homemade87

I have been struggling with a gear set I have . So I think it time to ask for help. I have a new gm8.5 gear set . I think it is a motive . I got it from a friend with no box . It has gm10-373 on it . I cant seem the get the sweet spot on this set . As you can see in the pictures the drive side is to the toe and I cant seem to get it to move to the center. The coast side is not to bad but does not look exactly right . Right now I am at a .039 pinion shim w/ .009 B/L . I would like to here what you think and what I may need to do at this point.

homemade87

Pictures did not load , Here they are

FirstYrLS1Z

iTrader: (4)

from a GM manual

01ssreda4

iTrader: (96)

Whats the spec supposed to be on the backlash? I like to run tighter then 9. I usually shoot for 6/7. Motive part number should be GM85373 or G885373. I don't think thats a motive.

homemade87

The gear has nothing on it stating backlash. So I am guessing .007 to .009. Heres what I am going by on the brand. http://www.summitracing.com/parts/mg...FQ_l7AodjzAAbg

I will adjust it to 6 or 7 and see what happens . This gear set is giving patterns different from what I have seen. I thought to move the drive pattern from toe to heal you added to the pinion shim. I have not tried to go the other way below .033. I may try a .031 and see what happens. I will post the results. This may help some of you with the pattern diagnosis .

01ssreda4

iTrader: (96)

Honestly, Ive found with a 6/7 backlash my patterns need very little work. I would add some shims to tighten down to 6/7 and rerun the pattern.

01ssreda4

iTrader: (96)

http://www2.dana.com/pdf/R-P%20TOOTH%20PATTERNS.PDF

silverLSWON

iTrader: (16)

seems like people had better luck with 3:73 with a pinion shim .027 to .032 on gm rears

homemade87

I am going to update this thread for my gear set up as I hate it when a threads does not have a final follow up for the problem .

I set this gearset I had up 3 times and could not get a good read, reason I asked for help . I have done several 8.5 gm rear with not much problem . All 3 times I had gear noise 2 times coast only and one coast and drive. I was just moving it around trying to figure this gear set out with no luck. I gave up and ordered a 3.73 aam gear set and installed it . Had it installed in a few hours and dead quiet with a great pattern.

I think in the end I just had a bad gear set . Created lots of work trying to figure it out . The aam gear was the second I had installed and from now on I will not use anything but the aam gears . They do not cost that much more than the others .

I have read of people getting bad aftermarket gear sets . I guess it was my turn.

guppymech

iTrader: (7)

When I had a 10 bolt I used AAM 4.10 gears and they were quiet.