LB 400 pistons repair

[Harry in Ky]

Installing those piston seals isn't all that difficult. I have replaced a few hundred of them without problems. In fact I just did two yesterday on a Kubota loader bucket and tilt cylinder. I don't heat them unless it's colder than 40 degrees ambient. I put the O ring on the piston, then carefully stretch the seal onto the piston and into the groove. Wrap it with a length of emery cloth turned abrasive side out and tighten a hose clamp around that. Let it sit like that while I assemble the shaft seal, wiper, and O rings in the gland nut. Assemble that onto the rod and then install the piston and the nut, leaving the hose clamp in place until I'm ready to put it all back into the barrel. Whether it's twenty minutes or three day, I've never had any problems with that method.

I think your friend may have more problems than just how to install seals, but somehow I don't expect a defective piston is part of it, or it would be pretty evident.

 

[rogerwrob]

Thanks Harry . I will give this to my friend and he can maybe give it a try again. Is there a part number for the PTFE Teflon seal that he can get just that seal? I thank you for your help.

 

[mrmikey]

This method maybe help at all:

 

[rogerwrob]

Thanks . thats a nice little trick there

 

[Harry in Ky]

Kubota parts website lists an LB400 as a basic loader with fairly standard looking lift and bucket cylinders. I see nothing unusual about those pistons that makes any sense concerning your description of those your friend is working on. No pins involved, just a single nut holding the piton onto the rod. Very similar to the ones I've recently been working on.

As for part numbers they only list the number for the kit, nothing individual. A good hydraulic shop will be able to supply the individual seals needed. That' where I get mine. These were 2.5" bore, 1.25" shaft. I got seals, wipers, and O rings for three cylinders under $20 each set. I rarely order seal "kits", too many variables, different cylinder part numbers, or else kits come with parts for multiple cylinder styles, just more trouble (and expense) than it's worth. I find it's more effective and less expensive to take it apart and match the individual parts I need.

 

[Carl_NH]

Harry - that's what I do - our local Hyd shop rebuilt 2 of my B21 cylinders $100 each for labor and $40 for the kit. I have some of the tools, and knowhow, but the gland nut tool is a $40. I figure $280 of seals and labor for over 20 years of use is the cost of maintaining the machine. The rebuilt have never leaked a drop and if there is any scoring or bent rods they will fix or straighten them if needed. (more $ but that hasn't been the case so far).

 

[rogerwrob]

Kubota parts website lists an LB400 as a basic loader with fairly standard looking lift and bucket cylinders. I see nothing unusual about those pistons that makes any sense concerning your description of those your friend is working on. No pins involved, just a single nut holding the piton onto the rod. Very similar to the ones I've recently been working on.

As for part numbers they only list the number for the kit, nothing individual. A good hydraulic shop will be able to supply the individual seals needed. That' where I get mine. These were 2.5" bore, 1.25" shaft. I got seals, wipers, and O rings for three cylinders under $20 each set. I rarely order seal "kits", too many variables, different cylinder part numbers, or else kits come with parts for multiple cylinder styles, just more trouble (and expense) than it's worth. I find it's more effective and less expensive to take it apart and match the individual parts I need.

Thanks Harry

 

[kneedeep]

Take the cylinders to a Hydraulic Shop.
Some things aren’t worth the effort and cost to do in-house.
Rebuilding cylinders or gearboxes is one of those.
3510 is at dealer to get backhoe boom cylinder out and rebuild,
Way too much for me to tackle.