homemade87

I just installed a set of motive gears in a 12 bolt . I even emailed pictures to motive to have there engineer to confirm pattern because of past problems with aftermarket gears . (I have swore to only use aam gears but aam does not have 12 bolt gears .) Motive said it looked really good so I buttoned it up . Took for a short test drive and I have gear noise on all three , decel , cruise , drive . Take a look at the pictures and see what you think . These pictures is before I buttoned it up .

01ssreda4

iTrader: (96)

G8 is your problem! Look at the part number. That series of gear is noisy. Your pattern looks good, I'd say the noise is from no fault of your own. I had G8 373s in my 10 bolt and now G8 373s in my 12 bolt. Both make/made a little noise. All other rears Ive done have been very quiet....

homemade87

what other gears have you used . Not sure if I am going to live with this . May wind up sending them back and going another route . Its hard for me to accept gear noise . Especially when its a every aspect of driving on the street. I do know set up has everything to do with it but I took every step to get this set right . I would like to have a quiet set . There seems to be limited gears for the 12 bolt for a street car .

guppymech

iTrader: (7)

The pattern looks a little high to me, maybe try a thicker pinion shim.

homemade87

Funny you should say that . After studying on the coast side I do see a little moon shape at the bottom with a straight line at the top . I was going to take it apart anyway so I thought I would add a little to the shim to put it a little closer to the ring and reroll it and see what the pattern looks like .

01ssreda4

iTrader: (96)

That pattern would be dead nuts silent on a set of Motive GM- or AAM gears......The g8s are freakin noisy! If you get a dead silent set of orange box Motives I'd say go buy some scratch offs.

homemade87

I have used the blue box motives with great success . The aam,s are great but they do not have then for the 12 bolt rear,s . Choices are limited .

01ssreda4

iTrader: (96)

I have used the blue box Motives (part number GMxxxxx) with good success too, and they are what I recommend to people wanting to put gears in their 10 bolts...

67SS509

iTrader: (25)

That pattern is pretty close. The most I would do is add .002" more to the pinion shim. It's probably still going to make noise because the 3.73 is meshing more and looking at the pics that is a 5 axis tooth and not 2 axis like OEM.

Dan

iTrader: (1)

I bought my motive gears on eBay, I don't know if I got a mismatched set, they went bad at 1,400 miles. I now have Yukons, we will see how long they last.

homemade87

Ok, Heres an update , Sent some pictures to motive engineer and he's not sure why the pattern looks different after running it about a couple miles . He has recommended to remove .003 from the shim and see what the pattern does . The drive side has a tail down to the root which he indicates pinion to deep . These picture are the same set up as the first pics but after run a couple of light miles .

67SS509

iTrader: (25)

What are you setting the backlash at?

homemade87

B/L is at .006-1/2 to .007-1/2 . Gear set request .006. I plan on running a few more pattern checks adding shim and removing shim with some higher b/l numbers . This gear set seems to be giving some decent patterns but obviously not correct after the short drive.

Spartan7

iTrader: (7)

IIRC I've got some orange box Motives in mine and they're silent.

homemade87

Thanks for the info . Did you set them up by gear pattern only . I have not given up on it yet . I am in the process of getting a pinion depth tool to see where they are actually set at . The gear is not giving me a clear pattern .The first pattern looked good but the motive engineers has given me a recommendation after looking at the pattern that has a couple miles on it when I first had it together . With the pattern not clear I thought it a good idea to get a actual pinion depth to help with the set up and adjust from there and see what happens . Just waiting on tool now . I will post results when I have thing sorted out . I hope it will be good news .

gmorris

I just did a set of USGear 3.08's in my 12 bolt and they are silent. 12 bolt street gears are getting hard to find it seems.

mikesimpalass

I read once that reading the pattern on gears is really only useful on a new set of gears fresh out of the box. So trying to trouble shoot and re adjust your gear pattern is going to be really hard after you put some miles on. Just my 2 cents.

homemade87

You are correct . But with just 3 or 4 miles on them it would not change it much , but it will change it a little . 50 miles is a different story. Wanting to see what the pinion tool says. just waiting on it to get here.


gmorris , You are right about gears being limited for the 12 bolt .

Spartan7

iTrader: (7)

I wish I could help you, but my uncle who works at a Chrysler dealership did them for me. He did mention that he was able to get the gear pattern perfect by swapping the stock shims around, since the ones that came with the rebuild kit didn't work too well. Good luck getting yours quiet, there is hope lol.

homemade87

Ok , Heres an update . I finally got my pinion tool in ( T&D pinion tool ) and tore it back down . I checked the depth and found I was .005-1/2 too much shim from the marking on the pinion .Top of Pinion said 2.859 , I was at 2.864-1/2 . So I removed the .005-1/2 and the pinion tool put me right on the 2.859 . So I run a pattern check and it looked pretty good .To double check the pattern I removed .002 and run a pattern( too shallow) and added .002 and run a pattern . The .002 added produced the best pattern . Gear set backlash specs was .006 . I wound up with .006-1/2 .

I am sorry I dont have pictures . I forgot the camera . In the end The pinion tool was a great tool for people like me to give a solid starting point . Not everyone is great at reading patterns . It is definitely a art form . This gear set in my opinion gave a decent first set up pattern that looked run worthy , but turned out it was not . Even the motive engineers thought it looked good before I buttoned it up the first time . But the motive engineers did say remove .003 after the first test run when I sent them the after picture pattern. So they were pretty close to what I wound up with .

I have not run it yet because we just got a snow storm in north Alabama ( not too often we see snow in Alabama ) . So I don't know if there will be any gear noise at this point . In the end in my opinion this may be some of the reason some have so much trouble with the aftermarket gears . Pattern looks good but not close enough .

By the way , the T&D pinion tool was dead on with the moves I made and very accurate . I should have had one of these years ago . To those who are professionals you may see this tool a waste of time , but for people like me its going to be a asset to my tool collection .

I will post the results after the test run . Sorry for the long post but the snow has me stuck at the computer .