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?