seanpaintsflames
Member
I just installed a new gasket kit on my NAA hydraulic system. I had a little hiccup with the leather backup ring on the hyd piston, and I thought I'd share it. I did as much research as the internet would allow before I did it, and seemingly everything I read said to put the leather ring in hot or boiling water for a few minutes to let it soften and it will be easier to stretch on to the piston. Well, I did that, and it didn't work. After just maybe 2 minutes the boiling water shrunk that ring so much that it could fit INSIDE the piston, but certainly not around it. It also didn't really make it more pliable. I tried the heat gun, but that shrunk it even more. Luckily, I had another one.
I've seen solvents stretch rubber before, so I had a brilliant idea for a second. Making do with what I had in front of me, I noticed that the PB Blaster can was tapered at the top, and the can itself was just about the same diameter of the piston. Starting dry, I pushed the leather ring as far down over the can as I could, working it in a circle. Then I squirt some carb cleaner on it and let it sit for a minute. I came back and worked it down some more and squirt more carb cleaner. It was almost over the whole of the can by now, so I pulled it of and worked it over the piston with two flathead screwdrivers; being careful not to gouge the piston or tear the seal.
I learned here that if you try with the rough side of the leather inwards, the smooth side starts to almost crack because it doesn't like stretching. BUT, if you flip it around and put the smooth side on the piston, the rough side stretches right around the piston without an issue. Well, now it was a little too stretched, so, remember that the heat gun shrunk the other one, I put some heat on the seal as it was in the groove on the piston. A couple passes around it and that thing was PERFECT.
Granted, I have yet to fire it up and see if it all works, but the leather ring was the same size as the rubber ring on the piston, and it went into the bore quite nicely. I don't know why the hot water didn't work for me, but I found something that did.
I figure maybe this could help someone else in future internet land!
I've seen solvents stretch rubber before, so I had a brilliant idea for a second. Making do with what I had in front of me, I noticed that the PB Blaster can was tapered at the top, and the can itself was just about the same diameter of the piston. Starting dry, I pushed the leather ring as far down over the can as I could, working it in a circle. Then I squirt some carb cleaner on it and let it sit for a minute. I came back and worked it down some more and squirt more carb cleaner. It was almost over the whole of the can by now, so I pulled it of and worked it over the piston with two flathead screwdrivers; being careful not to gouge the piston or tear the seal.
I learned here that if you try with the rough side of the leather inwards, the smooth side starts to almost crack because it doesn't like stretching. BUT, if you flip it around and put the smooth side on the piston, the rough side stretches right around the piston without an issue. Well, now it was a little too stretched, so, remember that the heat gun shrunk the other one, I put some heat on the seal as it was in the groove on the piston. A couple passes around it and that thing was PERFECT.
Granted, I have yet to fire it up and see if it all works, but the leather ring was the same size as the rubber ring on the piston, and it went into the bore quite nicely. I don't know why the hot water didn't work for me, but I found something that did.
I figure maybe this could help someone else in future internet land!