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D4-7 Bush Hog Rear End Troubles.

5K views 42 replies 5 participants last post by  VTXrider 
#1 ·
You may remember from last year I bought this bad boy for my daughter on her farm. The rear end (or differential) is binding as if there is a broken gear tooth or maybe a bearing is bad. Looking at the transmission, all gears are in good condition, even the shifting cluster gear (this is what I though may be broken). When rotating the wheel, it will bind in all gears at a certain point but I can rock through the bind but it will then bind in the opposite direction.

My concern is whether it is worth pulling the axles out and finding something I cannot repair or replace. Should I strip it for parts? It has been a great little work horse for her. She loves this thing for some reason.

Any comments are welcome.
 

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#2 ·
Sounding like the ring & pinion is screwed up. If that's all it is, I'd find a good used rear end to put under her. They are out there, just takes some time. I'd not strip it for parts. Even though kinda rare, the Bush hog parts don't command much money when selling. OH....did you check in both high & low ranges? I still figure it's the ring & pinion, as the hi/lo is on the pinion shaft.
 
#4 · (Edited by Moderator)
About a 99.999999% chance it is the ring gear. Like Daniel says they are out there, just hard to find. Take the rear end off and check. The cluster gear looks fine from what I saw.

I was considering at one point to see if one of the early cub cadet rear ends would work. From what I understand they were pretty stout rear ends. If it was my gt, that is the route I would try to go. If you get another bush hog rear end, good chance with the fel you will break another ring gear down the road. You have a nice set up with your d4-7. To nice to part.

Let us know what you decide, will try to help you either way.
 
#5 ·
Sorry, I realized you said the cluster gear did look good.

I have a D4-7 and a T-63 with the rear ends out. I have all the parts including a NOS ring gear. Just got to find the time to do it.
I know of another NOS ring gear. The guy wants $150 for it. I told him earlier i would be willing to pay $100 and he did not take it. I am sure he still has it.
 
#8 ·
Sounding like the ring & pinion is screwed up. If that's all it is, I'd find a good used rear end to put under her. They are out there, just takes some time. I'd not strip it for parts. Even though kinda rare, the Bush hog parts don't command much money when selling. OH....did you check in both high & low ranges? I still figure it's the ring & pinion, as the hi/lo is on the pinion shaft.
I did check hi/lo range. Same thing. I can see the output shaft move when it is binding.
 
#9 · (Edited by Moderator)
Those tires look huge!!! I hope they didn't cause this problem!
They may have caused the problem just from the traction. The diameter is about the same as originals.

Note: These tires are smaller in diameter so the front and rear can turn at the same ratio needed by the front drive. They would be fighting each other otherwise.
 
#10 ·
About a 99.999999% chance it is the ring gear. Like Daniel says they are out there, just hard to find. Take the rear end off and check. The cluster gear looks fine from what I saw.

I was considering at one point to see if one of the early cub cadet rear ends would work. From what I understand they were pretty stout rear ends. If it was my gt, that is the route I would try to go. If you get another bush hog rear end, good chance with the fel you will break another ring gear down the road. You have a nice set up with your d4-7. To nice to part.

Let us know what you decide, will try to help you either way.
If I went to another rear end, I would lose the 4WD option. The fel is used as more of a wheel borrow than anything else. Scooping horse poop and transporting it to a pile out back. The nice part is the scraper to clean the padock.
 
#11 ·
Do I have to remove the complete rear end to access the ring and pinion gears? Can I unbolt the axle plates to do that?
 
#14 · (Edited by Moderator)
You know, it could be in the front wheel drive. Maybe you should drop the drive off the front first to see if the problem is up there.
The front drive can be disengaged with a clutch lever. In fact, I told my daughter to not use the front drive unless traction is needed. It seems to put quite a load on the old girl when engaged. The front axle seems to be posi-traction or limited slip. It is nice the front drive can be disengaged.

The binding seems to occur at a longer rotation of the wheel that what the pinion would produce. Hoping it is the ring gear.
 
#15 ·
My T-63 had the same type of symptoms, pinion gear looked good, ring gear was damaged. It would catch one way then rotate back the other way catching again. It would rotate all the way around but would catch on each rotation.

I was thinking the axles are bolted to the frame? I guess you could pull an axle tube off with transaxle attached.

Look at the manual regarding these transaxles, I think there is one side that is the better side to pull off the axle tube to get access to the differential.

Hope you get it figured out!
 
#16 ·
My T-63 had the same type of symptoms, pinion gear looked good, ring gear was damaged. It would catch one way then rotate back the other way catching again. It would rotate all the way around but would catch on each rotation.

I was thinking the axles are bolted to the frame? I guess you could pull an axle tube off with transaxle attached.

Look at the manual regarding these transaxles, I think there is one side that is the better side to pull off the axle tube to get access to the differential.

Hope you get it figured out!
They are bolted to the frame with U-bolts. Unlike my 990s, which mounts the transmission to the frame leaving the axle tubes more accessible.
 
#17 ·
Sorry, I realized you said the cluster gear did look good.

I have a D4-7 and a T-63 with the rear ends out. I have all the parts including a NOS ring gear. Just got to find the time to do it.
I know of another NOS ring gear. The guy wants $150 for it. I told him earlier i would be willing to pay $100 and he did not take it. I am sure he still has it.
If you could connect me with your ring gear guy, I would be interested in buying it.
 
#18 ·
Looking at the manual, it indicates that the ring and pinion shaft are a matched set and should be bought together. What are my chances of problems if I get just the ring gear?
 
#19 ·
Looking at the manual, it indicates that the ring and pinion shaft are a matched set and should be bought together. What are my chances of problems if I get just the ring gear?
I don't know. Chances of finding a matched pair is pretty rare unless you find a used set. I am going to have to put mine together and it will not be a matched set. Will see how it works out.

I can see if he still has it.
 
#20 ·
Got the rear end apart and examined. While draining the oil, pieces of metal fell out. Once apart, the bottom of the case was littered with metal.

Removing the right side axle tube gave access to the gear cluster and it slide right out. The pinion is pretty beat up but not broken. The ring gear is destroyed. A new gear is in order and SACSR has offered to sell me a used but repairable unit.

Thanks for giving me the confidence to tackle this.
 

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#22 ·
Looks like what I saw on my other transaxles with issues. I will search for the part over the weekend. I am leaving early in the morning to go to Denton so will not have a chance to mail it. PM me with your mailing address, etc and I will send it asap....if they are open Saturday Hopefully I can find it and ship it then.

I have access to pinion gears as well....so let me know. From what I have seen the pinion gears usually look pretty good.....the major damage is always to the ring gear.
 
#23 · (Edited by Moderator)
Wow, Not wonder if was binding with the way that ring gear looks. Be sure to inspect those bearings and races for damage also.
Brian good idea.....my plan on putting mine back together is to check it with out a load first to make sure it is not binding.....then test it again with a load.......definitely need to watch it for a while to make sure it is connecting well. Since both of my transmissions are completely torn apart, I am replacing most of the bearings while I am there. They seem to spin freely with almost no play.....but figured I would get it done while it was already broken down.

Just a note about the axle on this unit. This is the earlier version, the axle housing are lighter steel and the axles are held to the frame by ubolts.

Also these mounts slide on the axle tube cover......the next version had the mounts welded to the axle tube cover....and the final version had a caste iron/steel axle tube cover and the mounts were cast into the cover.....the last one is much heavier and probably only found on the D4-10's.
 
#24 ·
What would cause this much damage to the gear? Could there be too much strain by adding the front wheel drive from the parking break drive shaft? Should I disconnect the front drive? Any comments welcome.
 
#25 ·
There should be no added strain on the ring & pinion IF the FWD is geared close to the ground speed of the rear wheels. The load on the park shaft can't affect the pinion in itself. But if ground speeds are different, then the front end will be fighting the rear.
 
#26 ·
To check the gearing between the front and back, I could measure 1 rotation of the front tire and apply that measurement to a marked point on the rear tire. If it is close then all is well. If not, then I will disconnect the front drive.

The work the PO did to modify this tractor is done well, I would think he did his math on this also. The gearing is determined by this sprocket setup to the front drive.
 

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