Help with Gear Install

[swflastang05]

I'm in the process of switching from 4.10's to 3.73's, got everything switched over using the old pinion shim which was .012, set the proper pinion preload at 20 inch lbs, installed the spool and ring gear and set the backlash at .008 - .010, it varies by the .002 depending on the gear position, according to the FRPP manual that go vary by up to .004 so that should be okay hopefully. Anyway I got to the part where you check the tooth pattern and I'm not sure about the results, thought I would post some pics and solicit some feedback, my concern is the contact pattern covers the entire tooth, there's little to no space around any of the edges, the coast side seems to have a little space but there's nothing on the drive side, what do you think?

I'm concerned maybe I need a thicker pinion shim? The rear end in my car has always been noisy, maybe this is why?






Or does this look okay?

 

[drive_55_not]

Tthe pinion depth is too deep, riding high on the tooth.

Since you're running a spool I'll presume it isn't a DD and you could try tightning up the backlash by putting a thicker shim on the driver side of the carrier moving the ring gear over and see if that moves the pinion further down on the tooth.

Good luck I know setting gears up suxs ..


.

 

[swflastang05]

Tthe pinion depth is too deep, riding high on the tooth.

Since you're running a spool I'll presume it isn't a DD and you could try tightning up the backlash by putting a thicker shim on the driver side of the carrier moving the ring gear over and see if that moves the pinion further down on the tooth.

Good luck I know setting gears up suxs ..


.

No, it's not a DD, just a street / strip weekend cruiser. I tried some new marking compound, the compound in the first pics is old and kind of dried up, you can see the pattern better now, do you still think the pinion is too deep?

 

[swflastang05]

Okay after staring at it for a while I took everything apart again and found the pinion shim was .024, I swapped it out for a .020 shim, reinstalled everything and checked the pattern again, I tightened the backlash as much as possible so it's now .008 and this is the pattern I have now, I think I may still need a thinner pinion shim? If so I don't have any thinner than .020 though, where do you get more of those, just order an install kit and hope one comes with it?

 

[drive_55_not]

To help bring the pattern out you can wrap a ratcheting tie down around the carrier and pumpkin bushing and get it as tight as you can to put pressue on the ring gear ... then spin the pinion several times to help smooth out the compound so you can see how it looks on all the teeth.

If you can try that see what it looks like. At your power level you wanna get as much tooth mesh as you can.



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[swflastang05]

To help bring the pattern out you can wrap a ratcheting tie down around the carrier and pumpkin bushing and get it as tight as you can to put pressue on the ring gear ... then spin the pinion several times to help smooth out the compound so you can see how it looks on all the teeth.

If you can try that see what it looks like. At your power level you wanna get as much tooth mesh as you can.

I've been leaning on it with a large pry bar as it turn the pinion but the pattern still isn't coming out that great, I'll give the tie down method a try also. I did find more shims from an old install kit with several thinner shims, I tried a few out going all the way down to .010 and it definitely got worse, the drive side just barely touches now so I know I'll have to go back up to a thicker shim.

 

[swflastang05]

Okay well over the past couple days I've tried just about every possible combination there is with Pinion shims ranging from .010 - .030 and everything in between in about .004 increments along with various back lash settings and as my luck would have it the shim I started with turned out to be the best! Pinion shim .023 with backlash set at .009-.010, slightly looser than I originally started with, here's the result:





This is as good as this rear ends' gonna get! Now I just need to install (when they arrive) the new bearings, seal, etc. and put everything back together for the final time, hopefully.

 

[lenko]

Pinion could be a touch deeper into the ring gear to have the contact appear as an oval. Right now it's a little boat shaped. It's close, but an oval would be better. Put a little gear oil in the marking paste and stir it in to show a better pattern. Here's what I got on my 410s. 373s are a little harder to do.

SUC53576.jpg

 

[swflastang05]

IDK, I tried a shim .005 thicker (.023 to .028) and it moved the drive side imprint out toward the heel and the coast side toward the toe, the .023 is by far the best pattern I could get, the rear end housing in my car probably has an issue from when it was originally machined, since every set of gears that's been in it have kicked the installers ass! I decided to take a stab at it myself this time, so I know every effort was exhausted to get it right. Maybe if I can find something b/w .023 - .028 I might try it one last time but failing that this will be it, thanks for the recommendation though,

 

[lenko]

Tthe pinion depth is too deep, riding high on the tooth.

Since you're running a spool I'll presume it isn't a DD and you could try tightning up the backlash by putting a thicker shim on the driver side of the carrier moving the ring gear over and see if that moves the pinion further down on the tooth.

Good luck I know setting gears up suxs ..




.

Then I would try his recommendation, but very tiny increases on the driver's side and same reduction on the passenger which should put the ring gear in a little deeper.

 

[swflastang05]

Well I installed the new permanent bearings last night, got everything set up and tested the tooth pattern and it was way off! drive side moved toward the toe and coast side toward the heel, looks like I'll be installing a thicker shim after all. This thing is fighting me to the end! The only thing I can think of is maybe the old bearing I'm using as a set up bearing got messed up when I pressed it off the old pinion gear, I triple checked the new races are installed correctly, nothing else is different. My luck strikes again!