rear end
Posting Legend
Joined: Sep 2001
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Hello- Welcome to FTE! I have moved your post to the specialized forum we have here for your question. Check out the list of tech forums we have here. There is a wealth of information and expertise here to help you. There are a number of links in my sig below to help you also. Have fun! 
Elder User
Joined: Apr 2004
Posts: 970
Likes: 3
I think the first thing I would do is get ahold of the pinion yoke (where the rear U
joint is) and try and move that up and down and side to side. If you can the pinion
bearings have failed. The noise sounds to me like gear mesh noise between the ring and pinion caused by bearings allowing the gear set to come out of proper mesh. Carrier bearings don't fail very often, and the differential setup gives different problems.
When you check the pinion make sure you have it out of gear.
joint is) and try and move that up and down and side to side. If you can the pinion
bearings have failed. The noise sounds to me like gear mesh noise between the ring and pinion caused by bearings allowing the gear set to come out of proper mesh. Carrier bearings don't fail very often, and the differential setup gives different problems.
When you check the pinion make sure you have it out of gear.
Elder User
Joined: Apr 2004
Posts: 970
Likes: 3
Yes you can pull the cover and try to move the carrier back and forth (in the direction the axles run) this would tell you if a carrier bearing has failed. You can also check the
lash between the ring and pinion. This is usually somewhere around 8 to to 12 thousands of an inch. That isn't much but it will let the ring gear move and seem like it
is moveing a lot more. Kind of a fooler, I remember when I was taught to set
them up and we had no dial indicator. I always thought they were to loose,
when the shop got the indicator we were pretty darn close. One more question
did you buy this truck with the condition or has it developed?
lash between the ring and pinion. This is usually somewhere around 8 to to 12 thousands of an inch. That isn't much but it will let the ring gear move and seem like it
is moveing a lot more. Kind of a fooler, I remember when I was taught to set
them up and we had no dial indicator. I always thought they were to loose,
when the shop got the indicator we were pretty darn close. One more question
did you buy this truck with the condition or has it developed?
Super Moderator
Joined: Apr 2004
Posts: 34,472
Likes: 2,799
My '98 Exploder did the same at about 50k. Fixed under extended warranty. Poor bearings or assembly at the factory.
Check the Exploder and F150 threads, lots of diff issues.
Check the Exploder and F150 threads, lots of diff issues.
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New User
Joined: Oct 2005
Posts: 9
Likes: 0
To Kotzy, They wont let me Email direct, Bought truck new 2001, 70000on truck noise started 2000miles ago. Something new to add Was passing and speeded up to 75 and noise increased to high pitched whine. I had the rear end serviced if friction reduce was not added would this cause my problem. Thanks for your help.BWoodliff
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Elder User
Joined: Apr 2004
Posts: 970
Likes: 3
The friction modifier is for the clutch pack in the limited slip differential. Usually it is not much more then a moly additive. You would have some other symptoms making turns if it was a differential problem When I worked for a fleet that had a large # of units with LS we simply had our lubricant supplier add about 5% moly to a drum of gear oil. Was the noise there before you serviced the rear? As you change speed the load on gear set changes and so does the relationship of the ring and pinion if a bearing is loose. I neglected to ask you if this truck has a center driveshaft bearing, and also you haven't changed tire design on the rear which could be a factor.
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New User
Joined: Oct 2005
Posts: 9
Likes: 0
To Kotzy, The truck has a center bearing, I dropped the the drive shaft down today so I could turn the bearing, turned nice don't think thats a problem.I moved front tires to back,still the same. Noise just started about 2500 miles ago.May have been there before but I did'nt notice it. Noise carries to front at first I though it was in Ftont end.BWoodliff
Elder User
Joined: Apr 2004
Posts: 970
Likes: 3
Do you have access to a lift? I hate to tell you to pull anything apart until we are sure
of what we are looking for. By running the truck on a lift you should be able to pinpoint what is going on. My experience has been the front pinion bearing fails more frequently then any, however you may be in the early throws of this and thats why you don't detect any play. The next question has to be do you feel at ease with doing the repair yourself. With the crush spacer to load the pinion bearings it requires a torque wrench, or you'll have early failure. But that is another thing and I would suggest you get a manual and follow it. If it were mine I might be tempted to drive it
and see if it gets worse so it would be easier to pinpoint the cause. Your ball game.
of what we are looking for. By running the truck on a lift you should be able to pinpoint what is going on. My experience has been the front pinion bearing fails more frequently then any, however you may be in the early throws of this and thats why you don't detect any play. The next question has to be do you feel at ease with doing the repair yourself. With the crush spacer to load the pinion bearings it requires a torque wrench, or you'll have early failure. But that is another thing and I would suggest you get a manual and follow it. If it were mine I might be tempted to drive it
and see if it gets worse so it would be easier to pinpoint the cause. Your ball game.
Senior User
Joined: Oct 2005
Posts: 125
Likes: 0
From: South Carolina
Well I hope you have better luck than me, I've had this problem for over a year now and it hasn't got any worse. It's actually the second time. I replaced my rear end once, and the guy who did it apparently didn't put any oil in it, and so i'm back to square one. And I don't know what he did wrong with my rear drive shaft because that sucker blew off one day after one of the bolts sheared off. Anyway, all the mechanics who have checked it out say it is probably my bearings going out, but I'm not sure this is something I want to tackle. At least it hasn't gotten any worse, but I also wont drive it over 65mph.
Cargo Master
Joined: Sep 2001
Posts: 3,135
Likes: 0
From: Canada
check the tooth contact pattern between the ring gear and drive pionion (use persain blue, paste 5 or 6 teeth) rotate drive yoke so the ring gear makes 2 or 3 complete turns then check the toothe contact pattern, should be centered between the root and land and 1/8" from the bottom of the tooth 2/3-3/4 the way up the tooth
if the pattern isnt good, could be something as simple as adjusting nuts or something major. this will give you a good idea where to start and it wont take long, just remove the carrier from the diff by takein out the u-joints and the 8 bolts and the carrier drops out
if the pattern isnt good, could be something as simple as adjusting nuts or something major. this will give you a good idea where to start and it wont take long, just remove the carrier from the diff by takein out the u-joints and the 8 bolts and the carrier drops out