AMC20 Wheel Bearing Install

[GravyProv1]

Replacing the outer RH wheel bearing on an AMC20 .

Couple of easy questions for anyone that has done this before.

Example: If the bearing protrudes 0.040" from the housing face, should the shims between housing face and brake backing plate be less than 0.040", exactly 0.040" or a little more than 0.040".

Thanks,
Gravy

 

[7D8CJ]

Replacing the outer RH wheel bearing on an AMC20 .

Couple of easy questions for anyone that has done this before.

Example: If the bearing protrudes 0.040" from the housing face, should the shims between housing face and brake backing plate be less than 0.040", exactly 0.040" or a little more than 0.040".

Thanks,
Gravy

If you didn't replace the axle I would install the original shim pack and measure end play. Spec is .004 to .008" end play. I guess your answer would be a little more than .040

 

[GravyProv1]

I have converted to a one piece axle. The problem is the Jeep rebuild only has 500 miles on it. The entire diff was rebuilt with the one piece axle and just used the same shims from stock setup.

After 500 miles, the bearings went out in the RH side. That's why I'm concerned about just doing the same thing again. Only issue I can see that would make a difference is the shims or the thickness of the bearing spacer in the housing.

 

[7D8CJ]

Did you remove the thrust block from the carrier? I had to do that with my G20 one piece shaft swap.

 

[Old Dog]

The instructions for my Superior I piece axles said to first install the seal and spacer in the axle housing and than the bearing and set (grind if needed) the spacer to have .020 - .060 of the bearing sticking out of the housing. than install the bearing on the axle shaft and bolt it together.

 

[GravyProv1]

My kit said same thing about .020-.060". But no shims? That indicates some compression of the bearing?

 

[Old Dog]

Yes no factory shims, you use the spacer instead of the shims.
And yes they want the bearing to be preloaded, or compressed as you put it. I set mine at .030 as I personally thought that was enough and had no problems.

 

[GravyProv1]

Thanks Old Dog, always very helpful. So you think maybe the failure was from leaving the original shims in there and not properly allowing for compression of the bearing. I'm guess that there's at least 0.050-0.060" of shim.

Next question, I know how the kit says to press the bearing onto the axle. Same way the bearing was in when it failed. The original Jeep manual says to intall the bearing opposite direction from how the kit says.

Basically it's a tapered bearing. The question is what direction does the taper need to run. Kit indicates the bearing should taper out to in. Larger dia of taper toward wheel. Smaller taper towards diff.

Any thoughts on this.

 

[Old Dog]

Thanks Old Dog, always very helpful. So you think maybe the failure was from leaving the original shims in there and not properly allowing for compression of the bearing. I'm guess that there's at least 0.050-0.060" of shim.

Next question, I know how the kit says to press the bearing onto the axle. Same way the bearing was in when it failed. The original Jeep manual says to intall the bearing opposite direction from how the kit says.

Basically it's a tapered bearing. The question is what direction does the taper need to run. Kit indicates the bearing should taper out to in. Larger dia of taper toward wheel. Smaller taper towards diff.

Any thoughts on this.

It could be that there was no preload on the bearing, that would make it fail.
Your right the larger dia. goes toward the wheel and smaller dia. toward the diff.

 

[BIGTRUCKNUT]

It could be that there was no preload on the bearing, that would make it fail.
Your right the larger dia. goes toward the wheel and smaller dia. toward the diff.

I concur.

 

[GravyProv1]

Ok guys, now the left hand rear is starting to squeak. WHAT THE HECK?

Could it be the axles? I went with the Crown 1 piece axle kit. Are the Moser axles better? Could that be the problem? Or are the AMC20 rear ends just this junky?

What would be a good replacement rear end for a CJ7 ? Dana 44 ?

 

[Torxhead]

Not really knowing squat about the AMC20 , have you considered that you might have a bent axle housing? I have the Dana 44 and have a slightly bent housing, but deal with it. I would suggest checking for that and getting tube braces welded on, that seems to be the remedy for the 20.

 

[Tommy]

Thinking outside the box a little. I had a bearing go out on the passenger side of the AMC20 and it turned out to be a bent rim was the culprit. Replaced the bearing and seal as per instructions and haven't had any problem in 15 years. The AMC20 is a great axle but gets a bad rap. My CJ5 is pretty much stock with a mild lift and I have run the Rubicon a half dozen times with no trouble with the axes. Anyway, something different to check out.

 

[Old Dog]

Ok guys, now the left hand rear is starting to squeak. WHAT THE HECK?

Could it be the axles? I went with the Crown 1 piece axle kit. Are the Moser axles better? Could that be the problem? Or are the AMC20 rear ends just this junky?

What would be a good replacement rear end for a CJ7 ? Dana 44 ?

Did you replace both side's last time?
Don't know where you are getting your bearings, but make sure you get Timken's, not some off the wall brand.

 

[GravyProv1]

Both sides were replaced with the one piece axle kit. Bearings are definitely Timken. After 500 miles rh went out and I replaced it. Now after another 100 miles the lh is squeaking like the rh did before it failed.

 

[mtnwhlr]

have you considered that you might have a bent axle housing?

This is what I would be looking at to make sure the are straight.

 

[Old Dog]

Do you remember how far the bearings were sticking out when you first put the axles in?
You did pack the bearings with grease before you pressed them on right? (sorry had to ask)
What did the bearing look like that went bad.?
I'm not a fan of Crown, but I doubt it is the axle's fault, unless they are both bent which is unlikely.

 

[Old Dog]

The pics in this link could be better but it might help diagnosing the bearing that is going bad now,
http://www.lmr.com.br/httpdocs/catalogos/TIMKEN/USA_chap_6.pdf

 

[GravyProv1]

I didn't do the initial rebuild. We are thinking that could be the problem.

The last Rh side bearing failure, the bearing was completely in pieces. When I removed the axle, pieces just poured out onto the floor.

When I reassembled, the protrusion from the housing was about 0.050". Was properly packed with grease.

Yea the Crown axles appear to be well made. And the Jeep has never really been off road before. So I can see that anything in the housing could be bent.

 

[Munypit]

Shouldn't the shims be on the drivers side only? I am in the process of installing mosers in my AMC20 and the only mention of shims refers to the drivers side of the vehicle (left hand drive)