Swaping 1973 8 1/4 axle to 1970 8 3/4 axle on Charger HELP

[Leo]

New to this and I need help. My 73 charger has an 8.25 axle dimensions: housing 63 inches, perch from center 47inches. I found a 70's b body axle and as we know are shorter 60 in thus perches are also different 44 in from center. Therfore I need help on this matter...will I be able to retro fit this axle to work on my charger without problems once put together? Any literature, websites, or personal knowledge will be greatly appreciated.

 

[mmissile]

https://www.bigblockmopar.nl/tech/mopar-rearaxle-dimensions/

 

[400sforever]

Look up doctor diff on the internet. They have a kit to move rear springs in just enough to clear a 10 inch wide wheel if you want to go that route without cutting up your car. No matter what, you will have to cut your perches off the 73 and weld them on your 8.75 so that they match up to your springs because 73 and up have a large hole in them whereas 72 and below don't.

 

[Bruzilla]

My advice would be to find someone who needs your housing and sell it to them, then take that money and buy yourself either a 71-74 housing and axles or an E body one. The E body ones are everywhere since they were standard on those cars, and you can usually find them pretty cheap. The E body rears are just 1.5" narrower, which is tough to notice on 71-74 Bs, and when I installed an E rear on my 74 B all I had to do was grind off the stock mounts and have new ones welded in .75" from the old ones. Much easier and cheaper than offsetting springs and cutting into the body.

Also, check if your car has the rubber isolated mounts or not. They came out midway through 73 so some have them and some don't... and some lost them decades ago when people changed them out.

 

[JG71B]

Yep, more work than its worth, perches have to be lined up, welded, etc

 

[SaskRunner]

New to this and I need help. My 73 charger has an 8.25 axle dimensions: housing 63 inches, perch from center 47inches. I found a 70's b body axle and as we know are shorter 60 in thus perches are also different 44 in from center. Therfore I need help on this matter...will I be able to retro fit this axle to work on my charger without problems once put together? Any literature, websites, or personal knowledge will be greatly appreciated.

I just did this swap on my 74 Roadrunner.

Axle out of a 1966 Charger

I used offset hangers from Doc Diff.

A new set of spring perches and springs from Calvert

Spring plates from the 66 Charger

The biggest hurdle is cutting the old perches off and welding the new ones on.

This will allow you to set the pinion angle to what you want.

The result is a increase of usable space in the wheel tub.

Another plus is you can ditch the ISO Clamp set up and use the 62-72 spring clamp arrangement.

You can reuse your shocks





This is 15x8 wheel with 3.5" BS with a M/T 295/65/15 tire on it.

 

[furryfrog]

For my 74, I just swapped out my 8.25 for an e body 8 3/4. An e body is just over 1/2 an inch narrower on each side versus 1 1/2 on the axle your trying to fit. All the 8 1/4 brake stuff fit right on the 8 3/4, even was able to take up the brake line slack without cutting the brake lines. Just had to cut and weld on new perches. There is no way your donor axle will fit unless you do what Saskrunner did. The perch would otherwise need to be welded on the bearing axle end which has a larger od than the axle tube, and your tires will hit the springs before they are tightened down.

I thought about offset hangers on my swap as well,like Saskrunner did, to get even more tire clearance, but then my swaybar would have been the next bottleneck in my setup.

 

[dodge1972]

Consider installing a 9.25 rear end and springs from a 75-79 b body. Rear end is a direct fit. 3.54 gears a common in trucks as a donor. Sure-grip units a common items as well.

 

[Leo]

I found 8 3/4 axle with 489 third member at a junk yard today and perches are 47 in from center. I left a deposit so they can hold it for me...However, not sure what it came out of, since the junk has it coming off a 55 Chrysler??? One thing for sure the drum hosing is huge (definitely a truck) I think. thus is this a rear axle I should buy to rebuild and would my current drum housing on the 8 1/4 work on this setup?

 

[dodge1972]

489 third member is the a 70's rear end. back plates were basically two sized, the same as your 81/4, I believe their 10", larger unit is a 11". Eleven inch are common on trucks and bake drum is wider, about 2.5 i believe. Good Luck

 

[Leo]

Thank you for all that info... will go and check it out with more detail this weekend...I hope that 489 is an LSD

 

[rs1]

I just sold a complete 8 3/4 rear out of a 72 charger they just wanted for the gears .he is looking to sell the housing if interested

 

[YY1]

The 71-74 seems to be the hardest one to find, except for the A body.

As stated above, the E body is plentiful and cheap, and is the closest dimensionally to the 71-74.

 

[Bruzilla]

For my 74, I just swapped out my 8.25 for an e body 8 3/4. An e body is just over 1/2 an inch narrower on each side versus 1 1/2 on the axle your trying to fit. All the 8 1/4 brake stuff fit right on the 8 3/4, even was able to take up the brake line slack without cutting the brake lines. Just had to cut and weld on new perches. There is no way your donor axle will fit unless you do what Saskrunner did. The perch would otherwise need to be welded on the bearing axle end which has a larger od than the axle tube, and your tires will hit the springs before they are tightened down.

I thought about offset hangers on my swap as well,like Saskrunner did, to get even more tire clearance, but then my swaybar would have been the next bottleneck in my setup.

The only issue I had with using an E Body rear in my 74 was when I went to put traction bars on. They were contacting the tire and I had to cut away part of the mounts for clearance.

 

[dodge1972]

Planning to part out a 72 Rally with a 8.75 complete with sway bar and springs. sent PM if anyone near Colorado is interested

 

[BigYellaStella]

Consider installing a 9.25 rear end and springs from a 75-79 b body. Rear end is a direct fit. 3.54 gears a common in trucks as a donor. Sure-grip units a common items as well.

This sounds like the ONLY way to go for strength and sure grip...

What do you use for mount plates? Original or donor?? Looking at a ratty 76 d150 with that exact rear in it and the price asked may justify the purchase if I can have a bulletproof (for my purposes anyway) rearend with limited slip and "more gooder" gears..

 

[dodge1972]

Checked on a ram charger 9.25 with sure grip rear end last year. Mounting plates are on top, thus a relocate is a requirement. Rear-end drum to rum I believe was an about 1" wider, but a b-body can absorb the difference. After plates are not expensive and your best option. recommend taking your springs to a spring shop to add additional leaf just below the full length leaf. Will lift the rear end about an 1.5 inches and stiffen the rear end. Especially if your only have four leafs now.

 

[Leo]

I found a 8 3/4 axle!!!d=Does anyone know if the shock plates from the 8 1/4 will work on the 8 3/4 since its the only part I cant seem to find on line for a 73 charger.
Any ideas will help. Thanks!!!

 

[Bruzilla]

I found a 8 3/4 axle!!!d=Does anyone know if the shock plates from the 8 1/4 will work on the 8 3/4 since its the only part I cant seem to find on line for a 73 charger.
Any ideas will help. Thanks!!!

8.25 ones will work on 8.75 and Dana.

 

[72RoadrunnerTyler]

I just sold a complete 8 3/4 rear out of a 72 charger they just wanted for the gears .he is looking to sell the housing if interested

Do you know if he's still trying to sell his 72 housing? I'm very interested.