AMC 20 with 1 piece moser axle shafts and Detroit locker

Rmhavema

Overlander
LIFETIME
CJ-8.com Member
City
Northville
State
MI
#1
Hey,

Upgrading my AMC 20 with 1 piece Moser axle shafts and Detroit Locker. I have been doing some research and had a few questions. From what I have read, when installing 1 piece axle shafts, you need to remove the thrust block from the differential in order to prevent excessive preload on the outer bearings. I have found instructions on how to do this for the standard diff, but nothing for the Detroit Locker. Anyone removed this thrust block from the locker? Or, maybe it is possible that the Moser axle shafts were designed shorter so there is no interference?

Second question, when looking in the 1982 TSM, on page 2F-29, the manual says to torque the ring gear bolts to 55 ft-lbs. But, on page 2F-40, the specs say 105 ft-lbs for the AMC 20. Anyone know what the correct torque is?
 

spankrjs

Scrambler Junkie
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City
Biloxi
State
MS
#2
I am pretty sure that only the factory Trac-Loc limited slips have the thrust block that needs to be removed. The factory open differential does not use them, pretty sure the Detroit Locker does not have an internal thrust block either IIRC :shrug: When you slide in the axle second shaft, you will find out. I have only ran across this issue with the factory LSD, and had to remove the thrust block out of everyone to get the Moser axles to fit correctly.

Not sure on the ring gear torque, would have to look.
 

Rmhavema

Overlander
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State
MI
#3
Thanks for the info. My factory open diff has a thrust block. And, from what I understand this is necessary with the stock 2 piece axle design as the inboard axle loads are reacted through this thrust block. With this design, end play is adjusted by shimming the left side axle shaft. It appears that my locker also has a thrust surface in the center. And, I would think this would be necessary if using the stock axle shafts. I called Moser and they said to remove any thrust block. I will call eaton to see if they have any insight. I will also measure the axle lengths to see if there is any difference between stock and moser.
 

spankrjs

Scrambler Junkie
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Biloxi
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#4
That would make sense that the open diff's have the thrust block, too, since all stock two piece axles shim the same way.

My tan Scrambler has a Detroit, but it has Warn full float axles. I don't remember jamming the axles into a thrust block, but it might be in there. If it is, it wasn't an issue with full float shafts.

I do know that my Green Scrambler/Tommy's white Jambo, both with Moser axles, both with factory LSD, the thrust blocks had to come out, no question. It was easy to remove the thrust block form the factory LSD carriers, a Detroit might be more interesting :eek:

My old '78 CJ7 ran Mosers and a Detroit with no issues, but that's not saying they will all be OK. It was a narrow track, then I put full float axles in it.

Post up what you find, I will be interested to know :thumbsup::wave:
 

spankrjs

Scrambler Junkie
LIFETIME
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City
Biloxi
State
MS
#5
Just found this on the internet:

http://www.alliedsystems.com/pdf/Wagner/Forms/80/80-919.pdf

Looks like the OLD style Detroit Locker/No Spin differentials DO NOT have a thrust block.

The NEW Soft Locker style Detroit DOES have a thrust block.


I do know that the Detroit in my old CJ7 was the old style, extra "clunky" model, no issue with the Moser axles.

I am not sure what style Detroit is in my tan Scrambler. I do know that it is a lot less "clunky", but that could be the longer wheelbase/automatic transmission making it behave better :shrug:
 

spankrjs

Scrambler Junkie
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Biloxi
State
MS
#6
I found these picture on my Tan Scrambler thread.


Picture of the Detroit Locker, not that it tells us anything:





But, I took this picture, looking down through the axle tube:




Looks like a thrust block is inside the Detroit Locker.

I "guess" the Detroit that came in this Scrambler is the "new/soft" version, that would explain why it behaves better then the Detroit that was in my old CJ-7. The old style would just about switch lanes when dumping off/on the throttle :crazy:
 

Rmhavema

Overlander
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City
Northville
State
MI
#7
Good stuff, thanks for the pictures and links. I did some measurements.

Stock open diff thrust block length = 1.5"
Stock right shaft length from outer hub surface = 28.5"
Stock left shaft length from outer hub surface = 25.5"
Total = 55.5"

Detroit Locker 187SL47A thrust block length = 1.42"
Moser CJ-L right shaft length from outer hub surface = 28.4375"
Moser CJ-L left shaft length from outer hub surface = 25.4375"
Total = 55.295"

If my measurements are correct, looks like I have approximately 0.205" of clearance, assuming the outer hub flanges are in the same position. It also looks like I would have to disassemble the locker in order to remove the thrust block (not going to do that). So, I am going to put it all together and see what happens. I will post the results... Now, just need to figure out the ring gear bolt torque.
 

SeeJayAte

CJ-8 Member
CJ-8.com Member
SOA Member
City
Greenfield
State
In
#8
Good stuff, thanks for the pictures and links. I did some measurements.

Stock open diff thrust block length = 1.5"
Stock right shaft length from outer hub surface = 28.5"
Stock left shaft length from outer hub surface = 25.5"
Total = 55.5"

Detroit Locker 187SL47A thrust block length = 1.42"
Moser CJ-L right shaft length from outer hub surface = 28.4375"
Moser CJ-L left shaft length from outer hub surface = 25.4375"
Total = 55.295"

If my measurements are correct, looks like I have approximately 0.205" of clearance, assuming the outer hub flanges are in the same position. It also looks like I would have to disassemble the locker in order to remove the thrust block (not going to do that). So, I am going to put it all together and see what happens. I will post the results... Now, just need to figure out the ring gear bolt torque.
My '83 MR252 says that 55 ft.lbs for an open diff. and 105ft. lbs for a Trac Loc diff. It also has a Service Recheck Torque of 95-115 ft. lbs for the Trac LOk diff. Hope this helps.
 

FLCJ8

Legacy Registered User
City
Palm Bay
State
FL
#9
My '83 MR252 says that 55 ft.lbs for an open diff. and 105ft. lbs for a Trac Loc diff. It also has a Service Recheck Torque of 95-115 ft. lbs for the Trac LOk diff. Hope this helps.
I think he was referring to these conflicting specs.
ring1.jpg

ring2.PNG

Do yours match?
 

Rmhavema

Overlander
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City
Northville
State
MI
#10
I ended up going with 105 ft-lbs. I am thinking the torque specifications table is correct, and the procedure is possibly a copy and paste error from the dana 30. Now to shim the carrier bearings!
 

Rmhavema

Overlander
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City
Northville
State
MI
#11
Everything went together ok. Looks like it will work with the thrust block installed. Axle shafts bolted on ok and spun freely.

IMG_4914.jpg
 

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jammer1

Scrambler Junkie
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Maple Hts.
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Oh
#12
I don't rebuild the rear ends so I may be off and someone on the site can chime in but the axles slid in the detroit locker with a little play in the depth of how deep the axle shaft goes. This doesn't effect the pattern on the ring gear. If the thrust block gets in the way when you bolt the axle plate on (at end of axle tube) this causes the axle to compress against the thrust block and you run into problems with the bearings because of the tight fit and pressure. If I'm wrong someone please chime in, but I don't think you can be sure of a good fit because of the ring pattern (concerning bottoming out the the axle against thrust block).
 

Rmhavema

Overlander
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City
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MI
#13
I agree with you. I guess I wasn't 100% clear in my post, but everything went together ok and the axle shafts spin freely.
 

jammer1

Scrambler Junkie
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Maple Hts.
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Oh
#14
No problem, just wanted to make sure. Hear enough of bearings going bad because of the thrust block. :wave:
 
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