Swapping out these horrible 3.08s for some 3.73s in my '12 Tahoe soon. Should I even bother getting the dealership or someone with a TechII hookup to fix the ratio in the ECM? Or just fix it with a tune? Not even sure what they charge now, last I heard it was like 2hrs labor for the whole 5min it takes to program, lol.

Just wanted it shifting right and the speedo to be right for a while and not have to rush getting the tune ASAP

 

A Gear ratio change can not be done with the Tech 2.

The dealer would have to do the gear swap and request a new file From GM. GM would then update all there records for your vehicle.

It's much cheaper to have a gear swap done else were and get some one to tune it.

 

Just get a tune & be done with it. Why pay for the dealer to reflash, then also pay for a tune later? Doesn't make sense.

 

Kind of what I figured from the dealer. Only reason I wanted to update on the base file was in case the tune needs to be removed to go in for anything(non tune related), so I don't get the third degree on having a tune. Already planned on getting a tune anyway, so tune it is!

 

Have you gone any further with this? I am in the same boat and was going to go down the same road as you have. I've talked to 01WS6/tamu about this and he said that GM won't care if you have a stock tune that's only been adjusted for gears, from a custom tuner I'm talking about. Might have to specify that they leave this specific tune unlocked. That's my plan with Blackbear and my autocal tune, then a second (real) tune file that I'll run when not at the dealer! I called my dealer who thought I was crazy with this question but he said he would call TAC about changing ratios on my VIN... never called me back. I got my true-trac ordered, got my 3.73s already, ordering install kits and a front carrier this week... the thought of going 4.11s still haunting me!

Keep me posted with your progress, I'm interested to hear how it goes for someone else. Not many on here with the big vehicles and 5.3/6l80 going from 3.08 to 3.73. Hoping my MPG jumps a little in this 4x4 crew. Don't forget a new front carrier for your 2012 3.08.

 

I put in 4.10s from 3.23 and nelson performance corrected my speedometer.

 

They usually wont care depending on the failure. I've had several geared only trucks that the rest of tune was bone stock on and all was ok. It's literally decided on a case by case basis based off of the failure not at the dealer level.

But yes flash it with hp tuners and call it a day gm route PITA for really much of nothing.

Yup 4:10's will be haunting you they are the cats ***.

 

New front carrier? Mines a 2wd, just swapping out the rear gears.

If you have a 4wd, might consider the 4.11s, I always hear of guys regretting not getting enough gear on a 4wd when later adding bigger tires.

Nah, I havent even had time to do it yet, I do already have a tune now from BB since I added headers, but havent had time off work to get the gears put in, had them sitting here for two months now, lol.