My 2012 used gear install
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JK Newbie
Joined: Jan 2012
Posts: 78
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From: Wolcott ct
My 2012 used gear install
Not certain if this is in the right forum, sorry in advanced if so 
.
Anyways, I know there were a few people concerned with installing used gears. This was my third used gear install. I don't see any issues in using used gears. As long as their inspected for pitting, chips, or any other types of abuse ,used gears are fine IMO. I usually look for gear sets that were factory installed also. Have to remember that most ring and pinions last the life time of the vehicle, unless its abused, in that case visual inspection will tell a lot. I set them up first with my old shims form the carrier and pinion, re shimming from there is usually minor differences. I've also noticed that honing out the old bearings for setup usually always throws off the backlash and pinion depth with new bearings, I like to use a good strong bearing splitter for pressing off the pinion bearing with out damaging it. For carrier bearing pre load I just make sure that i use the same amount of total shim thickness, for example I had .131 on the ring gear side and .128 on the non ring gears side from factory equaling a total of .259".
Reading the pattern on used gears is a little more difficult. I pay most of my attention to the coast side, the wear is less on coast. You will never get a perfect reading on used gears, so you have to have that in your head the whole time or you can drive yourself crazy trying to get a pattern that you would see on a new set. I try to get the pattern as centered as possible on the coast side, but i have noticed that every time I have been a little close to the toe end on used installs while staying with in spec. Its best being close to the toe instead of the heel because the gears move towards the heel while the vehicle is in motion. My first attempt I had a back lash of .006 and final was set at the end of spec at .008, which was what my factory ring and pinion was set at from the factory. Taking your time is the most important, its easy to get frustrated. I took my front drive shaft out so that i can do the rear one day and still be able to drive and do that front another day.
As far as many people saying used gears need to be installed exactly the same way they originally were, I would have to slightly disagree. If you know what the back lash and pinion depth was set at, that's great. I haven't found that to be the case, but i have found as long as you can get the pattern close to center as possible on the coast side and a little towards the top of the tooth while still be in spec you should be good.
These are my patterns, no noise from a couple mile road test. Pics aren't great i took them with my phone
Not claiming to be an expert by any means, this is just my experience on used gear installs for people who have been weary of it. $50.00 to $80.00 on used gears compared to 150.00 to 300.00 on new is a nice savings for us who are tight on cash.
Also thanks to Malan35 for the gear set.
. Anyways, I know there were a few people concerned with installing used gears. This was my third used gear install. I don't see any issues in using used gears. As long as their inspected for pitting, chips, or any other types of abuse ,used gears are fine IMO. I usually look for gear sets that were factory installed also. Have to remember that most ring and pinions last the life time of the vehicle, unless its abused, in that case visual inspection will tell a lot. I set them up first with my old shims form the carrier and pinion, re shimming from there is usually minor differences. I've also noticed that honing out the old bearings for setup usually always throws off the backlash and pinion depth with new bearings, I like to use a good strong bearing splitter for pressing off the pinion bearing with out damaging it. For carrier bearing pre load I just make sure that i use the same amount of total shim thickness, for example I had .131 on the ring gear side and .128 on the non ring gears side from factory equaling a total of .259".
Reading the pattern on used gears is a little more difficult. I pay most of my attention to the coast side, the wear is less on coast. You will never get a perfect reading on used gears, so you have to have that in your head the whole time or you can drive yourself crazy trying to get a pattern that you would see on a new set. I try to get the pattern as centered as possible on the coast side, but i have noticed that every time I have been a little close to the toe end on used installs while staying with in spec. Its best being close to the toe instead of the heel because the gears move towards the heel while the vehicle is in motion. My first attempt I had a back lash of .006 and final was set at the end of spec at .008, which was what my factory ring and pinion was set at from the factory. Taking your time is the most important, its easy to get frustrated. I took my front drive shaft out so that i can do the rear one day and still be able to drive and do that front another day.
As far as many people saying used gears need to be installed exactly the same way they originally were, I would have to slightly disagree. If you know what the back lash and pinion depth was set at, that's great. I haven't found that to be the case, but i have found as long as you can get the pattern close to center as possible on the coast side and a little towards the top of the tooth while still be in spec you should be good.
These are my patterns, no noise from a couple mile road test. Pics aren't great i took them with my phone
Not claiming to be an expert by any means, this is just my experience on used gear installs for people who have been weary of it. $50.00 to $80.00 on used gears compared to 150.00 to 300.00 on new is a nice savings for us who are tight on cash.
Also thanks to Malan35 for the gear set.
JK Enthusiast
Joined: Jan 2013
Posts: 259
Likes: 0
From: Bountiful, UT
I agree
Bought a set of 4.10s off a guy going to 4.88s and put them in when installing lockers in my 2012 JK auto. Been over 5000 miles and zero problems. I had 3.73s and the 4.10s are great with my 35" BFGs.