BX2660 Three point lift piston / cylinder scarred

[GreensvilleJay]

I've attached the pix from amazon.ca of a $107 auto tranny seal. Knowing how slipppppery TEFLON is I find it hard to believe it'll seal...
wonder how the Kubota seal is 'slit' ?

 

[PoTreeBoy]

I do NOT believe that an "angled factory cut" in that teflon seal was actually factory done!
I suspect that the "angled factory cut" may have been done by some backyard hack, because he could not stretch the seal to fit.
I had to take my piston and seal to a tractor dealer to have the seal stretched to fit.
I later learned how they did it!
There should be NO CUT in that teflon seal!

I agree. You can expand and soften that ring in hot water before installing it.

 

[ruger1980]

The white "plastic" ring everyone is referencing is not a seal. It is called a backup ring and it's purpose is to support and prevent extrusion of the o-ring into the gap between the piston and bore under pressure.
They can be found scarf-cut or not and there are some that have multiple wraps around the part it is used on.
It does not provide sealing for the oil.

I would recommend lightly sanding the piston and fine honing the bore lightly before assembly. The backup ring can be installed by heating in water or oil and sliding it around the piston. Then install the o-ring and if needed you can squeeze the rings back into shape using a piston ring compressor or a wide circular clamp.

 

[GNNOVA]

Left side, under rear axle.
View attachment 94390
There's a free downloadable pdf Workshop Manual available at Kubotabooks.

Thanks.

 

[GNNOVA]

I do NOT believe that an "angled factory cut" in that teflon seal was actually factory done!
I suspect that the "angled factory cut" may have been done by some backyard hack, because he could not stretch the seal to fit.
I had to take my piston and seal to a tractor dealer to have the seal stretched to fit.
I later learned how they did it!
There should be NO CUT in that teflon seal!

I do not believe anyone was in my tractor's trans before I got it since it only had just over 200hrs when I bought it and I know I didn't do it but anything is possible. I'll see when I get my seal kit next week what the seal looks like. If the teflon seal is solid then the guy I got my tractor from may have not been honest with me. But I will say if someone cut it they did a very accurate cut because I have built several automotive transmissions over the years and that is what it looks like.

 

[GNNOVA]

The white "plastic" ring everyone is referencing is not a seal. It is called a backup ring and it's purpose is to support and prevent extrusion of the o-ring into the gap between the piston and bore under pressure.
They can be found scarf-cut or not and there are some that have multiple wraps around the part it is used on.
It does not provide sealing for the oil.

I would recommend lightly sanding the piston and fine honing the bore lightly before assembly. The backup ring can be installed by heating in water or oil and sliding it around the piston. Then install the o-ring and if needed you can squeeze the rings back into shape using a piston ring compressor or a wide circular clamp.

Thanks for the info and how to install the new seal if solid. Thought it look factory made.

 

[North Idaho Wolfman]

I'll second what Ruger was saying, the white ring is not a seal it's called a backup ring.
it can be solid or have a split, it doesn't mater.
In this use it's so that when pressure is let off the O-ring does not get pinched when the piston slides up the bore.
Do a quick cylinder bore hone (use a ball hone it's safer) light scotch bright polish on the piston and call it good.
The flat spot on the O-ring definitely could be causing it too bleed down.

 

[GreensvilleJay]

You probably 'could' have seen if someone had been inside by looking for paint chips around bolt heads or where 'pieces of metal' join up...but... you're already in , oopsy...
Probably have to be real careful to not 'pinch' the new oring and 'backing when you install it.

 

[GNNOVA]

Thanks everyone for you info and support. The new teflon seal for the piston was scarf cut like the old one so I think the oil was not changed at the 200hr service even though the paper work said it was. When I pulled the screen and changed the oil there was some metal in the screen and oil so something is up. I'm going to run it a while and change the oil and filter again. I'll cut the filter apart and see what it looks like. If more metal is found I guess I'll be pulling the trans apart to investigate. The good thing is that the mower stays up now.

 

[RCW]

I found some machining debris in my screen years ago.

Lot of folks did also. RTV gasket material was common too. After a couple checks, didn't find any more.

If I recall correctly, metal pieces like bronze/brass chips are more of a concern, as an indication the plates in the HST tearing up.