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Truck having bouncing problems on take off from a stop sign
03-07-2012, 02:47 AM
Post: #1
Truck having bouncing problems on take off from a stop sign
When i stop at a stop sign, or red light, and start to go again, if i press my gas pedal more than 1/4 of the way, my whole rear end bounces REALLY BAD and the truck will not even spin the tires. It will move but not like it should. This only happens on dry pavement. If im in the gravel i can floor it and it will spin all day. Its only on dry pavement,,, Ive checked the u-joints, carrier bearing(which is bad), and i looked at my rear end and changed the differential oil WITH the friction modifier. Do you think this carrier bearing is my problem? Im in the middle of changing it BTW. Also there was a little up and down slack in my pinion bearing on my rear end. PLEASE HELP ME!!! Thanks James.
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03-07-2012, 11:14 AM
Post: #2
RE: Truck having bouncing problems on take off from a stop sign
Can't say as I have ever seen carrier or pinion bearings cause something like that over my 40 years in the business but there's always a first time. Wink

Usually rear end shudder is caused by excess slack in the various suspension busings or worn shocks as the load changes. If you had someone watch from the outside when this happens it looks like a rapid wheel hopping and most obvious on a hard surface. In gravel or sand you just get some wheel spin so the hop is not as easy to see.

Another thought that comes to mind is due to the excess wear in the dif you may actually have internal binding under heavy load. In this case the entire dif housing may "wind up" on the springs and exceed the normal drive shaft angle, which will cause the u-joints to bind. Either way, I figure you will need to do the dif work and see what happens afterward.

Let us know how you make out. Stuff like this helps others learn from your experience.
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03-07-2012, 01:47 PM
Post: #3
RE: Truck having bouncing problems on take off from a stop sign
(03-07-2012 11:14 AM)Rupe Wrote:  Can't say as I have ever seen carrier or pinion bearings cause something like that over my 40 years in the business but there's always a first time. Wink

Usually rear end shudder is caused by excess slack in the various suspension busings or worn shocks as the load changes. If you had someone watch from the outside when this happens it looks like a rapid wheel hopping and most obvious on a hard surface. In gravel or sand you just get some wheel spin so the hop is not as easy to see.

Another thought that comes to mind is due to the excess wear in the dif you may actually have internal binding under heavy load. In this case the entire dif housing may "wind up" on the springs and exceed the normal drive shaft angle, which will cause the u-joints to bind. Either way, I figure you will need to do the dif work and see what happens afterward.

Let us know how you make out. Stuff like this helps others learn from your experience.

Somebody else told me that my shocks could make it do this. Ive checked the inside of my differential and everything looks to be okay. I even changed the fluids AND added friction modifier. Is the shocks rumor true?
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03-07-2012, 11:03 PM
Post: #4
RE: Truck having bouncing problems on take off from a stop sign
If you re-read Rupes post, the second thing that he mentions is "Shocks."

I would like a little more information. Model? Year? Mileage? Transmission? 2 or 4 wheel drive? Any Modifications like a lift kit, over sized tires, etc.?

A slipping clutch on a standard or a slipping automatic transmission, or a failing transfer case can cause a shudder and lack of spinning on a hard surface. That's where knowing something about the truck helps us to give better advice.

Please get back to us.

Thanks for using the forum,
Garner

Interested in Mining? Look here: Coal Mining, PA
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03-07-2012, 11:52 PM
Post: #5
RE: Truck having bouncing problems on take off from a stop sign
(03-07-2012 11:03 PM)Garner Wrote:  If you re-read Rupes post, the second thing that he mentions is "Shocks."

I would like a little more information. Model? Year? Mileage? Transmission? 2 or 4 wheel drive? Any Modifications like a lift kit, over sized tires, etc.?

A slipping clutch on a standard or a slipping automatic transmission, or a failing transfer case can cause a shudder and lack of spinning on a hard surface. That's where knowing something about the truck helps us to give better advice.

Please get back to us.

Its a 1995 Dodge ram 1500 with a 5.2 v8. My transmission was just rebuilt three months ago. Its got no lift and completely stock. Two wheel drive
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03-08-2012, 01:06 AM (This post was last modified: 03-08-2012 01:09 AM by Rupe.)
Post: #6
RE: Truck having bouncing problems on take off from a stop sign
Yes, the shock issue is true. You also stated you were doing the carrier bearings and there was axial play (up and down) on the pinion, so you need to do the repairs anyway. This is stuff you can't see just by taking the cover off and doing a quick inspection, although if the cover is off you may find "metal flake" on the magnet or in the oil. That's a clue as to the problem.

BTW, I have found over the years that 90% of the time you can just replace bearings and get away with it. Don't let the job scare you. It's really not all that bad unless you can see obvious wear on the face of the gears. The hardest part is going to be setting up the preload on the pinion bearings and I can give you a few pointers on that as well.

Edited to ask: was that friction modifier for a "posi" type clutch or just a friction reducing agent?
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03-08-2012, 11:58 AM
Post: #7
RE: Truck having bouncing problems on take off from a stop sign
(03-08-2012 01:06 AM)Rupe Wrote:  Yes, the shock issue is true. You also stated you were doing the carrier bearings and there was axial play (up and down) on the pinion, so you need to do the repairs anyway. This is stuff you can't see just by taking the cover off and doing a quick inspection, although if the cover is off you may find "metal flake" on the magnet or in the oil. That's a clue as to the problem.

BTW, I have found over the years that 90% of the time you can just replace bearings and get away with it. Don't let the job scare you. It's really not all that bad unless you can see obvious wear on the face of the gears. The hardest part is going to be setting up the preload on the pinion bearings and I can give you a few pointers on that as well.

Edited to ask: was that friction modifier for a "posi" type clutch or just a friction reducing agent?

I'm not exactly sure. I would really like some help with the pinion bearings... it does scare the crap out of me haha
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03-08-2012, 12:02 PM
Post: #8
RE: Truck having bouncing problems on take off from a stop sign
If you can handle a hammer, punch, and have access to an inch pounds torque wrench then all you need besides that is to have someone press the new bearings on. It's actually not to hard if you understand what needs to happen.
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03-08-2012, 12:08 PM
Post: #9
RE: Truck having bouncing problems on take off from a stop sign
What do I need to take off to get to the bearinggs
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03-08-2012, 09:09 PM (This post was last modified: 03-08-2012 09:14 PM by Rupe.)
Post: #10
RE: Truck having bouncing problems on take off from a stop sign
The basics are to jack it up and support it as if you were going to do a brake job, remove the wheels, drums (discs?), remove the cover plate and catch the drain oil. Disconnect the drive shaft then spin the pinion yoke till you see the small bolt for the cross shaft in the carier. Take out the bolt, slide the cross shaft out, and now you are ready to remove the "horse shoe clips" that retain the axels. Push each axel in a half inch and you will probably hear the clips fall. Fish them out with a magnet or fish them off the axels then slide the axels out about 6 inches. It's ok to leave them hanging like that unless you are prone to walking into things. (can be shin bangers in a small garage) Spin the small gears around and fish them out one at a time, noticing where the shims go. Place all of these parks into a brownie pan, then cover.

At this point you remove the bearing caps for the carrier and keep everything in order. I use a couple of punch marks to designate left / right and then place everything in the brownie tin then cover it up again Using a LARGE screwdriver or crowbar you can now pry out the carrier. It's heavy and has sharp teath so use a shop rag or heavy work gloves to catch with one hand while you evenly pry with the other. There may be shims that fall out as you pry. Keep an eye on which ones are on which side for later.

Hint: I usually place a large flat cardboard on the ground so if I have to put anything down it stays clean.

Now you are down to removing the pinion shaft itself. You will need the proper size socket for the center nut and a rather large pipe wrench to hold the yoke if you don't have shop air and an impact gun. What I do first is count the exposed threads on the nose of the pinion (write it down) then using a punch I mark the edge of the nut and the edge of the shaft so you know EXACTLY where that nut sits. (this is aproximately where you will tighten it to later) Now you remove the nut, bang off the yoke (you may need a puller in some cases) then drive out the pinion shaft with a hammer and large punch.

Hint: place shop rags in a pile inside the housing and on the floor in case it flies out. This will help prevent damage.

Now that the pinion is out you can pry out the pinion seal and pull out the front bearing with your finger. After that use a long punch to bang out the two pinion bearing races. The bearing and shim / spacer that remain on the shaft will need to be pressed at a machine shop, and so will the two bearings on the carrier.

'nuther hint: don't put dirty parts like the drive shaft yoke in the brownie pan. This is for "clean" internal parts only!

OK, if you have a grasp and I have not scared you yet just let me know and I will post more on the reassembly part. If you feel I am getting over your head then it's time to seek professional help. Also remember that if you feel the gears themselves may be too worn then you should seek a junk yard "complete" unit or outside help. If the rear end already hums at highway speeds you probably have too much wear for this DIY repair and should seek another assembly either at a junk yard or new.
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