Pinion Gear Pattern

[wiseman]

Just installed a Detroit Truetrac unit,all new bearings and races (including pinion bearings and races) and reused my original 3:42 gears. I know adjustments are needed, and its a bear to constantly remove the carrier (have done it twice already).
The pattern was taken with axles and drive shaft installed, but no wheels or tires, and no load on the suspension (just installed a rear disc conversion kit, and waiting for an adapter so that i can attach the cables). Backlash is set @ .008

Picture 1 - Drive Side
Picture 2 - Coast Side
Picture 3 - Pinion

 

[wiseman]

As a reference, here is my original pattern of my stock differential before the uninstall

Picture 1 - Drive Side (original setup)
Picture 2 - Coast Side (original setup)

 

[No disintegrations]

https://w05.dealerconnect.chrysler.com/service/mds2002/serviceInfo/en_US/80d04e58.gif

I'd say you need a thinner pinion depth shim as this handy chart indicates. (Pinion closer to transmission) The oe shims are under the pinion bearing as a starting point? Make sure you're not contacting the tooth "peeks" some of the compound was wiped off , not sure the gears did it or just happened to look that way.

 

[wiseman]

I have only the factory shim installed between the pinion gear and inner ponion bearing. I believe it was like .025 or .035. When decreasing the shim thickness, should in .001 or .005 increments as a rule of thumb?

(I cleaned the other teeth to see the pattern better)

 

[wiseman]

https://w05.dealerconnect.chrysler.com/service/mds2002/serviceInfo/en_US/80d04e58.gif

I'd say you need a thinner pinion depth shim as this handy chart indicates. (Pinion closer to transmission) The oe shims are under the pinion bearing as a starting point? Make sure you're not contacting the tooth "peeks" some of the compound was wiped off , not sure the gears did it or just happened to look that way.

From the link, the bottom picture is what you are referring to, right? Is it saying to adjust the pinion depth "and" decrease backlash. Or is it saying , by changing the pinion depth, it will decrease the backlash....(not sure if i am interpretating it correctly)

 

[No disintegrations]

From the link, the bottom picture is what you are referring to, right? Is it saying to adjust the pinion depth "and" decrease backlash. Or is it saying , by changing the pinion depth, it will decrease the backlash....(not sure if i am interpretating it correctly)

No I was thinking of the second one down. To me you look centered ok but low on the drive and high on the coast. low meaning near the center and high meaning near the outer rim. I think you only have to work on the pinion shim. Oh and i'd try taking out quite a bit. maybe .025 and check. Could be more though.

 

[pacecarta]

make sure you crushed the pinion sleeve and seated the pinion bearings to the race
agree it look like pinion is too tall and you will have to redo side shims for backlash after the pinion height is changed
dropping pinion will require more shim to the ring gear side bearing pack ( driverside) to get the backlash back to spec

 

[wiseman]

No I was thinking of the second one down. To me you look centered ok but low on the drive and high on the coast. low meaning near the center and high meaning near the outer rim. I think you only have to work on the pinion shim. Oh and i'd try taking out quite a bit. maybe .025 and check. Could be more though.

Ok, thanks.....it does look like the second one. Ok, I will make adjustments tomorrow. Hopefully I can get a shim kit from the local parts store for the pinion. I have shims for the carrier, but not the pinion, unfortunately. I will report back my results, thanks

 

[pacecarta]

looking at your coast and drive patterns it looks like the pinion is moving
reuing the original pinion and ring gear with the factory installed pinion shim is all you shoud have had to do , it looks like it moved up and that could only be that the lrg pinion brg isn't seated , the race isn't seated or the crush collar hasn't been crushed and you dont have proper preload keeping the pinion centered
verify the pinion is correctly preloaded (a new crush collar can take up to 300ft lbs to start the crush ) before you do anything

 

[wiseman]

make sure you crushed the pinion sleeve and seated the pinion bearings to the race
agree it look like pinion is too tall and you will have to redo side shims for backlash after the pinion height is changed
dropping pinion will require more shim to the ring gear side bearing pack ( driverside) to get the backlash back to spec

I didn't use a crush sleeve, I used a Ratech spacer kit in place of another crush sleeve to make things easier for me

 

[fastblackracing]

Make sure that you use loctite on that pinion nut once you are done seating the races and changing pinion shims.
I have seen a number of them back off once the car is driven a while and some loctite will stop a potential issue.

I agree with pacecarta on this putting the new bearings on should not have moved the depth very much If any.
Bad foreign country bearing quality?

 

[No disintegrations]

Make sure that you use loctite on that pinion nut once you are done seating the races and changing pinion shims.
I have seen a number of them back off once the car is driven a while and some loctite will stop a potential issue.

I agree with pacecarta on this putting the new bearings on should not have moved the depth very much If any.
Bad foreign country bearing quality?

I agree with both of you on this also. Pacecarta said to double check the bearing race is seated in the axle housing. Just bearings seems odd to cause this much variation.

 

[wiseman]

looking at your coast and drive patterns it looks like the pinion is moving
reuing the original pinion and ring gear with the factory installed pinion shim is all you shoud have had to do , it looks like it moved up and that could only be that the lrg pinion brg isn't seated , the race isn't seated or the crush collar hasn't been crushed and you dont have proper preload keeping the pinion centered
verify the pinion is correctly preloaded (a new crush collar can take up to 300ft lbs to start the crush ) before you do anything

I rechecked the preload and i was at exactly 25ft lbs. I double checked the races and they were seated prefectly amd The pinion had no play

 

[wiseman]

The factory shim was .035in. I replaced it with a thinner .025in shim and here is what i got with .009in. Backlash, axles in, and parking brake applied

Picture 1: Drive Side
Picture 2: Coast Side

 

[No disintegrations]

I'd say that was too much. Looks like the .030 will be perfect. My guess sucked what can I say. You're getting it done though.

 

[fastblackracing]

The factory shim was .035in. I replaced it with a thinner .025in shim and here is what i got with .009in. Backlash, axles in, and parking brake applied

Picture 1: Drive Side
Picture 2: Coast Side

Looks like .030 shim and tighten up the backlash a bit will be good.

The dimensions on the bearing height...from the face of the tapered rollers to the shoulder that gets seated against
the pinion gear had to be off. What brand bearing is it so I know to stay away?

And good job on the extra work and follow thru to make it as good as possible, A lot of guys would not put the extra effort in.

 

[wiseman]

I'd say that was too much. Looks like the .030 will be perfect. My guess sucked what can I say. You're getting it done though.

No worries, you definitely helped me out alot with your advice.

I just finished changing the .025 to a .030 shim stack up. Here is what i got now with .009in. backlash, axles in, a load on the suspension, about 23 in lbs of preload, and caps torqued to 55 ft lbs.

Picture 1: Drive Side
Picture 2: Coast Side

 

[wiseman]

Looks like .030 shim and tighten up the backlash a bit will be good.

The dimensions on the bearing height...from the face of the tapered rollers to the shoulder that gets seated against
the pinion gear had to be off. What brand bearing is it so I know to stay away?

And good job on the extra work and follow thru to make it as good as possible, A lot of guys would not put the extra effort in.

I am using all timken bearings and races. The the gears are all stock 3:42.

I will tighten up the backlash to see if that will help me out just a tad bit more. I dont think i can get too much more better than this, been working since early this morning on this.

I am thinking adding about .005 to the ring side, and removing .005 from the other side......?

 

[fastblackracing]

I am using all timken bearings and races. The the gears are all stock 3:42.

I will tighten up the backlash to see if that will help me out just a tad bit more. I dont think i can get too much more better than this, been working since early this morning on this.

I am thinking adding about .005 to the ring side, and removing .005 from the other side......?

Looks much better. usually you have to take .002 of side shim out to change back lash by .001. .005 swap will probably make it as good as u can get.

 

[wiseman]

Looks much better. usually you have to take .002 of side shim out to change back lash by .001. .005 swap will probably make it as good as u can get.

I finally finished last night at around 12, and here is what pattern that i got.

Picture 1: Drive Side
Picture 2: Coast Side

I think its right on the money on thw drive side, and coast side is ok.....what are your thoughts?