Fun with a B21 Differential

[Temp97]

Yubby, Great post, Why, because I'm ready to split my B1700 to replace the Hydro pump. It works but the power is at a much less rate. I am not looking forward to it, but with winter right around the corner and never being able to use it for months. Now is good. Keep the pictures coming.

Sarge

 

[bx23barry]

Yubby, did ya get it back together? How's it work?

 

[scott_vt]

When you knurl the case to allow the bearing race to fit better, make sure you do it equally all the way around. Keeping the bearing centered will probably make a difference.
Another way would be to use some very thin shim stock to take up the space.
David from jax

Hi Yubby,
Dave has given you some good advice ! You can buy .001 or .002 feeler stock to accomplish what he is talking about. It would be nice to know what the specs on those bores were when new. But no, those bearings should not be spinning. The loctite can work also but, but I kind of like the feeler stock better.

Keep us posted!

 

[schmism]

If you want to tighten the fit of that outer race in the bore of the case , you can take a center punch and punch all the way around the bore, do a couple of rows. This will raise some of the parent metal and make an interference fit if bore is not too large. I believe that Loctite also makes a liquid chemical product for this purpose , can't remember the name tho. Loctite is the brand name of thread locking compound , should be able to find it at a good NAPA parts store.

the punch theory does work but shouldnt be used for excessivly loose fitment (if you can spin it by hand)

the loctite product your looking for is "Loctite Retaining Compound"

Loctite Retaining Compounds

you can reserche the various flavors on the net to see which one is best for your application. (#648 has come up in the past)

for setting gears check out this page. while it deals with toyota difs, he details the setup procedure very well. The theory is the same for any diff, implimentation is just diffrent (were the sims go for instance)

Toyota Gear Installs

 

[wrenchturner]

I have used Loctite 609 Retaining Compound before with success. A cam bearing spun in an engine block enlarging the bore. I advised the owner he could pay for another block or I could use the 609. To my knowledge the repair never failed. I have also peened bores with a punch and never had a failure.

Great repair job and photos. I am very impressed by the size of the bearings.
Looks to me like the snap ring got worn by the spinning outer bearing race.

 

[yubby]

Thanks for all the great replies and suggestions. I ended up getting a new differential casing, as I found a few cracks in the existing one and could not get the differential to come up to spec on Backlash without putting excessive shims in.

I figured the $200 additional cost for the case was well worth it if I do not have to take the tractor apart again!!

I ended up getting 7 thousandths backlash using 0.7 mm shims on the ring gear side and 0.6 mm on the casing side.

Attached is the picture of the new case and the first step of reassembly; installing the HST unit and transmission. [note the picture of the transmission is actually the HST return spring, that you don't want to forget to install!!!!!!!]

cheers -y

 

[yubby]

Once the HST and transmission were installed, I used the tractor as a base to install the rest of the components.

I installed the Differential, then the rear finals.

Then I added eassembling the loader subframe.

If all goes well I will have the loader on tommorrow and be able to test it out. I guess I could have tested the tractor w/o the loader but I would need to make a hydraulic hose to loop the loader circuit.

-y

 

[yubby]

Sorry here is the right picture of the differential being added to the HST/Transmission.

Happy holidays!

-y

 

[scott_vt]

Mornin Yubby,
Thanks for the update ! Looks like your well on your way to getting your tractor back online !

We all want a finished pic with a smiling operator !

 

[bx23barry]

Amazing how a repair can get more involved the deeper ya get into it. Looks like you're gietting it done right.

 

[zenmek]

Hey Yubby...don't want to bring ya down, but it looks like you're puttin' your seat on backwards just kiddin' great job

Will

 

[yubby]

Finally had a chance to finish up the job. Once the subframe was installed the rest went really fast. Put the loader back on and the ROPS in less than 1 hour. Then another hour to put the fenders and tires back on.

Then the true test, no hydraulic leaks, went into every gear, pto started, 4wd worked.

The only issue I ran into was the differential was locked, but after pressing the pedal a few times it came loose.

All told took about 8 hours to disassemble, 12 hours back together, and 3 weeks waiting for various parts to arrive.

merry xmas -yubby

 

[yubby]

See attached picture for smiling operator!

cheers -y

 

[Wclark160]

Hello Yubby. It痴 13 years later and your post is bringing a lot of knowledge to me. I have almost exact same issue. I知 looking for a new case and Kubota is very proud of them. Messicks is a little better but not much. Do you remember if you bought straight from a dealer? I know it痴 reaching way back in time and I understand completely if you have no recollection. Thanks

 

[Wclark160]

Hello Yubby. It逞ｴ 13 years later and your post is bringing a lot of knowledge to me. I have almost exact same issue. I遏･ looking for a new case and Kubota is very proud of them. Messicks is a little better but not much. Do you remember if you bought straight from a dealer? I know it逞ｴ reaching way back in time and I understand completely if you have no recollection. Thanks

It痴 obvious I have used incorrect syntax. I apologize and will go see if any posts are out there stating what can and cannot be used.

 

[goeduck]

It looks like yubby has not posted since 2012. If I may ask, how many hours on your B21 and what is the work history of it?

 

[Wclark160]

It looks like yubby has not posted since 2012. If I may ask, how many hours on your B21 and what is the work history of it?

I was afraid Yubby might be available! It has 1500 hrs on it and I知 not sure of the history. I think I might have caused it by being pretty rough with it. it seems to be a weak point. I busted my differential case as well. Oh well, live and learn.

 

[dfkrug]

it seems to be a weak point. I busted my differential case as well.

In my case, it was parts of the transmission breaking off internally and getting into the differential gears. My full rebuild is posted.

 

[goeduck]

Oh great, I have about 1600 hours. Tick, tick, tick,,,,

I am not hard on it but the previous owner could have been, I do not know.

 

[dfkrug]

Oh great, I have about 1600 hours. Tick, tick, tick,,,,

One of the failure modes is to force the range shifter and break an internal part. I think an owner who cares (not a renter) can avoid this behavior. It is interesting that many/most CUTs don't shift ranges easily since the gears are often straight-cut, and sometimes under small loads.

I think the B21 is a good tractor, if somewhat under-powered, and with a weak 3-point. Many of them are in rental fleets.