Kubota B21 clutch replacement...(I tore the tractor in half already)

GaryInWA · Jul 19, 2014

My B21 quit moving a few weeks ago and a grinding noise was coming from the clutch housing. I spent 2+ days tearing the tractor in half and found that my clutch plate splines had been stripped almost smooth and the clutch spline/pilot shaft had damage to the splines.

I am not a professional Kubota mechanic/technician so bear with me......

Was it just normal wear and tear? The tractor has over 1800 hours of hard use on it and I do not know if the clutch has ever been replaced.

Was the clutch plate perhaps made of cheap material?

Did something bind up further back (HST pump,something in rear axle, or ?)and cause the clutch shaft to bind which stripped the clutch plate splines?

Should I just replace all the clutch components/clutch shaft and all its components (almost $1000 in parts) and hope thats all it needs?

I took some photos of the damage and was wondering how the damage could have been caused.

Any advice or information is appreciated.

Gale Hawkins · Jul 19, 2014

Just look at my other post.

Gale Hawkins · Jul 19, 2014

Gary it is hard to know but that is not normal for a low hour tractor like yours or a high hour tractor. While it could be a defective part(s) I would guess misalignment from the factory if the tractor has never been split before. Bearings can fail and let things wobble too. How were the bearing holding the shaft in place?

Is the rest of the tractor in top condition? Are the rest of the parts worth more than is the tractor if it was running?

troutsqueezer · Jul 20, 2014

A B21 with that many hours is certainly worth putting $1k into.

brain55 · Jul 20, 2014

Normal wear and tear on that machine. Think about it though, next time you're jumping on and off the hydrostat pedal or engaging the PTO.

What does the pilot bushing look like? Is there even one still there? My opinion is that the spline wear has a lot to do with the length of the shaft, the somewhat soft pilot bushing, and the nature of the shaft coupler to the transmission. I'd like to see that shaft supported in the middle somewhere instead of just at both ends. Notice that I'm saying it is normal for that machine, not that it's right.

Brian

PS. Notice that it is a rigid disc and not a spring cushioned disc.

skyhook · Jul 20, 2014

Gary, are you the original owner of this machine?

Did something bind up further back (HST pump,something in rear axle, or ?)and cause the clutch shaft to bind which stripped the clutch plate splines?

That would be my guess also,,

CHDinCT · Jul 20, 2014

skyhook said:
Gary, are you the original owner of this machine?

That would be my guess also,,

Doubt it. He's a former Kubota mechanic that now owns/runs his own mobile heavy equipment repair service. Nice to get his opinion on something like this if your the OP.

GaryInWA · Jul 20, 2014

Gale Hawkins - My friend looked at the clutch shaft bearings and said they are shot which could have caused the damage to the clutch, there is someone local to me that is looking for B21 parts and may be interested in buying some bits and pieces if I go that route...hate to part it out but I may go that route.

troutsqueezer - yes, it may be worth putting $1k into machine but if the HST is shot its a very expensive part to replace I have heard.

brain55 - the pilot bushing is still there and has some life left in it and yes the clutch is rigid without springs like a cars clutch, that could have been an issue.

skyhook - I am not the original owner of this machine, I bought it at an auction with 800 hours on it and have no idea of its maintenance before me...but its been very very dependable since i have owned it...it just sucks that you have to do sooo much work to replace a clutch on a kubota tractor compared to a car.

CHDinCT - I am not a kubota mechanic or mechanic period, I am a tractor owner that isnt afraid to turn wrenches.

JRL305 · Jul 20, 2014

I don't see a pilot bearing or bushing in the picture. If the shaft isn't supported when you engage and disengage the clutch, there's a possibility that the shaft could become misaligned and put extra wear on the splines. It would probably be vibrating too.