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70 AMX rear axle ring/pinion brand question

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bvpotash1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bvpotash1 Quote  Post ReplyReply Direct Link To This Post Topic: 70 AMX rear axle ring/pinion brand question
    Posted: Jul/04/2019 at 9:21pm
Many years ago I bought a motive gear 3.73 ring and pinion for my 70. I'm just getting around to installing it. Has any one had a experience with this brand? It is made in Italy. Also I misplaced the pinion shim that goes behind the large bearing race. Any ideas what shim I should star with when setting up this new gear set? I also need new posi clutch plates. I bought the ones with the round corners, later model? I have the carrier that bolts together with square corner plates. As always thanks for your help, it is greatly appreciated.

-Bernie  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NCSteve Quote  Post ReplyReply Direct Link To This Post Posted: Jul/10/2019 at 7:10pm
I just installed 4.88 motive gears in my JKU Rubicon. Lots of folks in my area use them with no issues. I always start with what was originally the housing and normally is really close starting point. 
1970 Big Bad orange AMX, 390 4speed, Go Pac
1979 Jeep Cherokee, 360, 4 speed/D20
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401MATCOUPE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: Jul/10/2019 at 7:28pm
You may have issues with Motive or any brand for an AMC 20, they are not machined to use thefactory tools and I have little luck with them, actually sources a used set and returned all new ones.  Pit Crew AND i have had same experience.....good luck. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/10/2019 at 9:45pm
Since you don't have the original pinion shim, setup will be a little more difficult.  I'd start with a pinion shim of around .085-.095".  Pretty thick, the factory shim was cast iron.  The Yukon 3.73s in my AMX ended up taking about .102" to get a good pattern.

I recommend getting a shim kit from Ratech.  They have enough shims in their kit to build a pack that thick.  Most master kits use GM size shims which don't quite fit the AMC needs.

Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1970390amx Quote  Post ReplyReply Direct Link To This Post Posted: Jul/10/2019 at 10:12pm
several sets of gears I set up ended up with a pinion shim in the area of .100 Do you want to sell the wrong set of posi clutches you have?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Jul/11/2019 at 5:59pm
Get the solid pinion spacer from Ratech as well, should make it easier to swap in and out without having to worry about the crush tube.
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pit crew View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pit crew Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2019 at 7:25am
Originally posted by 401MATCOUPE 401MATCOUPE wrote:

You may have issues with Motive or any brand for an AMC 20, they are not machined to use the factory tools and I have little luck with them, actually sources a used set and returned all new ones.  Pit Crew AND i have had same experience.....good luck. 
Yes, we went through every brand of new gears you can think of and they all had the same problem. The pinions are all made in Italy now. They are too long and have a square shoulder that will not let the pinion nut lock all the way down.

Of course calling all of the "manufactures" tech support produced the same answer. "Never hear of that before.". This was in spite of the fact I had talked to other AMC people that said they had already called in the issue themselves.





Edited by pit crew - Jul/12/2019 at 7:30am

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steve_P Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2019 at 8:59am
I haven't done any in a while, but .08-.10" sounds like what I've seen with OE gears. I use the TSM method and measure off the back of the pinion gear like Ross.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bvpotash1 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2019 at 11:37am
I'd like to thank every one for the fantastic information and incite! This Form and its members are truly the best!

THANK YOU!
-Bernie
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2019 at 3:46pm
Did someone already mention using some "old" pinion bearings and honing the id so they are slip fit and use those to get a set up shim size, then do final assy with new pressed on bearings only 1 time, hopefully?
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