Which is simpler to change gearing in: 8-1/4 or 8-3/4 rear end?

[barracuda-67]

Is it easier to change gearing in an 8-3/4 inch unit than the 8-1/4?

A friend once told me you need a spreader to take the gears out of the 8-1/4 style, is that correct?

(guide to the different rear ends: Moparts on the Web - Main Index)

 

[67Dart273]

Think about THIS. the whole thing with a 3rd member (I have a Linc Versaille / Ford 9) is that you just set it up and then SWAP 3RD MEMBERS. Then you don't NEED to change ring/ pinion.

 

[1WildRT]

I've never needed a spreader for an 8.25... But like a 9" ford the Chrysler 8.75 you swap the pumpkin.. Back when I was younger & motivated I had a few pumpkins & would swap depending on my plans.. Friday night fun? 3.91 S/G or 4.30 S/G... Saturday cruise up to Tahoe? (450 mile round trip) 2.76 open...

 

[barracuda-67]

Think about THIS. the whole thing with a 3rd member (I have a Linc Versaille / Ford 9) is that you just set it up and then SWAP 3RD MEMBERS. Then you don't NEED to change ring/ pinion.

Thanks. That's what I was thinking - it's easier to change the whole unit in that design (8-3/4 Mopar).

 

[PROSTOCKTOM]

If you're changing just the pumpkin then Yes it's faster, but it takes about the same effort to setup up either if you are changing the gears out on the pumpkin carrier.

Changing gears in an 8.25" is not hard and I personally wouldn't change an 8.25" over to a 8-3/4" just so I could swap the gears unless you plan on swapping

them several times a month. I've had better luck with a 8.25" staying together than any 8-3/4" I've ever owned.

Tom

 

[GTX JOHN]

I have had a different experience respectfully than Tom.

I raced several Aspens in both Stock and Superstock years
ago with the 8 1/4 that were 11 second cars. I broke several
8 1/4s and then the supply of Gears for that application totally
disappeared everywhere (480/510 no longer available as well as others).

I run the 8 3/4 regularly with very few issues even in 3200 lb car
in the 9s unless it has a transbrake (Then Dana 60 or Ford 9 or needed).

I did sell my Mirada 318 O/SA to a friend years ago and he is still winning class
and going strong with the 8 1/4 but it is a 12 Sec. Racecar. That rearend with spool
has been in the car since mid 1985.

 

[RustyRatRod]

This is like asking someone what tools to use for a given job. It all depends on the person. And yes, the "correct" way to do the job on the 8 1/4 is to use a case spreader, though many people do not. Not using a spreader can result in broken shims when you try to tap them in with a hammer. Even a brass one. Ask me how I know. Del is right though. Once you have more than one third member set up for the 8 3/4, it is easier to swap the whole thing out. But a re-gear for each individual assembly is probably about a tie.

 

[barracuda-67]

If you're changing just the pumpkin then Yes it's faster, but it takes about the same effort to setup up either if you are changing the gears out on the pumpkin carrier.

Changing gears in an 8.25" is not hard and I personally wouldn't change an 8.25" over to a 8-3/4" just so I could swap the gears unless you plan on swapping

them several times a month. I've had better luck with a 8.25" staying together than any 8-3/4" I've ever owned.

Tom

Thanks @PROSTOCKTOM .

I'm exploring all options to go from my 7-1/4 rear end, small bolt pattern 5x4, to the big bolt pattern 5x4.5, so I can install Wilwood disk brakes. The current diff ratio is 2.something. The car was nice on the highway from what I remember driving it long ago, so a tall 2.xx differential probably.

There are soooo many options...
* buy 5x4.5 inch axles for my 7-1/4 - but out of stock at DrDiff now, and other brands don't seem to carry it at all
* find an 8-1/4 diff from an A-body: as rare as unicorns; haven't seen one yet
* get an 8-3/4 or the rarer 8-1/4 from a B- or C-body and have it narrowed
* get one of those from a B-body, leave it alone, buy wheels with odd back spacing
* get a Ford 8.8 inch and have it narrowed
* get a Ford 8.8 inch, leave it alone, buy wheels with odd back spacing. Might be able to get disk brakes on it, already assembled for a good price

So that's why I'm exploring the two types: dropout like the 8-3/4 versus carrier like the 8-1/4 or 8.8 inch Ford. (Moparts on the Web - Main Index)

 

[barracuda-67]

This is like asking someone what tools to use for a given job. It all depends on the person. And yes, the "correct" way to do the job on the 8 1/4 is to use a case spreader, though many people do not. Not using a spreader can result in broken shims when you try to tap them in with a hammer. Even a brass one. Ask me how I know. Del is right though. Once you have more than one third member set up for the 8 3/4, it is easier to swap the whole thing out. But a re-gear for each individual assembly is probably about a tie.

This is good to know, thanks, @RustyRatRod.

I have had a different experience respectfully than Tom.

I raced several Aspens in both Stock and Superstock years
ago with the 8 1/4 that were 11 second cars. I broke several
8 1/4s and then the supply of Gears for that application totally
disappeared everywhere (480/510 no longer available as well as others).

I run the 8 3/4 regularly with very few issues even in 3200 lb car
in the 9s unless it has a transbrake (Then Dana 60 or Ford 9 or needed).

I did sell my Mirada 318 O/SA to a friend years ago and he is still winning class
and going strong with the 8 1/4 but it is a 12 Sec. Racecar. That rearend with spool
has been in the car since mid 1985.

Thanks @GTX JOHN. We are so far away from those power levels that I won't worry about it right now. But it is good to know

 

[A body]

like 1wild back in our street days with the 8.75 we’d run 4.10/.56s for fun, but had a 2.7 gear chuck we could throw in for road trips. Weren’t making enough power to hurt them back then.

 

[TrailBeast]

This is like asking someone what tools to use for a given job. It all depends on the person. And yes, the "correct" way to do the job on the 8 1/4 is to use a case spreader, though many people do not. Not using a spreader can result in broken shims when you try to tap them in with a hammer. Even a brass one. Ask me how I know. Del is right though. Once you have more than one third member set up for the 8 3/4, it is easier to swap the whole thing out. But a re-gear for each individual assembly is probably about a tie.

My 8.25 doesn’t use shims, but the same type setup as the 8.75 with the preload adjusters like this.
Its supposedly a 73/74 housing.
As far as which one is easiest to change gears in, it’s a pain in the butt setting up a pinion under the car. (8.25)
With the 8.75 you can pull it out and do it on the bench.
Obviously another whole unit with different gears ready to drop in is best.

 

[340six]

If you're changing just the pumpkin then Yes it's faster, but it takes about the same effort to setup up either if you are changing the gears out on the pumpkin carrier.

Changing gears in an 8.25" is not hard and I personally wouldn't change an 8.25" over to a 8-3/4" just so I could swap the gears unless you plan on swapping

them several times a month. I've had better luck with a 8.25" staying together than any 8-3/4" I've ever owned.

Tom

My 73 Dart Sport 340 came with a mint 8 1/4 231-1 sure grip big bolt like they all were.
Being A E Body guy i gave various 8 3/4 centers of Diff Gears.
Friend sold me the 8 3/4 A Body rear 80 bucks with small bolt axles less center and less brakes.
Sold the axles on eBay 50 buck's. New Moser BB axles
YouPullIt 11" drums
Could not sell the 8 1/4 321-1 Sure Grip, so gave it away. It passed few guys hands and ended up being sent to scrapper
I can swap 430, 410,391,323,294, and 276 easy as pie.
In.my younger days would drive to track with 276 swap to 410s. And swap back to get home.

 

[RustyRatRod]

My 8.25 doesn’t use shims, but the same type setup as the 8.75 with the preload adjusters like this.
Its supposedly a 73/74 housing.
As far as which one is easiest to change gears in, it’s a pain in the butt setting up a pinion under the car. (8.25)
With the 8.75 you can pull it out and do it on the bench.
Obviously another whole unit with different gears ready to drop in is best.
View attachment 1716138978

Well, I've never done a salisbury rear unless it's either out of the car and on the bench or the car is on a lift in the air, so there's that.

 

[cpearce]

As was mentioned in previous posts, the drop out third member of the 8.75 allows it to be set up on the bench rather than in, under, the vehicle. There is that convenience, although the process of the setup is very similar.

I feel the beauty of the banjo style drop out center sections is the ability to quickly change ratios by swapping carriers, although this assumes you have more than one. Just last night I swapped out 3.55's for 3.23's for a long distance road trip next week, pretty quick and simple task. Although there is a cost to having various carriers sitting around, it is likely less money, or modifying, than retrofitting some OD transmission in our A bodies.

 

[RustyRatRod]

As was mentioned in previous posts, the drop out third member of the 8.75 allows it to be set up on the bench rather than in, under, the vehicle. There is that convenience, although the process of the setup is very similar.

I feel the beauty of the banjo style drop out center sections is the ability to quickly change ratios by swapping carriers, although this assumes you have more than one. Just last night I swapped out 3.55's for 3.23's for a long distance road trip next week, pretty quick and simple task. Although there is a cost to having various carriers sitting around, it is likely less money, or modifying, than retrofitting some OD transmission in our A bodies.

Right....and if ONE center section is all you have and you have to regear it, then the 8 3/4 is arguably "a little" harder, because you have to wrestle that whole thing around.

 

[RustyRatRod]

My 8.25 doesn’t use shims, but the same type setup as the 8.75 with the preload adjusters like this.
Its supposedly a 73/74 housing.
As far as which one is easiest to change gears in, it’s a pain in the butt setting up a pinion under the car. (8.25)
With the 8.75 you can pull it out and do it on the bench.
Obviously another whole unit with different gears ready to drop in is best.
View attachment 1716138978

I will come back and say this.....as far as servicing one, I've done plenty of those on jack stands. But I won't build one on the ground. Just not that may bolts and it's outta there.

 

[33IMP]

Changing gears in an 8 1/4 (if you don't have a lift) on your back, under the car.
Changing gears in an 8 3/4 (if you don't have a separate pumpkin) sitting down at your workbench.
I know which I would choose.

Not to mention 8 3/4 gears are easier to get than 8 1/4.

 

[Brooks James]

Some of the parts on a sure grip are hard to source

Roy, SGBARRACUDA looked for months for spider gears in a 742 case sure grip he built for me. After months he found a used one.

I say get a more modern carrier for the 8 3/4

 

[TrailBeast]

I will come back and say this.....as far as servicing one, I've done plenty of those on jack stands. But I won't build one on the ground. Just not that may bolts and it's outta there.

I hear ya.
Did an 8.75 entire rear end, and a gear and bearings change in an 8.25 both on gravel with stands.
Yea, it sucked.

I need a “go fund me” for a nice garage with a lift.

 

[toolmanmike]

I hear ya.
Did an 8.75 entire rear end, and a gear and bearings change in an 8.25 both on gravel with stands.
Yea, it sucked.

I need a “go fund me” for a nice garage with a lift.

Yep, what a pain. There are some old driveline tech's in town that do a lot of rear gear installs. They won't do 12 bolt Chevy's and Dana's. If you carry in a 8 3/4 or 9" and they are all over it.

 

[RustyRatRod]

I hear ya.
Did an 8.75 entire rear end, and a gear and bearings change in an 8.25 both on gravel with stands.
Yea, it sucked.

I need a “go fund me” for a nice garage with a lift.

Yeah, I have the building. I just need the lift.......but I'd put it outside though. lol

 

[GTX JOHN]

My main building is 5000 ft with 2 two Posts and two
4 Posts, My boy has one of each in his shop at home.

The ONLY good thing about getting old is not being poor
anymore. But I miss being young!