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

[Plymouthy Adams]

I'm not confused..if you have parallel lines at 3 degrees..move forward or rearward along the lines..you still at the same angle..key is to remember the forward and rearward points are fixed..

[ssdodge51]

Check out this website, it is from Inland Empire in California, they have been building drive shafts forever and they have a good driveline document online that should explain how to set up your drive line.

http://www.iedls.com/Education-Zone.asp?CID=6

Steve

[Dave72dt]

Maybe what I should have said, in Young Ed's case is the driveshaft angle will increase when he puts in the longer transmision, all other constants remaining the same., which is what I was trying to say from the start but apparently not well.

[JoelOkie]

Great article Steve. I have had several driveshafts sized, and I have been ok in my measurementsr, as I have never encountered a problem, (and also because I use a good local driveshaft company), but it sure never hurts to get better educated, and not just know what works, but understand why it does (or doesn't) work. Joel

[Dennis_MN]

I've finally completed my project and now am ready to report the details

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=26779

This above is a thread that I showed progress

I selected a 1997 Jeep Grand Cherokee with a 3.73 ratio and disk brakes.

I purchased a "core" from a guy on craigs list for $100 and then spent $275 on new seals and a pinion bearing and torch work to cut off all of the jeep brackets. It cost another $600 to get the brakes and other misc stuff.

I've never had a rear end swap that I didn't need to modify the drive shaft and this was no different. I couldn't find a conversion U-joint part number so I had a drive shaft shop cut the end of my drive shaft and add a jeep yoke on it so now I have a Jeep U-joint on the back. The spring perches from Northern Tool worked perfectly.

I used a center junction block and hose from Jeep, Part number napa 380-889 and I secured it to the axle with a breather bolt from Old Mopar on E-bay. That part was hard to find, keep the one from your old axle.

My motivation was to finish with the brake improvement that I started by adding front disks from Old Daddies Kit. Then I had a delimina in that I had one wheel on the truck with left hand threads. I could have solved that by getting a drum from a right side donor truck but then I'd need a wheel puller. So problem solved, disk brakes on all four corners and all wheels have right hand threads.

Now if someone has a part number for a conversion U-joint please post it.

Or if some knows the napa part number for a 49 Dodge rear U-joint, I'd like to know that as well.

[NiftyFifty]

Conversion joint part number (Napa) 3-3140

This is the one I used in my 50 1 ton to go down to a rear end from a 93 Jeep YJ, which is the same dana I'm guessing as you got...with 3:73

I'm going to a T-5 swap this spring, so I will also be going to a 2 piece drive shaft now as the shaft length changes...but it worked well when I ran it with the stock trans.

I've finally completed my project and now am ready to report the details

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=26779

This above is a thread that I showed progress

I selected a 1997 Jeep Grand Cherokee with a 3.73 ratio and disk brakes.

I purchased a "core" from a guy on craigs list for $100 and then spent $275 on new seals and a pinion bearing and torch work to cut off all of the jeep brackets. It cost another $600 to get the brakes and other misc stuff.

I've never had a rear end swap that I didn't need to modify the drive shaft and this was no different. I couldn't find a conversion U-joint part number so I had a drive shaft shop cut the end of my drive shaft and add a jeep yoke on it so now I have a Jeep U-joint on the back. The spring perches from Northern Tool worked perfectly.

I used a center junction block and hose from Jeep, Part number napa 380-889 and I secured it to the axle with a breather bolt from Old Mopar on E-bay. That part was hard to find, keep the one from your old axle.

My motivation was to finish with the brake improvement that I started by adding front disks from Old Daddies Kit. Then I had a delimina in that I had one wheel on the truck with left hand threads. I could have solved that by getting a drum from a right side donor truck but then I'd need a wheel puller. So problem solved, disk brakes on all four corners and all wheels have right hand threads.

Now if someone has a part number for a conversion U-joint please post it.

Or if some knows the napa part number for a 49 Dodge rear U-joint, I'd like to know that as well.

[95ttoplt1]

Just slid a 62 Sunliner 9 inch under mine, had to weld on new peches but that was it!!

[Dodgeb4ya]

Make sure the ends of the driveshaft are in phase when you install it.

when it is built. It'll onl;y go one way whenb instaslled.

Thats not always true. The driveshaft in my 46 pickup could be installed out of phase. The front ujoint is before the slip joint so if you dont install the shaft into the slip joint in the proper orientation its out of phase.

A picture sure would be good to see on this issue.

[Dennis_MN]

As long as this thread is back up, I thought I'd make one more comment.

I have a 1949 1/2 ton and there was a change in the yoke bracket attached to the transmission from a one piece to a two piece design. This means there is a difference in the U-joint after 49. The 2 piece design was used for many years and that one was retro fitted to my drive shaft and to the transmission.

So I'm guessing that napa part number works for 50 and later.

Was that piece a bugger to remove from my transmission! I borrowed a 1 inch drive socket and power handle and gave it all I had, laying on my back and prying against the frame with my legs. I had to tighten the brake band to help hold the transmission from turning. There is a poem in this experience about the problems of a 71 year old man working on a 61 year old truck!

[Young Ed]

A picture sure would be good to see on this issue.

No shaft installed but you can see the front u joint followed by the slip joint. The slip joint is splined uniformly so the shaft itself can be installed anyway.

[Dodgeb4ya]

Are there alignment marks on the yoke and shaft?

[ggdad1951]

Are there alignment marks on the yoke and shaft?

the shop manual implies there are, mine were either rusted off or whenthe shaft got sanblasted they took them off. My yoke had a nice arrow forged in it.

[Dave72dt]

No shaft installed but you can see the front u joint followed by the slip joint. The slip joint is splined uniformly so the shaft itself can be installed anyway.

The U joints need to be phased correctly with that type of setup so you can't put them together wherever you want or whatever spline happens to line up first. The U joint in the picture shows the trans part vertical and the slip joint part horizontal. The other end of the drieshaft must also put the u joint horizontal and the part on the diff needs to be vertical. There may be a special spline on the driveshaft and one missing on the yoke to iondicate where it goes or some other type indicator.

[Shan]

Hello All, I need your advice! I have a 1949 B100 B flat bed with a dually rear end. The truck has been modified with a 360 and a 3 speed automatic trans. At 55 mph she sounds like I going to take off. Gas millage very bad.  What rear end do I need fix this. Or can I change the gearing to what and from where?  I want to keep the lug pattern if possible. I'm setting up truck to tow vintage trailers. 

 

Thank You

 

Shannon

[Merle Coggins]

Shannon,

You have a B-1-D, not a B100. Anyway… direct swap axles for the 1 ton trucks isn’t as easy as it is for the 1/2 and 3/4 ton trucks. You can likely find a more modern axle that will give you the gear ratio you want, and retain the dual wheel configuration, but it certainly won’t have the same lug pattern. I don’t have the lug pattern handy but I recall that it is pretty unique to Dodge. And different differential gears for those trucks are almost non-existent. 

I think you’re going to have to compromise a bit to get the gear ratio you desire.

 

Merle 

[Shan]

On 7/4/2021 at 4:30 AM, Merle Coggins said:

Shannon,

You have a B-1-D, not a B100. Anyway… direct swap axles for the 1 ton trucks isn’t as easy as it is for the 1/2 and 3/4 ton trucks. You can likely find a more modern axle that will give you the gear ratio you want, and retain the dual wheel configuration, but it certainly won’t have the same lug pattern. I don’t have the lug pattern handy but I recall that it is pretty unique to Dodge. And different differential gears for those trucks are almost non-existent. 

I think you’re going to have to compromise a bit to get the gear ratio you desire.

 

Merle 

Thank you for the help. I'll look into finding a axle that would work. Do you think a 3.21 or a 3.92 ratio? If I can find them. 

 

Edited July 13, 2021 by Shan