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Slack in my rear-end

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Question on B12 rear-ends. The rear-end on my B12 has slack in it. If you have it stopped and in gear you can rock the tractor about 1 to 2 inches without turning the drive pulley. You can also notice it driving on uneven ground. Also the tube axle on the differential side shifts in and out about a 1/8 of an inch. Words of wisdom concerning the cause and cure would be most welcome. Tim

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At my age it's practically dragging the ground!
Seriously, Tim, I've noticed this on many Sovereign-style tractors, and attribute it to the long gear train. If the axle has no unusual noises or such, I wouldn't worry much given its age. I think though that the loose tube is cause for concern, but don't know more than that.

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This problem is fairly common. the side play is cumulative from wear in the case and thrust washers on the drive axle tube. These often leak because of wear in the bushings and on the tube.
Slack has several causes. The first is as Fred said due to the long train of gears. The second cause is slack in the square keys in the final drive. If you pull the differential off you will probably find the keys that hold it from turning are hourglass shaped from rocking in the keyway. You probably will find the keys in the big final drive gear on the axle tube may be worn also. The slack in these keys often are the start of a stress crack that is normally the cause when the axle tubes break. In the newer series 7000 the keyway was modified to reduce the axle tube failures. Third the keys in the inner differential gears also often have slack, plus the backlash in thes gears all provide quite a bit of backlash for the whole drive train. In our shop we NEVER reuse any of these keys because when they get slack they hammer on the axle tube when going from fwd. to rev. When I used to commercial mow with dual 6-12 ag tires and 100 lb lead weights in each wheel, we ran these tractors as hard as they could be ran, including full fwd to full reverse, and in 9 yrs. we probably broke 6 axle tubes. When they break you have FREE WHEELING. We took some exciting rides down through the tombstones. Hope this sheds a little light, Good luck. Al

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Al, This tractor is used for mowing, tilling, snowblowing, and sometimes with a dozer blade. Should the rear-end be torn down and these keys replaced. Also should the side play in the axles be corrected. I'd like to avoid a failure. Tilling in this rocky PA soil can shake the H out of the rear of the tractor. I don't know if the side play was in the axle before tilling this spring. And Fred I knew someone would have to come back on that message title and I was counting on you or Jack to do it. Tim

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Hi tim, I went thru my whole differenial and replaced all the gears-spacers-washers and all keys-and the axle gears. Personally I feel everyone should inspect all keys and keyways for wear and replace every part as needed on your axle tube-diff.-axle shaft as you will some day end up just setting on your tractor taking the ride of your life as Al stated. I found my diff. gears all wore out and also some of the keys were rocking back and forth in there keyways. I ended up replaceing the axle shaft while I was at it. The tube was replaced about 2 years ago and now I don't have but about half as much play and I also added springs to the diff while I was at it. Good Luck ->jackl-happyjack<-

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