JD 855 MFWD Frt Spindle Broken Spider gears

[thiel17]

Trying to help a friend. JD 855 R-4 frt's, Turf rears,Belly mower, FEL.
1st time - Dropped bearings out of LS assem - Rebuilt Spindle - All good
2nd time - Knocked teeth off LS Spindle top spider gear - Replace/Rebiuld - All good
3rd Time - Knocked teeth off same LS Spindle top spider gear and drive axle internal splined spider gear !!

Though I missed a shim or snap ring, reviewed all assemble drawings, had all parts installed correctly.

Something has to be moving or need to reshim, backlash needs to be tighter.

Any help would be greatly appreciated !! Thanks.

[Mechanos]

How is the tractor being used when this breakage is happening?

[RoyJackson]

You need the tech manual for this kind of work.

BTW, R-4 Industrials on the front...turfs on the rear? Good possibility the front/rear ratio required for MFWD is wrong and may be overstressing the front axle gears.

[Mechanos]

You need the tech manual for this kind of work. Missing a shim or snap ring isn't a minor issue.

BTW, R-4 Industrials on the front...turfs on the rear? Good possibility the front/rear ratio required for MFWD is wrong and may be overstressing the front axle gears.

Good point, Roy. OP did not mention what size tires on the tractor. When I got my 955 it had R1s on it. It uses 11.2-16 rears and 7.00-12 fronts. Someone had put a 6.00-12 on one side and a 6-12 on the other. Two completely different size tires and both of them the wrong size. The front d-shaft was out of it and before I reinstalled it, I made sure to replace both fronts with the correct size 7.00-12 tires. The rears were almost bald and I needed rears with better traction. I had a set of 12-16.5 R4's off another tractor, and before installing them, I made sure to measure them both for height. They were very close, so I went ahead and installed the R4's until I can get a new set of R1 rears.

[thiel17]

Mechanos - The 2nd time it broke the tractor was holding a broken square bale of hay on flat grd. Not sure if 4wd was engaged at that time.
I need to check tire size, although time intervals between falures has become shorter and shorter. Kind of strange.

Roy - I have tech manual, exploded views, parts lists, part numbers, part quantities. Not missing or forgetting any parts by looking at all that info, so ??

Pretty frustrating ! Please keep throwing ideas my way. I feel like there is too much backlash in the assembly ??

[RoyJackson]

Roy - I have tech manual, exploded views, parts lists, part numbers, part quantities. Not missing or forgetting any parts by looking at all that info, so ??

Pretty frustrating ! Please keep throwing ideas my way. I feel like there is too much backlash in the assembly ??

Your first post:

Though I missed a shim or snap ring, reviewed all assemble drawings, had all parts installed correctly.

Was that supposed to be "Thought"?

[thiel17]

Roy - Yes "Thought" wow I "fat fingered" that one

[Mechanos]

Mechanos - The 2nd time it broke the tractor was holding a broken square bale of hay on flat grd. Not sure if 4wd was engaged at that time.
I need to check tire size, although time intervals between falures has become shorter and shorter. Kind of strange.

Roy - I have tech manual, exploded views, parts lists, part numbers, part quantities. Not missing or forgetting any parts by looking at all that info, so ??

Pretty frustrating ! Please keep throwing ideas my way. I feel like there is too much backlash in the assembly ??

"Holding a broken square bale".... holding it how? FEL? on the 3pt? How much would you say that square bale weighs?

What I'm getting at is this.... if you've got a substantial amount of weight on the FEL and do not have enough or any ballast weight hanging off the rear of the tractor, the rear axle becomes pretty light and offers very little tractive effort. You are then asking the front axle to provide the lion's share of the tractive effort to move the tractor. This can easily overwhelm the front axle drive components and send them crying to mommy.

[thiel17]

Sq bale = 35lbs I know what your saying. This friend's unit has no ballast, always has belly mower and FEL on at all time never takes it off. I have same machine (855) belly mower no FEL no problems at all R-4's frt and turf rears