Need some advice on 8 3/4 rear

[340_Scamp]

I just installed an 8 3/4 rear in my Scamp. I'm having problems getting the axles in. I have read about an adjuster on the passenger side to allow the axlesto go in deeper. they act like they are about 1/4 inch too big..push one in, it pushes the other side out. Does any one have any decent pics of this adjuster and how it works? Any help would be appreciated.

PS..they are stock axles and fit without touching prior to installing 3rd member.

 

[66dartgt]

You are running the stock type bearings I assume ? If so the right side adjuster needs to be backed off , thread it out in order to allow for adjustment. What you might be seeing is the push (compression) of air from one axle shoving the other out- sounds weird but it happens. Install and bolt in the left side, then install the right side, if it wont go in all the way then the adjuster needs to be turned out, counter clockwise i believe, check the threads. Then install the right axle and adjust per the service manual - install the lock to hold the adjuster. I think the end play is supposed to be .008". Check Mopar actions web site for adjustment data - I seem to recall them having the whole procedure there. The problem I had seen with these is if your axles are in good shape and the seals new it creates an air lock causing a false fitment issue, resistance to installation, odd but understandable when you consider there is no place for the air inbetween these seals on the out board sides of the axle to escape.

 

[krabysniper]

I would add that if you are running a sure grip, there is a "spacer" or "thrust block" that is made up of three pieces two halves held together by a drift pin in the very heart of the pumkin, the ends of the axle ride against this "spacer" I would be for looking in the end of the axle tube with a flash light and make sure they are in their proper location. One good site I found, while looking for a schematic of this thrust block to show you, is 8 3/4's guide

I did find a site the sells the parts and has a picture of them so you can have an idea of what they look like and maybe figure out what your looking for when you shine your light in the end of the housing, look for PTS834" - Differential Pinion Thrust Spacer Kit towards the bottom of THIS PAGE When installed or in their correct position you will only be able to see the fatter side face and the head of the pin in the center of that face, ie the skinny parts of the spacers actually slide into the center of the pumkin like the axle splines in.

 

[Ace]

Where did the 8 3/4 come from? Is it a complete A-body unit with known correct axles? Was any work done on the diff/gears prior to installation?

Troubleshooting this would be alot easier knowing the answers to these questions.

 

[70Valiant]

There is a vent on the axle housing so the pressure theory is only possible if the vent is clogged.

 

[340_Scamp]

yes, it's a complete A body rear with correct axles.

 

[340mopar]

There is a vent on the axle housing so the pressure theory is only possible if the vent is clogged.

66dartgt was talking about the area between the seal and the bearing flange, the vent is on the inboard side of the axle seals.

 

[340_Scamp]

You are running the stock type bearings I assume ? If so the right side adjuster needs to be backed off , thread it out in order to allow for adjustment. What you might be seeing is the push (compression) of air from one axle shoving the other out- sounds weird but it happens. Install and bolt in the left side, then install the right side, if it wont go in all the way then the adjuster needs to be turned out, counter clockwise i believe, check the threads. Then install the right axle and adjust per the service manual - install the lock to hold the adjuster. I think the end play is supposed to be .008". Check Mopar actions web site for adjustment data - I seem to recall them having the whole procedure there. The problem I had seen with these is if your axles are in good shape and the seals new it creates an air lock causing a false fitment issue, resistance to installation, odd but understandable when you consider there is no place for the air inbetween these seals on the out board sides of the axle to escape.

Good info..thanks! Where is the adjuster at? On the outside edge of the flange?

 

[66dartgt]

The adjuster is part of the axle flange bearing retainer on the passenger (right) side axle, the part that the studs run thru. Its rather obvious when you look compare left and right.

Also as mentioned above make sure your thrust buttons are in place, check by shining a flashlight down the axle tube on both sides, should look like a brass button about 3/4-1 " diameter.

If you are still uncertain you can do some backyard mechanic measuring by using a tape measure. Measure from the axle housing flange to the thrust buttons on both sides,keep in mind the buttons move a little back and forth. Then measure the axles themselves from the end of the splines to the axle bearing retainer. This will give you a ball park idea of where they are, and if you really have something odd going on.

One other thing - was your diffferential rebuilt ? Is it a sure grip ? Was it rebuilt ? Sometimes the splines, (there are two per side), inside the differential on a suregrip can move a little causing an impossible axle installation. I suggest if this is the case - you can try turning the pinion with the axles installed as far as you can - and see if you can realign the splines inside the sure grip. Maintain moderate inboard hand pressure on the axle shaft while turning the pinion with a wrench, I had this happen to me, and this worked.

Good luck.

 

[340_Scamp]

The adjuster is part of the axle flange bearing retainer on the passenger (right) side axle, the part that the studs run thru. Its rather obvious when you look compare left and right.

Also as mentioned above make sure your thrust buttons are in place, check by shining a flashlight down the axle tube on both sides, should look like a brass button about 3/4-1 " diameter.

If you are still uncertain you can do some backyard mechanic measuring by using a tape measure. Measure from the axle housing flange to the thrust buttons on both sides,keep in mind the buttons move a little back and forth. Then measure the axles themselves from the end of the splines to the axle bearing retainer. This will give you a ball park idea of where they are, and if you really have something odd going on.

One other thing - was your diffferential rebuilt ? Is it a sure grip ? Was it rebuilt ? Sometimes the splines, (there are two per side), inside the differential on a suregrip can move a little causing an impossible axle installation. I suggest if this is the case - you can try turning the pinion with the axles installed as far as you can - and see if you can realign the splines inside the sure grip. Maintain moderate inboard hand pressure on the axle shaft while turning the pinion with a wrench, I had this happen to me, and this worked.

Good luck.

I purchased the sure grip seperate from the housing & axles. It's not rebuilt, but out of a very low mileage car. Thanks very much for the info, it's been VERY HELPFUL! The only rearend swaps I have ever done before was complete rear for complete rear. I have a bunch of Mopar buddies in the area, many of them great mechanics. But NONE of them have ever pulled an 8 3/4 apart. So this has been a learning process for all of us. Thanks again for all the help!