Rear differential

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Brian Mauro

Brian Mauro

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I have been researching this problem and spoke with numerous techs on the phone and still to no avail. I have not solved the problem. About 5 years ago I began assembling parts for the rebuild of my 69 Dart GTS and some of the parts were the green gearings for the axle shafts for the 8 3/4 Posi differential I also sent out the differential to be rebuilt, fast forward till now, I have all of the components installed and ready to test the rear end, I have the rear of the car on stands to test the speedo which works fine, however, when the car is in gear the rear end made a huge racket and sounded like the bearings were square. Ok so here is what I found the axles are not going into the carrier far enough, they only go into the differential spline about a 1/8 inch, I measured the total length of the axle and came to about 27 inches or so up to spec, I went ahead and checked to see if the green bearing were seated all the way down, they were. Nothing has changed on the rear end, with the exception of the green bearings.

This sounds crazy I know I have had the diff out 3-4 times I am looking into tearing into it to see if there is anything that stares out at me, the shop that rebuilt the diff said it looked fine and changed all of the bearings and cones. I did remove the axle seal in the tube on both sides, any help is appreciated.
 
If you have a clutch type sure grip unit, you must remove the center thrust button to run green bearings. That might be your issue.

OR if it is a cone type sure grip, the cones and side gears are probably out of alignment. They must be aligned properly in order for the axles to fully engage. My guess is, it's one or the other.
 
RustyRatRod said:
If you have a clutch type sure grip unit, you must remove the center thrust button to run green bearings. That might be your issue.

OR if it is a cone type sure grip, the cones and side gears are probably out of alignment. They must be aligned properly in order for the axles to fully engage. My guess is, it's one or the other.
Click to expand...
I tore it down late last night and found that I couldn't fully seat one of the axles because the inner splines were not aligned, which would prevent the shaft from fully engaging, so hopefully, this takes care of the issue.
 
Bad Sport said:
How are you determining that?
Click to expand...
Here's what I found,

IMG_0312.jpg
 
RustyRatRod said:
If you have a clutch type sure grip unit, you must remove the center thrust button to run green bearings. That might be your issue.

OR if it is a cone type sure grip, the cones and side gears are probably out of alignment. They must be aligned properly in order for the axles to fully engage. My guess is, it's one or the other.
Click to expand...
Yes a cone type sure grip,and they were out of alignment,
 
Brian Mauro said:
I tore it down late last night and found that I couldn't fully seat one of the axles because the inner splines were not aligned, which would prevent the shaft from fully engaging, so hopefully, this takes care of the issue.
Click to expand...

It should.
 
Brian Mauro said:
I have been researching this problem and spoke with numerous techs on the phone and still to no avail. I have not solved the problem. About 5 years ago I began assembling parts for the rebuild of my 69 Dart GTS and some of the parts were the green gearings for the axle shafts for the 8 3/4 Posi differential I also sent out the differential to be rebuilt, fast forward till now, I have all of the components installed and ready to test the rear end, I have the rear of the car on stands to test the speedo which works fine, however, when the car is in gear the rear end made a huge racket and sounded like the bearings were square. Ok so here is what I found the axles are not going into the carrier far enough, they only go into the differential spline about a 1/8 inch, I measured the total length of the axle and came to about 27 inches or so up to spec, I went ahead and checked to see if the green bearing were seated all the way down, they were. Nothing has changed on the rear end, with the exception of the green bearings.

This sounds crazy I know I have had the diff out 3-4 times I am looking into tearing into it to see if there is anything that stares out at me, the shop that rebuilt the diff said it looked fine and changed all of the bearings and cones. I did remove the axle seal in the tube on both sides, any help is appreciated.
Click to expand...
Are the bearing retainers bolted tight against the housing flange?
 
RustyRatRod said:
So are you saying you got it fixed now?
Click to expand...
Well, not yet I am saying that the splines were misaligned, I ordered another set of green bearings when they come in I will update, however by all accounts the shafts go in a lot further than before
 
Magnum Valiant said:
Are the bearing retainers bolted tight against the housing flange?
Click to expand...
yes they are I am going to set it up, I just aligned everything and put it back together to see if the shafts fully seated in the center section, this weekend I am going to set the lash and end play
 
You should install the axel seals even when using the green bearings. I would not trust that tiny o ring on the od of the green bearing to make a perfect seal.
 
my68barracuda said:
You should install the axel seals even when using the green bearings. I would not trust that tiny o ring on the od of the green bearing to make a perfect seal.
Click to expand...
Yes I am going to install new inner axle seals and an ounce of prevention is worth a pound of cure...thanks
 
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