I have a 07 Tahoe LS 4.8L with 3.23:1 gears 2WD. Is it possible to change the gears to 3.42:1, 3.73:1 without complications from the vehicle computer system. Or does the computer even care? If there is, is there a patch or can the computer be reprogrammed? Thanks. Chevrolets Rock!

 

4.8L ouch... why do they bother with that engine?

GM did the same thing in my friend's caddy... a 3.0L V6 and its overworked for the heavy *** car + AWD, so he gets like 20 MPG. while my 5.3L tahoe that's 2x bigger and fatter averages 17.4! (the 3.6L gets MORE MPG and has MORE HP. how do you lose?!)

anyway, no, the computer won't care much, but your speedo, and odometer and shift points may be off... but the dealer should be able to reprogram the ECM/BCM for whatever gears came factory...if any of those were a factory choice.

Sometimes i still think about having ordered mine with the 6.2L... ohh what fun it is to ride on a 400HP sleigh tonight...

 

and I thought the 5.3 with 3.42 gears was a speed racer...I could only imagine the 4.8 with 3.23 gears
but like Sabr said you should be able to get it all reprogramed at the dealer or maybe the shop installing the gears if you have issues. go with teh 3.73 gears!

 

Just ran into a guy at Home Depot w/ a 2010 Sierra Crew cab who was getting ~11 mpg w/ 3.23 gears. Put in 4.56 gears and claims he's getting ~16 mpg now. Supports the 5.3 "sweet spot" theory.

 

the 2010 will have a 6 speed with a lower first gear, making the axle ratios almost the same as 1st with the 4.56s or at least closer...

someone post the 4 and 6 speed ratios, then we can compare actual drive ratios. just knowing the axle, if the tranny is different, doesn't mean much...

 

Hi Guys: Thanks for the information. It was just what I was looking for.
I will probably go with the 3.73:1's that little engine doesn't seem to mind higher RPM's. Thanks again.

 

Please explain "sweet spot" theory. First time I have heard the term but I think I may have an idea as to what you are saying.

 

ZX (GM engr) explained it in response to why were folks w/ 4.10 gears getting better mpg than those of us w/ 3.70 gears. IOW the engine was more efficient at the higher rpm.

 

A lot of times on the open road ie: Interstate, I will run in the tow mode a little over 60 mph and Tahoe will remain in V4 mode what seems like a lot longer than normal and mpg on the DIC will show higher than than runnig in a normal lower rpm mode.

 

I noticed a similar effect w/ my 07 but haven't tried it w/ the new one.