HELP!!!!Put in 8 3/4 rear and it vibrates real bad

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The Precision part number for the conversion u-joint is #347. That was the first thing that came to my mind, u-joint not centered. When i was 16 i had a 65 273 4 speed Dart and I forgot to put the clips on the u-joint and vibrated like you said yours is doing.
 
SGBARRACUDA said:
The Precision part number for the conversion u-joint is #347. That was the first thing that came to my mind, u-joint not centered. When i was 16 i had a 65 273 4 speed Dart and I forgot to put the clips on the u-joint and vibrated like you said yours is doing.
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But, in an earlier post he has one wheel that wobbles, he switched the wheels and still has the wobble. Either the new bearing he put in isn't seated properly OR something is bent or possibly both.

I don't know how much strain the driveshaft would have put on the rear after the car was set down with full weight on the rear. If it wasn't shortened it probably went in with the rear suspended and then bound up right good after the weight was put on it. I can only guess right now.

I asked if he had it shortened and haven't heard.
 
Bad Sport said:
But, in an earlier post he has one wheel that wobbles, he switched the wheels and still has the wobble. Either the new bearing he put in isn't seated properly OR something is bent or possibly both.

I don't know how much strain the driveshaft would have put on the rear after the car was set down with full weight on the rear. If it wasn't shortened it probably went in with the rear suspended and then bound up right good after the weight was put on it. I can only guess right now.

I asked if he had it shortened and haven't heard.
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Sounds like he has more than one problem. I agree you need to post a picture of the yoke so we can see what yoke you have. Hell it could be a 1330 or 1350 also. And your right we can only guess without more information.
 
I will send some pics. But yes I did have the driveshaft shortened. Yes my drive shaft is smaller than the yoke.
 
loganscuda said:
I will send some pics. But yes I did have the driveshaft shortened. Yes my drive shaft is smaller than the yoke.
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OK, that's eliminated, but you still need to deal with the U joint issue. Get the combo U joint that will fit both driveshaft and the larger yoke on the diff.

I guess if you have the wobble on one side, I would start looking at the new bearing install and make sure it's centered/seated. Is the brake drum seated properly around the center register?

Did the axle appear bent in anyway when you changed the bearings? Or did you buy it that way?
 
Bad Sport said:
OK, that's eliminated, but you still need to deal with the U joint issue. Get the combo U joint that will fit both driveshaft and the larger yoke on the diff.

I guess if you have the wobble on one side, I would start looking at the new bearing install and make sure it's centered/seated. Is the brake drum seated properly around the center register?

Did the axle appear bent in anyway when you changed the bearings? Or did you buy it that way?
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I don't think it's possible to get the bearing so far off that it tweaks the axle that bad (where you could see it)

A person could run it on a stand with the wheel and drum off also.
That way you can check it right at the axle flange as see if it has runout.
 
TrailBeast said:
I don't think it's possible to get the bearing so far off that it tweaks the axle that bad (where you could see it)

A person could run it on a stand with the wheel and drum off also.
That way you can check it right at the axle flange as see if it has runout.
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Just throwing ideas out there, I've never installed the green bearings, I prefer the factory rollers.. You're most likely correct, but if the wheel is wobbling somethings whacked for sure.
 
If you swapped wheels side to side and the wobble also changed sides, it's the wheel.

If you swapped wheels side to side and the wobble did not change sides, it's the axle.
 
Sounds like you have a 5380 series end yoke, which that center would have been from a truck.
7290 is not 4" even across the outside.

A crooked wheel won't make that vibration, but sticking a 7260 or 7290 where a 5380 should be and you'll lose your teeth.

.
 
Supershafts said:
Sounds like you have a 5380 series end yoke, which that center would have been from a truck.
7290 is not 4" even across the outside.

A crooked wheel won't make that vibration, but sticking a 7260 or 7290 where a 5380 should be and you'll lose your teeth.

.
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My thoughts exactly when I posted. I've had really bent wheels in the past that I couldn't notice till someone following me said something.
 
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