Re: 8.25 Rear End Strength
[Re: Pacnorthcuda]
#3190506
11/12/23 06:19 PM
11/12/23 06:19 PM
|
Joined: Mar 2006
Posts: 9,835 MI, usa
dvw
master
|
master
Joined: Mar 2006
Posts: 9,835
MI, usa
|
It'll more than likely be fine. If it breaks? A B body 8 3/4 is a bolt in using a factory 727 Duster drive shaft. the 81/4 brake parts will bolt up as well. Doug
Last edited by dvw; 11/12/23 06:22 PM.
|
|
|
Re: 8.25 Rear End Strength
[Re: dvw]
#3190522
11/12/23 08:08 PM
11/12/23 08:08 PM
|
Joined: May 2019
Posts: 6,250 nowhere
Sniper
master
|
master
Joined: May 2019
Posts: 6,250
nowhere
|
It'll more than likely be fine. If it breaks? A B body 8 3/4 is a bolt in using a factory 727 Duster drive shaft. the 81/4 brake parts will bolt up as well. Doug Not really, at least not without new axle shafts. bolt pattern and flange offsets are different. Ran an 8 1/4 behind a warm 360 and an A833 in my Diplomat for years. SG with P255/60R15 BFG's. No issues
|
|
|
Re: 8.25 Rear End Strength
[Re: dvw]
#3190528
11/12/23 08:36 PM
11/12/23 08:36 PM
|
Joined: Jan 2003
Posts: 10,562 Freeport IL USA
poorboy
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,562
Freeport IL USA
|
I broke one once. it was out of a 73 Duster 340 car with near 100,000 miles on it, installed in a 35 Dodge 2 door sedan with my 150lbs son sitting directly above the rear end. It was a "limited slip" 3:55 gear rear.
It was a fairly cool Sunday morning, we were heading to a car show. I was having issues with the carb. The stupid thing would cough and die every time I was trying to get through a stop sign on a busy street. After about the 4th attempt, I put the car in neutral, revved it to about 2500, and shifted it it into drive. Away it went, for about 2 feet before the bang and the sound of breaking gear teeth joined with the car no longer moving under power. Lets say we didn't make it to the car show that day. One of the two bolts that holds the carrier bearing cap on one side broke off even with the housing and allowed the carrier to get cocked. That action stripped off about 6 teeth from the ring gear, and most of the teeth from the pinion gear. I replaced the 8 1/4 with a 9 1/4 I had in my pile of parts.
The odds are about even that if my son wasn't sitting directly above the rear end, the tires would have spun and the rear probably would have survived. It is also possible that the failed bolt was already cracked from previous abuse. I bought the Dusted used, and beat the crap out of it, then I beat the crap out of the sedan before the axle failure. The axle failure didn't change my driving habits, I was pretty used to accumulating broken parts.
How tough that 8 1/4 is depends on how bad you plan on treating it. My broken 8 1/4 went 100,000 miles on the street (and the strip at least a few times) before it got to me and then was in the sedan at least 3 years before I broke it with the neutral drop.
|
|
|
Re: 8.25 Rear End Strength
[Re: Sniper]
#3190547
11/12/23 11:02 PM
11/12/23 11:02 PM
|
Joined: Jan 2004
Posts: 8,264 fredericksburg,va
cudaman1969
master
|
master
Joined: Jan 2004
Posts: 8,264
fredericksburg,va
|
It'll more than likely be fine. If it breaks? A B body 8 3/4 is a bolt in using a factory 727 Duster drive shaft. the 81/4 brake parts will bolt up as well. Doug Not really, at least not without new axle shafts. bolt pattern and flange offsets are different. Ran an 8 1/4 behind a warm 360 and an A833 in my Diplomat for years. SG with P255/60R15 BFG's. No issues Hmmm, the drums off my 73 8-1/4 are the same as the 68 b-body 8-3/4, same for the shoes and backing plates.
|
|
|
Re: 8.25 Rear End Strength
[Re: cudaman1969]
#3190599
11/13/23 12:14 PM
11/13/23 12:14 PM
|
Joined: May 2019
Posts: 6,250 nowhere
Sniper
master
|
master
Joined: May 2019
Posts: 6,250
nowhere
|
It'll more than likely be fine. If it breaks? A B body 8 3/4 is a bolt in using a factory 727 Duster drive shaft. the 81/4 brake parts will bolt up as well. Doug Not really, at least not without new axle shafts. bolt pattern and flange offsets are different. Ran an 8 1/4 behind a warm 360 and an A833 in my Diplomat for years. SG with P255/60R15 BFG's. No issues Hmmm, the drums off my 73 8-1/4 are the same as the 68 b-body 8-3/4, same for the shoes and backing plates. Ah fudge, I read it as an A body 8 3/4, not a B body one, you are correct there.
|
|
|
Re: 8.25 Rear End Strength
[Re: Sniper]
#3190656
11/13/23 04:58 PM
11/13/23 04:58 PM
|
Joined: Mar 2006
Posts: 9,835 MI, usa
dvw
master
|
master
Joined: Mar 2006
Posts: 9,835
MI, usa
|
It'll more than likely be fine. If it breaks? A B body 8 3/4 is a bolt in using a factory 727 Duster drive shaft. the 81/4 brake parts will bolt up as well. Doug Not really, at least not without new axle shafts. bolt pattern and flange offsets are different. Ran an 8 1/4 behind a warm 360 and an A833 in my Diplomat for years. SG with P255/60R15 BFG's. No issues Hmmm, the drums off my 73 8-1/4 are the same as the 68 b-body 8-3/4, same for the shoes and backing plates. Ah fudge, I read it as an A body 8 3/4, not a B body one, you are correct there. I think you are thinking of A body with 1 3/4" shoes. The bolt pattern of a F body and a B body are the same. The 66-70 B body axle is 3/4" wider overall. So 3/8" on each side. The driveshaft definitely works. So do the backing plates. Both are on my Volare currently. I have heard some 8 1/4 backing plate are missing the lower hole which can be drillled. Doug
|
|
|
Re: 8.25 Rear End Strength
[Re: dvw]
#3190833
11/14/23 01:50 PM
11/14/23 01:50 PM
|
Joined: Jan 2011
Posts: 15,871 Central Florida
larrymopar360
Stud Muffin
|
Stud Muffin
Joined: Jan 2011
Posts: 15,871
Central Florida
|
I've had several factory 8.25 rears in AHB Diplomats that I've put in a warmed up/heated up engine. Mine have always held up well. I put 60k miles on my first one with a MP 360/300hp that was pushing 400 lb/ft torque. And this is after the car was used as a police car so the rear end had plenty of miles on it. I had 2.92 and then 3.21 gears and 235/70/15 on factory rims. My current one has a stroked 408 that dyno'd on engine stand at 469hp and 528 lb/ft torque and it's held up perfectly. Same tires and a 3.21 rear gear and sure grip. I don't beat my cars but I certainly enjoy a good punching it now and then and a little tire smoke occasionally. As written, if you aren't running fat slicks and making a bunch of hard launches you'll be fine. I think the 8.25 is underrated.
Also if you find one out of a police car it will have the setup for the larger 11" brakes.
Facts are stubborn things.
|
|
|
Re: 8.25 Rear End Strength
[Re: 5thAve]
#3191536
11/17/23 05:53 AM
11/17/23 05:53 AM
|
Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
|
for what it's worth if you're looking for deeper gears on the cheap, a jeep XJ cherokee after '87 uses either a dana 35 or an 8 1/4 in the rear. the easiest to find are 3.55 geared 8 1/4's that typically came in autos. manuals had 3.07's, I think the tow package had 3.73's...they are 60.5" wide, basically the same as an FMJ, and I can find them all day on facebook marketplace locally for $150 or less. just need to cut off the shock mounts and spring perches, and weld new spring perches in the correct location. IIRC the spacing is about right, but they're on the wrong side of the axle (spring over vs. under)
also, the rear disc brakes from a liberty or late 90's grand cherokee with an 8 1/4 are a bolt on if you want rear disk.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
|
|
|
|
|