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post #1 of (permalink) Old 01-20-2001, 03:19 PM Thread Starter
 
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AMC20 gear set up help

im heading out the door to the local library to see if a shop manual is available.

But if any one has done this and could answer a few specific questions I would greatly appreciate it!

thanks!


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post #2 of (permalink) Old 01-20-2001, 05:16 PM
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Re: AMC20 gear set up help

Watcha need to know?

Brad
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Vice-Pres. Rock Garden 4 Wheelers, Farmington, NM
post #3 of (permalink) Old 01-20-2001, 06:12 PM Thread Starter
 
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Re: AMC20 gear set up help

can I set the pinion depth with junk bearings, then later switch to the good bearings?
are the bearings made to precise tolerances?
since Im having to beat the races in and out to get my pinion depth set, Im afraid Ill bang them up ( the good bearings)

Or should I use an empry cloth or something similar to make a test race to fit in and out of hte housiong really easily until I hit the correct depth?

also, is one bearing the depth, and the other the preload?
there is a large and a small bearing, which do the shims go under to set depth?

I had some other questions, but thats the most recent I can recall!

if you can help at all Id appreciate it, the library closed right befpore I got there, so I got no manual.

Im trying to get a service manual to answer these questions, but havent procured one yet that I can afford ( FREE)

thanks!


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post #4 of (permalink) Old 01-21-2001, 08:24 AM Thread Starter
 
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Re: AMC20 gear set up help

ok I partially answered my own question last night while pondering it.

let me verify this.

shimming behind the larger pinion bearing will decrease the pinion depth, shimmin the smaller bearing will increase, and pinion nut itself controls the preload.

am I on the right track?

also,should the large pinion bearing race be so tight?
Im really having to pound it in and out, can I smooth it up a little, use the old race with the new bearing on the pinion until I hit the target depth, then the final time pound the good race into the housing? will this change my depth? ( onviouslly Ill check it again to make sure)

also IM measuring the depth from a parrallel across the carrier bearing caps flat surface is this proper?

will a good quality 500 Ft/LB impact wrench tighten the pinion nut the last time when I install the crush sleeve ( I know Ill have to sneak up on it to keep the preload within spec, ive got 2 crush sleves just in case)

If I get to checking the pattern ( after setting the Backlash) and its off will it be a result of the inaccuracies of my pinion depth measuring?

any help?
I know its alot to ask, but im determined to figure this out.


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post #5 of (permalink) Old 01-21-2001, 08:41 AM
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Re: AMC20 gear set up help

Quote"OZARKJEEP"

ok I partially answered my own question last night while pondering it.

let me verify this.

shimming behind the larger pinion bearing will decrease the pinion depth, shimmin the smaller bearing will increase, and pinion nut itself controls the preload.
<font color=blue>You only place shims under the large pinion bearing race, the crush sleeve determines pre-load</font color=blue>

am I on the right track?
<font color=blue>Close...</font color=blue>
also,should the large pinion bearing race be so tight?
Im really having to pound it in and out, can I smooth it up a little, use the old race with the new bearing on the pinion until I hit the target depth, then the final time pound the good race into the housing? will this change my depth? ( onviouslly Ill check it again to make sure)
<font color=blue>Definitely shave down an old race(I used a grinder),it will work with the new bearing.</font color=blue>

also IM measuring the depth from a parrallel across the carrier bearing caps flat surface is this proper?
<font color=blue>I am not sure what you mean?, The pinion depth is determined by the gear pattern that you use marking compound to determine.</font color=blue>

will a good quality 500 Ft/LB impact wrench tighten the pinion nut the last time when I install the crush sleeve ( I know Ill have to sneak up on it to keep the preload within spec, ive got 2 crush sleves just in case)
<font color=blue>I really had a hard time getting the crush sleeve to actually crush. But once it starts to go it goes really fast, I had to buy an additional sleeve after screwing up the first one. Go SLOW!!!</font color=blue>

If I get to checking the pattern ( after setting the Backlash) and its off will it be a result of the inaccuracies of my pinion depth measuring?
<font color=blue>You need to use one of those gear pattern charts, it will tell you what to do depending on what your pattern looks like.</font color=blue>

any help?
<font color=blue>Check out my website, there is a write-up on the Model 20 and links to some other sites.</font color=blue>

I know its alot to ask, but im determined to figure this out.
<font color=blue>Good luck, let me know if you have any more questions.</font color=blue>

http://home.off-road.com/~tom85cj7/home.htm
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post #6 of (permalink) Old 01-21-2001, 09:10 AM Thread Starter
 
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Re: AMC20 gear set up help

Ive seen your site, its been a while, so I added to my list of references again.

I checked the specs from Unitrax? and they differ from teh specs Ive gotten from Randys.

ive been told the pinion depth is a the distance from teh end of the pinion to teh centerline of the axle ( and its really close from my testing my target is 2.562, right now its at 2.685 without the pinion nut tightened down)
so I can assume this is true, I just droppped it in, the race was probably not seated completely either as I was scared to beat on it much more.

so you are saying that its ok to use a grinder on teh race so it will fit easily, and then use that race in the final install? I can forsue like that idea. as long as its still tight enough not to wobble or spin.

also ive heard of having the carrier preload as tight as you can get it but never the backlash, in fact Randy's site mentions NOT to get it tighter than the specs?

I think im realizing why this is so hard! everyomne does it differently!

its a miracle than any diff has ever worked according to all of hte conflicting information ive seen.

from what you told me, I assume you checked the gear pattern first before setting the pinion depth? did you use the old shim pack to get a starting point?
how close was it with a new carrier?

thanks!


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post #7 of (permalink) Old 01-21-2001, 09:29 AM
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Re: AMC20 gear set up help

Okay,
You need to use an old race and grind it down so it will slip in and out easily. Use the old shims as a starting point. Measure your pinion depth and get it as close to your target as possible. Install the carrier using the original shims and check your pattern. Based on your pattern you will either have to move the pinion up or down, and/or move the carrier right or left. On my CJ the original shims were almost perfect, I made a slight adjustment and I was done. You don't have to have the pinion nut or carrier bolts installed to check the pattern.(just make sure gravity is holding them together) Once you have a good pattern, take everything apart, note the shims and there locations. Now install the new pinion bearing race on top of the necessary shims and hammer it all the way in. Install the outer pinion bearing and crush sleeve and set the pre-load. If you get the pre-load out of spec it will ruin your bearings.(I don't remember if you set pre-load before or after the carrier is installed) Put everything to gether as you noted and as a double-check do the pattern once again. If everything works out you should be able to install the cover and fill the case with oil.

Later,

Carrier pre-load as tight as you can get it.
Backlash within specs.
Pinion pre-load within specs.

Once you know all the terms and understand how all the parts go together and what the pattern should look like it becomes pretty easy. It took me a couple of days to do my Model 20 and only a couple of hours to do my Dana 30.

http://home.off-road.com/~tom85cj7/home.htm
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post #8 of (permalink) Old 01-21-2001, 09:36 AM Thread Starter
 
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Re: AMC20 gear set up help

thanks Tom,

thats pretty much wat I had envisioned, no big secret just has to be accurate.

Im on it buddy!

thanks again!


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post #9 of (permalink) Old 01-21-2001, 11:36 AM Thread Starter
 
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Re: AMC20 gear set up help

oops,. one more question

Ive been told the carrier shims ( for preload and backlash) go between the bearing races and the housing. thats good so I dont have to press the bearings on and off the carrier to adjust.

most exploded diagrams Ive seen of the amc20 diff show the shims between the bearing and the carrier?
does it actually make any difference where they go?

also does a dana 44 carrier use shims between carrier and bearing or bearing and housing?

thanks!


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