Rear end swap

[Smokeybear]

Well, it's a little ahead of schedule but I started into the rear end swap today since the brake drum and wheel cylinder problem I had the other day forced my hand. I got all the old stuff out without any damage and I started cleaning up underneath for the new rear end. Hopefully I'm picking that up today and can get it cleaned and installed tomorrow. I'll take lot's of pics and measurements for anyone interested. One thing I did find odd. I have read where the rear of our cars are 60" wm to wm. Measurements of mine indicate almost 61 1/2. No problem though, the new one is close enough. I'll post up the pics later.

[1940plymouth]

Not to hyjack your thread, but what year and make rearend are you going to replace the old one with?

The rearend in my '40 is real bad and I may convert to newer rearend if it turns out to be an expensive project.

Thanks and good luck with your project,

Bob

[oldodge41]

Keep us posted Smokeybear. The rear in my '41 was wider than I expected too.....Tim

[Dennis_MN]

For a story of the Axle Update, go over to the truck side and read the thread on the Axle Update for a tail of woe about the drive shaft modification.

If only my NAPA guy found a conversion U-joint I would have been in luck, but as it turned out, I had to replace both ends of my drive shaft.

[Smokeybear]

Not to hyjack your thread' date=' but what year and make rearend are you going to replace the old one with?

The rearend in my '40 is real bad and I may convert to newer rearend if it turns out to be an expensive project.

Thanks and good luck with your project,

Bob[/quote']

I'm looking for an explorer rear end as they are 59 3/4. The 96 and newer ones have disks and they are usually found with 3.73 or 4.10 with limited slip. One other thing I found odd was my original had somewhere around 2.0 gears in it. Awful high for a flat six and three speed I thought. After getting the rear out I checked by doing the rotation trick and the and the driveshaft rotated twice while the wheel rotated just a fuzz over one time.

[Smokeybear]

For a story of the Axle Update, go over to the truck side and read the thread on the Axle Update for a tail of woe about the drive shaft modification.

If only my NAPA guy found a conversion U-joint I would have been in luck, but as it turned out, I had to replace both ends of my drive shaft.

Tim has shared his knowledge with me and says the explorer rear end is 1 1/2 in shorter than the original and he made an adapter to go between the driveshaft and the new rear, I'm going to try my hand at that too.

[mossback44]

I'm looking for an explorer rear end as they are 59 3/4. The 96 and newer ones have disks and they are usually found with 3.73 or 4.10 with limited slip. One other thing I found odd was my original had somewhere around 2.0 gears in it. Awful high for a flat six and three speed I thought. After getting the rear out I checked by doing the rotation trick and the and the driveshaft rotated twice while the wheel rotated just a fuzz over one time.

If only one wheel is turning, as is often the case with an "open" rear end when it's off the ground, it would be rotating at double speed. If that is what happened during your test, it would actually have taken four turns of the drive shaft to rotate both wheels a full turn.

[oldodge41]

Smokey, Like Mossback44 said, to test an open type rear you have to turn the wheel two complete rotations and count drive-shaft rotations to find your true ratio. Some people recommend 20 revolutions and divide the shaft rotations by 10 but I didn't see a difference with mine. The explorer 8.8 I used was 1.5 inches shorter from the center of the axle to the face of the pinion flange than the old rear. I also used 1.5 inch spacers on each side to center my wheels in the fenders. I may end up going to deeper dish wheels so that would would be fine without the spacers.............Tim

[mossback44]

I just finished installing a '96 Mustang Cobra rear end in my '47 Plymouth. It came with disc brakes, traction lock and a 3.27 ratio and is almost exactly the same width as the original rear and the same bolt pattern. Like the Explorer, the Cobra uses an 8.8 inch differential, but the axle housings are 2.75 inches in diameter, rather than 3.25 inches like the Explorer. I had to cut off four brackets associated with the Mustang's coil spring suspension and also removed a pair of bolted on reinforcing brackets before I welded on new spring perches. I fabricated some 1-inch lowering blocks and used them with the original Plymouth U-bolts. I may drop it more later if I locate some longer U-bolts for the right price.

I'm putting it behind a 360 engine with a 727 trans and was amazed to find the Mustang drive shaft was just the right length. I only needed a combination u-joint to couple the Mopar yoke to the front end of the shaft. Sometimes a guy gets lucky!

[Robert Horne]

I did a measurement on my friend's 98 Grand Cherokee rear end, from the outside edge of tire tread is 66 inch. My 38 Plymouth has an outside edge of 64.75 inch, with the original type wheels/tires, but does not fill the wheel wells up very nice. The 66 inch or a 67 inch tread to tread would look alot better. I have a 96 Ford Ranger rear, that has a 65 inch tread to tread width. With so many wheels have different back space, I would rather change the wheels than use spacers.

[Robert Horne]

I just pulled the wheels off the Grand Cherokee rear. The disc brake pads are very small. Not much bigger than on my Goldwing.

[Smokeybear]

I just pulled the wheels off the Grand Cherokee rear. The disc brake pads are very small. Not much bigger than on my Goldwing.

After research, I've found the Grand Cherokee Dana 35's are not a real good swap. As you've mentioned the disks are small and they have a lot of pinion bearing failures and leaking problems. I've read that toyota pickup axles are a good swap too. The 86-95 are 58 1/2 wide and some time after that they changed to 60 inch wide. They are 30 spline and can take some horsepower, most guys doing 350 swaps are leaving them in. They also have low gears 4.10 is the tallest gear they have and they go up to 4.88

[Robert Horne]

The wheels that are on the Grand Cherokee have a 5 inch back space. My stock 15 inch Plymouth wheels have a back space of 3.5 inch. I have been measuring the different wheels to see what would fit the best on each rearend, for total width.