Rear-end question

[lobo loco]

Not being an automotive proctologist, I have a question. I have a 78 with a lock-right in the rear. Since most of my driving is on pavement and fairly good dirt roads, I don't really need it.

Question is what's the best approach considering I have a spare complete and good third member with spiders and carrier installed and I also have two more carriers with spiders, shafts, pins, bearings, etc. from a friend who had ARBs installed. ( Long story as to how I wound up with all these parts)
Considering I don't have a lift, but a good floor jack and several jack stands...which is the easier way to get rid of the lock-right? Swap the complete third or change out to the spiders thru the back cover?

 

[marks69cruiser]

Leave it in is the easiest!

 

[Poser]

Not being an automotive proctologist, I have a question. I have a 78 with a lock-right in the rear. Since most of my driving is on pavement and fairly good dirt roads, I don't really need it.

Question is what's the best approach considering I have a spare complete and good third member with spiders and carrier installed and I also have two more carriers with spiders, shafts, pins, bearings, etc. from a friend who had ARBs installed. ( Long story as to how I wound up with all these parts)
Considering I don't have a lift, but a good floor jack and several jack stands...which is the easier way to get rid of the lock-right? Swap the complete third or change out to the spiders thru the back cover?

You can remove the rear differential cover and then remove the locker and replace the axle side gears and the spider gears and thrust washers. That would be far easier than changing out the complete differential.


Put the rear of the truck up on jack stands, drain the gear oil in the rear differential and get after it.


No big deal.

 

[MD11Fr8Dog]

Put the rear of the truck up on jack stands, drain the gear oil in the rear differential and get after it.


No big deal.

I agree, can be done on the trail as well

 

[Mark W]

To swap out the diff... you have to remove the lockright first. at that point... there is no point in changing out the diff


Mark...

 

[Poser]

Field repairs are a hoot!

 

[e rock]

Draining, opening, pulling the locker out, re-installing spider gears, replacing cover, filling with oil is - what - about an hour with beer breaks (assuming you've done it a few times before)?

Weren't there center blocks with different thicknesses? I guess that would be the only thing to really watch out for.

Not to promote project creep, but just make it an afternoon and replace the axle seals and bearings while they're easy to get to. Take your time, and by the end you'll have a good working knowledge of your rear axle. If you're nervous, have a local 'Mudder on speed-dial just in case.

 

[Rigger]

Lobo, I hope you don't mind a slight hijack on your thread.

On the '40, how come the rear axle has an inspection cover but the front axle doesn't? I've been wondering about that. Anyone know?

End of hijack.

 

[Mark W]

Because in the rear semi-floater you have to remove diff components to remove the axles and remove the diff.
in the front full floater you do not.

It is not an inspection cover, it is an access hatch


Mark...

 

[Mr. Toad]

Because in the rear semi-floater you have to remove diff components to remove the axles and remove the diff.
in the front full floater you do not.

It is not an inspection cover, it is an access hatch


Mark...

That explains why there must be one on the back, but not why there isn't one on the front. Couldn't there be an advantage to an access hole in the front too? Like not having to pull the diff out of the housing?

 

[lobo loco]

Draining, opening, pulling the locker out, re-installing spider gears, replacing cover, filling with oil is - what - about an hour with beer breaks (assuming you've done it a few times before)?

Weren't there center blocks with different thicknesses? I guess that would be the only thing to really watch out for.

Not to promote project creep, but just make it an afternoon and replace the axle seals and bearings while they're easy to get to. Take your time, and by the end you'll have a good working knowledge of your rear axle. If you're nervous, have a local 'Mudder on speed-dial just in case.

Thanks guys... I appreciate the comments. When it comes to differentials, axles, etc. , I'm kinda out of my zone of comfort. I know just enough to be cautious and my concern and reason for suggesting use of the complete third was in regard to clearances, spacer thicknesses, etc. I've worked on my own cars/trucks since I started driving, but have never had the need to tear into a diff. My 40 has had the locker in it since I got it and I just want to go to a std diff, until I have the money for something better. I like the idea of a 'selective' locker, not one that is engaged most of the time. Also thx for the suggestion of replacing the seals and bearings...more parts to order.

 

[Poser]

That explains why there must be one on the back, but not why there isn't one on the front. Couldn't there be an advantage to an access hole in the front too? Like not having to pull the diff out of the housing?

What are you going to service in the front differential that is not going to require you to remove the front axle shafts in order to perform the work?



USA front axle manufactures install the inner axle seals in the axle housing, on the outboard side of the carrier bearings instead of out by the steering knuckle, which, when an inner axle seal of this design is leaking, not only requires you to remove the axle shaft on the side that is leaking, but also on the other side as well, because you have to remove the differential carrier in order to replace those inner axle seals.

If my front Dana 60 axle assembly was not as strong as it is and have worked as well as it has since 1999, I certainly would not have spent a moment or a penny on building it, because I do not like the design of the inner axle seal being directly adjacent to the carrier bearings in the housing, and the fact that the axle tubes fill up with debris.

 

[Poser]

Thanks guys... I appreciate the comments. When it comes to differentials, axles, etc. , I'm kinda out of my zone of comfort. I know just enough to be cautious and my concern and reason for suggesting use of the complete third was in regard to clearances, spacer thicknesses, etc. I've worked on my own cars/trucks since I started driving, but have never had the need to tear into a diff. My 40 has had the locker in it since I got it and I just want to go to a std diff, until I have the money for something better. I like the idea of a 'selective' locker, not one that is engaged most of the time. Also thx for the suggestion of replacing the seals and bearings...more parts to order.

There is not any magic happening inside the axle housing in regards to the differential. Yes there are torque specifications, yes there are specific clearances for components, yes there bearing pre-load specifications, but removing the valu-lok and installing a set of axle side gears and spiders is not that big of a deal.

The most difficult part of the install will likely be trying to get the spider gear pinion shaft back into the spider gears and thrust washers after you install the c-clips in the axles.

 

[Mr. Toad]

What are you going to service in the front differential that is not going to require you to remove the front axle shafts in order to perform the work?

Well, you can't service anything in the rear diff until the axle shafts are out either. I'll grant you that after going all the way into the knuckle to get the front shafts out, it's not that big a deal to go ahead and remove the entire diff. But if the front had an access/inspection cover, wouldn't you have the same options for diff-still-in-axle work in the front as you do in the rear?

The Danas: Any idea why Dana's design put the seals so far inboard? Do the shafts rust between those inboard seals and the seal at the end of the tube? Does that system make seal failures more difficult to notice? I like the Toyota design too.

The most difficult part of the install will likely be trying to get the spider gear pinion shaft back into the spider gears and thrust washers after you install the c-clips in the axles.

For me it's when a couple spiders and their washers fall out and I sit there like a monkey with a Rubik's Cube until I accidentally get it all back.

 

[MD11Fr8Dog]

Field repairs are a hoot!

I gotta tell you, it sucked breaking a pinion, but I had a blast doing the trail repairs, and am extremely grateful for the help of those that stayed behind to "assist" me (my first stop after getting off the trail was the beer aisle at the local grocery store repay my those that got me out of there). I could probably do it on the trail again in about an hour, it took less time in camp later that night!

 

[MD11Fr8Dog]

Thanks guys... I appreciate the comments. When it comes to differentials, axles, etc. , I'm kinda out of my zone of comfort. I know just enough to be cautious and my concern and reason for suggesting use of the complete third was in regard to clearances, spacer thicknesses, etc. I've worked on my own cars/trucks since I started driving, but have never had the need to tear into a diff. My 40 has had the locker in it since I got it and I just want to go to a std diff, until I have the money for something better. I like the idea of a 'selective' locker, not one that is engaged most of the time. Also thx for the suggestion of replacing the seals and bearings...more parts to order.

I feel the same way you do about diffs, but the only way to learn is to tear into it! All my breakage in Moab, while it sucked, was great for learning and relearning stuff about my truck, and how to be a little more self sufficient - nothing like setting up gears on a picnic table during a cotton wood "storm" using toothpaste to mark the gears! Even if you do more than you need to do, you have knowledge and experience for later!!

 

[Poser]

Well, you can't service anything in the rear diff until the axle shafts are out either. But if the front had an access/inspection cover, wouldn't you have the same options for diff-still-in-axle work in the front as you do in the rear?

Toyota Land Cruisers, Corporate GM, Dana or other manufactures use a removable cover on the rear axle housing to permit access to the differential, in order to remove the axle shaft retaining components, read semi-float c-clip axle designs found in Land Cruiser 40/55/60/62 series found in the USA. GM and Dana have both used c-clip axle shaft retention methods in the past, even as recent as the TJ Wrangler with the Dana 35, and the Corporate 10 and 12 bolts found in Tahoes, pickups, and other GM lighter truck products.


There are other manufactures that use a semi-float axle design that do not use c-clips to retain the axles, but rather, a bolt on retainer that keeps the bearing assembly that is pressed onto the axle shaft, attached to the end of the axle housing using bolts and nuts. Ford 9” and the 8.8” Ford, along with the Toyota 8” mini truck rear axles are a couple examples.

Dana makes semi-float rear axles that use the same style of bearing retainer keeping the bearing and axle assembly secured to the end of the axle flange with bolts. However, they do not use the third-member/center section design, which necessitates the removable differential cover in order to service the carrier assembly for the ring gear.


You do not need to have a removable differential cover on an axle that uses the third-member or center section design differential. If there were a justifiable reason for having a removable cover on a full-float axle housing, Toyota, Ford and others would have made it so. (Land Cruiser full-floats, 80/100 series in the USA) There is not anything that is really serviceable on those differentials. In the event your spider gears fail, they will likely find their way into the ring and pinion, only to ruin more components, resulting in the need to remove the center section from the axle housing for cleaning and repair. There is not enough room in a Land Cruiser axle housing to set up a differential and properly adjust carrier-bearing backlash with the differential center section mounted in the axle housing.

The Danas: Any idea why Dana's design put the seals so far inboard

When Dana changed to an open knuckle and exposed u-joint instead of a closed knuckle/u-joint or CV affair, they figured there was no reason for oil to be out by the knuckle if there is nothing to lubricate there.

Do the shafts rust between those inboard seals and the seal at the end of the tube?

The axle shafts rust and the tubes collect all sorts of dirt/mud/sand/abrasives, etc. There are not any seals on the outboard section of the axle housing preventing debris from getting into the axle tube.

Does that system make seal failures more difficult to notice?

No, not really. When the inner axle seal is leaking, it just weeps down the axle tube and makes a mess at the knuckle, very similar to what happens when a inner axle seal is leaking on a Land Cruiser or mini truck front axle assembly.

 

[e rock]

The Danas: Any idea why Dana's design put the seals so far inboard? Do the shafts rust between those inboard seals and the seal at the end of the tube? Does that system make seal failures more difficult to notice? I like the Toyota design too.

In addition to what Poser said, there is an inherent problem with trying to seal the outer end of a shaft with a conventional universal joint. The stub shaft is essentially held in a constant rotational vector by the spindle. And the single u-joint design does not provide consistent rotational torque under deflection, so the joint has to move laterally to accommodate.

An outer axle seal on a u-joint axle would fail quickly since the axle shaft moves around so much under use.

 

[Mr. Toad]

Great info. Thanks for taking the time.