Correct.
8 1/4 rear end 2.45 gears!
- Thread starter ScampChamp
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lemondana
BlackDart
I have seen 2 cases, 1 a 2.94 ring and pinion in a 2.45 housing and another with 4.10 gears into a 2.45 housing. Might have not been right, but they worked. The carriers are different, break between 2.45 and 2.71. I even saved a Sure Grip and gears from a 2.45 F body 8 1/4.
Read through this. It has some good info in it.
The 8 1/4 thread
@memike and myself decided to start a thread all about 8 1/4 rears and common problems. Lets start with carriers and housings. The housings are two different distinct easy to identify The first is the most common with the pinion centered for 2.57 ratio and down the other is the off center...
www.forabodiesonly.com
RPMagoo
Just An Old Motorhead
I'm still a bit confused -- I guess more info than I can absorb. ----- My question is can I put a 3.55 posi unit, into a housing that currently has 2.45 gears in it, without any modifications ? -- Both housings are 8-1/4".Read through this. It has some good info in it.
The 8 1/4 thread
@memike and myself decided to start a thread all about 8 1/4 rears and common problems. Lets start with carriers and housings. The housings are two different distinct easy to identify The first is the most common with the pinion centered for 2.57 ratio and down the other is the off center...
I'm not 100% sure myself.......but I don't think so. Maybe someone with more sense can answer more solidly.
The 2.45 gear has its own carrier specific to 2.45 ratio be it an open or sure grip. You cannot go numerically higher on that gear ratio using that carrier. 2.76 and above all swaps on same carrier. Physical 8.25 diff is no different just use the higher numerical ratio carrier and gears.
lemondana
BlackDart
There was also a 2.24 gear set, fits with 2.45. Then 2.71 and up are all interchangable.
2.24. Boy what a cruiser with an A500. lol
You're close but there was no 2.76 ratio with the 8 1/4" axle. The closest to that was a 2.71.
There were no "Posi" units either, technically.
RPMagoo
Just An Old Motorhead
Is the "carrier" the housing ? --
People keep using the term carrier when it is just as easy to use the word differential.
The axle housing can accommodate all of the factory ratios that were offered. From memory, they ranged from 2.24 to 3.92.
The info I have states that the differential case application is as follows: 2.45 and lower numerically is ONE differential, 2.71 and numerically higher is the other differential.
The axle housing can accommodate all of the factory ratios that were offered. From memory, they ranged from 2.24 to 3.92.
The info I have states that the differential case application is as follows: 2.45 and lower numerically is ONE differential, 2.71 and numerically higher is the other differential.
No.. the carrier is what the ring gear mounts to. Does the housing make it a sure grip? No the carrier does.
For the moment let's ignore the terminology used by Chrysler in the service manual and parts catalog.
Out in the real world, how do people define the 8 1/4
" Carrier "
Does it include spider gears and bearings or is the Carrier bare with no other parts?
Out in the real world, how do people define the 8 1/4
" Carrier "
Does it include spider gears and bearings or is the Carrier bare with no other parts?
Yep, I wish there wasn't, but there are two different housings
RPMagoo
Just An Old Motorhead
That's My real question -- Thanks
DoctorDiff
Well-Known Member
You can install ANY 8.25" gear ratio offered into ANY 8.25" housing if you use the correct CARRIER and the correct carrier bearings. For example, you can install a 2.71 and up sure-grip with 3.55 gears into an 8.25" housing that was originally built with 2.45 and down gears/carrier.
There were 2 housings, but it did not affect gear ratio fitment. '76 and newer housings came with larger diameter carrier bearings than the '75 and older version.
There were 2 housings, but it did not affect gear ratio fitment. '76 and newer housings came with larger diameter carrier bearings than the '75 and older version.
Thanks, Cass.
I knew that there was a "break" in the axle in the same way that some axles from other manufacturers had. In short, the differential carrier was different based on the gear ratio. The taller the gear, the thinner the ring gear so the carrier/differential had to be built closer to the centerline of the housing. I've read that some GM axles used a thin shim that went between the ring gear and carrier to make things work.
The "break" is as stated. 2.45 to 1 and taller is one carrier/differential, 2.71 and lower is another.
I didn't know about the difference in housings but now I do.
I have a disassembled 8 1/4" axle that came with 3.21 gears and a 69 Dart 4 door with transplanted 8 1/4" axle with a 2.71 Sure Grip. I'm contemplating having a shop swap the 3.21 gears into the Dart axle. I wish I knew how to set up gears myself!
I knew that there was a "break" in the axle in the same way that some axles from other manufacturers had. In short, the differential carrier was different based on the gear ratio. The taller the gear, the thinner the ring gear so the carrier/differential had to be built closer to the centerline of the housing. I've read that some GM axles used a thin shim that went between the ring gear and carrier to make things work.
The "break" is as stated. 2.45 to 1 and taller is one carrier/differential, 2.71 and lower is another.
I didn't know about the difference in housings but now I do.
I have a disassembled 8 1/4" axle that came with 3.21 gears and a 69 Dart 4 door with transplanted 8 1/4" axle with a 2.71 Sure Grip. I'm contemplating having a shop swap the 3.21 gears into the Dart axle. I wish I knew how to set up gears myself!
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