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8.25 swap for a 9.25 rear end assistance needed

71GTX440

71GTX440

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I currently have a 1971 8.25 rear diff under my ride, looking at swapping for a newer dodge 9.25 rear end with disc brakes and 3.92 gears. What all will be needed for this to happen? Any help would be greatly appreciated!
 
How close is the 9.25 in width to a B body rear? Otherwise I think it would be a matter of cutting and re-welding the perches to the same B body position and some new U bolts. Not sure about pinion angle and all that though. Or driveshaft.
 
I honestly cannot find any good reference material online. I found a ton of info for Mopar rear ends from the 1970's, but nothing showing similar for more modern rear ends.
 
71GTX440 said:
I honestly cannot find any good reference material online. I found a ton of info for Mopar rear ends from the 1970's, but nothing showing similar for more modern rear ends.
Click to expand...
Yeah, it's hard to find material on line because it's not a very popular swap. You might have to get on a couple or more sites to try and find others who have done it. Any reason why you don't want to do an 8 3/4 instead?
 
Well, one issue will be your donor rear. Depending on the source, the width might not be correct, and if its a newer truck rear end, the pumpkin may not be centered which is a no-go. Secondly, depending on how new it is and if it is a truck rear, the bolt pattern is 5x5.5 instead of 5x4.5. I explored this option for about the 3 minutes it took to crawl under a 2003 Ram. However, I am not completely convinced that with some ingenuity, the 14" rotors and calipers won't work. The tube flanges appear to be the same but I have not pulled everything off to check the caliper mounts etc. The bolt pattern could be overcome in my case as I am 2" narrower than I need so I can run 1" wheel adapters.
 
Well, one issue will be your donor rear. Depending on the source, the width might not be correct, and if its a newer truck rear end, the pumpkin may not be centered which is a no-go. Secondly, depending on how new it is and if it is a truck rear, the bolt pattern is 5x5.5 instead of 5x4.5. I explored this option for about the 3 minutes it took to crawl under a 2003 Ram. The rear is a 4.56 with a Detroit locker and has lived behind a 580hp 6.1 based 426. They are "weak" but maybe this one lived because of the lack of traction. However, I am not completely convinced that with some ingenuity, the 14" rotors and calipers won't work. The tube flanges appear to be the same but I have not pulled everything off to check the caliper mounts etc. The bolt pattern in the rotors could be overcome in my case as I am 2" narrower than I need so I can run 1" wheel adapters.
 
I swapped a 9 1/4 for a 8 1/4 and needed a new drive shaft
or have yours shortened and larger yoke installed
again check width and bolt pattern
 
A few questions regarding your swap.

What car did you do this swap on?
What car did the 9 1/4 come from?
Was the 9 1/4 the same width drum to drum?

Thanks much!
 
73 SSB and it came from a 76 cop car fullsize
and yes width wise it was same if I remember right
I did this 35 years ago
and I still have car that I hope to fix damage from my youngest daughter from about 20 years ago
has been parked in dry storage so next year
 
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