The Official 1LE 3.91 gear swap thread

[jeremywes]

I thought I could reprogram the factory computer for the new axle ratio with a handheld programmer but it didn't seem to fix the TCS lights on my dash. Any ideas?

[stikSS]

Originally Posted by jeremywes

I thought I could reprogram the factory computer for the new axle ratio with a handheld programmer but it didn't seem to fix the TCS lights on my dash. Any ideas?

I don't know if you can... The dealership may be able to do it for you as well.

[CAP'N B]

Anybody know about this on the Z/28? "Power is distributed to the rear wheels via a limited-slip differential, which features a helical gear set rather than traditional clutch packs. Would this be like a Detroit True Trac?

[slickz28]

Well thanks to this thread and jeremywes' thread i was able to do my own 3.91 gear change and ted's clutch packs was also pretty easy. If you have a little know how and the right tools its pretty straight forward. Getting my tune changed tomorrow for the speedo, took it out today and no whine. Sure can feel ted's clutches around slow deep corners, but heard that goes away after time. Thanks again and a must have mod on these heavy beasts.

[CamaroRBT]

Awesome! Glad it worked out!

[Jrichards73]

Anyone with an Auto should know that 3.91's are AWESOME!!! She isn't a track car, but sure is a blast on the street now! Should have come with these gears! The hole that she had to dig herself out of when you floor it is GONE! When you want to cruise she just purrs along nicely! (I have no AFM FYI) 315/35ZR20 Continental ExtremeContact DWS's in the rear hold perfectly!

[JCunningham]

I have some questions as ill be doing this maybe tomorrow. Will I need a new diff cover gasket or any seals? Do you have to remove the axles on both sides as in can I remove one side then tilt the diff down on that side so I can pop the axle out of the diff on the other side? Will this require a rear end alignment? Anyone know a good shop in western NY to do gears?

[mat300z]

My 3.91's are done Total Cost was 211 for the gears..36.00 for the gear oil (royal Purple) and 250 for the professional install. Grand total almost 500.00 for everything.

[Brandonss]

I am gonna just do the whole Diff with the 3.91 gears in it... i think that swap will go smoother. It will not be no need to crack open the Diff it will be a safer play I would say. I read on the Diff that it come with tru track posi traction.

[JCunningham]

it comes with the same posi as the SS camaros. its not the detroit.

[CamaroRBT]

Well i got my 3.91 gears done. I had a shop do it i took him just the diff and he charged me $337 to put the gears in. About 3k miles on them now and i cant imagine this car without them.

[rmilcic]

Originally Posted by CamaroRBT

Well i got my 3.91 gears done. I had a shop do it i took him just the diff and he charged me $337 to put the gears in. About 3k miles on them now and i cant imagine this car without them.

GOt a 2013 Camro 2ss\rs Just pulled my rear diff last night. Dropping my gears/ Diff off today to get the3:91 installed!!

[Pro Stock John]

Daniel how many hours do you think a highly experienced tech will take to swap the gear, including pulling the diff?

Originally Posted by danielblack60

About to order my 1le gears. I got really lucky being a tech at a gm dealer and getting them 10% above cost!

In my experience with doing countless gear swaps both under warranty and on other vehicles at my own shop, if you buy aftermarket gears, go ahead and get the shim kit. You will need it. If you buy oem gears, the tolerances are so close that really the only variance is in the housing. 99 percent of the time you can use the original shims and be spot on. Out of all of the oem gears I have installed only a few have required tweaking.

If this tells you anything, the gm kent Moore pinion depth tool they supplied us doesn't even use the pinion gear to measure pinion depth. If I think of it tomorrow I will post a picture of our pinion depth tool.

So the main thing is to check your pattern once you get it installed. Worst case scenario you may be the one unlucky guy that has to take it back apart to put a different pinion shim in. With me being flat rate I would rather take the chance and install with the original shims. Then check the pattern and go from there. If it is spot on I just made money. If I have to re shim it I may have wasted a little time but oh well, it doesn't happen that way often haha.

[danielblack60]

Originally Posted by Pro Stock John

Daniel how many hours do you think a highly experienced tech will take to swap the gear, including pulling the diff?

A highly experienced tech should be able to do the job in 4 solid hours. And that's being generous. It took me about 2 and a half but i had a lift, air tools, and have had that rear diff out several times already haha. I pulled the axles, hub assembly, and knuckle and rotor off all in one piece. Just bungee corded the calipers to the upper control arms. Little shortcuts like that is how i make my money lol.

Also i didn't have to touch the pinion depth. Just added the factory shim to the new pinion gear and pinion depth was spot on

Last week i put an evap canister and vent solenoid on a v6 Camaro at work. Got paid 3.2 hours to pull the rear cradle and replace the canister. Did it in about an hour and a half (with an apprentice helping me watch as i raised the car off the cradle and lowered it back down onto the cradle)