Inspection pics, things to look for in gear swap

[guidoverduci]

Hello!

I’ve removed my carrier and am in the process of having it updated with 4.56 gears and swapping out the Detroit locker. With everything apart, what are some things I should look for and consider.

I’ve attached a couple pics... 1 of a crack in the axle. I suppose I should replace? The other pic is of my wheel spacers. What could cause all the grind marks? Everything was torqued and seemed smooth when installed.

Thanks!

 

[langester]

Looks like you caught that bearing just in time. The spacer and rim almost look like some kind of electrolysis or reaction of some kind. Might just be my eyes. Looking forward to what you find out from others.

 

[Timmy390]

Looks like you caught that bearing just in time. The spacer and rim almost look like some kind of electrolysis or reaction of some kind. Might just be my eyes. Looking forward to what you find out from others.

Ditto......

Tim

 

[B RON CO]

Hi, the crack, as mentioned, is the bearing. I would let the rear end guy change both bearings on the axles. Good luck

 

[guidoverduci]

Thanks everyone. I’m trying to track down the right bearing replacement kit. These are 31 spline axles... Is that considered the large bearing kit?

 

[Apogee]

X2 on the bearings, Ø80mm [Ø3.15"] OD would be a "big-bearing" application, which those appear to be.

As for the wheel spacers, it looks like you have localized yielding of the material to the outside of each of the wheel studs. I would be very concerned given that that's usually what precedes a loss of lug nut torque and leads to broke wheel studs and wheels falling off at speed. Your wheels have torque pockets cast into the mounting pads between the studs, but not around them to provide a more uniform clamping stress between the wheel and bolt-on wheel spacer.

Just to confirm, are the wheel studs 1/2-20? What are you torquing your wheel studs up to? Are you getting any similar wear/failure patterns on the inboard surface of the wheel spacer where it contacts the hub? Does it have torque pockets/rings?

Tobin

 

[guidoverduci]

Yes, 1/2-20. I believe I torqued to 90 ft lbs. No wear on the inboard surface of spacer. But both rear wheels showed similar marks. I’ll have to check the front when I get the rear buttoned up. Thanks for the info!

 

[Apogee]

Yes, 1/2-20. I believe I torqued to 90 ft lbs. No wear on the inboard surface of spacer. But both rear wheels showed similar marks. I’ll have to check the front when I get the rear buttoned up. Thanks for the info!

I would be tempted to add torque pockets around the wheel stud holes on the wheel pad, but that's a bit of a pain to do, especially with rubber on the wheels. That said, I've be concerned about running them as they are without resurfacing the mating surfaces first.

Were you checking your lug nut torques frequently when you first installed the spacers? Just like aluminum wheels, they have a break-in period where the lug nuts will find their happy place and seat into the material slightly, requiring you to retorque them frequently for the first 200 miles or so. That said, were your lug nut torques staying consistent or were you losing torque?

The reason I ask is because some wheel spacer manufacturers use OEM wheel studs that were designed for steel or cast-iron hubs/axles, many of which have relatively small heads and therefore not a lot of surface area under the head of the stud. When you torque your wheel stud, almost all of that tensile force is being transmitted directly into the head of the stud and whatever it's contacting, so you may be locally yielding the material under the head of the wheel studs if you're exceeding the yield strength, which is allowing things to loosen up and bit and "wiggle" under the fully fluctuating load due to the rotation of the tire and weight/dynamics of the rig.

I've seen wear patterns similar to yours on drag cars where the preload on the wheel wasn't great enough to overcome the forces imparted during launch.

 

[74 Bronco Billy]

^^^
This is great info. Now I gotta make sure my rig's Aluminum rims are mated well, and torqued right. Is there a go to name brand wheel lug nut that is best for these Aluminum rims or when using spacers?
Sorry for hijack.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[guidoverduci]

Now I don’t know if I should buy new spacers with the wheel mating surface messed up. But definitely good info! I don’t have more than a few hundred miles on these spacers and wheels. I do recall one wheel became really loose.. almost as if I forgot to tighten them (maybe I did?!).. but that was only one wheel.

 

[DirtDonk]

Am I wrong? Or is that a Set-20 bearing? Or maybe one of the special bearings used to mate a 31 spline axle to a small bearing housing end?
Whatever it is, it just doesn't look "normal" from here.

Either way, since it's a 31 spline axle, it's not stock, so you need to measure. Both the outer bearing diameter and the axle shaft diameter at the bearing I would say.

Hope that doesn't happen again!

Paul

 

[WILDHORSES]

My guess is it's a conversion bearing which allow you to run 31 spline axle in a small bearing housing. Pretty simple if the OD is under 3" that is what it is. If it's over 3" ???. Grab a set of calipers the check it out.

The cool think about the conversion bearing is the OD on the axle will allow for the installation of large bearings. You would have to change the housing and brakes but in the long run those are good ideas.

Jim

 

[guidoverduci]

OD is under 3” and I’ve got the 10” brake drums. I’m going to bring it to my local brake / wheel service place and see if they stock the bearings and can pop them on.

 

[tirewater]

My guess is it's a conversion bearing which allow you to run 31 spline axle in a small bearing housing. Pretty simple if the OD is under 3" that is what it is. If it's over 3" ???. Grab a set of calipers the check it out.

The cool think about the conversion bearing is the OD on the axle will allow for the installation of large bearings. You would have to change the housing and brakes but in the long run those are good ideas.

Jim

Considering the crack, I'd be concerned that they used the wrong ID bearing. That crack is a catastrophic failure of the bearing imho.

Guido, when you take it in make sure they measure and use the correct bearing size.

 

[Apogee]

OD is under 3” and I’ve got the 10” brake drums. I’m going to bring it to my local brake / wheel service place and see if they stock the bearings and can pop them on.

The small bearing is nominally Ø72mm OD [Ø2.835], so if you have 31-spline axles and a small bearing housing end, then like Jim stated, you must have the "conversion" bearings. A lot of folks are running them without issue, but that might explain why they look a little funkier than what we're used to seeing.

Also as stated, you could swap housing ends to a proper big-bearing housing end (old-style big bearing or new-style big bearing Torino), but you would need to swap the brakes at the same time since the backing plates, axle offsets, etc would not match.

 

[guidoverduci]

Thanks guys. I dropped off the axles at my local shop. He said he could measure and make sure he gets the right bearings replaced. What about seals / rings on the inside of the housing ends? Are those something that I need to replace?

 

[DirtDonk]

The good news is that there is also usually a bearing number stamped right on to an edge somewhere. Usually...

On the seals, YES!
I would never go to all this trouble and reuse an old seal, unless I knew it was almost new already and also knew for a fact that I had not damaged it removing the axle.
And anytime there is damage to an axle and/or bearing, it's possible that excess movement has worn even a newer seal excessively.

In other words, it's just cheap insurance to change the seals at the same time.
Sounds like you just need the standard small bearing seal, but you can measure that and remove the old one that's still in your housing to verify.

Paul

 

[guidoverduci]

Here’s a couple other things that don’t look right to me inside the housing. The first 2 pics are side where the broken bearing came out of.

Also, the axle shop said that had trouble finding the same bearing as a replacement. There was a spacer with it and he’d never seen that before. Still said it won’t be an issue with replacement of the same one.

 

[DirtDonk]

What does not look right to you about the ends?
The little bit of surface rust on the bearing surface should not be an issue. And even the slight radial scratch(?) in the third pic is not an issue because that's your bearing surface, and not a sealing surface.
And when I say "bearing surface" it's not a point where anything is spinning. Just that the bearing's outer case sits in that spot and does not spin. If those marks are from the bearing spinning inside though, then yes you have a problem.
But it just looks like surface rust to me.

If you mean the divots in the area just outside the seal, then those are very likely just tool marks from some slightly over zealous use of a seal remover tool.
Won't hurt anything in that area.

About the spacer though, where is it? Captured on the axle shaft by the pressed-on bearing? Or are you saying it's that plate in your pictures?
In our pics the outer plate is the brake backing plate, correct?
Usually there is a metal gasket between the backing plate and axle housing end.
My memory tells me that they're thinner than the inner one showing in your pics, but that's an old memory but someone who's worked on one more recently might be able to tell.

Is that what you were talking about?

Paul

 

[guidoverduci]

Thanks for the info Paul. The area inside of the bearing surface seems a little beat up, but it sounds like it’s not a concern.

The spacer is on the axle captured by the bearing. All of it is probably ok, I was just making sure. Hopefully I’ll have everything back in and up and running in the next couple weeks. Been a bit busy. I need to start researching how to break in the new gears.