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I just installed a set of motive 3.90 gears in my 2002 trans am. I got the pattern set up as shown and it whines at 60. its hard to tell if it whines on the coast or drive side, since its a cruising speed, but I think its mostly on the coast side. where should I go with this pattern? I have a .034" pinion shim, with .008" back lash.
10 bucks say nothing you do gets rid of the whine. Because if memory serves thats a set of orange box motives (they dont make blue box 390). They are just noisy.
I went thru the same thing with the orange box gears . They are just noisy . I tried several pinion positions and finally just set it up with a pinion tool to within .001 of spec . Still noisy but within spec .
My opinion on the pattern . The coast and drive side looks like it has a straight hard line at the bottom and a softer side on top . I would remove .002 or .003 from the shim and try a .009 b/l and see what it looks like .
Don't be surprised if you cant get rid of the noise .
I pulled the cover off tonight to check everything and found the backlash wash at .0095" and the rotating torque of the pinion with the carrier was 10 in-lbs. I didn't feel any play in the pinion, but I'm guessing it must have loosened slightly, since the rotating torque was so low. this might also explain why the whine on the coast side got louder after a few miles. here is the pattern as it sits.
I'll still add a few thousands to the pinion shim to try and remove the line at the bottom of the pattern.
To me the pattern still looks like you have to much pinion shim . Remove .003 from the shim and get the pinion torque close to 20 in lb since you have run the bearing already . After that move the back lash between 6 to 9 to see what that does for the pattern . Let us know how it looks .
here is the new pattern, after removing .004" from the pinion shim and setting the backlash to .007. there is still a slight flat spot on the bottom of the pattern, but I'm not sure if the pattern should come up anymore toward the crown of the tooth.
so I finally got everything put back together and went for a ride. There is still a slight whine at 60 but its barely noticeable above the radio. here are some pictures of the final set up. this is with a .030" pinion shim and .0085" backlash. I'll be happy as long as the whine doesn't get any worse...but a guess time will tell.
That pattern looks pretty good . More even top to bottom . If you only have a barely noticeable noise from the orange box motive you are better than most . I think you are good with that pattern . Also I think the torque arm magnifies any noise from the rear end . Sound like you are ok .
05-04-2015, 06:57 PM
pattern adjustment 
