Rear end issues
Thread Starter
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Mountain Pass
Joined: May 2011
Posts: 235
Likes: 1
From: Alamo, TN
Rear end issues
I'm looking for some advise fellas. I have a vibration coming from my rear end. I don't have any slack in the U-joints, so I'm thinking its the carrier bearing.
Is it a nightmare to swap out the carrier bearings?
Should I just get a complete rear end from the salvage yard?
can someone point me in the right direction please.
Is it a nightmare to swap out the carrier bearings?
Should I just get a complete rear end from the salvage yard?
can someone point me in the right direction please.
Laughing Gas
Joined: Aug 2010
Posts: 979
Likes: 40
From: Colorado Springs CO
There's 2 kinds of carrier bearing.
A 2 piece driveshaft has a carrier bearing in the middle (bolts to the frame & holds up the driveshaft). That is fairly easy to change & can cause big vibrations if bad.
There's 2 differential carrier bearings in the rear axle. These don't go bad very often, but when they do, it's major surgery. The complete axle has to be dis-assembled, and the bearings pressed on & off.
A 2 piece driveshaft has a carrier bearing in the middle (bolts to the frame & holds up the driveshaft). That is fairly easy to change & can cause big vibrations if bad.
There's 2 differential carrier bearings in the rear axle. These don't go bad very often, but when they do, it's major surgery. The complete axle has to be dis-assembled, and the bearings pressed on & off.
Thread Starter
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Mountain Pass
Joined: May 2011
Posts: 235
Likes: 1
From: Alamo, TN
There's 2 kinds of carrier bearing.
A 2 piece driveshaft has a carrier bearing in the middle (bolts to the frame & holds up the driveshaft). That is fairly easy to change & can cause big vibrations if bad.
There's 2 differential carrier bearings in the rear axle. These don't go bad very often, but when they do, it's major surgery. The complete axle has to be dis-assembled, and the bearings pressed on & off.
A 2 piece driveshaft has a carrier bearing in the middle (bolts to the frame & holds up the driveshaft). That is fairly easy to change & can cause big vibrations if bad.
There's 2 differential carrier bearings in the rear axle. These don't go bad very often, but when they do, it's major surgery. The complete axle has to be dis-assembled, and the bearings pressed on & off.
So the complete rear would be the easier.
sorry I forgot to post that my truck is a 94 xlt, reg cab, short bed, F150.
Can someone tell me what to look out for when swapping a rear. my tag says 3.55 8.8.
Fleet Owner
Joined: Oct 2005
Posts: 20,783
Likes: 1,751
From: Kentucky
Major surgery? It's not that bad of a job. Before throwing money at the problem drain the fluid then remove the rear cover. Look for signs of metal flakes in the fluid and in the bottom of the axle housing. A bad bearing will typically fill the fluid with metal flakes.
Laughing Gas
Joined: Aug 2010
Posts: 979
Likes: 40
From: Colorado Springs CO
I dunno-for a novice it would be quite a job. Pull both axles, remove the carrier, press the bearings off & on, fight the carrier back into the housing...
The other problem is, if the replacement bearings differ from the old ones by even a few thousands of an inch, then you get into re-shimming the carrier (I've seen that more than once).
I agree that it would be time well spent to pull the cover and inspect everything closely-it may be some other problem entirely.
The other problem is, if the replacement bearings differ from the old ones by even a few thousands of an inch, then you get into re-shimming the carrier (I've seen that more than once).
I agree that it would be time well spent to pull the cover and inspect everything closely-it may be some other problem entirely.
Super Moderator
Joined: Apr 2004
Posts: 34,470
Likes: 2,799
Vibrations are usually wheel balance, bent wheel, or out of balance DS, or bent DS. Bad bearings in the rear axle will a LOT of noise long before vibrations can be felt. A bearing so worn that it would cause rear axle components to vibrate like that would destroy the assembly in short order.
What speed is the vibration?
Can you tell the difference between driveshaft frequency--fast, and almost immediate--vs. wheel speed frequency--at 1/3 or 1/4 of the DS depending on your gearing, slow to start, and sometimes not there until you reach speed?
Postmaster
Joined: Jan 2009
Posts: 4,558
Likes: 2
Its a reg cab SB so it has a one piece shaft , also to check the u joints you need to remove the drive shaft , sometimes they just seize up ...
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Elder User
Joined: Jan 2004
Posts: 920
Likes: 2
From: Colville
I doubt the ring gear carrier bearings are bad as someone stated your gear set would be gone by now. If it is a U Joint problem it should almost go completely away just by pushing in the clutch when it is bad. If you have an automatic trans bump it into neutral when the vibes are bad, should go away if a bad U Joint. In other words they vibrate much worse under load than not loaded. If it is a speed related issue and just gets worse the faster you go regardless of accelerating or not, then it could be out of balance tires. It doesn't matter if they are brand new or not they could be out of round and causing your shaking. I had to have Schwab warranty 3 sets due to out of round before I gave up and just bought BFGs.
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Thread Starter
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Mountain Pass
Joined: May 2011
Posts: 235
Likes: 1
From: Alamo, TN
What happens is this. The speed doesn't really have an effect. I get a low roar and a vibration under load. If I let off the accelerator it goes away. if I'm cruising on a flat road it's almost non existent, but if I start up a grade it comes on. I don't feel it in the steering and the trucks not shaking, so i don't think its the tires. And they only have about 3500 miles since the last balance.
I've checked the u-joints for slack by, putting it into rev and the dropping it into drive, with my foot on the brake. I've also grabbed the drive shaft and tried to shake and see if there's any slack.
I replaced the fluid and conditioner about 2500 miles ago. I didn't pull the pan though. I pumped it out, but the fluid didn't show any metal.
U-joints are cheap so I guess I'll start there. I've never had one seize up, but I've had them go out before.
I've checked the u-joints for slack by, putting it into rev and the dropping it into drive, with my foot on the brake. I've also grabbed the drive shaft and tried to shake and see if there's any slack.
I replaced the fluid and conditioner about 2500 miles ago. I didn't pull the pan though. I pumped it out, but the fluid didn't show any metal.
U-joints are cheap so I guess I'll start there. I've never had one seize up, but I've had them go out before.
Thread Starter
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Mountain Pass
Joined: May 2011
Posts: 235
Likes: 1
From: Alamo, TN
I've found a rear end under a friend of a friend's truck, but he didn't know what the gear and dif it has. it's a 351 motor, did they come with the bigger gear and a limited slip or was it an option like the 5.0?
Elder User
Joined: Mar 2011
Posts: 923
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From: North Central MA
More Turbo
Joined: Jun 1999
Posts: 532
Likes: 1
From: Las Vegas
Just because there isn't any slack at the U joints doesn't mean they are still good. My front U joint was so seized up with internal rust that the cups and some needle bearings broke when I finally got it to come out. Replaced all the joints and center support bearing; driveline vibration disappeared.
Cargo Master
Joined: Jan 2011
Posts: 2,791
Likes: 8
From: Edmonton AB, Canada
i have something similar happening with my truck as well. when turning at a slow speed like just above idle it feels like there is a rubbing/grinding and a squeak comming from the back end. when driving on the road its smooth till about 110km/h then there is a vibration/rubbing sensation (its kinda like a harmonic vibration as its not constant it fluctuates if that makes sense).....there is no clunking or anything that aeems to be comming from the rear end. both tires spin when i step on it. also going from drive to reverse there is a decent clunk that happens...
FTE Chapter Leader
Joined: May 2009
Posts: 8,843
Likes: 27
From: Eastern Ky
Just because there isn't any slack at the U joints doesn't mean they are still good. My front U joint was so seized up with internal rust that the cups and some needle bearings broke when I finally got it to come out. Replaced all the joints and center support bearing; driveline vibration disappeared.
Had the same thing happen to mine....$35, and a couple of torched U-Joints later....I had my vibration issues resolved, and actually picked up about 1-2 mpg....
Elder User
Joined: Jan 2004
Posts: 920
Likes: 2
From: Colville
Also the 8.8 rears are known for the crush sleve on the pionion shaft to crush a bit due to thrust from the ring gear pushing it forward. If this happens you loose your preload on the pinion shaft tapered bearings. I would recomend when you pull the driveline off to check U Joints that you feel for any movment in the pinion yoke. If there is movment than you will need replace your crush sleve and torque the Yoke nut untill you have 6-7 Inch pounds of rotational torque. This may take up to 250 FT-LBS to crush the sleve. If you over crush it you must replace it and start over so go slow.