Originally Posted by
luns
Later heads are reversible, and parts are as you received. I don't think the old parts are still available new. A few years back I was still able to find the part numbers for the older sets and the parts were still available NOS on eBay, but I can't find the part number now, and the parts supply seems to have dried up.
If you have the means to shorten your plastic plunger, you could probably make it work with the newer parts. I have access to an early HPX configured for schrader, so I could measure the gasket length and pin washer thickness - maybe next weekend - but my head might not even be the same as yours. From the diagram, schrader and presta gaskets appear to be the same length for the early heads, but your presta gasket looks shorter than my schrader, which in turn looks similar to the new reversible gasket.
If your head is the same as mine, then the difference between the lengths of my parts and your new replacements would tell you how much to shorten the plunger.
I had a closer look at my head, and between that and JaccoW's picture, I think my understanding of the later heads was wrong. Things look to be more alike between early and late than I previously thought. It looks like the plunger at the back may well be the same and what I said about shortening was completely off the mark. The black plastic spacer in the current kit, I previously thought stacks on top a shorter plunger, but after having a closer look at mine, it looks like it would actually nest inside. My plunger, despite being an older chuck, does have a 3.5mm step inside of it that the edge of the new spacer would rest on, with that much depth available for the Schrader pin to hide inside
So, I think a full conversion to the new parts would be to omit both of the springs and the metal washer of your original stack up and put the plastic spacer inside the plunger instead, but then you say it didn't seem to fit for you. The inner bore of my plunger is about 10.5mm in diameter - is the new plastic piece bigger than that? My Schrader rubber is 10.6mm long, and the pin plate (equivalent to your metal washer) is 1mm thick. I think extra length of the new washer is supposed to make up for the space the metal washer used to take.
Originally Posted by
rosefarts
Of course I tried this first. Depending on the valve, it kinda worked but I lost a lot of air from the threads.
My 3 year old has guaranteed that I can never quite find what I need. No roll of teflon tape but a little sliver on a hose fitting I'm not using now. I used that and it improved the seal. On one wheel, it was perfect and on the other, it was okay. The air loss is coming from around the valve now, not the threads in the head.
Unfortunately, I have to change how far it's screwed for each valve or I'd silicone it in.
This doesn't sound right to me. The inside of the rubber is supposed to seal against the valve, and the outside of the rubber should be sealed against the inside of the pump head bore. No air should be getting to the threads and there shouldn't be any adjusting necessary from valve to valve. The seal may be a little undersized for easy installation, allowing leakage on the outside, but when you actuate the lever to compress the rubber, that should swell it up enough to seal. Any variation from valve to valve should only affect how much drag you have on the rubber as you put the chuck on, but that difference is taken up in the rubber's compliance when you actuate the clamp lever to get the proper seal, .