mopar rear axle

garyc · 03-31-2021, 08:25 AM

Hello,
what are you using for rear axle assy for L M/SA? 4000lb car, will a 8 1/4 work? c-clip? 4:88's ? I can deal with changing ring/pinion each season just don't want to spit pinion out on starting line
building 1975 cordoba 400 4V for L/M
thanks gary

Demon340 · 03-31-2021, 12:52 PM

Quote:

Originally Posted by garyc

Hello,
what are you using for rear axle assy for L M/SA? 4000lb car, will a 8 1/4 work? c-clip? 4:88's ? I can deal with changing ring/pinion each season just don't want to spit pinion out on starting line
building 1975 cordoba 400 4V for L/M
thanks gary

Moser 8 3/4
Drop out center section. Will hold up for a long time.

GTX JOHN · 03-31-2021, 01:22 PM

I run a N/O/P Mopar
@ 3500 to 3700 Lbs.
I would strong recommend to 8 3/4
The 8 1/4 is had to find gears for and
really much weaker!

Even in the Mid 70's Larry Shepard at the Mopar
Performance Seminars strong recommended losing
the 8 1/4
He stated that Mopar save a little over a single dollar
when they replaced the 8 3/4 with the 8 1/4. I guess
every dollar counted with a Mfg. that was bleeding money
at that time!

GTX JOHN · 04-01-2021, 12:10 AM

My boy runs a 400 Roadrunner usually in I/SA at around 3700 Lbs

We have broken several expensive 8 3/4 third members before we went

to a Dana 60.

Race Clean · 04-01-2021, 10:10 AM

It's the weight you should go by,Heavy = Dana
Based on my observations a 283 in a heavy Car could be thougher on rears than a 396/427 in a lighter car.
Trying to move a lot of weight from standstill in a hurry is what takes a toll on stuff.

My experience with 8 3/4 is that they start breakin up around 3500 pounds and even earlier if you have some serious power.
Then some say the Dana is faster also...sorry about the rambling,your question was about the 8 1/4 and 8 3/4 and I have zero experience with the first one!

mopacltd · 04-01-2021, 10:54 AM

My experience is with the length. Axle tube flex caused most of the failure.

03-31-2021, 08:25 AM	#1
garyc Member Join Date: Mar 2021 Posts: 124 Likes: 0 Liked 51 Times in 30 Posts	mopar rear axle Hello, what are you using for rear axle assy for L M/SA? 4000lb car, will a 8 1/4 work? c-clip? 4:88's ? I can deal with changing ring/pinion each season just don't want to spit pinion out on starting line building 1975 cordoba 400 4V for L/M thanks gary

03-31-2021, 01:22 PM	#3
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,736 Likes: 2,808 Liked 2,488 Times in 698 Posts	Re: mopar rear axle I run a N/O/P Mopar @ 3500 to 3700 Lbs. I would strong recommend to 8 3/4 The 8 1/4 is had to find gears for and really much weaker! Even in the Mid 70's Larry Shepard at the Mopar Performance Seminars strong recommended losing the 8 1/4 He stated that Mopar save a little over a single dollar when they replaced the 8 3/4 with the 8 1/4. I guess every dollar counted with a Mfg. that was bleeding money at that time! __________________ John Irving 741 Stock 741 Super Stock Last edited by GTX JOHN; 04-01-2021 at 10:21 PM.

04-01-2021, 12:10 AM	#4
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,736 Likes: 2,808 Liked 2,488 Times in 698 Posts	Re: mopar rear axle My boy runs a 400 Roadrunner usually in I/SA at around 3700 Lbs We have broken several expensive 8 3/4 third members before we went to a Dana 60. __________________ John Irving 741 Stock 741 Super Stock Last edited by GTX JOHN; 04-01-2021 at 12:12 AM.

04-01-2021, 10:10 AM	#5
Race Clean Member Join Date: Aug 2017 Posts: 159 Likes: 18 Liked 129 Times in 53 Posts	Re: mopar rear axle It's the weight you should go by,Heavy = Dana Based on my observations a 283 in a heavy Car could be thougher on rears than a 396/427 in a lighter car. Trying to move a lot of weight from standstill in a hurry is what takes a toll on stuff. My experience with 8 3/4 is that they start breakin up around 3500 pounds and even earlier if you have some serious power. Then some say the Dana is faster also...sorry about the rambling,your question was about the 8 1/4 and 8 3/4 and I have zero experience with the first one! __________________ Stop global whining Last edited by Race Clean; 04-01-2021 at 10:19 AM.

04-01-2021, 10:54 AM	#6
mopacltd Member Join Date: Aug 2009 Location: yarnell,az Posts: 312 Likes: 418 Liked 124 Times in 44 Posts	Re: mopar rear axle My experience is with the length. Axle tube flex caused most of the failure.