School me on the 8.25

Alright, So i know plymouth introduced it in 69 from what i've read. Apparently they have made their way under everything from a-bodies to trucks, to Jeeps and remained fairly unchanged till 96. Although there are some different bearing sizes and small variations in casting.

I've also noticed that the sping perches can be very different between model cars, however the differential is still internally the same.

Then it was upgraded with 29 spline axles. Also called the 8 3/8 it has a different carrier, axles, and bearings. I've also read that there are different carries for the gears. However, i have read different things regarding the split. I have heard its a different carrier from 2.56 up and 2.4# down. Is this correct?

What are the exact differences in carriers between the gear split? I know it has something to do with the height (if stood upright) of the ring gear flange. Does anyone have anymore insight into the difference as well as exact measurments?

I have a couple cone style LSD carriers for the 8.25 but which fits the smaller gears. I'm curious as to if the ring flange is the only thing stopping me from running larger gears in it.

If that's the only difference then why not just use a gear spacer like in any other differential?

Lastly, if the gear spacer is unavailable then I will make one. We run a machine shop and operate wire EDM. I would think that a 4140 tool steel would be strong enough to work as a spacer. Are the ring gear bolt threads on a GM 8.25 the same as on a Mopar 8.25. If they are, i know that non-oem bolt lengths are available through summit.

Any input and schooling here would be MUCH appreciated. I'm looking for ANY information no matter how novel or technical. The web is swamped with 8.75 and I can't find any decent info on the 8.25. I found a few XJ jeep sites with some decent information, but not really any breakdowns between years and models.

I know this was a large post, and thanks for reading. Thanks even more in advance for any input!

I found this.


http://www.dippy.org/svcman/sm03a.html

there is limited info for a reason. put a 9 inch or a 8.75 in your car and you'll be better off.

dont get me wrong 8.25 is a good rear, but if your going to put any power through it or run slicks dont waste your time or money.

for a daily driver these rears are great because they offer the large bolt pattern and they accept drum brake backing plates from pretty much any mopar other rear with the same bolt pattern.

your going to want to look out for limited gear ratios with the 8.25 rear

The axles are held by C-clips. And I've never seen any C-clip eliminator kits for the 8.25

lookup doctor diff - he has alot of information on them

I am running one for 15 years, 17,000 miles and 12.56 @108 with slicks - 1.74 60' times - never had a problem with mine!

The split is one carrier for the 2.24 and 2.45 gears, and another for 2.71 and lower gears. The difference between the 2 carriers is approx 5/16" but I measured with a tape measure so it isn't going to be all that accurate of course.

I don't think a spacer would work because the only thing centering the ring gear would be the bolts...I don't think there's enough meat on the hub to space it out that much and still center the gear. Also the center pin would probably be impossible to get in.

This pic doesn't show it very well but here are both side by side, with a 2.45 carrier on the right.

Thanks 440. Thats exactly what i was looking to know. I guess i will just have to wait for my gears to get in and find out.

As far as the pin goes, if i had to cut down a gear tooth a little to fit the pin in I could always do that. I have seen that done for some of the lower gears as it is.

I see the concern with the hub height. I was not aware it was as close to a 5/16 difference and you may be correct about not having enough material to center the gear.

I have that exact LSD unit you have (the one on the right). I can't find out what those were out of. I mean, why would anyone get 2.54 or higher with posi? Could that be out of the front differential of a 4wd truck at all? I have no clue.

But, this coming week I am gonna get to work trying to make a spacer work. If it doesn't then i'll just buy another sure-grip unit for the lower gears.

If it does work and anyone is interested let me know, I am going to make a few if it does work because i have quite a few small carriers for the 8.25.

I wish i had the money for the 8.75 but given that so far i bought everything i need for this rear differential including the Sure-grip for 255.00$ including an install kit, thats why i am using it. Around here i find just the housings going for 350$ for an a-body 8.75. And thats the lower end that i've found.

I am a 3/4 fan me-self ... but I am looking in the direction of the 1/4 ... because of the short-gear-selection. LIKE the 2.24.

I need a couple of these....prefer with sure-grips.

well, i will PM you later this month if you're interested in any Cone style posi units for the taller gears for the 8.25. I have a couple. I also have a bunch of open carriers for the lower gears.

I also think i have a set of 2.26 gears from a police car is my guess what they came out of.

PM sent Royce.

Let us see if anyone else is a fan of the 8 1/4.

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The axles are held by C-clips. And I've never seen any C-clip eliminator kits for the 8.25

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I've never heard of the 8 1/4 have a C Clip related failure, unlike GM and Ford's C clip axles. Not to say it never happened, but it isn;t as common either. I put about 200k miles on an 8 1/4 with a 360 and a stick in front of it in a heavy 87 Diplomat. YMMV