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Unread 07-10-2008, 05:58 PM   #16
bdmonist
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OK - Got back in town today and had a little package at the door - shims came in. I was very happy with the number of shims that Ratech provided, but the thicknesses were "interesting". No real rhyme or reason that I could tell. Thicknesses like .011, .015, .017, .020, etc. Anyway, I think it'll work. Spread the shims out and mic'd them all to get the thicknesses, AGAIN.


So, went back out to the garage for trial 5.
Pinion Shim = .100
RGCS = .051
NRGCS = .127




Once I got the carrier in, I installed the bearing caps and bolts finger tight. Checked backlash
Backlash = .018.
So, I still need to move the carrier closer to the pinion, i.e - add more shims on the Ring gear side (and remove the same thickness from the Non Ring Gear side)

Trial 6
PS = .100
RGCS = .066
NRGCS = .112
And the backlash is.......


.007, within spec so we are off to checking gear patterns.

I put some of the gear marking compound that came with the setup kit, yellow, onto the ring gear. You want to put it on the coast and drive side and cover three to four teeth. I did it in two places just to be sure.


Not sure that I used enough, we'll see.

When you check your pattern, you want there to be a slight load between on the pinion/ring gear. I used a towel wrapped around the pinion and held it with one hand to apply a load and turned the ring gear with my other hand. If you have some help, get your buddy to apply some pressure on the ring gear and turn the pinion with your beam torque wrench. You want at least 40 ft-lbs or so load so you get a good reading. My brother in law was MIA, so I was on my own.
Here are the patterns I got.




Now from my amature readings - The Drive side contact is a little toward the heel and the top.
Coast Side - Reading is toward the toe and there is top contact.

Now - If your reading is toward the top then the pinion is too far and should be moved closer to the ring gear. Add shims between the inner race and housing. If it was toward the root (base of the gear), then you would move the pinion away from the ring gear.

On the Drive Side - Heel(outer side of ring gear) contact would mean you have too much backlash and the ring gear should move toward the pinion, toe contact(inner side of ring gear) would mean I need to move the ring gear away from the pinion to increase backlash. Now since I measured backlash and know I am in spec, AND I did not have heel or toe contact, I think I'm OK on my ring gear shims.

Coast side is opposite - Toward the toe you move the ring gear toward the pinion to decrease backlash, toward the heel you increase backlash by moving the ring gear away from the pinion.

SOOO - from my reading - I will leave the backlash as is and move the pinion closer to the ring gear by .010.

Experts - Please review and let me know if my readings are correct or way off. I'll be adding shims while you review.

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1984 CJ 7, SBC 350TBI, 700R4, D 300, AMC 20, D30, 35" Mickeys, 3.54 Gears, 4" susp. Lift, 2" body lift.

AMC 20 Write Up
In Progress - 4.56 gears, Aussie Rear Locker, Moser 1 Piece Axles
Coming Soon - CV Shafts, Welded Tubes, trusses

Last edited by bdmonist; 08-13-2008 at 06:38 PM..
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Unread 07-10-2008, 06:13 PM   #17
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Your pinion needs a thicker shim maybe about .006 from looking at your last pic. Keep your back lash where it is 007-.008. Maintain this back lash until you get good pinion depth meaning centered face/flank wise.

Don't use too much marking compound. I usually thin it down some with a couple drops of gun oil. Apply it thin but evenly. When I take my patterns I roll the ring gear agains the pinion about 3 times. I usually have my pinion preloaded about 15 in lbs or so. That way you have some pressure between the gears when you take a pattern.
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Unread 07-10-2008, 07:07 PM   #18
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Went up to .105 on Pinion Depth Shims and kept Carrier shims the same. Preloaded the pinion to 12 in-lbs, backlash went up to .009???? POS Centec indicator maybe - Don't know. The pattern doesn't seem to have changed much. Still need to go closer to the ring gear. I'm thinking .115 for next try.



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1984 CJ 7, SBC 350TBI, 700R4, D 300, AMC 20, D30, 35" Mickeys, 3.54 Gears, 4" susp. Lift, 2" body lift.

AMC 20 Write Up
In Progress - 4.56 gears, Aussie Rear Locker, Moser 1 Piece Axles
Coming Soon - CV Shafts, Welded Tubes, trusses
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Unread 07-10-2008, 07:56 PM   #19
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Trial 8
PS = .115 - Preload = 10 in-lbs
RGCS = .066
NRGCS = .112
Backlash = .004
I just left backlash as is even though it was low. I assume it went down since I was moving the pinion into the ring gear.

Readings - To me the top to root looks good, may still need to come a little closer with the pinion. Let me know what you think.

My question is this - My backlash is too small, but it looks almost perfect to me from heel to toe, which indicates backlash - So what reading do I go by, dial indicator or pattern.










I'm done for the night so I can get some opinions from you Gear Gods out there Let's hear it.
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1984 CJ 7, SBC 350TBI, 700R4, D 300, AMC 20, D30, 35" Mickeys, 3.54 Gears, 4" susp. Lift, 2" body lift.

AMC 20 Write Up
In Progress - 4.56 gears, Aussie Rear Locker, Moser 1 Piece Axles
Coming Soon - CV Shafts, Welded Tubes, trusses

Last edited by bdmonist; 07-11-2008 at 02:38 PM..
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Unread 07-11-2008, 12:57 AM   #20
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Looks like you about got it. AMC 20's seem to like about .008 -.009 backlash so see what happens with that adjustment.
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Unread 07-11-2008, 11:51 AM   #21
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Great job on the write up! I am getting ready to do this here pretty quik and this should help alot!! Again great job.
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Unread 07-11-2008, 02:34 PM   #22
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Trial 9

OK - Moved the carrier 5 thou away from the pinion to increase backlash.
PS = .115
RGCS - .061
NRGCS - .116

Backlash was .0085 - So I'm good there. Let's look at the pattern








I think it's a little toward the top, so I'm thinking I may add 5 thou to the pinion stack to move it a little closer. OR just I leave it alone????? - What do you think?
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1984 CJ 7, SBC 350TBI, 700R4, D 300, AMC 20, D30, 35" Mickeys, 3.54 Gears, 4" susp. Lift, 2" body lift.

AMC 20 Write Up
In Progress - 4.56 gears, Aussie Rear Locker, Moser 1 Piece Axles
Coming Soon - CV Shafts, Welded Tubes, trusses

Last edited by bdmonist; 07-11-2008 at 02:45 PM..
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Unread 07-11-2008, 02:46 PM   #23
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I think if you went down about .007" in backlash, you should be OK. Looks like you're good with pinion depth, though.
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Unread 07-11-2008, 02:51 PM   #24
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Quote:
Originally Posted by 80cj View Post
I think if you went down about .007" in backlash, you should be OK. Looks like you're good with pinion depth, though.
Is there something in the pattern you're seeing that's telling you that?
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AMC 20 Write Up
In Progress - 4.56 gears, Aussie Rear Locker, Moser 1 Piece Axles
Coming Soon - CV Shafts, Welded Tubes, trusses
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Unread 07-11-2008, 02:55 PM   #25
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You have some of the pattern favoring the heel. closing the backlash a little will bring it toward the toe a little. Having the pattern centered or favoring the toe slightly is ideal but not always attainable. I think it is in you case.
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Unread 07-11-2008, 03:17 PM   #26
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Quote:
Originally Posted by 80cj View Post
You have some of the pattern favoring the heel. closing the backlash a little will bring it toward the toe a little. Having the pattern centered or favoring the toe slightly is ideal but not always attainable. I think it is in you case.
With where I am top to root, would it better to close the backlash by increasing the pinion shim. moving the pinion closer, since I am a hair toward the top - or should I just move the carrier 2 thousandths or so?
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AMC 20 Write Up
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Unread 07-11-2008, 03:26 PM   #27
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Quote:
Originally Posted by bdmonist View Post
With where I am top to root, would it better to close the backlash by increasing the pinion shim. moving the pinion closer, since I am a hair toward the top - or should I just move the carrier 2 thousandths or so?
From looking at your pics it looks like you're pretty good face/flank wise unless the camera angle doesn't exactly show what you see physically looking at it. Try closing the backlash a little and see what the effect is.

Edit: That is, move the carrier to the right a little to close backlash.

Last edited by 80cj; 07-11-2008 at 04:25 PM..
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Unread 07-11-2008, 05:15 PM   #28
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Trial 10

PS = .115
RGCS = .063
NRGCS = .116
Backlash -.0065 -.007

Heel to toe was about the same, maybe a little movement. Still a hair toward the top on the coast side, but the drive side looks good. All opinions welcome.




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AMC 20 Write Up
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Coming Soon - CV Shafts, Welded Tubes, trusses
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Unread 07-11-2008, 10:27 PM   #29
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Quote:
Originally Posted by bdmonist View Post
PS = .115
RGCS = .063
NRGCS = .116
Backlash -.0065 -.007

Heel to toe was about the same, maybe a little movement. Still a hair toward the top on the coast side, but the drive side looks good. All opinions welcome.




That's great. More important than the heel to toe is that you have very good pinion depth. You should have a nice quiet running gear set. Follow the manufactuer's break in procedure and after 500 miles or so, change the oil. You'll see that the pattern will spread out and pretty much have full gear tooth mesh.
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Unread 07-11-2008, 11:31 PM   #30
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Here are some pics I took of my AMC 20 gears about 5 years ago when I went from 3.54's to 4.10's. I did a small final pinion depth adjustment after this shot. Can't remember if I took a shot of the final result. Gears run nice and quiet.



This is the best heel to toe position I could get. This is a set of Precision gears.


This is a shot of the drive side of the ring gear at about a 300 mile oil change. Notice how nicely the pattern has spread out over the gear teeth.



This is the coast side.

Last edited by 80cj; 07-11-2008 at 11:45 PM..
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