Rear end swap list.....let's make one

[woodscavenger]

I have been searching the archives for information on a rear end swap.

I am not interested in changing out the pumpkin but am interested in an entirely new axle. I think this would give a better gear ratio as well as newer style drum brakes which would be easier to service.

I would like to see list of axles that can be swapped that maintain the same lug pattern for those who have stock front drums.

It would also be nice to have a list of axles with a GM application for those who have switched to disk brakes upfront using the GM disk brakes from Charlie.

Those who have input please also tell us how difficult to swap was and how much machine work was needed in terms of grinding/welding, etc.

1)Dana 44 from a 1987 Jeep cherokee under my 51 B3B, cut and move spring perches, drive shaft fits without change (carl b51)

2)66T-bird with 3.0 ratio (Reg Evans)

[Reg Evans]

I've had a 3.0 rear end installed in two trucks. The first was done by the previous owner and was a complete axle from a 65 Ford wagon. The spring perches in both cases needed to be removed and re welded to the opposite side of the axle. Also some mods were made to the drive shafts before attaching to the new axle.

The second one I did myself. This axle was from a 66 T-Bird and also had the 3.0 ratio. Ford cars of that vintage have the same lug pattern as our 1/2 ton trucks ......4 on 4.5

[Don Coatney]

Here is a car list. Not sure of the truck differences.

[carl b51]

Well I put a Dana 44 from a 1987 Jeep cherokee under my 51 B3B.

The spring perches were cut off and moved, the drive shaft fits without changing it and the Brakes are Great. The front brakes are drums off a 71 D100. Hope this wll do. Carl

[NiftyFifty]

Has there been any further updates on this, or some more options to be had? I would really like to go to a later model chevy rear end if possible to make a match set with the kit I plan to buy from Charlie. I do have a 1 ton as I find out today with a 126 whell base but that shouldn't really affect anything as I'm looking to lowr it a bit abyway with spring removal, or complete swap to the new hangers etc....but any further swap info would be great!

[Dan Babb]

I'm also interested because I'll be changing out the rear end in my truck.

Between the v8 swap and the fact that I want to be able to tow with my truck, I think I need to do a swap...right?

Will the Dana rear from a Jeep do the job or do I need a stronger one?

[pflaming]

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Some Pilot-house Differential Choices. These are comments from search (differential) threads. They are anonymous. The authors’ full story is in the original thread. THESE ARE NOT differential switchs I have made. These are statements from others, I just cut and pasted the information that identified a differential and any ‘special’ info that pertained thereto. Hope this is helpful to someone. I would guess there are more, but this will give one a start.

• 1951 was the first year the factory had 3:73 gears in the pilot house trucks as an option.

Mopar Switches

(1) a Dana 44 from a 1987 Jeep Cherokee under a 51 B3B.

The spring perches were cut off and moved, the drive shaft fits without changing it and the Brakes are Great. The front brakes are drums off a 71 D100.

(2) 1987 Jeep Cherokee 3.54 gears had to move the spring perches but the drive shaft bolted right up with No modifications . . . on a B3B.

(3) a Jeep Cherokee (94). It is not as wide as the original by an inch or so. Running 15" tires with Mopar Police wheels and hubcaps they are 235.75R15. (two wheel drive model)

(4) a 8 1/4 diff from a Dodge Dakota from a 89 has 5 bolt lugs fit a 51 Just fine

Some General Cherokee specifications:

4.0 liter/auto Cherokees have 3:55 gears,

4.0 liter/manual Cherokees have 3:73 gears,

all 4 cylinder Cherokees have 4:10 gears.

Some 87-89 4.0 liters have the Dana 44 rear end.

This information is for the XJ, not the full size Cherokee.

And, is also applicable to the Comanche/MJ.

(5) The differentials in Mopar cars of the same era are a direct swap. The only thing you have to watch is the spline count on the axle shafts. With a little hunting find a Plymouth or Dodge car from the late 40's - mid 50's with a 3.90 or 3.73 rear gear. Running a 3.73 diff from a '50 Plymouth car in a truck and it'll easily do 70 - 75 on the highway

(6) a mid 60s Dodge A-100 van or pickup. Put one under a 52 and the width, hub to hub, was within less than an inch different from the original. These are 8 3/4" rear ends, the small pinion 741 casting. But all those pumpkins will interchange. These will give a 5 on 4 1/2" bolt circle, parts are available for them and with the right pumpkin, darn near any ratio you would ever want. Would need to cut and re-weld spring perches and have a driveshaft built.

Switches from other makes;

(1) 65 Ford Wagon, 3.00 ratio. The spring perches in both cases needed to be removed and re welded to the opposite side of the axle. Also some modifications were made to the drive shafts before attaching to the new axle.

(2) 66 T-Bird and also had the 3.0 ratio. Ford cars of that vintage have the same lug pattern as our 1/2 ton trucks ......4 on 4.5

(3) Put a Ford 9 inch in a ‘53 with 3.50 gears in.

(4) Used a 3:21 from a 73 dodge pickup. Used ‘53 mount pads as newer pads were wider.

Edited May 14, 2010 by pflaming

[greg g]

readem and choose

http://www.carnut.com/specs/rear.html

[Flatie46]

Do the jeep rear swaps have to be from a 2wd? 4wd is much more common at the pullaparts. Also is track width considered being from drum to drum?

[carl b51]

I used the rear end from the 4wd it was a dana 44 with 3.54 gears I have been told the 2wds will fit the same . Carl

[greg g]

i think 2wd is spring under and 4wd is spring over but since the sadles need moved it not a big concern. However most 4wd were not limited slip while many 2wd drive are.

[Dave72dt]

I'm running an 8" Merc Monarch under mine. Perches need to be removed and repositioned, narrowed to work with original springs. Offset on original rims may not work. Brake lines a bit tight to springs.

[HanksB3B]

My Trucks rear end is in bad shape. It works fine, but it leaks from the round dish shaped part of the housing. Someone must have backed into a stump or something of that order. It's been patched with "Kitty Hair" (that chopped fiberglas and resin combination).

I just looked at mine and the only numbers I find are 1141544-69 and on a small tag that looks like it was attached the numbers 0.250.

My friend Bill has one also from a 1951 B3B and the numbers that appear on it 11412544-37 and 2168. (I dont know if I missed or Bill added a "2" in the otherwise exact number)

I would like to not have to re-weld spring perches, and for the time being would like to remain stock, but change the pumkin and re-build the one from Bill.

I am guessing they are both 4.11 differentials but I can't tell. I know that the 3.73 first became available in 1951, but my friend Dennis told me it would be too much like the 4.11. I'm not sure of all the options that would be able to be swapped. I know Reg has 3.00's in a couple of his trucks.

I think the 1951 B3B has a 8-3/4" rear. I don't know all the options I can choose from. Any help would be appreciated.

Thanks,

Hank

[NiftyFifty]

anyone attempted a swap out on a 1 ton yet? I'm guess when you re-weld the perches you must have to have the angles just percise or your drive shaft will be off no? Wish there was a straight swap with newer drums, be so much easier.

I found a Cherokee rear diff with 3.54 so that might be the next option, however I may ask for the whole shootin match and upgrade the springs and shackles if I can make it work.

[Young Ed]

Hank I dont agree with the comment a 3.73 would be too much like the 4.11. You would notice a sunstantial drop in RPM.

[HanksB3B]

Ed,

My goal is to be able to do 65-70 mph without straining the engine. I have a 3-speed transmission. My tires are oversized P235/75/R15 (if I'm not mistaken). I've got more than enough power if first, but starting from 2nd gear is just possible. I don't know what my top end is now because of the taller tires, but will try to use my GPS to find out. I'd really like to get er up on the highway.

Thanks,

Hank

P.S. Do the numbers in post #13 above have anything to do with the ratio?

Edited April 28, 2010 by HanksB3B

[Dan Babb]

65-70? That sounds like it would be a fun ride.

I've only driven my truck around the neighborhood so far...probably 35mph. I think doing over 55 would be a bit scary. It's not a smooth ride at the lower speeds in my truck. Might just need to grease up the suspension though to smooth it out.

With the larger tires, your truck would actually be going faster than your speedometer registers, so the GPS will help you get the real reading.

[albolton]

I put a dana out of a 93 cherokee 4X4 3:54 in mine...took about 7 hours start to finish by myself, including new steel lines and brakes ,

very simple, torched off the old spring perch use new 3" perches from Northern tool, about 5 bucks each..I set the pinion angle by setting the wheel cylinders level, and then leveling the perches on the tube...i dont know if thats the right way, but ive never seen an axle with the wheel cylinders cocked so i figured id do it that way....works fine, ujoint fits ...driveshaft fits, bought adapter fittings for the smaller sttel lines on the cherokee, to the larger stock flex line from the dodge, had new u bolts made at a local spring shop ...6$ each, stock shock mount from my pickup, and a can of black tremclad, thats alll she wrote,..even if you had dont have a welder and someone else had to weld it for you...there isnt 5 minutes of welding required, should be very cheap. Made a huge difference and the cherokee axle is a bit narrower, so with my truck being lowered it gives me a little more fender clearence....This is the single best modification I have done to my truck as far as making it driveable....do it!!! I added a before and after picture so you can see the extra tire clearence

[Merle Coggins]

Ed,

My goal is to be able to do 65-70 mph without straining the engine. I have a 3-speed transmission. My tires are oversized P235/75/R15 (if I'm not mistaken). I've got more than enough power if first, but starting from 2nd gear is just possible. I don't know what my top end is now because of the taller tires, but will try to use my GPS to find out. I'd really like to get er up on the highway.

Thanks,

Hank

P.S. Do the numbers in post #13 above have anything to do with the ratio?

As I've mentioned here many times, I have a 3.73 diff in my axle with 235/75R-15's and I can run down the highway at 65 - 70 easy. I've even had it up close to 80 once. I don't know what the RPM is at highway speed, but it runs just fine. (I've been thinking about how I can rig up my tach/dwell meter so that I can monitor the RPM at highway speed to find out.)

Merle

[Reg Evans]

I've done that before with my tach/dwell meter but it only goes up to 1800 rpm so I didn't learn much.

I now have a 6 volt tach for my coupe but it's still in the package

[slicknapier]

I have a Volare rearend under my truck now. If I remember right the perches were pretty close. The axle is a little to narrow for the look I want, but if you wanted to run a fatter tire it might be an option. I think its only the 7 1/4 though...

[blohmiller]

how about the Rear End from a '94 TBird

[John-T-53]

Here's a good reference I found for calculating your engine RPM's without a tach. If you don't know the height of your tires, there's a calculator on the same page too....just plug in the tire size.

http://www.ringpinion.com/Calc_RPM.aspx

Here's a couple other threads on the subject of rear ends too:

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=16579&highlight=rear+gears

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=15477&highlight=rear+gears

Edited April 29, 2010 by John-T-53

[NiftyFifty]

I put a dana out of a 93 cherokee 4X4 3:54 in mine...took about 7 hours start to finish by myself, including new steel lines and brakes ,

very simple, torched off the old spring perch use new 3" perches from Northern tool, about 5 bucks each..I set the pinion angle by setting the wheel cylinders level, and then leveling the perches on the tube...i dont know if thats the right way, but ive never seen an axle with the wheel cylinders cocked so i figured id do it that way....works fine, ujoint fits ...driveshaft fits, bought adapter fittings for the smaller sttel lines on the cherokee, to the larger stock flex line from the dodge, had new u bolts made at a local spring shop ...6$ each, stock shock mount from my pickup, and a can of black tremclad, thats alll she wrote,..even if you had dont have a welder and someone else had to weld it for you...there isnt 5 minutes of welding required, should be very cheap. Made a huge difference and the cherokee axle is a bit narrower, so with my truck being lowered it gives me a little more fender clearence....This is the single best modification I have done to my truck as far as making it driveable....do it!!! I added a before and after picture so you can see the extra tire clearence

Spoke to a pretty hard core old car guy today that's done many swaps and although the idea of the wheel cyls being level sounds right, it's only right when you apply it to the vehicle that it was set up for. You still must calculate the angle at the back of the transmission first and make the rear axle the same, and this may cause things not to be level in the new application, but will save you from drive line vibrations of an incorrect angle, you must also consider that when your hard on the gas the angle changes somewhat and then returns once the power has smoothed.

All great stuff to learn when you get into these swaps...I'm busy looking for my Cherokee diff now

[HanksB3B]

Merle,

I'm picking up a used differential this Saturday. I'm hoping it's a better candidate than mine (housing damage) also like the steering box, I'd rather continue driving and enjoying my truck this Spring and Summer and work on a second differential at my leisure. Not being in a rush sure helps me do a better job.

I posted some transmission numbers (in post #13 above). I can't tell what I've got but I'm guessing it's a 4.11 as was most common with 51 B3B's. I am in the market for either a 3.73 or hopefully a 3.54 will work (Reg). I have a job interview coming up so maybe I'll be able to afford to do it.

Appreciate everyone's input, as I'm definately out of my skill set on this one. Glad I have friends on the board and a neighbor across the street.

Thanks,

Hank

As I've mentioned here many times, I have a 3.73 diff in my axle with 235/75R-15's and I can run down the highway at 65 - 70 easy. I've even had it up close to 80 once. I don't know what the RPM is at highway speed, but it runs just fine. (I've been thinking about how I can rig up my tach/dwell meter so that I can monitor the RPM at highway speed to find out.)

Merle