Thought I'd get sum input on this if you guys don't mind,First off done a 4.11 Motive gear change yesterday everything went together good,went from 3.23 to the 4.11 so I added 30 thousands of shim to the pinion gear,and set backlash at 10 thousands,painted the gear,run the pattern look real good,put good oil in added the additive,button up,took it for test run gotta little whine at accelerating,but it's gotta ringing like sound on decelerating,not bad but it's there,you guy's think the backlash might be to much?think I need to tighten'er up a bit?,And also the ABS light is on as well as the parking brake light,what the hell?...........thanks in advance....

 

.010" is a little much for your backlash. Did you check to see what size shim was on your old gear set (the shim under your pinion bearing)? It has been my experience that almost every time you just reuse the same size shim for the new gear set and it goes back just right. Your ABS light will stay on until you update your module for the new gear ratio. It is sensing the different rotation speed vs. your front wheels.

 

Well we were using an old dial indicator we first got 8 on the backlash then checked again and got 10,I'm gonna check it again with a new dial,But yea the factory shim on the pinion was 35 thousands, my bud that was helping me said he always added bout 10 thousands for every jump,but if I need to go back to factory shim I will,,,hoping sum more people thats done it will chim in..thanks Scott

 

Set new gears tighter than used gears. New gears should be set at 5-6 thou.

Also, check your pattern in regards to pinion depth.

 

your buddy is a fruit loop!!!!!! you use the stock shim, or atleast the same size shim. .005-.007 should be your backlash....

 

So let me get this completely clear ...your saying DO NOT shim up the pinion gear anymore than what came on the factory 3.23 pinion gear....so reuse the 35 thousands shim ONLY?

 

Do whatever you have to do to get backlash around 5-7 thou. 10 is too much.

 

Good luck im about to jump in to a rear end myself.

 

Had an 08 silvy rear apart today putting axle seals in it,so while we had it apart thought we'd check the backlash and it was 5 thousands,So tearing mine back down tommorrow and tightener up will share the results..........

 

OK....heres tha update shimmed it up,set at .005 on the backlash,now I got me a real 747 bitch is howling,the damn pattern looks good,so I don't know,bout ready to roll the 3.23 back in and say the hell with it,But I guess I'm gonna try onemore thing and that'll be take the 30 thousands of shim out of the pinion gear,and just leave the 35 thousands shim on that came on the factory pinion gear,if that don't change things **** it! I sure would like to know what everybody else has done on this pinion gear shim set up that has went from 3.23 to 4.11 on an 05 silvy,I guess theres probably more people paid to have it done than tackle it themselves so they really don't know,but I like doing my own ****,so just trying to figure it out.......thanks to everybody that has replied...