cylnder rebuild questions

[joea99]

I am attempting to rebuild a welded double action cylinder. 2x1.5x6 (bore/shaft/stroke). Happens to be for a WR Long bucket on a Kubota, but I doubt that matters.

I've done brake calipers before, but never something like this. Seems simple enough, except . . .

The actual piston seal seems to be a problem. The piston itself is threaded (I assume) onto the end of the rod and held on by a nut. I don't know how to install the new seal, a rather thick piece. Seems to me it is too far to stretch a seal like that to go over the lip. I thought I might get cute and fabricate a "cone" to slip over the rod and meet the outer diameter of the piston, thus to slip the little bugger over it. But still gives me enough resistance to think "this just ain't right".

I also wondered about the piston itself. I wonder if it is built as a press fit? Meaning in two pieces so as to install the seal. Seems unlikely that it could be "leak free" under such pressure, no matter how well machined. Looking it over under a magnifying glass is inconclusive.

edit: In case there was any question, yes, I would appreciate advice from those in the know . . .

Here are the bits :View attachment 505176

 

[joea99]

Well, after suffering through a bunch of yoo toob videos, finally found one that, almost as an after thought, mentioned how he heats that type of seal in hot water, then slides them over.

I guess there is something to be said for simple commons sense approaches. And physics.

Also showed removing piston, which showed an o ring behind it.

I removed the piston and, sure enough that explains the extra o-ring in the kit I had no place for. Till now.

But, seems the seal in question is not exactly like the original, in that it is not quite symmetrical and may be correct only one way. I'll call the supplier tomorrow and maybe they will enlighten me.

 

[BigDog1956]

Well, after suffering through a bunch of yoo toob videos, finally found one that, almost as an after thought, mentioned how he heats that type of seal in hot water, then slides them over.

I guess there is something to be said for simple commons sense approaches. And physics.

Also showed removing piston, which showed an o ring behind it.

I removed the piston and, sure enough that explains the extra o-ring in the kit I had no place for. Till now.

But, seems the seal in question is not exactly like the original, in that it is not quite symmetrical and may be correct only one way. I'll call the supplier tomorrow and maybe they will enlighten me.

Joe, I fought with my seal being TOUGH getting on also, owner's manual for frt loader say's NOT to use water, also talked to frt loader MFG and they said they heat hyd oil to 160deg and let seal's sit in it for a couple minute's-I will try the hyd oil heated my next time.

 

[joea99]

Joe, I fought with my seal being TOUGH getting on also, owner's manual for frt loader say's NOT to use water, also talked to frt loader MFG and they said they heat hyd oil to 160deg and let seal's sit in it for a couple minute's-I will try the hyd oil heated my next time.

Thanks. I will try the oil route then. I really don't see the difference, but maybe it only has to do with trapping water behind the seal and causing issues down the road?

 

[wdchyd]

stretch it, no need for hot water, just clean and grease.........put one side in the groove and use a long slender screwdriver to wind it on in one clean twist.......think tire machine

 

[wdchyd]

How To: Re-Seal Hydraulic Cylinders - YouTube

at 35 secs

 

[joea99]

Thanks for that. If I had waited a day longer it would have saved me some sore fingers. I struggled with it and finally got it on there using just hand pressure. I am paying the price now with very sore thumb. But, I learned a lot in the process. Both cylinders are back on the machine. Next step is to change the hydraulic fluid and filters. Another thread.

(edit - I did soak them in hydraulic fluid, heated to 180. On the kitchen stove. Yes, I am divorced)

However, the second one gave me a big fight. The gland did not come loose and off without a real struggle. Then, when removing the piston nut it suddenly got very hard to turn right at the end. Then would not move either way. After a struggle, it did come off but was galled beyond salvage. The last couple of threads on the rod were badly mangled. Had to use a dremel to clean it up enough to get the piston off. Then, a bit of determined hand work with thread restore file and some tender dremel work got the replacement nut (3/4 -16, thanks Fastenal) to go on smoothly. I hope loctite is my friend. Used 195 ftlbs torque from a chart based on size.

This is almost on thread, but when draining the fluid, is it worth trying to drain all the other cylinders as well, or just hope the new fluid dilutes the old well enough?