I'm changing out my gears in my IROC. I have never built a rearend before. The car is strickly for dragging. Am i gonna be able to adjust the gears by trial and error. i dont have a dial indicator and not sure i would know how to use it if i had it. I have read that the stock pinion shim can be reused and usually is the correct thickness. does this apply if you are using bigger gears? Is there a simple way to get a proper backlash by visual adjusting? i have also read that you use the marking compound and spin it a few times to see if it has the correct pattern. what kind of pattern am i looking for? Is it ok to reuse the crush sleeve? any help would be appreciated. sick

 

The FSM has a 30 page section on setting up the differential. You may want to try the local library and check on the Mitchell service manuals. Not as detailed as the FSM but better than a Haynes manual.

 

The stock shim pack is for the same gear ratio. Your chances of setting up a new gear set is in my opinion is Slim to None. I would get someone with experience setting gears to give you a hand & help. Or your first run done the strip will be the last for your new gear set.

 

Setting up a rear end is mostly trial and error, if it's a 7.5 inch 10 bolt they're not to bad. Who's gears are you using? I have been able to get a good pattern with the stock pinion shim, but going to 4.11 I doubt it very much, you have to check the pinion gear for a eched number indicating the checking distance +/- a few thousandths, Spicer eches these measuerments on the bottom of the pinion gear. The shims you take out will not set up with the new gears, they are tailored for the 3.23's. you will need a master overhaul kit, We use Precision Gears kits, they come with all new bearings, shims, crush sleeve, pinion seal, nut, paint, loctight,and a gaskett that you dont use, silicon(black RTV) is better. You NEED a dial indicator. You want .007 to .008 backlash for new gears. Ideal pattern is a broad contact patch centered in the middle of the drive side of the tooth, coast side should be about the same. There's two types of gears; 2 cut and 5 cut. 2 cut have a tooth that is the same depth across the whole tooth. 5 cut have a tooth that tappers towards the inside of the tooth. Know what you have b/c they both throw different patterns. get as close as you can to ideal contact. DO NOT REUSE ANY OLD BEARINGS OR THE CRUSH SLEEVE YOU WILL REGRET IT! DO IT RIGHT ONCE, OR RED NECK IT FIVE TIMES. watch your bearing preload, pinion preload is between 15 to 18 inlbs. on a torquemeter not a torquewrench, carrier preoad about 18-20 inlbs. a faily snug fit in the housing that may require the use of a deadblow hammer to seat the carrierin the housing. I have fixed alot of first timer mistakes, it's usualy pretty costly, just pay attention, watch what the gears are doing as you make adjustments, and take your time. Good luck