure probably 99% of the time is relieved of pressure for the time the truck is sitting and the little used reverse direction poppet gets to share the wear.
Regards Marti

 

[groundog]

did you disassemble the springs--o rings---detent balls etc/ thanks for the advice about using reverse gear to help even out the wear Groundog

 

[M543A2]

Yes, I disassembled everything I could in the valve I removed from the trans cover and cleaned it. I did replace o-rings from my stock. I should have mentioned that, but I was focusing on the worst part which was the worn rubber poppet seals. They are pushed with so much air pressure against such a small port! I also did not mention I glued the replacement seals in such that the sealing pressure of the port was against the smooth side of the belting. My theory was that the tough belting with the smooth poppet side and the woven fiber backing would withstand the pressure better without deforming. So far so good! I still have a large piece of belting. I can send you a piece if you want.
The price I saw they get for a replacement valve made me look for a better way.
Regards Marti

 

[groundog]

mine was leaking in neutral and first but not reverse---do you know which valve controls first and reverse? thanks for all the info---I have a used re-placement that seems to be working OK but I want to keep the original as a back up Groundog