Question for the gear swap gurus- Gear swap backlash problem

[Spaffy]

I'm in the middle of a gear swap on my JL; the front axle I'm doing pretty well with and just cleaning up the pattern- I actually have to add some backlash. I am; however, running into an issue with my rear axle. I have a 2021 JL with the m220 narrow axle.

Im going from the Sport 3.45 to 4.88 gears and installing OX lockers front and rear.

Original Shims were: Pinion: .048 small bearing: .083 large bearing .117

Im using Spicer gears and install kits. Both pinions marked 0.

I get to the point where I'm installing the gears and checking the backlash. I started with the same pinion shim and was planning to try the same carrier shims... There was ZERO chance of me getting those shims in there with the Ox locker. There was ZERO chance of getting either shim by itself in the case with the Ox locker.

I started to investigate the maximum shim size I could get in there. In the end, the max total shim size I could fit in the carrier was .035 [which worked out nicely as thats just about exactly .117 minus .083.]

So I shimmed the large bearing [ring gear side] with .035 and finessed it into the case with no shims on the small bearing side. Honestly I think the OX plus .035 shims total was as tight, or a little tighter than stock shims with the LSD. I was just barely able to get it in the case though with a but of percussive persuasion. I don't think I could fit any more shims in the case with the OX locker.

Then I was going to get my dial indicator and check the backlash. Before I did I gave the ring gear and tug and I could tell the backlash was massive even without my dial. I checked it with the dial anyways. I could tell you the reading; but Id have to go to my garage and see what 1.25 revolutions on my dial indicator is it was easily 10-20x's spec.

My issue is, I have no more shims to remove on the small bearing side, and I cannot physically fit any more shims on the large bearing/ring gear side.

I increased the pinion shim from .048 to .080- I think it helped slightly but I still had over a full dial turn. Im not a gear expert, could the pinion be that far out of shim to affect the backlash that much? My next step was trying a pinion shim of .110... but I had to call it for the night.

Am I missing something else?

@chevymitchell any ideas? I know this is a brand new OX locker model- I did email OX before I bought it to verify it was for a m220 narrow and not wide- if that makes a difference - and they confirmed it was..... Im not a gear pro, so my money is on me missing something... but I have done a couple and Im a bit at a loss with the backspacing out that much with no more carrier shims in play....

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[asuperheat]

Sounds like the pinion depth is wrong. Need to add shims to get the pinion deeper. Then try and set the carrier shims making sure you have a good contact pattern and backlash. Unfortunately it can take several try's to get it right. I you have not yet you need to make a set of set up bearings. it will help speed up the process.

Using a case spreader helps also. Make sure you have some preload on the carrier bearings when you get it dialed in.

 

[Spaffy]

Sounds like the pinion depth is wrong. Need to add shims to get the pinion deeper. Then try and set the carrier shims making sure you have a good contact pattern and backlash. Unfortunately it can take several try's to get it right. I you have not yet you need to make a set of set up bearings. it will help speed up the process.

Using a case spreader helps also. Make sure you have some preload on the carrier bearings when you get it dialed in.

Being a rookie gear guy I just wanted to make sure it sounded appropriate to add that much to the pinion shim. I hadn't seen that before.

I do have a case spreader; but I honestly think the carrier preload is as much or more than stock. I think those carrier shims are about maxed out.

 

[asuperheat]

If I needs pinion shim you have to add it. If you have that much backlash and you are maxed out on adjusting carrier shims the pinion is not deep enough. There are tools used to measure pinion depth but I have just done it by trial and error myself. Probably done it a dozen times personally. Some take more time to set up than others.

How are you pulling the pinion bearing to add shim? Do you have a puller made for that or are you using set up bearings? Only ask because with out the right tools for that it sucks. If using set up bearings are you sure they are the correct bearing?

 

[Spaffy]

If I needs pinion shim you have to add it. If you have that much backlash and you are maxed out on adjusting carrier shims the pinion is not deep enough. There are tools used to measure pinion depth but I have just done it by trial and error myself. Probably done it a dozen times personally. Some take more time to set up than others.

How are you pulling the pinion bearing to add shim? Do you have a puller made for that or are you using set up bearings? Only ask because with out the right tools for that it sucks. If using set up bearings are you sure they are the correct bearing?

I don't have setup bearings for the m220 sadly; or in the case, a setup race. I may try and grind the old one a bit tomorrow to make one.... I have been having to knock out the inner pinion bearing race each time as the m220 has the shim behind the bearing race.

I was kinda figuring that I needed to just add more pinion shim, but after 7 hours beating on it today I wanted to make sure that was the proper course. [Not that I could see another....] It just set off alarms in my head possibly tripling the pinion shims and I needed to ask if that was normal.

 

[asuperheat]

If the pinions were marked the same I would measure the old pinion bearing against the new pinion bearing. If they are the same and the pinions are the same then I guess the difference would have to be in the Ox locker. Don't know if you have a way of measuring it but it seems that is the other variable.

 

[chevymitchell]

I'm in the middle of a gear swap on my JL; the front axle I'm doing pretty well with and just cleaning up the pattern- I actually have to add some backlash. I am; however, running into an issue with my rear axle. I have a 2021 JL with the m220 narrow axle.

Im going from the Sport 3.45 to 4.88 gears and installing OX lockers front and rear.

Original Shims were: Pinion: .048 small bearing: .083 large bearing .117

Im using Spicer gears and install kits. Both pinions marked 0.

I get to the point where I'm installing the gears and checking the backlash. I started with the same pinion shim and was planning to try the same carrier shims... There was ZERO chance of me getting those shims in there with the Ox locker. There was ZERO chance of getting either shim by itself in the case with the Ox locker.

I started to investigate the maximum shim size I could get in there. In the end, the max total shim size I could fit in the carrier was .035 [which worked out nicely as thats just about exactly .117 minus .083.]

So I shimmed the large bearing [ring gear side] with .035 and finessed it into the case with no shims on the small bearing side. Honestly I think the OX plus .035 shims total was as tight, or a little tighter than stock shims with the LSD. I was just barely able to get it in the case though with a but of percussive persuasion. I don't think I could fit any more shims in the case with the OX locker.

Then I was going to get my dial indicator and check the backlash. Before I did I gave the ring gear and tug and I could tell the backlash was massive even without my dial. I checked it with the dial anyways. I could tell you the reading; but Id have to go to my garage and see what 1.25 revolutions on my dial indicator is it was easily 10-20x's spec.

My issue is, I have no more shims to remove on the small bearing side, and I cannot physically fit any more shims on the large bearing/ring gear side.

I increased the pinion shim from .048 to .080- I think it helped slightly but I still had over a full dial turn. Im not a gear expert, could the pinion be that far out of shim to affect the backlash that much? My next step was trying a pinion shim of .110... but I had to call it for the night.

Am I missing something else?

@chevymitchell any ideas? I know this is a brand new OX locker model- I did email OX before I bought it to verify it was for a m220 narrow and not wide- if that makes a difference - and they confirmed it was..... Im not a gear pro, so my money is on me missing something... but I have done a couple and Im a bit at a loss with the backspacing out that much with no more carrier shims in play....

Check to make sure you pressed the small bearing on all the way. It's easy to lose .010"+ by thinking you're bottomed out with the bearing when you're not. Same with the larger bearing. Good to double check that they're pressed on all the way when you have shimming issues. Also, make sure that you're not pressing against any debris, RTV, or left over shim that may be stuck to the housing you didn't see.

Otherwise, if you're truly and physically out of room, the only thing that remains is the locker.

If both pinions were 0 etch, then the absolute most adjustment you'll end up with is +/- .001-3". Adjusting from .048" to .080" is way too much when both are etched 0.

If everything is checking out and you're out of room on the small bearing side, call OX and let them know this. There may be a machining error, but the first thing to check is to make sure the bearings are pressed on all the way.

 

[Spaffy]

Check to make sure you pressed the small bearing on all the way. It's easy to lose .010"+ by thinking you're bottomed out with the bearing when you're not. Same with the larger bearing. Good to double check that they're pressed on all the way when you have shimming issues. Also, make sure that you're not pressing against any debris, RTV, or left over shim that may be stuck to the housing you didn't see.

Otherwise, if you're truly and physically out of room, the only thing that remains is the locker.

If both pinions were 0 etch, then the absolute most adjustment you'll end up with is +/- .001-3". Adjusting from .048" to .080" is way too much when both are etched 0.

If everything is checking out and you're out of room on the small bearing side, call OX and let them know this. There may be a machining error, but the first thing to check is to make sure the bearings are pressed on all the way.

Thank you for your response and everyones responses! I was starting to go crazy yesterday trying to set this thing up.

I'll double check all of those things in a little while; when it's an acceptable hour for me to be making a ruckus in my garage....

I did use a little 10 ton press to get the carrier bearings pressed on with my bearing puller husk on the large side and the old bearing race on the small side. I'll thow them back in and make sure they're bottomed out.

I also checked the bearing number on the inner pinion bearing. It was the same as the old one. I could measure it with my calipers to be absolutely certain.

I'll double check the tube walls too, I test fit the shims against the tubes prior to re installing, and didn't see any RTV in the way or other shims. With the force I had to use to get that carrier in with the .035 shims I'd be amazed if there was a second shim stuck on the small bearing side that didn't fall off. Id love for that to be the case, just don't think I'm that lucky!

I could break out my case spreader, but comparing the force it took for me to get the stock carrier out and the force it took to pull out the locker plus .035 shims- the locker took more force. I think it'll be too much preload if I just try to force another .020 in there....

I was actually worried about not being able to pry out the locker with .035 shims. It was TIGHT.

Lastly, I did buy Spicer install kits, but I ordered the OX install kits as well. I'll measure the Spicer kit carrier bearings compared to the OX install kit carrier bearings. If the used differently spec bearings I'll be a little upset. I don't foresee it as I don't know why they would do that. At this point I'll check though.

If all that fails and everything looks right, I guess I'll have to throw my 4.88 gears on the LSD and reinstall that for now and call OX tomorrow.

 

[Spaffy]

UPDATE:

I double checked everything today and didn't find any errors from yesterday. Bearings pressed on the carrier fully, no more shims in the axles, no RTV. With how tight the OX was in there yesterday, there was no physical way I was going to be able to add more shims.

I gave up on the OX, used the OX install kit on my original LSD and put the 4.88 on the LSD. Boy was I glad I had a spare set of carrier bearings and ring gear bolts!

I used the original pinion shim, had to tweak the carrier shims a bit for the different brand carrier bearings but was able to get a good pattern without too much effort!

I'm going to give OX a call tomorrow and see what they say.

 

[word302]

UPDATE:

I double checked everything today and didn't find any errors from yesterday. Bearings pressed on the carrier fully, no more shims in the axles, no RTV. With how tight the OX was in there yesterday, there was no physical way I was going to be able to add more shims.

I gave up on the OX, used the OX install kit on my original LSD and put the 4.88 on the LSD. Boy was I glad I had a spare set of carrier bearings and ring gear bolts!

I used the original pinion shim, had to tweak the carrier shims a bit for the different brand carrier bearings but was able to get a good pattern without too much effort!

I'm going to give OX a call tomorrow and see what they say.

Yeah you can’t shim only one side of the carrier and expect your backlash to be anywhere near close. Either the locker is machined wrong or your bearings aren’t seated.

 

[Spaffy]

Yeah you can’t shim only one side of the carrier and expect your backlash to be anywhere near close. Either the locker is machined wrong or your bearings aren’t seated.

Yeah, it seemed wrong in my head. Trying to shim one side; not the smartest thing I've ever done. Also not the dumbest....

I did throw it back in my press this morning and checked both bearings. Neither budged at all, the needle on my press just climbed as soon as I applied pressure.

I tried to fit it back in once last time this morning just to double check the bearings didn't seat more. It was still every bit as tight with the .035 shims.

That's when I aborted and just did the gears with the LSD.

 

[Spaffy]

@chevymitchell

The mystery has been solved!

I finally got ahold of OX and they had me verify all 3 part numbers of the components of the locker. I had verified the part number before install, or so I thought...

The carrier and large bearing Side cap were correct, when I checked the small bearing side cap I saw this:

It got assembled at the factory as a JL carrier, with a JL large bearing side cap, and a JK Rubicon small bearing side cap! (Which uses the same size bearing but is longer)

They're going to make it right.

Anyone putting in a rear OX for a m220, just double check ALL THREE part numbers.

I don't feel as stoopid now.

 

[chevymitchell]

@chevymitchell

The mystery has been solved!

I finally got ahold of OX and they had me verify all 3 part numbers of the components of the locker. I had verified the part number before install, or so I thought...

The carrier and large bearing Side cap were correct, when I checked the small bearing side cap I saw this:

It got assembled at the factory as a JL carrier, with a JL large bearing side cap, and a JK Rubicon small bearing side cap! (Which uses the same size bearing but is longer)

They're going to make it right.

Anyone putting in a rear OX for a m220, just double check ALL THREE part numbers.

I don't feel as stoopid now.

Very nice, man. I'm glad it's an easy fix and it's always nice to hear that a MFG is willing to make things right quickly.

Thanks for the updates.

 

[asuperheat]

Glad you found it and glad they are going to make it right for you.

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