b21 clutch

[clucks]

Hi all,

Great site...Actually inspired me to tackle the replacement of the clutch in my B21 (well, the $3000 quote I got my a local dealer kinda helped also). I have to say I was heart broken when it failed, understand that this tractor would be parked in my living room if my wife would let me! 2004, with 850 hours (I've owned her for the last 200 hours or so). The dealer had never heard of similar failures and were blown away by the wear on the shaft. A smooth notch almost in each of the splines that tapered out towards the other side, eventually taking out all the splines on the clutch disk (all other components were in excellent shape, although I still replaced everything). Before it failed, I was in high gear, not under load when it started to make a grinding noise. I stopped, geared down, proceeded to move forward when it finally blew out the splines on the disk.

I've got about 10 hours of light work (moving dirt around my farm) since repairing a couple of weekends back. I had her out today, running around out back in high gear when I heard a sound that sounded an awful lot like the one just before it failed last time. I tried to duplicate it with no success in low/med, just high. Disengaging the clutch stops it.

I realize that its pretty difficult to judge without hearing or seeing, but does anyone have any thoughts to something I may have overlooked? I'm cringing at the thought of having to split her again.

[Michael]

Did you have the flywheel resurfaced and replaced the pilot bearing? If these are not done it can cause abnormal wear to the clutch.

[Mr. K]

Hello clucks, welcome to the site and thanks for posting your question. Also, good on ya for tackling a repair yourself - splitting a tractor is a lot of work!

This part here:

the $3000 quote I got my a local dealer kinda helped also

made me laugh. If you are in Surrey then I know what "local dealer" you are referring to. Was down there the other day actually and they were busy busy.

Anyway, regarding your problem at hand - I do not know personally, BUT, Vic might. I've left him a message to come in from the shop when he gets a chance and to look at and recommend on your situation. Hang in there, we'll get you sorted. :)

[clucks]

Yes Michael, resurfaced the flywheel and replaced the pilot bushing, along with all new bearings, seals, release bearing/ holder and spring. I figured if I was going in, I was doing everything. I am going to take her out later today and see if that noise reappears, and if so that it is absolutely coming from the clutch housing.

Well Mr. K...in defense of that " local dealer" (not that I want to ), it was quite the job. Lucky enough I have a friend who is a HD mechanic with all the goods to make it happen, just the same it took the two of us had about 16-18 hours (at least two were wasted on trying to bolt on that oil line to the gearbox through the little access holes of the center frame- bad mistake not to connect prior to rejoining). Oh well, I learned a whole bunch about that little machine.

[Service Dept Vic]

Clucks,

That issue may reside in the transmission and not the clutch. Kubota did have issues pertaining to bearing failure and fatique on the main input shaft bearing cradle.

The failure is exasperated by the use of PTO driven/operated implements, and fails "early" in the hour life of the affected machines.

I'm not suggesting that this IS the problem, but it MAY be the root cause in the first place, and as such should be looked at to determine the strength and worthiness of the main shaft front transmission bearing.

Kubota does offer an over the counter parts department re-enforcement "Bearing Holder Service Kit" part# 32721-12100 that was engineered to address this service complaint. It's a $350 touch.

If the main transmision input shaft is not adaquetly supported, the main input shaft will "walk" from the back end (pilot bearing maintains front plane of alignment) eventually burning the splines off the clutch disc, similar to what you have described.

Offer your serial number up to Avenue Kubota over there in Surrey and ask them to tell you if your machine is equipped with a "from the factory" re-enforced main input shaft bearing or could it be included in the serial number que of B21's known to prematurely fail.

Hope this helps you to diagnose your Kubota Service Complaint.

[Mr. K]

$350... USD.... so closer to $400+ for that kit.

[clucks]

Thanks for the insight Vic. Seems my # (62639) does not have the same input shaft support as part # 32721-12100. Avenue said there was a number of repeated replacements and service bullitens on this issue for and my machine was the 2nd to last series by serial #'s.

Thought I'd throw in a little pic of what the worn clutch shaft looked like for anyone else that may come across this issue, the pics a little blury, but you can see how the wear tapers.

43

As I mentioned in my previous post I had a heck of a time bolting in the oil line to the gear box after rejoining, so when i realized that I had an oil leak due to a couple of missing o rings on a particular "oil line flange", I decided to cut myself a little 4x4" access hole on the front top of the center frame -figured this was acceptable as I'm just a farm kid :). Is there any way to test that bearing on the tranny input shaft without splitting? I did notice that there is forward/ back play in the propeller shaft (maybe 1/4" tops).

I had her out today, runs fine, no noise at all rpms and gears ...just wish I would've joined into this site before I had put this little machine back together.

[Service Dept Vic]

Clucks,

The wear pattern and area of damage that I see in the picture is exactly where the splines from the clutch disc reside, with the wear getting more pronounced as the splines on the clutch shaft progress from flywheel to transmission. This premature wear pattern and resultant failure may be something as simple as an incorrect clutch pedal free play travel, or an operator using the tractor with his foot resting on the clutch pedal.

It's a new one for me too, so I'm going to toss something out that may sound crazy, but it may explain the wear.

Is it possible, that the clutch disc that you took out, was installed backwards? The "shorter" end of the clutch disc boss should face the flywheel when correctly installed on the B21.

Can you recall the orientation of this boss when you removed the old disc? Is it possible, it was installed backwards at the factory, with the shorter end towards the transmission?

BTW, I'm thinking 1/4" end play in anything related to clutch, transmission, gear box, steering box etc, is way too much tolerance. I went looking for a spec on that from Kubota, didn't find one. :(