Repair: Kubota B7100 dropping 3pt hitch

[charlz]

I thought I would share some pictures of the 3pt o-ring change out I did. Here is the background/detail:

I bought this 1970's or so Kubota B7100 along with some attachments. I found that with heavy implements the 3 pt would go down almost as fast as it goes up this necessitated me constantly bumping the control handle whenever I had an implement on that I did not want dragging. The 3 pt 'speed control' could slow it down but than meant taking forever to purposely let the implements down as well so that was not the problem. After reviewing the parts manual and searching posts here on TBN I decided the o-ring on the 3pt lift cylinder was the culprit. I purchased a new o-ring from the dealer for about $2.50 as well as new o-rings for the cover. About $5.00 in parts altogether.

The first pic is the cover coming off, about a cup of fluid spewed out but I had already put something on the concrete to catch the oil

The second pic is a close up of the piston. This is as far forward as it comes with the lift arms all the way up.

Pic three I used a magnet to pull the piston out of the cylinder.

Pic four shows the inside of the cylinder, not too bad for about a 30 year old tractor.

Pic five shows the piston, old o-ring in place and new o-ring leaning next to it, you can already see the old o-ring probably isn't even making contact with the sides of the cylinder anymore.

Pic six shows old o-ring on the left and new o-ring on the right. This really gives you an idea of how badly the o-ring was worn.

Pic seven is the piston with the new o-ring in place.

Put it all back together, topped off the oil and took it for a test run. The 3 pt hitch is now good as new, even with my almost 400 lb tiller it didn't drop even a little bit in a 15 minute period.

If you went straight to it you could probably do this in under an hour but I got side-tracked a few times Gotta say I am pretty happy with this $5.00 repair.

(Hopefully all the attachments work)

Charles

[wushaw]

Good job

[Soundguy]

Nice job, and nice pics.

i must say.. kubota sure made it easy to change that piston oring.

on an old ford that might have been a 4 hour job, pulling the seat, side cover , 3pt linkage, and then removing the entire top cover, unbolting the cyl from the cover, replacing the piston/rings and then reinstalling using 5 more gaskets, plus the 2-3 rings on the piston.. etc.

Soundguy

Originally Posted by charlz

I thought I would share some pictures of the 3pt o-ring change out I did. Here is the background/detail:

I bought this 1970's or so Kubota B7100 along with some attachments. I found that with heavy implements the 3 pt would go down almost as fast as it goes up this necessitated me constantly bumping the control handle whenever I had an implement on that I did not want dragging. The 3 pt 'speed control' could slow it down but than meant taking forever to purposely let the implements down as well so that was not the problem. After reviewing the parts manual and searching posts here on TBN I decided the o-ring on the 3pt lift cylinder was the culprit. I purchased a new o-ring from the dealer for about $2.50 as well as new o-rings for the cover. About $5.00 in parts altogether.

The first pic is the cover coming off, about a cup of fluid spewed out but I had already put something on the concrete to catch the oil

The second pic is a close up of the piston. This is as far forward as it comes with the lift arms all the way up.

Pic three I used a magnet to pull the piston out of the cylinder.

Pic four shows the inside of the cylinder, not too bad for about a 30 year old tractor.

Pic five shows the piston, old o-ring in place and new o-ring leaning next to it, you can already see the old o-ring probably isn't even making contact with the sides of the cylinder anymore.

Pic six shows old o-ring on the left and new o-ring on the right. This really gives you an idea of how badly the o-ring was worn.

Pic seven is the piston with the new o-ring in place.

Put it all back together, topped off the oil and took it for a test run. The 3 pt hitch is now good as new, even with my almost 400 lb tiller it didn't drop even a little bit in a 15 minute period.

If you went straight to it you could probably do this in under an hour but I got side-tracked a few times Gotta say I am pretty happy with this $5.00 repair.

(Hopefully all the attachments work)

Charles

[Mat]

nice job , well done,

Looking at the picture of the cylinder bore does show some marks or scratches, did you hone the bore before you put the piston back or not. What does everyone think - would this ruin the replacement seal as you need a smooth bore to seal well, or would honing improve the seal?

[Soundguy]

I would try to hone down any scratches I found. Deep scratches will eventually degrade the orings. etc.


soundguy

[Egon]

Many thanks for the concise description and the accompany series of pictures. Job well done. Report well done.

[charlz]

From what I remember the scratches look worse in the photo than they really were. I did not hone it out and still works fine almost 2 years later.

[hosejockey2002]

I did the same job on a Yanmar 1401D about a year ago. It's remarkable how much the Kubota parts look the same. Makes sense, since they are around the same year and size. It was a pretty easy job, if I did it again I could probably tear it down and reassemble in less than two hours.