I’m attempting to reseal a power steering gear using a Gates 350510 kit. This kit is supposed to fit most everything from 1962 to 72 and while sold under the Gates name I suspect the parts in the kit are the exact same as those sold under other brands names. Two blue seal rings that appear to be Teflon come in the kit. A small one for the worm shaft that is split and replaces the original nylon ring- this one fits fine. The larger Teflon ring that is used in place of the OEM steel ring on the piston doesn’t look right to me. As it came from the factory there is an o-ring that goes in the piston groove first and then the steel ring rides on top of that o-ring. The combined height of the o-ring and steel ring is approx .250 whereas the groove depth is approx .230 so the steel ring is effectively compressing the o-ring which makes sense. This would keep the steel ring pushed out against the cylinder wall.

The Teflon ring uses the same o-ring arrangement at the base of the groove but the Teflon is thinner than the original steel ring so the combined height of Teflon ring and o-ring is only .170 or about .060 less than the groove depth. So unless this arrangement is somehow energized by hydraulic pressure and pushed out against the cylinder wall, I can’t see how the Teflon will do anything other than just ride along in the groove.

Also I think the Teflon ring is simply too large in diameter. I’ve never had a steering gear apart but it’s not my first rodeo with hydraulics and Teflon seals. Every Teflon seal I’ve installed on other types of equipment had to be heated in hot oil or boiling water in order to get enough stretch to slide over a piston and into a groove. This ring literally drops over the piston OD so you’re left with much of the ring’s circumference sticking out beyond the piston OD even after it's in the groove. I’m fairly certain if I tried to install the piston in its bore, the ring would simply shear on the way in because the little bit of chamfer at the top of the bore wouldn’t provide enough lead-in to help guide the ring back in the groove. For those that aren’t familiar, the “power train” as the FSM calls it, is installed in the housing as an assembly so it’s basically a blind stab. There’s no way to see or help the ring find its way into the bore.

I bought a second kit to see if by chance the kit was packaged with the wrong ring but it was identical to the first.

I googled and searched this site as well as others but found nothing. I can’t be the first person that’s run into this. Looking for suggestions.

Answering my own post in case somebody is searching this topic in the future. I ended up using two o-rings under the Teflon ring to fill the gap and keep the Teflon centered on the piston. A dash 150 o-ring was part of the kit but as mentioned above this left a gap between the o-ring and Teflon which allowed the Teflon to move off center making it hard if not impossible to get the piston started back into the bore.

The o-ring I added was -041 which has a smaller cross section (.070) than the -150 (.103) I would have preferred to use two rings of the same cross section but this is the only combination of sizes I could come up with that would center the Teflon and not over compress the o-rings once the piston was in the bore.

Since I had to buy the -041 I bought a new -150 at the same time and got them both in Viton. I’m sure the Gates kit uses import o-rings made of who knows what so at least I know these two are decent quality.

The box was installed a few months ago and works great with zero leaks.

very interesting.
thanks for the update !