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Hello Moses,

Finally got the Rinky Dink jeep through the byzantine maze that is the Calif DMV, BAR Smog Referee and the CHP. Got the title completed and a new set of plates. 1st drive reveals mucho noise and vibration from the rear axle. Long story short, the axle should have .008" end play shows .250." Open the thing up and the carrier has .125" play. Not good. I questioned whether I wanted to tackle this as I have never built an axle. Talking with my son he said, Why not, If you can build a bevel Ducati engine  (8 bevel gears) you can certainly build an axle.

So, this is my question. Everything is out of the axle but for the pinion. Nut & yoke off. Everything is clear. Smack the pinion with the dead blow and its not budging. There is not clearance to put a puller to from the back side. I don't want to beat the crap out of it. Any insight or suggestions on removing this?

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In my Jeep CJ Rebuilder's Manual: 1972-86, I cover the rebuild of the AMC 20 thoroughly...In a nutshell, you do need to drive the shaft through the forward/nose end pinion bearing.  I use a blunted, pointed chisel and air hammer to carefully drive the shaft through the bearing.  Keep the point centered carefully in the pinion shaft's nose end recess.

You will quickly "dance" the bearing off the shaft as the shaft drives through.  Unless the bearing has seized on the shaft, this should only take a minute once the shaft starts moving.  Impact force is entirely different than beating on the shaft with a dead blow hammer.  The dead blow absorbs too much of the energy.

Let us know how this works.  Stay centered on the pinion shaft and wear eye protection—this is hard steel!

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Finally ended up pulling the axle and pressing it out before I saw your reply. Cleaned out the housing really well. You would think I hit the Comstock lode from all the silver flakes that came out of that thing. I put it mostly back together last night, starting with the original pinion depth shim. Made up a set of "fitting" bearings for the pinion. Did a pattern check. The depth looks good but need to move the ring gear inward, or that's what I believe. Drive side looks good but the coast side is biased toward the toe. Made a case spreader at a total cost of about $40.00. We will see how it works tonight with setting the carrier preload. Wouldn't mind having a pinion depth gauge but I don't want to pop for a tool I'll use once a decade or two. Its a bit more work doing a trial fit and modify but I prefer to spend the money elsewhere. The pinion gears were both sketchy and needed replacing. I can't imagine a two legged 4x4 so  I made the obvious choice. With comparable cost to replacement spider & side gears, I went and ordered one of the "lunchbox" lockers. We will see how it works. 

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Did you use the pinion head markings as a reference for pinion depth and the starting shim stack thickness?  You started with the original shim but changed the pinion gear.  You can get a very close pinion depth setting by using the markings chart and adjusting the shim stack.  A tooth contact pattern will confirm whether the pinion depth is correct—once you set the ring gear backlash to specification.  

I like to load the pinion shaft when doing a tooth contact pattern test.  I tie a rag around the backside of the pinion flange, tourniquet fashion to create drag, and rotate the ring gear carrier with a box wrench on the ring bolts.  The resistance will create a better tooth impression in the titanium dioxide or marking compound. 

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Ordered a Motive Gear Master rebuild kit along with a Spartan Locker. Ran into two problems, one my fault, one not. Turns out I ordered the locker for a Dana 30 rather than the AMC M-20. So I now have a locker to fit the front. Reordered the correct one for the rear so I'll have both axles locked. That'll be a first for me.

What I did was replace the pinion bearings and used the original shim thickness as a starting depth using new shims.

The AMC axle carrier has a minimum/starting shim of 0.080" per side. Both of the fat carrier shims in this axle were toast. It turns out the shim set in the Motive Gear kit was insufficient to actually shim it from scratch.  I called them up to tell them of this. They were completely cooperative on getting me an additional shim set but I needed to order it through a dealer. Called Summit Racing. No problem. Had it in two days at no cost.

Anyway, Carrier is installed with saddles bolted tight. Haven't done the carrier preload yet but it looks pretty good. 0.007-.008 backlash. I think the pattern is ok, showing centered on coast side and a bias toward the toe on the drive. From what I have read that is normal for a used gear set. What do you think?

Time to set the carrier shim preload and If everything look good it'll be back together this weekend, just in time for the 4th.

Very happy with these vendors; Fast shipping and good communication from both of them.

Summit Racing - Motive Gears Master kit

Completeoffroad.com - Spartan Lockers

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Ok, got the dif all back together. The right axle is in and retainer plate torqued to spec. Interestingly the axle has about a 1/4" end play. I figured that might go away with the left side installed. Left side bearing and seal in and it also has about a 1/4" end play. Both bearing races are flush with the axle flanges. It now has the Spartan locker replacing the spider & side gears. Their instructions did not call for the OE axle spacer block to be reinstalled. I am thinking perhaps it should be, assuming there is enough space to do so. Time to take it back apart.

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If side movement is zero (preloaded or not) and the pattern is what you describe, the pinion gear is either too deep or normal wear is accounting for the pattern.  Doesn't sound serious as long as the pattern is close to the same tooth alignment as before the teardown.  

You could try raising/shimming the pinion height slightly if you're still in trial bearing mode and don't have to press or drive out the pinion.  Otherwise, recheck the pattern after full set up, before installing the axle shafts, and check the tooth pattern again.  Create some drag on the pinion to get an accurate tooth contact pattern.

What torque setting did you use on the ring gear bolts?  Was the gear runout within normal range (less than 0.002")?

Glad you've commented about the vendors, very helpful to others!

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The pinion & carrier is installed. Carrier preloaded @ .008. This was set after setting the backlash. Reconfirmed backlash @ .008 ' after final setup. The pattern looks good, the backlash is in spec. The torque spec on the ring bolts is 105 ft/lb. I set them at 90-95 ft/lb along with red locktite. Ring gear run-out is .001 - .0015 so within spec.

The axle side movement is the current issue.I am hoping that spacer block is the solution. 

Edited by Rinky Dink
clarity

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Sorry you've run into axle shaft end play and added work!  On the stock arrangement, the spacer or "thrust block" helps determine and limit the axle shaft end play.  The Spartan Locker uses the stock Model 20 differential cross pin, which is designed to accept a thrust block.  You do need the thrust block between the axle shaft inner ends.  This keeps the axle shafts from moving inward to the cross pin.  If left out, the missing thrust block is likely the end float you have at each side of the axle. 

Let us know... 

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I had read on some on-line commentary that the spartan instructions left something to be desired. I'll be sure to send them a note on the matter.

The locker kit came with a new cross pin.

 

 

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Aside from the axle shaft end play, your axle/differential setup sounds correct and thorough, Rinky Dink...Spartan apparently expects you to use the original axle thrust block/spacer with the new cross pin.  

Worst case scenario, you remove the bearing caps and carrier/ring gear without upsetting the carrier preload shim arrangement.  With the carrier out on your bench, you can disassemble the differential enough to install the thrust block on the cross pin.  Reassembly should produce the same tooth pattern and carrier bearing preload once installed.

Here's some additional info I just posted at the axle seal question in reply to your comment about the retainer plate/seal orientation:

Correct, Rinky Dink.  On an AMC Model 20 Jeep CJ rear axle shaft outer seal, the raised shoulder of the plate/seal faces outward from the brake backing plate.  The spring end of the seal faces inward toward the axle center.  In the July 10, 2014 reply above, the upper photo is the raised shoulder side that faces outward.   A retainer plate/seal fits outboard of the brake backing plate at each side of the rear axle.

The axle shaft end float shims go between the axle housing flange and the brake backing/support plate.  Shims go at the left side of the axle housing only.  The differential thrust block floats between the inner ends of the two axle shafts and helps establish the axle shaft end play measurement.  Again, the retainer/seal plates fit outside the brake backing plates.

If you're using stock axle shafts and OE hubs, be sure to install the axle shaft nuts securely, to a minimum of 250 ft-lbs then completed by meeting the proper axle shaft thread stick-out length. Most loose rear hubs begin with an under-torqued nut.  Correct thread stickout length may require significant torque beyond 250 ft-lbs.

Note:  I cover this procedure in my CJ rebuilder's manual, and if not torqued to specification, the hub will loosen on the axle shaft—even more likely with oversized tires.  Jeep actually suggests replacing the hub with a new one if you separate the hub from the axle shaft.  This is the reason many owners go to a one-piece aftermarket axle shaft set.  However, if done safely and correctly, installed in exactly the original position, an intact original hub can be reinstalled successfully on the axle shaft. 

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I ended up removing the axles (& bearing races) in order to pull the locker and install the axle spacer block. I was able to do this without pulling the carrier. The axles had to clear splined plates of the locker. Had to remove the entire locker in order to fit the spacer block within it. A few hours later I have it all buttoned up. Axle end play set to .005." So far the axle has about 10 miles on it. Nice & quiet. Really no sound at all.  Locker is very evident, clacking quite loudly in tight radius turns, the inner wheel chirps & scrubs coming out of corners on the throttle.  Went and jacked the axle off the ground and checked the shimming. As I expected, it feels to have loosened a bit so I'll be revisiting the left hub soon just to tighten it a bit.

Thanks for the feedback on this project.

Next up: Dana 300  & T-176 Rebuild. Let the fun begin!

Edited by Rinky Dink
typo

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Yea, Rinky Dink!  Job well done...great that the tooth pattern worked, a quiet and fully functional Model 20 AMC rear axle!  On the axle shaft end play, Jeep recommends tapping the axles shafts at each side with a "lead hammer" (translates as a plastic sand-filled dead blow type hammer these days).  This seats the bearing races outward and gives a more accurate read on actual shaft end play.  You understand the premise, it's all fresh in your mind now.

The Dana 300 and T176 should go well...you're warmed up and in the swing of it...

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