JD 4200 pinion replacement

[jdjunk]

After several months of only having low range I finally found the time to split the machine in half and investigate the problem. What I found was the 50 tooth gear stuck to the pinion shaft. The pinion is destroyed along with the gear and sleeve bearing. Ordered all the parts from my local JD dealer, $1300 later, I have new parts. JD does not offer the pinion alone it comes with the ring, would I be in the wrong if I do not change the ring? It is not that I cant change the ring it is the amount of extra work to get to it. The machine has close to 1000 hours on it, the existing ring and pinion do not show excessive wear or sharp edges. On a truck or car's differential I would definitely change both but I feel in this case it is unnecessary, I am not planning to be doing 140mph down the quarter mile. Any one have any thoughts on this please let me hear them, I am on the fence with this. Tom

 

[beenthere]

Sure can't blame you for not wanting to do it.
But would have to consider the risks if it doesn't work out, and you have to repeat the exercise (and new parts) to do it right.

Hard one to answer for someone else.

 

[jdjunk]

Beenthere,Thanks for the reply. In any other case it would be a no brainer, I would change it in a heartbeat. I dont know if any one has performed this task with any success.

 

[dfkrug]

, the existing ring and pinion do not show excessive wear or sharp edges.

So Tom, to be clear, the gear that is stuck on the shaft is the big one in
my photo? I assume you bought that gear and the shaft, but you also
already bought a new ring/pinion pair? Have any photos of the damage?

It IS a much bigger jpb to remove the ring gear/differential, so I understand
why you don't want to do that. You have to take off the axle
housings to get the diff basket out.

It is certainly not recommended that you change only the pinion gear and
not the ring. But, if you decide to do so, go thru the shimming process and
paint the gear faces for proper contact. One thing in your favor is that
your tractor's final drive goes thru one more huge gear reduction before it
turns the wheels. This significantly reduces the forces on the ring/pinion
gears.

 

[jdjunk]

Thank you dfkrug for the reply. Yes, the large gear pictured was stuck, I was able to press it off the pinion shaft to revel the damage. I purchased the pinion and ring set, new gear, sleeve and a new bearing, I also picked up more shims. I had all intentions to make sure the pinion was shimmed as per JD specs. I am not the type of person to do a half-*** job but to me it does not look to be necessary to change the ring gear with all the work involved. I have seen and changed some bad ring and pinions before. This is not much different then a car or truck diff, just more things to take apart to repair it. If I cannot get the old ring and new pinion to mess properly I will be sure to replace the ring. By the looks of your pic, you have already gone through what I am doing. I do not have any pics of the damaged parts as of yet, but will post some soon. I still do not know how some thing like this got damaged, the pinion sits in six gallons of oil! I was driving along the road way in high gear and the machine came to a dead stop, after that nothing but low gear.

 

[dfkrug]

I still do not know how some thing like this got damaged, the pinion sits in six gallons of oil! I was driving along the road way in high gear and the machine came to a dead stop, after that nothing but low gear.

My theory is that part of the PTO clutch/brake system came apart and
lodged in the gears. If you followed my 4300 thread, I found some debris
in my gears, but not enough to break them. In my B21 thread, the
final drive ring gear was destroyed....pieces of the parts that caused the
initial failure were in the sump. The other broken gears were removed and
discarded by the dealer who did the first analysis.

If you DO decide to remove the axle housings, the hardest part by
far was getting the brake levers off the shafts. I would probably do what
you are considering: see how the new pinion matches up with the old
ring gear and likely go with that.

 

[arrabil]

I would replace the ring. They're a matched set for a reason in my opinion. But you sound like you know exactly what you're doing so....

 

[AKfish]

A thousand hours isn't a whole lot in the life of a tractor but it is enough to get parts to wear enough that they're "married".

And when you replace one partner with a brand new gear there's bound to be some uneven meshing of surfaces and the load (forces) along the gear face are not distributed uniformly.

That can cause an increase in the rate of wear on both gears and/or earlier failure.

That said; if you paint the gear surfaces and they do in fact "mate" -- well, then; that's a "match made in heaven"!

Good luck and please post with details of how everything works out.

AKfish

 

[dfkrug]

And when you replace one partner with a brand new gear there's bound to be some uneven meshing of surfaces and the load (forces) along the gear face are not distributed uniformly.

I did not get into all the detail I went thru when replacing the ring and
pinion gears on my B21, but I did buy extra shims from Kubota to get the
mating pressures right. The first time I installed them, the pinion shaft
was binding a bit, so I had to take it all apart and change the shim
combo to get some more clearance. Thankfully, I was right on on the
2nd assembly. I am not always that fortunate.

 

[jleonardwv]

I feel like I have a problem with the assembly pictured by @dfkrug. I am pretty much a novice and never split a tractor. My gears whine/drag in all ranges (A,B,C) and all gears (1,2,3). I thought maybe it was my hydraulic oil, so I drained it all, replaced the filter and suction screen. When I took the suction screen out, that area was filled with bits of aluminum, which I removed. Since the previous owner claimed to have replaced the transmission, I thought maybe this was leftovers from previous work. I also found a single ball bearing. Didn't think much of it. Refilled the machine with new oil. Still dragging/whining. I thought maybe too much hydraulic oil, so I drained about 1/4 qt at a time to see if I could get it to quit whining. No luck, but I did find another ball bearing.

Looks to me like if one of the bearings in the assembly shown by dfkrug was losing balls it would cause every gear to whine?

Can you help me with a diagnosis?

 

[Zebrafive]

Since whine/drag is in all gears/all ranges, it MIGHT be a problem in your rear axle?
I would try driving and then apply just one rear wheel brake, then the other. See if that makes any difference. If it does, the side that was braked and stopped the whine would be side I took apart.
You need to find where those balls came from before you have any (more) damage.

 

[dfkrug]

Looks to me like if one of the bearings in the assembly shown by dfkrug was losing balls it would cause every gear to whine?

Clearly, one bearing has failed, and this has caused some mis-alignment of gears. Since it happens in all ranges, it is most likely the main shaft of the trans, which turns in every range. Regardless, you need to stop driving it before you break a gear ($$$).

When you split the tractor, you should check for smoothness of all bearings. They are not expensive, but gears are.

Also note that if this happens in neutral on range selector or neutral on gear selector, you may be able to deduce which shaft is likely to have the bad bearing. You still have to open it up to find it.

 

[jleonardwv]

@Zebrafive, The balls were smaller than 1/4" diameter, so I'm thinking wheel bearings would be larger?

@dfkrug, I put the tractor in neutral range (ABC) and tried all the gears (R123) and got the whine/drag every gear. I put the tractor in neutral gear (R123) and tried all the ranges (ABC) and I heard no whine/drag.

When you say "split the tractor" this is a bit intimidating since I've never done it. So, if I split it myself, replace a bearing or two and put it all back together, I'm guessing it's less than $100 repair. I could get the service manual and give it a go over winter. I'm in no hurry. Can it be done without any special equipment? You mentioned a fork lift in your 4300 rebuilt thread. Since I've never split one before, is it something that a guy could do with a little patience?

If not for the novice, any idea what a dealer would charge assuming only the bearings are bad?

 

[beenthere]

jleonard
You can see a 4200 split in this thread..
https://www.tractorbynet.com/forums...erating/428810-jd-4200-wont-go-forward-3.html

A couple fabricated stands for the rear, and couple with wheels for the front bolted up will work.. have ability to adjust up/down for alignment and a flat floor to work from.

Figure a dealer's shop will have to go through the same tear-down time as you, and prolly $150 an hour shop time, likely a $3000 dollar job. But would be best to talk to your dealer of shop mechanic to find out for sure.

For a service manual in .pdf format, contact member "joecdeere" with a PM and send him your email as he just might be able to get you a copy for the 4200. He has been very generous and helpful to members here, if he has the right manual available.

 

[Zebrafive]

You had not stated the size of the balls, so I was trying to guess what would cause a whine in every gear and range.
You should replace every gasket, o-ring, packing, rubber washer you disturb when you split. Your tractor may have sealant rather than gasket(s). Spend some time at JDparts.com I doubt you will have less than $100 in repairs.
Special equipment; main thing will be splitting stand, then you "might" need bearing puller, snap ring pliers, o-ring picks. I assume you have metric tools.


If you really wanted to do some "leg work" you could find the P/Ns for all the bearings and if your local JD dealer has them in stock so you can check the balls you found and see if they match any bearings.

 

[DLTTrekkers]

Mybe even in 4x4 ? And tyres do not match ?

 

[jleonardwv]

Mybe even in 4x4 ? And tyres do not match ?

Mine is 2WD, which I guess simplifies the repair?

 

[dfkrug]

In splitting the tractor, it is nice, but not necessary to have another tractor or forklift to move the halves around. It is harder, but not impossible to do that with a cherry-picker engine lift and some helper(s). I have no helpers and do not use cherry-pickers since I have a tractor and an overhead hoist/trolley in my workshop.

I do not make any special dollies to support the split halves. I do use an hydraulic floor jack with wheels. It is important to have a level paved surface to work on, but plenty of folks do everything outside on the dirt. THAT makes it a lot tougher, IMO, and you add the cleanliness challenge.

 

[jleonardwv]

Finally have time to work on my 4200 with presumably bad ball bearings. I've gotten everything necessary taken off (almost) and need some advice on the split. I'm planning to split at the rear, since I assume I need only access the rear drive. (previous owner said JD dealer did the clutch)

Now, I'm planning to tightly wedge the front axle so it can't pivot. Support rear with jack stands. Use a floor jack to support the front half. Remove all bolts holding the halves together. Carefully roll the front forward and support it with jack stands. Anything I'm missing?

 

[dfkrug]

Sounds like you are almost ready. The project is easier if you remove anything in the way, including body panels, electrical wiring, etc.

I am splitting a Kubota B20 right now, and this time did not use a rolling floor jack or forklift. This time I am splitting inside the workshop and this tractor is like no other, so far. I can't emphasize enough how useful it is to use the front and rear wheels to guide the castings apart and together.

Now starts the wait for parts.