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Rear end swap upgrade


Edrowesuave

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I have a 51 b3b it has the 218 flathead with 3 on the tree.

My differential went out.I want to put in a replacement rearend that is geared for a 65mph highway speed.Could ya'll give me some suggestions on a good choice for my truck.If I knew what vehicles have the rearend I need that would be very helpfull.

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Jeep Cherokees and Ford Explorers, with or without disc brakes have been popular choices as well as some 8 3/4 Mopars.  Search button will net you a bunch of threads on the subject for further research.

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You can find a differential section from a late 40's to mid 50's mopar car. You would probably want to look for a 3.73:1 or 3.54:1 ratio. It will bolt right into your truck axle housing. The only potential problem may be the spline count on your axle shafts. There was a change somewhere in the early 50's. You may need to stay with a '50's era car diff to keep the right spline count.

 

I have a 3.73 diff assembly form a '50 Plymouth in my truck axle. It was a direct swap for me and gives me good highway cruising speed.

 

Merle

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You can find a differential section from a late 40's to mid 50's mopar car. You would probably want to look for a 3.73:1 or 3.54:1 ratio. It will bolt right into your truck axle housing. The only potential problem may be the spline count on your axle shafts. There was a change somewhere in the early 50's. You may need to stay with a '50's era car diff to keep the right spline count.

 

I have a 3.73 diff assembly form a '50 Plymouth in my truck axle. It was a direct swap for me and gives me good highway cruising speed.

 

Merle

 

If you do run into that spline count issue you can swap your original side gears in and make 1 out of 2. That is what I had to do for the 3.73 I have in my 48 Plymouth.

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Thanks everyone for your suggestions.I bought this truck this past September.I was told it has a 61 Plymouth rear, geared for the highway.I never got to try it.

These mountains here must have put a big strain on it.Anyway first I will open up the pumpkin and see whats going on.

I like the idea of swapping out the diff assembly like Merle did.

It may be easier to find a jeep whole rear end though.

Thanks again now I know what to look for.

Ed

Edited by Edrowesuave
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Someone above mentioned an explorer rearend, You can get the same thing from a mustang gt. Its a Ford 8.8 and they are pretty stout. 

 

Here is a chart of a few Ford axles.

 

rearswapcopy-1.jpg

 

I used that when I swapped a 8.8 into my 53 cranbrook, not sure on the stock axle width of your truck but hopefully this can be useful.

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I think that 3 speed is likely hurting you a bit too, my first year I ran the stock 4 spd with the YJ rear end and it still screamed on the highway, that's why I went to T5 swap.....night and day difference

The 3spd and 4spd wouldn't make any difference at highway speed. You can keep the stock 3spd and pick a higher ratio. A 3.73 with 16" wheels will cruise nicely. Or go 3.54 with 15s

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Edrowesuave,

 

Welcome to the Forum and congratulations on your 51 B3B (I have one too) It sounds like a previous owner swapped your original truck differential in exchange for a car differential. Everyone (Tim) knows I've wanted to find/exchange my original 4.11 for either a 3.73 or 5.54. Some things take a long time to find and I'm so thankful that a fellow Forum member Jeff Balaz gave me the heads-up on a differential from a 1955 Dodge Royal Lancer not too far from where I live and a family that had a whole bunch of old Dodges and a small fleet of new Mopar family models. I'll post some photos as sonn as I t can. I'm not a follower of the Car side of our Forum but like us truck guys I'm sure there must be some real knowledgeable members and then some with cars they take it a notch up because of the many options that were made available by Mopar back in the day.

 

55_Dodge_Lancer_zps41979ec9.png

(not the actual donor car just the make and model)

 

(I'll most likely post the request for assistance on the Car Side as well but not yet)

 

1. Please attach, forward or direct me to where I can find pages from the Parts Manual and the Repair Manual for a 1955 Dodge Royal Lancer

2. It seems I can piece together information as to what is interchangeable and necessary to make the transition from my 4.11 to the new 3.54

 

My plan is to pulls the drums, brakes, backing plates and axles, remove the pumpkin, clean, replace any worn/damaged parts and get it to work in my currently installed housing (which must have backed into a tree strum by a PO). By what I've read/reading I'm fairly confident this can be accomplished. Hopefully if the housing from the car is adaptable with the possibility the perches are/made to work. The car housing could then be reconditioned (maybe powder coated, maybe rustoleum or POR product.

 

Thanks in advance, Merry Christmas to all and to all a good night,

 

Hank  :)  

 

and Thanks Mopar Santa ! 

Edited by HanksB3B
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Thanks rolnthunder for the info on the Ford 8.8 those width measurements and the year,models to go with it is exactly what I need to find a replacement .So what is the T5 swap?

It's a 5 speed transmission...very popular swap, beware...many types out there not all will fit well in your truck.

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A Mopar Family

 

It was totally un-expected when I pulled up to David Kings house. There were not any cars (or truck) that were not Mopar. David was not there yet but we got to talking with David's dad, a heavy equipment operator that drives his slant six truck everywhere (the only other person I know that does that is Rod. Well there's the donor car a 1955-56 Dodge Royal Lancer. The good news is that my 4.11 has 11 nuts and the 3.54 also has 11 nuts that mount the pumpkin to the housing. In general it looks like a match. My next step is pulling the axles and then unbolting the pumpkin.

Composite_zpsd5638ae4.png

 

Christmas Day....can't get greasy, maybe at David's house..they're all into it even the girls in the family !

 

Hank  :)

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That is a 55 Custom Royal Lancer. It looks too good to get parted out. What are they doing with it?

 

Tricking it out, but don't worry the familys tat's are  all "Mopar" (and then some could be an offshoot of the Evans clan for all I know)

 

 

That is cool Hank. Looks like you even found a good fellow to coach you through things. :)

A very Merry Christmas to you!

Jeff

 

And Jeff, I can't thank you enough, but then it's not every man you meet that retrieves his grandfathers fishing book like three generations later. Maybe my little B3B will cruise right along with your well thoughtought ride. After the pumkin, it's only a kingpin rebuild, Rusty Hope Kit, and seatbelt install away from doing the distance....(hint Tim)

 

Merles_Composite_zps74facd13.png

Merles (ref pics)

 

 try to be more inTIMidating !  next time...my starter leg is starting to "hang" and I can't afford to let that happen..so there's another get-busy...IOU big time buddy and Thanks mucho much that and the differential looked great under my imaginary Christmas tree.  

 

Mark I am all geared up and ready to rebuild your radio if I said nex t year would you have still bought it ? Happy farm property hunting (what a few of us need too)

 

Paul hope Santa bought you an HLVP gun a roll of plastc and a stack of 2x2's for Christmas (if not make sure it's on the list next year) I took me two solid years to rebuild my truck the first time so stay healthy, take your time, work hard and you'll be done in no time (less than it took Noah to finish the ark).   

 

Happy New Year Everyone,

 

:) Hank :)  

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Thank Don,

 

I'm sure there's good information there. it's just that I can't figue out how that works between car/truck. The approximate center to center of the spring perches on my B3B is 41" I don't expect to just be able to swap Axle for Axle but I am hopinhg the Pumkin to Pumpkin swap works without touching anything else. There will be a moment in time where my pumkin is out from under the truck and that is my chance to properly (weld) the original carrier that a PO must have backed into a tree stump or rock. Once I'm running and I know all the measurements hopefully the better housing from the Custom Royal Lancer can be modified an used. (I'm afraid it might be narrower) I wonder if you'd be my uncle Bob on the car side and find out if someone can scan any and all  nomenclature that the guys on the car side have for the 1956 Dodge Custom Royal Lancer. It would really help at this information gathering stage.

 

Pg-43_zps499139e7.jpg

 

Did I ever tell you about when I was a small boy visiting Maryland and met Cornel Studeler who had a horse 22 hands high and told me he fought in the Civil War ?   (Well I just did)

 

Your help is always welcome Don and I know it's not just by me. Happy New Year and many more,

 

Hank  :)

Edited by HanksB3B
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I like the idea of a 5 speed,because it would get the most out of the 218 motor.

First I want to get her running.I've had it 3 months and drove it not even 1 mile (a fun mile though).

So step one is find a rearend with the gears that go well with the T-5 swap.

Drive it awhile till I get the parts for the big tranny swap.

4mula-dlx can you tell me what gear ratio you have in the yj rearend?

I really like my Pilothouse.It'll be alot of fun.

Ed

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