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rear end swap


dr47

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anyone change out the rear end in a 51 plymouth l'm looking to do the swap was wondering what might be a good fit  what is the best way to measure hub to hub or with the drums on ,thanks

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I looked at an explorer rear axle, but reconsidered after looking at the pinion companion flange (uses a 6 or 8 bolt flat disk arrangement). Decided to buy a late model jeep cherokee (not a grand cherokee) from a 2001 model which uses a spicer type companion flange (standard old style u joint). Almost all of them are 3.55:1 and are slightly (1 inch or so) narrower than the stock axle, its an 8 1/4" ring gear chrysler axle. These cherokees were all the same for a lot of years 90's to 2000's using that axle. The later models use a higher axle spline count (stronger) than the earlier ones something like 2000 and down. Measure from wheel mounting to wheel mounting to get accurate measurement for comparison. I have not installed it yet. You will need to buy spring perches and weld them on, because the jeep perches are on top of the axle vs below which our cars use. Look at early 50's chevys for the correct width perches.

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43 minutes ago, Dartgame said:

I looked at an explorer rear axle, but reconsidered after looking at the pinion companion flange (uses a 6 or 8 bolt flat disk arrangement). Decided to buy a late model jeep cherokee (not a grand cherokee) from a 2001 model which uses a spicer type companion flange (standard old style u joint). Almost all of them are 3.55:1 and are slightly (1 inch or so) narrower than the stock axle, its an 8 1/4" ring gear chrysler axle. These cherokees were all the same for a lot of years 90's to 2000's using that axle. The later models use a higher axle spline count (stronger) than the earlier ones something like 2000 and down. Measure from wheel mounting to wheel mounting to get accurate measurement for comparison. I have not installed it yet. You will need to buy spring perches and weld them on, because the jeep perches are on top of the axle vs below which our cars use. Look at early 50's chevys for the correct width perches.

 

The XJ Cherokee 8.25 is definitely a good swap candidate, with the later 29 spline axles being the very best.  That's what I run in my truck; 29 spline 8.25 with 3.55s. Be aware some XJs were equipped with Dana 35 rear axles vice the stronger Chrysler.  The D35 is considered wimpy by Jeep guys but I believe it would be more than fine in a flathead Mopar.  Both YJ and TJ Jeeps use rear axles the same width and bolt pattern as the XJ Cherokee so they will also work.  I have seen people literally  give away Wrangler D35 rear ends for free.  

 

Less common, but another great rear end that is the right width and wheel bolt pattern is the Ford 9" from a 71-73 Mustang. 

 

 

 

 

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1 hour ago, dr47 said:

can i ask (why not a grand Cherokee ) rear end ? on other jeep rears should i be two  wheel drive or four .thanks

 

The ZJ Grand Cherokee is the same width and bolt pattern but most are D35; the 8.25 is simply a better unit.  ZJs have coil spring rears so there's a little bit more cutting off unnecessary bracketry.  XJs are also typically more plentiful in wrecking yards.  I would only consider using a Grand Cherokee rear end if one with the right gear ratio presented itself for free or nearly so.

 

2 or 4 wheel drive doesn't matter.

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I've done the 8.8 in three different 48-51 Plymouths. Good fit, just had to change the spring perches and get a driveshaft made. The center section is offset on these But I haven't had any issues with it not being centered.

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I put an 8.8 from an explorer in mine about 2 years ago.  I forgot to move the bumpstop and the flange rubs on it on bumps (I've lowered the car as well).  I had to put spacers to keep the proper look to the car. I think it was 1" spacers.  I may be changing to 12v at some point in time, so the locker might be useful, but I'd have to do some other work to the motor and transmission to take full advantage of it, LOL.

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On 10/22/2019 at 2:09 PM, derbydad276 said:

 

 

yeah but finding those in scrap yard is almost the same as one of our cars today

 

Your donors are

1976-80 Dodge Aspen
1976-80 Plymouth Volare

1977-81 Chrysler LeBaron
1982 Chrysler New Yorker
1982-87 Chrysler New Yorker Fifth Avenue
1988-89 Chrysler Fifth Avenue
1977-89 Dodge Diplomat
1982-89 Plymouth Gran Fury

1980-83 Chrysler Cordoba
1981-83 Chrysler Imperial
1980-83 Dodge Mirada

 

That said, I have an 8 3/4 I was building for my 65 Cuda that looks like it will swap in fairly easily

Edited by Sniper
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The 8 3/4 from the rear looks almost like the original.

If you find a 1964 and earlier they even have tapered axles (or so I am told).

The ratios available are numerous and there are limited slip differentials (Dana Power-lok being the most desirable).

Unusual is the fact that they only have one differential design. If you need to change the ratio all you have to buy are the gears.

Some axles have a cutoff point where the next ratio requires the purchase of a different differential.

Strength wise they are very well engineered and rival the Ford 9 inch (or so an article in Hemmings says).

The 8 3/4 is my plan "B" if my 3.73 stocker doesn't work out and I can't find a 3.54.

To keep my car period correct (within 5 years) I am willing to paying up and I don't mind a little work.

An 8 3/4 would be an admission to the difficulty of finding the right original part.

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8 3/4 is a good option assuming you can find the right width, best candidate is a 1970 B body axle, nearly the same width as the 52. The center section castings used in these axles can be one of three types #741, 742 and 489 case (last three casting digits). Each has a different pinion gear shaft size or shape. 741 is small, 742 large and 489 tapered. All are overkill for a flat head powered car (nothing wrong with that)...each can be put in place of one another, and carriers interchange, but the gear sets do not and are specific to the case number. Hope this helps a little when seeking parts.

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On 10/23/2019 at 6:55 PM, Sniper said:

 

Your donors are

1976-80 Dodge Aspen
1976-80 Plymouth Volare

1977-81 Chrysler LeBaron
1982 Chrysler New Yorker
1982-87 Chrysler New Yorker Fifth Avenue
1988-89 Chrysler Fifth Avenue
1977-89 Dodge Diplomat
1982-89 Plymouth Gran Fury

1980-83 Chrysler Cordoba
1981-83 Chrysler Imperial
1980-83 Dodge Mirada

 

That said, I have an 8 3/4 I was building for my 65 Cuda that looks like it will swap in fairly easily

Here in MN those cars have long ago returned to the earth! Seeing something even late 90s is almost unheard of....

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Don't forget the Ford 8"....

Maverick if you can find one 

65-66 Mustang with tapered axle tubes (not desirable with hotrodders but PLENTY strong for our applications including LA V8 swaps)

Ford Falcons (I used this one) 

 

Width is about 1" narrower which allowed me to fit 8" wheels under my 49.

Edited by Adam H P15 D30
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