8 3/4 posi unit change

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oldkimmer said:
Yes, but they are exactually the same unit. Kim
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I know we're little off subject here but the Chevy posi used 17 splines.
The Mopar 8 3/4 has always used 30.

So therefore they are not the exact same units to start with. But they may share some of the same parts.
 
You can be “posi-tive” about those splines when you first get a “sure-grip” on your “third member”.
 
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See post number 6. That's all you need.
 
dewsky said:
I currently have an 8 3/4 with a 489 case with a set of 3.91 gears and a posi unit installed. I am wanting the make the car (75 Duster) a bit more friendly on the highway by installing a set of 3.23 gears. I have a complete rear end out of a D200 with a 489 case that has the gears, but it does not have Posi. My question is, how hard is it to swap the posi unit from case to case? I dont know, but I believe it's a stock unit with the posi.
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oldkimmer said:
Yes, but they are exactually the same unit. Kim
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I have a stock 8 3/4 rearend and it has shims in both ends of the axle housing I'm putting a posi track 8 3/4 489 case in it do u know if I have to reuse the shims or not and if I do where do I need to put the shims at I'm new to this set and have no clue can u help me out with this situation
 

DFX 340 Duster said:
Have you considered installing the 3.23 carrier as is and driving it for a while? You may find that it does quite well on the highway without the sure-grip feature. How often are you going to race the car?
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I'm needing help on my 8 3/4 rearend if u could give me help on it I'm taking the stock one out and putting a posiv track in it with 3.23 gears to race with but the stock rearend has shims on each side I'm needing to know if I need to reuse them with this posi unit or I don't need to use them
 
I'm putting a posi track in my 8 3/4 rearend but the stock rearend has shims on it do I need to reuse the shims with this posi track or not and which sides do I need to put them shims on ur help would b greatly appreciated
 
Welcome aboard.

If you read through this thread you would know it's not called a posi trac. But enough on that.
The only thing on an 8 and 3/4 on the end of the axles that would resemble a shim is the metal gasket between the housing and the backing plate. That is not a shim that is a gasket or seal.
However if you were to post a picture maybe we would better understand what you're referring to as a shim.
The original 8 and 3/4 has an adjuster on the right axle so you can adjust the end play in your differential.
That's if you're using original bearings. If you are using what they call the green bearings then end play is basically adjusted by grinding the end of the axle off or removing the Cross Pin from the differential.
 
dsppre1963 said:
I have a stock 8 3/4 rearend and it has shims in both ends of the axle housing I'm putting a posi track 8 3/4 489 case in it do u know if I have to reuse the shims or not and if I do where do I need to put the shims at I'm new to this set and have no clue can u help me out with this situation
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Posi track won’t fit… you need a Sure grip
 
Jadaharabi said:
If you read through this thread you would know it's not called a posi trac. But enough on that.
The only thing on an 8 and 3/4 on the end of the axles that would resemble a shim is the metal gasket between the housing and the backing plate. That is not a shim that is a gasket or seal.
However if you were to post a picture maybe we would better understand what you're referring to as a shim.
The original 8 and 3/4 has an adjuster on the right axle so you can adjust the end play in your differential.
That's if you're using original bearings. If you are using what they call the green bearings then end play is basically adjusted by grinding the end of the axle off or removing the Cross Pin from the differential.
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I looked at my axle housing there isn't any adjustments on the right side on the housing just the metal seal but what I need to find out is if I put this posi track in it do I need to put the plates back on the rearend axle housing
 
dsppre1963 said:
I looked at my axle housing there isn't any adjustments on the right side on the housing just the metal seal but what I need to find out is if I put this posi track in it do I need to put the plates back on the rearend axle housing
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Yes the plates go on. That’s what holds the axles in. If you don’t want your axle sliding out on a curve and waltzing across the road, put them on.

Two, again, no posi-track will fit a Chrysler 8.75.
 
dsppre1963 said:
I looked at my axle housing there isn't any adjustments on the right side on the housing just the metal seal but what I need to find out is if I put this posi track in it do I need to put the plates back on the rearend axle housing
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You're not reading what I wrote. I said the adjuster will be on the right axle. Not on the housing it is between the flange and the bearing. If it is a stock Mopar tapered bearing.
If it is a green bearing it will have snap rings and plates and rubber o-ring going around the bearings. How about a picture so we see what you're talking about.
 
Jadaharabi said:
You're not reading what I wrote. I said the adjuster will be on the right axle. Not on the housing it is between the flange and the bearing. If it is a stock Mopar tapered bearing.
If it is a green bearing it will have snap rings and plates and rubber o-ring going around the bearings. How about a picture so we see what you're talking about.
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Yeah I can take a pic of it once I get home in the morning and u can see what I'm working with then maybe I'll know what needs to b done but yes I am using new bearings and races not the green bearings
 
This is the adjuster I am talking about that goes between the bearing and the flange of the axle where your brake drum mounts. There is a little J hook looking thing that bolts onto one of the studs and that prevents this from adjusting itself when you're going down the road.

Screenshot_20230705-164235_Google.jpg
 
It's the guy's first day on here and giving him grief is not my idea of a warm welcome. He asked for some help how about we give it to him and present ourselves as being better than a bunch of dipshits.
 
Jadaharabi said:
This is the adjuster I am talking about that goes between the bearing and the flange of the axle where your brake drum mounts. There is a little J hook looking thing that bolts onto one of the studs and that prevents this from adjusting itself when you're going down the road.

View attachment 1716110858
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Mine has nothing like that on it I'm gonna get pics of my axle housing and axles and back plate and then u can see what I'm working with like I said before I'm new to this stuff but I've been told by others that it can work so I'm reaching out for the best advice I can get to get thus together and go racing
 
dsppre1963 said:
Mine has nothing like that on it I'm gonna get pics of my axle housing and axles and back plate and then u can see what I'm working with like I said before I'm new to this stuff but I've been told by others that it can work so I'm reaching out for the best advice I can get to get thus together and go racing
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Well they obviously didn’t tell you that Posi track doesn’t fit in a Chrysler…
 
Jadaharabi said:
It's the guy's first day on here and giving him grief is not my idea of a warm welcome. He asked for some help how about we give it to him and present ourselves as being better than a bunch of dipshits.
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agreed. let him get acclimated. I mean if it was the 6th of July then all bets are off. :)
 
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