Fliping the rear end to put the offset on the dr side?

Drew M. · Post by **Drew M.** » Fri Sep 26, 2008 11:29 am

Terry had an interesting idea about flipping the M37 rear to put the offset to the driver's side. Expanding upon the idea. . .

Steps: 1. remove spring backing plates (rivets); 2. remove differential; 3. grind clearance in housing for ring gear using gasket as template; 4. reinstall differential rotated 180 degrees; 5. flip differential housing to put differential on dr side; 6. cut off top arch section from housing mounts for spring plates and weld them to the original flat edge now facing down using brake plate as guide - so can continue using all the five brake platebolts/rivets; 7. cut off spring perches and put them on top of axle tubes; 8. set pinion angle; 9. weld spring perches keeping heat to min; 10. reinstall brakes/hubs/axles/oil. 11 - drill and thread new oil drain hole for housing (almost forgot).

This sounds like a sound way to get an offset rear as to run the M37 off the ebrake yoke.

Anyone see any problems with this? [This saves me all the hassles of getting a WC rear for my truck too:)]. Thanks
-Drew M.

mattveeder · Post by **mattveeder** » Fri Sep 26, 2008 12:37 pm

If you flip your carrier upsidedown it will be reverse rotation. Trust me it sounds good until you try it. A thick headed buddy of mine wanted to do a spring over lift and tried it. He had four reverse gears and only one foreward gear.

mattveeder · Post by **mattveeder** » Fri Sep 26, 2008 12:40 pm

But if you keep the ring gear on the correct side like you said it will work fine. All you have to do then is make sure that the axle shafts can slide in and out. Please keep me posted sounds like a good idea to me.

ELBUFO · Post by **ELBUFO** » Fri Sep 26, 2008 3:43 pm

What's the point???

Drew M. · Post by **Drew M.** » Fri Sep 26, 2008 5:20 pm

Not reverse rotatation - #4 - reinstalled pinion is still right-side up. That is why the housing needs the ring gear clearance added.

Why? Running off ebrake output makes it more like a NP205. Advantages? Many!!!! Less friction in t/c, less wear in t/c, less heat in t/c, less t/c noise, longer lasting t/c, better gas mileage (slightly) . . . I'm sure I left off a few.

Swapping in WC centered rears in the M37 and PW and using the ebrake for the rear output is very common for the above reasons.

Of course, I gave away my spare M37 housing a few weeks ago . . .. This sounds like a nice spring time project article for Gordon. (PWA).

mattveeder · Post by **mattveeder** » Sat Sep 27, 2008 7:18 pm

I will give you my spare housing for free if you promise to post pics. Like I said you are keeping the ring gear on the correct side of the truck so I see no reason why it would not work. The advantages like you said are endless.

greencom · Post by **greencom** » Sat Sep 27, 2008 10:17 pm

There may be one disadvantage in doing this. The transfer case puts both differentials to one side of the chassis giving good ground clearance to the other side with no differential cases in the way. If you flip the rear axle you will stagger the cases so you have less clearance on both sides instead of one. Just a thought.
Greencom

Lifer · Post by **Lifer** » Sun Sep 28, 2008 3:49 am

Another problem with flipping the axle that I can see is that the diff would still be offset. It would be on the left rather than the right, but it would still be offset. The e-brake yoke is centered. This means that the rear drive shaft would have to be angled to the left to match up, creating a problem with the u-joints.

Drew M. · Post by **Drew M.** » Sun Sep 28, 2008 5:24 am

The ebrake and pinion do not have to line up. They just need to be w/in the u-joint's angle limits. Dodge used centered rears with offset trans/engine for decades - 1950's delivery/ milk trucks ect. Also, the M715 series uses a centered rear but runs the rear drive shaft off the NP200 pass side output shaft just like the M37.

But, you have a point. I need to measure to see if flipping the rear end to put the pinion on the driver's side does anything to reduce the drive shaft angle when looking downward. I pretty sure it will. I also think the ebrake was slightly offset to the driver's side too.

The nice thing about trying the flip is it would be easily reversible if not beneficial or if the truck gets restored by a future owner.

I learned a bit about setting up rears when making and installing a narrowed Dana 60 rear end into my wife's Jeep CJ7. The rear driveshaft is 18" long.

Lifer · Post by **Lifer** » Sun Sep 28, 2008 1:00 pm

I'm glad to know that you have some experience with rear ends. I just wanted to make you aware of a possible problem, but I see it wasn't really necessary.

knattrass · Post by **knattrass** » Mon Sep 29, 2008 4:16 am

Beyond the technical merits discussed, I don't get it either. Seems like all the troubles would be better served up on an old Chevy chopped versus taking an M and making into something else? This topic seems like a better "mudder" over on the PWA site?

Drew M. · Post by **Drew M.** » Mon Sep 29, 2008 12:21 pm

knattrass wrote:Beyond the technical merits discussed, I don't get it either. Seems like all the troubles would be better served up on an old Chevy chopped versus taking an M and making into something else? This topic seems like a better "mudder" over on the PWA site?

This is still the "Technical group
Discuss fixes, upgrades and modifictions to your M37" forum right?

Lifer · Post by **Lifer** » Mon Sep 29, 2008 1:00 pm

E-e-e-ew! Blunt! Correct, but blunt!

knattrass · Post by **knattrass** » Mon Sep 29, 2008 2:32 pm

My experience with this site is more toward the restoration of the M37 whereas the group over at the VPW site tend to head for the extreme mods via "mudders." It was only a suggestion to help you find a more difference of background for guys that tend towards off road jeeps/pw versus restoration. Hey in the end, its your call.

Fliping the rear end to put the offset on the dr side?

Fliping the rear end to put the offset on the dr side?

Say What?

Reverse rotation/Why?

Ebrake and pinin not aligned . . .