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Discussion Starter #1
I am chasing a vibration issue that I believe is coming from the rear end. It's more pronounced at speeds above 60mph. I like to cruise around 70 mph. When I'm driving alone, I can see the passenger seat back shaking and if I have a bottle of water in the cup holder, you can see the vibration in the water.

I have replaced the carrier bearing and U-joints I believe 2 years ago and had it balanced by the driveshaft shop. All the driveline components were replaced with Spicer stuff.

What I've been noticing lately is the rear end of the truck starts to bounce when I apply the brakes. I am wondering if the drums are out of round or have a balance issue. There is no steering wheel shimmy or pulsation in the brake pedal. Or something going on with the rear end.

I was thinking about taking the rear driveshaft off and running in with the front wheel drive. Could I bring the front end up to 70 mph?

Anyone know what the pinion nut torque suppose to be? Is the pinion a crush type collar? I'm wondering if it backed off slightly?

I need help on this as I have a 2000 mile round trip coming up in 2 weeks and hopefully I can figure this out. All the shops and mechanics I spoke with, don't really want to be bothered with this.

Oh yea, I put the truck on jackstands and drove up to 70 mph and the vibe was there. To eliminate the tires/rim, I took them off and put all the lugs back on....the vibe was still there.

I'm at wits end on this. I also took off the traction bars in order to isolate this issue. I do have the carrier shimmed down 1" (have it like that for years). I have played with shimming the carrier down, up and removing the shim with no difference in the vibration.

Billy T.
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Don't EFN worry about it
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yeah you can run 70 mph it will not hurt anything .
 

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Discussion Starter #3

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Don't EFN worry about it
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I meant you can run the front end to 70 mph.
 

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Demon Dually
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In order for the pinion to have backed off enough for it to cause vibration you would be able to take the driveshaft and move it up and down with noticeable movement. Take a block of wood and put the rear up on jackstands again and put the truck in neutral. Place the block of wood right up nest to the tire on the side of it and slowly rotate the tire and watch for the tire either pushing against the block of wood or moving away from it. Repeat on other side. That will tell you if you have a warped rotor or bent axle.
 

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Discussion Starter #6
UPDATE:

Found the problem......all the tires had atleast 5-6 broken belts/cords. The bad tires were Coopers ATR 265/75-16 with 30K on them. Plus they were dry rotted after 2 years.







Billy T.
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Wow, that sounds just like my truck. I just did the rear brakes and it helped a bit. Had a tire blow a sidewall and on my spare waiting on my new tires to arrive. I hope that my problem is the same so my vibration will be gone as well!
 

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Demon Dually
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That is the sixth or seventh set of Cooper tires that I have read about them having blown a belt in the last couple days. That's not a good sign for Cooper.
 
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