8.25 upgrade

[justanotherguy]

Alright all, I'm about to give up hunting for a 71-74 b body 8 3/4 to bolt into my 73 satellite. I can't find anything local in Oregon.

So, i'm toying with refreshing and regearing and adding a suregrip to my 8.25 that is in there now. Problem is, the more research I do, the more confused I am.

Here are my problems. Chrysler used 2 different carriers depending on the gear ratio? I know there should be a tag with the ratio attached to the cover, but it looks like it's gone missing over the years and I have no idea what gears are in there. Looking at the housing, looks like it is offset and not centered. The only marking on the housing is "2 11P9". Can't find any info on that.

I'd like to put in 3.55 or 3.73 gears with a suregrip. Is this even possible on my current rear end? I guess i want to know what my options are. I appreciate any advice in advance. I know nothing about the 8.25. BTW, I have 30" tires in the rear.

DrDiff obviously has 8.25 gearing but says it requires a carrier intended for at least 2.71 gears.

 

[bm02tj]

I put a 9 1/4 in my 73 just check spring pad width mine was from a 77 or78 full size

 

[#41]

It's a drive for you, but I had Randy's Ring and Pinion in Everett WA go through an 8-1/4 with new axles and bearings (quite awhile ago now). I wanted the 8-1/4 with 2.45 gears for a racing project. Give them a call.

But... I would suggest holding out for an 8-3/4 still. It's just so handy to be able to drop gears in and out plus the extra strength. There are C-body axles that are just a hair wider that will bolt right in. Have you looked for those?

 

[Kern Dog]

Alright all, I'm about to give up hunting for a 71-74 b body 8 3/4 to bolt into my 73 satellite. I can't find anything local in Oregon.

So, i'm toying with refreshing and regearing and adding a suregrip to my 8.25 that is in there now. Problem is, the more research I do, the more confused I am.

Here are my problems. Chrysler used 2 different carriers depending on the gear ratio? I know there should be a tag with the ratio attached to the cover, but it looks like it's gone missing over the years and I have no idea what gears are in there. Looking at the housing, looks like it is offset and not centered. The only marking on the housing is "2 11P9". Can't find any info on that.

I'd like to put in 3.55 or 3.73 gears with a suregrip. Is this even possible on my current rear end? I guess i want to know what my options are. I appreciate any advice in advance. I know nothing about the 8.25. BTW, I have 30" tires in the rear.

DrDiff obviously has 8.25 gearing but says it requires a carrier intended for at least 2.71 gears.


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Before the pandemic, we used to be able to CALL companies and talk to experienced people to learn this stuff.
Dr Diff used to answer the phone and sometimes talk and talk. Now he never seems to answer but he does respond to emails. That is okay in some instances but some stuff gets lost through text/type where an actual conversation can really clear things up immediately.
Here is what I know:
The 8 1/4" axle is great for medium weight vehicles with moderate power. You'd be fine with a stock 318, 360 and 400. If you didn't push it, you'd probably be okay with a 440 and automatic. This is a decent axle and was original in my 2 Chargers, one a 318 model, the other a 383 2 barrel.
The "break" is the 2.45 ratio and UNDER. 2.71 and OVER use a different carrier.
You can slip in a mini-locker for far less than a whole LSD differential.
The stock 8.25 gear ratios as far as I recall were 2.21, 2.45, 2.71, 3.21, 3.55 and 3.91. I may be wrong about the last one. The 9/25 used similar ratios and they had a 3.92. I know, small difference but I like to be accurate.
There may be an aftermarket 3.73 gear but no stock gear of that ratio.
Good luck.

 

[Curiousyellow71]

You can always jack the car up and count tire revolutions if the tag is gone. Since it does not have limited slip you can keep one wheel on the ground and turn the other tire 2 full revolutions, count the driveshaft revolutions. I would guess it has 2.71s and all of the gears mentioned and sure grip would fit.
The gears numerically lower... 2.45, 2.21 had a special carrier. If you have that housing...it may still accept 2.71 gears and carrier...not completely sure, but I think it can be done. I know 2.45s and carrier will not fit in place of 2.71s.


The c body 8 3/4 built from 70-71 is the exact same width as the b body in 73. The 66-69 c body is a little narrower but still works. Both would require the moving spring perches. 9 1/4's in the later 70s also a upgrade.

 

[YY1]

I'm not sure I've ever seen that early of a B body with anything numerically lower than a 2.71.

2.45's I've seen in F/M/J body cars and 75 and newer B body cars....and Feather Dusters/Dart Lite's.

You could pull the cover and spin the ring gear around until the ratio stamp comes into view.
Just costs a gasket.

Hamtramckhistorical might have the standard ratio for the model in their literature collection.

 

[justanotherguy]

Thanks for the replies, fellas. Ironically, I found an 8 3/4 with 489, suregrip, and 3.91 gears about 4 hours away today. Guy wants $1400. Guess I'll be shelling out the money and the drive.

 

[1STMP]

Before the pandemic, we used to be able to CALL companies and talk to experienced people to learn this stuff.
Dr Diff used to answer the phone and sometimes talk and talk. Now he never seems to answer but he does respond to emails. That is okay in some instances but some stuff gets lost through text/type where an actual conversation can really clear things up immediately.
Here is what I know:
The 8 1/4" axle is great for medium weight vehicles with moderate power. You'd be fine with a stock 318, 360 and 400. If you didn't push it, you'd probably be okay with a 440 and automatic. This is a decent axle and was original in my 2 Chargers, one a 318 model, the other a 383 2 barrel.
The "break" is the 2.45 ratio and UNDER. 2.71 and OVER use a different carrier.
You can slip in a mini-locker for far less than a whole LSD differential.
The stock 8.25 gear ratios as far as I recall were 2.21, 2.45, 2.71, 3.21, 3.55 and 3.91. I may be wrong about the last one. The 9/25 used similar ratios and they had a 3.92. I know, small difference but I like to be accurate.
There may be an aftermarket 3.73 gear but no stock gear of that ratio.
Good luck.

"If you didn't push it, you'd probably be okay with a 440 and automatic."

That's what I run, but the
axles have been shortened,
disc brakes installed, plus
a girdle with bearing cap
reinforcement. Hooked up
to a 4-link with rubber
bushings. (No heims).
The 8-1/4 is tougher than
most give credit. The cost
of beefing it up is far less
than just the initial cost
of locating an 8-3/4 plus
the parts needed for rebuild.
The 8-3/4 is becoming
harder to find, and much
more expensive. $1400
for a used 8-3/4 is nuts!

 

[justanotherguy]

Ya know how you get your mind set on something and you just don't want it any other way? That's why I paid for the 8 3/4. Good news is, it's in great shape and will be in my mopar before too long.

I figure a suregrip is 400, new gears are 200, finding someone to install is 300+...not that far off from 1400.

 

[1STMP]

Ya know how you get your mind set on something and you just don't want it any other way? That's why I paid for the 8 3/4. Good news is, it's in great shape and will be in my mopar before too long.

I figure a suregrip is 400, new gears are 200, finding someone to install is 300+...not that far off from 1400.

Just curious as to what you
paid for the 8-3/4 before
any improvements?
I'll not dispute any diff in
stock form is stronger as
they step up. Of course they
are. But there are ways to
upgrade a weaker axle to the
next level for a lot less $
and time tracking down
a dwindling supply. Rarity
drives the price up.
Next on the list will probably
be the Dana 44.

 

[justanotherguy]

For the 8 1/4, nothing. It was in the car. For the 8 3/4, 1400 with the suregrip, 3.92 gears, 489 housing, good axles... honestly, price is pretty much ebb and flow. Just gotta decide how badly you want something with how long it'll take to find another one.

 

[1STMP]

For the 8 1/4, nothing. It was in the car. For the 8 3/4, 1400 with the suregrip, 3.92 gears, 489 housing, good axles... honestly, price is pretty much ebb and flow. Just gotta decide how badly you want something with how long it'll take to find another one.

Thanks for the reply. The
supply for the 8-3/4 has
rapidly dried up, and for
good reason. Easy swap
with minimal changes, to
a more robust set up for
higher HP and TQ. But with
anything, supply and
demand drives the price up.
I have a couple friends who
run the lowly 8-1/4 on the
strip, but they have alternate
assemblies ready to go.
Configured with their
specific parameters, mainly
looking for weight savings.

 

[YY1]

8 1/4 is also a LOT lighter than an 8 3/4.

 

[Curiousyellow71]

8 3/4 is pretty lean and mean though.
Imo..Not much comparing the two.
29 spline 8 1/4, 30 spline with upgrades up to 35 for 8 3/4" and no c clip. 8 1/4.. break a axle and tire goes..see ya. It is "almost" fun setting up the 8 3/4 gears on the workbench vs 8 1/4 in the car. Setting the backlash and preload is easy on a 8 3/4...no shims like the 8 1/4. 8 3/4 is so easy to switch out gears by swapping the pig...lost track how many times that took place for a trip to the strip. Axle tube on the 8 1/4 is smaller and weaker and the axle axle bearings don't have a inner race...they are roller bearings and wear on the axle. Lots of aftermarket parts for the 8 3/4...even a aluminum pig.
8 3/4s are still pretty plentiful A,B,C,E bodies and D100s had em. Everything is harder to find then they once were..that goes for a 8 1/4 too.

I get why you would run a 8 1/4. I am not bashing them. Good little rear end, it does suit some builds just fine.

 

[justanotherguy]

I'm not knocking the 8 1/4 by any stretch. Just something I wanted to do with my car because I could. I know, I know, if it ain't broke, don't fix it....but I love doing that

.

I didn't want to make a new post, so maybe someone can chime in. Just by looking at this, is this already set for the iso clamp system? The guy I got it from believed it came out of a 72, but that's an awful large central hole....insert joke.

 

[hofferwood]

I know, I know, if it ain't broke, don't fix it....

Look at my signature line VVVVVV-----------LOL

 

[mrhemi]

Before the pandemic, we used to be able to CALL companies and talk to experienced people to learn this stuff.
Dr Diff used to answer the phone and sometimes talk and talk. Now he never seems to answer but he does respond to emails. That is okay in some instances but some stuff gets lost through text/type where an actual conversation can really clear things up immediately.
Here is what I know:
The 8 1/4" axle is great for medium weight vehicles with moderate power. You'd be fine with a stock 318, 360 and 400. If you didn't push it, you'd probably be okay with a 440 and automatic. This is a decent axle and was original in my 2 Chargers, one a 318 model, the other a 383 2 barrel.
The "break" is the 2.45 ratio and UNDER. 2.71 and OVER use a different carrier.
You can slip in a mini-locker for far less than a whole LSD differential.
The stock 8.25 gear ratios as far as I recall were 2.21, 2.45, 2.71, 3.21, 3.55 and 3.91. I may be wrong about the last one. The 9/25 used similar ratios and they had a 3.92. I know, small difference but I like to be accurate.
There may be an aftermarket 3.73 gear but no stock gear of that ratio.
Good luck.

"There may be an aftermarket 3.73 gear but no stock gear of that ratio."
The 2007 and earlier Jeep Liberty came with a 3.73 ratio 8 1/4" rear from the factory in auto trans versions.

 

[Kern Dog]

The 8 1/4" axle changed in 1996 so I don't think much interchanges between 1996 and newer and the 1995 and older versions.

 

[1STMP]

8 3/4 is pretty lean and mean though.
Imo..Not much comparing the two.
29 spline 8 1/4, 30 spline with upgrades up to 35 for 8 3/4" and no c clip. 8 1/4.. break a axle and tire goes..see ya. It is "almost" fun setting up the 8 3/4 gears on the workbench vs 8 1/4 in the car. Setting the backlash and preload is easy on a 8 3/4...no shims like the 8 1/4. 8 3/4 is so easy to switch out gears by swapping the pig...lost track how many times that took place for a trip to the strip. Axle tube on the 8 1/4 is smaller and weaker and the axle axle bearings don't have a inner race...they are roller bearings and wear on the axle. Lots of aftermarket parts for the 8 3/4...even a aluminum pig.
8 3/4s are still pretty plentiful A,B,C,E bodies and D100s had em. Everything is harder to find then they once were..that goes for a 8 1/4 too.

I get why you would run a 8 1/4. I am not bashing them. Good little rear end, it does suit some builds just fine.

"break a axle and tire goes..see ya"

Not when you're running rear
disc brakes....

 

[Curiousyellow71]

"break a axle and tire goes..see ya"

Not when you're running rear
disc brakes....

Yes disc brake is going to help keep it in place. Still not as good as retaining the axle outside of the bearing.
In a drag racing application 11.0 is the fastest allowed for clips in NHRA, IHRA. They don't care what brakes... if you aren't a racer.. it don't matter.
I think the carrier is likely the weak spot on a 8 1/4. I would think running a light weight car(or '40 truck) should help.