I’m stuck on differential rebuild.

[Ram06_1500]

i have a 2006 ram 1500 with 9.25 rear. Had stock 3:55 open gears. Spider gears chewed up so I decided to rebuild. I purchased everything at Moe’s performance. 4:10 gears with master rebuild and trutrac LSD.

I’ve never rebuild a differential and was aware of its intricacies but all shops were closed due to the pandemic. I followed the guide lines as far as factory specs. Should factory specs be called when upgrading to 4:10 gears from 3:55?
I was told by Moe’s that I should be able to get away with reusing shim. Which I did. I had the pinion depth set at 15in lbs with new crush sleeve. I’ve since tried backlashing the gears but cannot get it lower than .12. Factory calls for .05-.07. I’ve tried adjusting and any tighter it locks up. So I’m assuming pinion depth might be off. There’s really no where to turn to as far as setting pinion depth with my setup. I’ve tried YouTube but got nowhere. Can anyone shed any light and possibly help out?

 

[muddy12]

What does your marking compound look like?


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[Ram06_1500]

I didn’t attempt the marking compound seeing as how I could not get it below .12.

 

[muddy12]

Using marking compound will let you see your pinion depth, and will also show if you need to move shims around to move the dif left/right.
My guess, without seeing what the contact looks like, is that you may need to move some shims around to move the dif slightly to the right.
If that’s the case, doing so should also reduce your backlash.


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[Travelin Ram]

Existing shims are just a starting point, not likely to be correct for an all new set of gears and a new carrier.

 

[Karlsweg]

You are using the tool that slides in the axle tubes to adjust the carrier right to left and left to right? How are loosening one and tightening the other side to move the ring gear correct?

 

[smiley]

Since ring gear is thicker you will need to make adjustments. I am not certain how the shims work but I would think less shim will be needed due to the thicker ring gear. I haven’t done the job myself I always chicken out. My 09 had the rear open a lot. So did talk to mechanics a lot about it. If I were you I would ditch the crush sleeve and go to a washer setup like GM uses then things will be easier too.

 

[chri5k]

Here is a good primer on the steps to set pinion depth and backlash. Good chart showing proper marking compound traces. I usually set pinion depth first to get the trace centered between the heel and toe of ring gear teeth. Then adjust carrier left or right to get the trace centered between the root and top of the ring gear teeth with a bias towards the top. If it is too low (towards the root) you risk binding the gears when the diff heats up.

https://www.racingjunk.com/news/how-to-set-up-your-rear-gear-correctly/

 

[Ram06_1500]

Thank you for the replies. As far as pinion preload and black lash still the same as factory specs considers I’m installing aftermarket (bigger) gears?
I’ve loosened both side carrier adjusters while main bearing cap bolts are finger tight. I’ve adjusted driver side to the farthest and the lowest I got it to .12. Passenger side was loose. I then tightened it to snug. Torqued main caps and carrier locked(could not rock back and forth. I’d assume pinion may need more shims. As mentioned I contacted moe’s And they said they never had a problem reusing factory shim. Not saying that isn’t the problem, but that’s where I am at the moment. I supposed I can loosen and retry one more time and see marking. I do want to verify pinion depth. I believe the pinion depth is printed on the end of the pinion and I’d have to compensate for what the factory pinion was set at. Anyone have any idea what the factory pinion depth is?

I’ll factor all your opinions and thanks again. I just don’t want to junk parts(was a lot of money)

Lastly, the main bearing caps was marked but it looks to have come off and it did throw me off and which side goes where. Obviously you can see the indentation as far as what position caps are supposed to be, but can I just buy and install new main caps or do plastigauge?

 

[chri5k]

I worked in a Ford dealer many years ago doing driveline work. In the 50 or so diffs I rebuilt I think maybe 1 or 2 did not need different shims. This was using all OEM parts. The few aftermarket jobs I did for friends always needed different shims. I would use factory specs for backlash unless the gear vendor has a different recommendation. I would start at the middle or upper end of the factory range and go down from there if I get noise. Too tight will ruin the gears in a few miles of test driving. Too loose (within reason) won't hurt them for short test drives.

Definitely need to paint the gears to see how they are meshing. It is the only economical way of getting it right. I have seen people try to use measuring from the end of the pinion to the case sealing surface, length of pinion protruding from the front of the case and all manner of "substitutes" to simply painting them. None of those will work. Paint the the gears and read the pattern. Only way I know to get it right.

 

[Ram06_1500]

I’ve managed to take apart. I’m getting it more and more each day. Would anyone have an idea on the factory pinion depth? I tossed my old pinion. I’m trying to compensate with shims based on current pinion. Would anyone know what the top portion(97?) indicates?