GM Drivetrain & Suspension Chassis | Transmission| Driveshaft | Gears/Rear End/Differential | Traction Aids

Not So Good Vibrations

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Old Dec 23, 2006 | 08:11 PM
  #21  
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Originally Posted by CHEVRACER83
AWW I MISS YOU TOO.... SO HOPE YOU HAVE A GOOD CHRISTMAS BRO..... HOPE THE TRUCKY DOESNT MAKE ANOTHER DRIVESHAFT GO BOOM
lol I cant afford for another to take a ****! Im sooo broke!
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Old Dec 23, 2006 | 08:29 PM
  #22  
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you can get new motormounts from your local autoparts store that carries dorman producs

49.99 a pair

-Erik
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Old Dec 23, 2006 | 09:05 PM
  #23  
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Well, i can probably get my old ones back for free and they worked well before without a hiccup. I think these are bent in some way from the wreck they came out of. I swear if its not the pinion angle, im gonna light this sumbitch on fire. (ive been threatening for quite some time now.)
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Old Dec 23, 2006 | 10:48 PM
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If you think it is the motor mounts (which I doubt) that is easily measured at the tranny yoke. For one, does your tranny mount close to the same location as before?
Take side measurements of your u-joint angles on both side of your u-joints at the tranny. If you have an angle sideways, then the motor mounts could be bent.
Also, check your axle for being off to one side further than the other. Belltech makes a kit to correct this issue many have, but tend to ignore. With this being off, you can also create another side angle at the u-joint at the pinion yoke.
You can do these measurements on your own with a $12.00, 1* increment dial. I picked mine up from Sears Hardware. It's a craftsman brand. DO NOT buy the smaller 5* increment dial. It's useless.
If you can change a cam, you can do these measurements on your own. If you rather a shop do this, then that's more money your wasting.
Hope you get it fixed.

Jim
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Old Dec 23, 2006 | 11:24 PM
  #25  
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Originally Posted by CHEVY6000VHO
If you can change a cam, you can do these measurements on your own. If you rather a shop do this, then that's more money your wasting.
I had two shops perform the measurements (just to be sure) and neither one charged me a dime. It took all of about 90 seconds once the vehicle was on the lift. If it takes more they don't know what they're doing.

The verdict of the measurements was...
Tranny output shaft angle: 4 degrees downward
Pinion angle: 7 degrees upward
Angles should be equal and opposite.

I got longer lower control arms that effectively lowered the pinion 4 degrees to 3 degrees upward. This actually worked well, since power torques the rear axle upward, so under heavy acceleration, the angles would be 4 degrees each.

FYI, I don't think lowering the vehicle 2/3 made the pinion that far off, I think there was a pre-existing condition that was exacerbated by the drop. The reason I'm saying this is just because your vehicle "shouldn't" have a problem, doesn't mean that it doesn't.

Good luck - report back your results.
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Old Dec 24, 2006 | 01:06 AM
  #26  
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Originally Posted by TBSS
I had two shops perform the measurements (just to be sure) and neither one charged me a dime. It took all of about 90 seconds once the vehicle was on the lift. If it takes more they don't know what they're doing.

The verdict of the measurements was...
Tranny output shaft angle: 4 degrees downward
Pinion angle: 7 degrees upward
Angles should be equal and opposite.

I got longer lower control arms that effectively lowered the pinion 4 degrees to 3 degrees upward. This actually worked well, since power torques the rear axle upward, so under heavy acceleration, the angles would be 4 degrees each.

FYI, I don't think lowering the vehicle 2/3 made the pinion that far off, I think there was a pre-existing condition that was exacerbated by the drop. The reason I'm saying this is just because your vehicle "shouldn't" have a problem, doesn't mean that it doesn't.

Good luck - report back your results.
Very few shops would do this for free. At least here in Houston or surrounding.
I totally agree with your measurements and where you set them at. Looks about perfect to me. I'm sure you have no vibrations with those angles.
Too bad a 2-piece shaft is not as easy as a 1-piece....... As I had a custom carrier bearing bracket made for full lateral movement to get my angles exactly where they needed to be. The aftermarket carrier bearing relocator bracket raised my carrier bearing up way too high. So a custom one was built. Problems solved.

Jim
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Old Jan 19, 2007 | 09:18 AM
  #27  
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Originally Posted by TurboGibbs
I was going to suggest the jackstand run. Take the tires off while on the jackstand and see if there are any changes. Also rotate tires from back to front. Just to make sure you don't have a tire seperating internally. Sounds like a bent output shaft on the trans. maybe. You said stock yoke, as in the one that was on it when it broke? If so, that may be an easy fix with the new yoke.

I was reading threw the old posts. Have you tried the jackstands? Any separations in the belts on the tires. If you try this and the tire are still true, then I'd suggest yankin off the tires and jack the rearend up and pull the tires off and put it in gear. You should be able to hit 65 fast so take up the gas slowly.

If you're still getting the vibrations, then pull the cover and pull the shafts out of the carrier, but still leave them in the housing. Fill the diff back up with oil. This way you'll be able to run the truck while it's in the air. This way you can eliminate the axles and the tires from the problems.
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Old Jan 19, 2007 | 09:38 AM
  #28  
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don't take the tires off and run your truck with out tires on the back unless you put the lug nuts back on cause your rotors will move .

also make sure when you put it on jack stands you put them under the axles so it will put them in normal ride height
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Old Jan 19, 2007 | 10:30 PM
  #29  
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Lightbulb Drive shaft vibration

Farm man I have the same problem with my truck. I had a possie unit eaton put in my rear with a 410 gear. I have vibrations at the same speeds and lost a drive shaft. I got a gm tec near my house to put in a new drive shaft and yolk back in. I still have the same problem still he said the shade tree man that put in my unit did not set up the pinion right. I had this problem for about a year. I think I finally found my problem He also said the bearing in the rear could be bad too. If you get you problem fixed before I do advise
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