rear axle housing flip

[jsum40]

Just begining the complete rebuild of my 71 40. While disassemblin the rear axle housing it occured to me that it may be possible to just flip it over, reassemble, and have the spring purches on top for a SOA. I know the breathers would have to be relocated to the new top side. It also appears as though the pinion angle would be offset in the right direction as well. Any thoughts? Idea came from a quick observation while the housing was on the bench, maybe I'm missing something.

 

[leftarmtan]

Pretty sure the third only goes in one way,without modification so it would rotate backwards.And it would be a driver side drop instead of pass.

 

[jsum40]

I have the third out, cover off, axles pulled. So I was looking at the bare housing when I had the idea. It looked like I could just rotate it 180 degrees and put it back togather with the spring perches on top. When I was cleaning and repainting the housing, I used the rear cover to keep out the overspray, and it fit fine on both sides of the axle, all the holes lined up.

 

[Bret]

Is there a notch cut on both sides of the housing for ring gear clearance? Another thing to consider is if your flipping the axle you are adding a good bit of lift, might look at a CV rear driveshaft??? If so then you will need to rotate anyway. Angles may be a bit steep depending on drivetrain.

 

[jsum40]

Yes there is a notch on both sides of the housing. I need new driveshafts anyway, and have liked using the CV's in the past.

 

[bigneily]

its been years since i had mine apart but i think if i remember , the third member only goes in the housing one way therefor rotational problems, driveline issues , as well as the diff would have to be almost comepletely full of oil in order to lube the pinion bearing. but you are right the driveline angles would be better for sure. i think some dana diffs were a high pinion setup, but they requre reverse cut ring and pinions. am i on the right level track here fellas, feel free to elaborate....

 

[jsum40]

I think you are misunderstanding my idea. I pulled the 3rd member out the front, and the cover off the back. I rotate the housing 180 degrees, so that the bottom of the housing is now the top. I reinstall the third member and rear cover as they were. Now the spring perches are on top. I realize the drain plug is now on top, and the vent hole are now on bottom, but that seems minor compared to welding new perches on the top (and getting them right) like most do for a SOA. Seems easier.

 

[Bret]

If your using a CV d-shaft you should have the pinion pointing up toward the output on the transfer case. If you rotate the axle the perches will be pointing the pinion pretty straight ahead. Double check your brake backing plate brackets/bleeders/brake line retainers etc. too. The brake shoes may need to be properly oriented to work right.

 

[409impala1]

if you swap it end for end it will run backwards. although 3 speeds in reverse is cool. we used to do it on demo cars.

 

[joeyg1973]

I think I get what he is saying... he didn't flip it 180 wheel end to wheel end, he flipped it so that the place where the back cover used to be attached is now where the 3rd member attaches.

 

[rusty_tlc]

Re- locating the breather etc will be a lot more work and cost more than welding on a $30 set perches.

That aside, when you do the SOA you need to rotate the axle up to get the correct pinion angle.

 

[Mark W]

I almost never rotate the rear axle. Never unless I have a real long drivetrain.


Mark...

 

[bigneily]

I almost never rotate the rear axle. Never unless I have a real long drivetrain.


Mark...

really? what kind of driveshafts do you use mark?,, hows the vibrations....thanx

 

[numby]

I almost never rotate the rear axle.

Pinion angle should be parallel to the transfer output as per factory spec. This maintains proper u-joint phasing. Why rotate anything unless you have serious axle wrap at higher rpm.

Will flopping the housing over maintain this geometry or will you need to relocate your perches anyway?

Never unless I have a real long drivetrain.

Hence a very short driveshaft and the need to add a CV.

 

[Isotel]

and with a CV, You want to point the pinnion straight at the T-case..

This idea has come up here before, and its way easier to just weld on new perches

 

[Mark W]

really? what kind of driveshafts do you use mark?,, hows the vibrations....thanx

Regular ujoints. high deflection yoke assemblies. Zero vibrations. Would not be correct if it was vibrating.


Mark...

 

[jsum40]

Thanks for the input everyone. It was just a quick observation while the housing was on the bench. It seemed like the perches would be angled in the right direction, but maybe not enough. Drilling and tapping holes for a breather seemed easier to me. As far as CV driveshafts go, my last one came from Tom Woods, and we pointed the pinion at the T-case, and all the vibrations went away. Worked great! It was on a jeep that saw lots of road miles, as well as off road, and it worked perfectly. This is my first cruiser, and I am trying to think my was through as I go, so sorry if I hit on an old idea that has already been discarded.

 

[numby]

It seemed like the perches would be angled in the right direction, but maybe not enough. Drilling and tapping holes for a breather seemed easier to me.

Well, it's not too difficult to just bolt it in and see where you end up. No need to re-drill until you're certain. Leaving the rear up on jack stands would saver the effort of reinstalling the axles/wheels.

Lots of years ago I thought it might be possible to install FJ60 knuckles on an earlier DB front axle housing. I didn't know who to ask so I gave it a shot. Worked great. I think this is quite common now.

I say give it a try. Might have to do a little shimming, though.

 

[fj hunter]

using news eye to ...

reexamine old ideas is never bad. if that was not the case, i would not have a four barrel carborater on a f engine.

on another line... i was looking at my next fj40 frame just this AM and was wondering the very same things that you have addressed here, and i am thinking that the welding should be very easy for me. but, i do like your ideas, and i have a few weeks before my start, so you bet i am going to do some serious measuring and hum/haw about the idea. thanks for the new eyes, and i bet there is at least one fj40 in Manila that has been done that way and runs just fine.

i spent time over there, and if you want to see how to just get by you need to see what folks in a third world country do. they use little to no resources to accomplish what we send out to the shop and pay labor for. i have seen broken/split frames re-attached by welding with a piece of rebar and parts of a white phos grenade.

u-joints are made for a certain angle of dpearture for the shaft, but you would be surprised how far they go even when used well past the "factory" specifications.

good eyes. keep us thinking.

 

[jsum40]

I may just bolt it up and see what I get. The whole cruiser is stripped to the frame. Bolting the axle back together is not a big deal, just to see what happens. I am just begining the reassembly, and still have many details to work out. I thought this idea of a spring over in the rear might be easy and save me a few bucks for something else. I would still keep the front end as is, with lift springs to avoid complications caused by a spring over in the front.
Thanks for all the comments. I'm sure I will have many more observations/questions for you guys as I go.