I have a 3.42 rear with a worn out posi and i was wondering if i just changed the posi out, would I have to reset the gears, since everything is already set and im not changing to a new set of gears? Just tryin to figure out whether to go to a shop, or do it myself. I will have no prob doin it myself if I dont have to reshim the gears, but I will leave shimming the gears up to a shop.

 

When you change the posi you still have to double check the gear contact pattern and backlash. There is no need to change anything with the pinion gear. The reason is that not all posi's are machined the same and a very slight variation will cause the ring gear to be positioned differently. Because of these variations one must double check the gear contact and backlask.

 

Yes check it.

 

In most cases you can reinstall the original shims back in place and the contact patter and backlash will be perfect. Just make sure to keep the carrier bearing shims seperated so you know which ones go on each side of the case, same thing with the caps. You might aswell throw some lower gears on while you have it appart, that is if you have the proper equipment and the knowledge to press on the new pinion bearing and get the turning torque right. With new bearings you want to set the turning torque a little on the tight side to allow the bearings to wear and seat in properly About 20-25 in. lbs. of turning torque. With your old gears make sure your backlash is around .005-.008. With the new gears set it on the tight side .005. Also make sure you have a good contact pattern on the heal and toe side of the ring gear teeth, this is very important for strenght and avoiding that annoying high pitch whine down the highway. Take your time and double check your work, you can buy an installation kit that comes with all of your bearings and additional shims (if needed) to set it up correctly.

 

Thanks for all the input guys. Well I have 4.10s in my car right now, its an m6 and I hate them, They are great between 30 and about 100 mph, but under 30 all i do is spin, and after100 im runnin in 5th gear. I just want to go back to stock.