6.2 Z71 Gears?

cborgstedt · November 5, 2015

I have a 2014 LTZ Z71 with the the 6.2, I just recently had a 9" lift installed and have 22X37s on there. I'm out of town so have not had much time to drive it but was wondering what gears I currently have and if anyone has my same setup if they needed new gears or not? And if so what gears would be best? Thanks in advance!

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Rme2513 · November 5, 2015

If it's a 14 with the 6 speed you have 3.42 if its the max tow (NHT) you have 3.73 if I was you I would put 4.88 in there

cborgstedt · November 5, 2015

I believe I have the 8 speed since I have the 6.2

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redwngr · November 5, 2015

I believe I have the 8 speed since I have the 6.2

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2014's have a 6 speed. -- 3.73's for max tow

2015's have an 8 speed. -- 3.42's for max tow

crafferty · November 5, 2015

I believe I have the 8 speed since I have the 6.2

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You have a 2014 so you have the 6.2L mated to the 6 speed transmission with 3.42 gears and 9.76" rear end (NOT the 9.5"). Regearing your truck will be a HUGE pain in the ass. If you have any luck in doing so please let me know. I have not been able to find a local shop that has regeared the new 9.76" rearend nor can I get an answer from places like East Coast Gear Supply (they haven't done one either last time I checked with them).

If it's a 14 with the 6 speed you have 3.42 if its the max tow (NHT) you have 3.73 if I was you I would put 4.88 in there

Any particular reason for the 4.88's? Once I figure out a solution for my truck I was thinking about 4.56.

robvas · November 5, 2015

2014's have a 6 speed. -- 3.73's for max tow

2015's have an 8 speed. -- 3.42's for max tow

Z71's can't have the max tow package...

4.88's would be insane with the 8 speed, the first few gears are lots steeper than the old transmissions were.

4.10 would put it close to feeling like 3.42's with a 37" tire. It'd have a hair more pep.

There's a guy on here who did a set of 3.73's not that long ago. Those are available as OEM gears not sure about other ratios

http://www.gm-trucks.com/forums/topic/177704-2015-ltz-62l-rear-axle-gearing-change/?p=1704787

cborgstedt · November 5, 2015

Thanks for all the input, I finally got ahold of the dealership and I have the 6 speed with 3:42s

Rme2513 · November 5, 2015

4.88 better then 4.56 imo for 37" tires and all the weight of moving them it's not like your after good gas mileage so I would go with lower gears

IOMike · November 5, 2015

4.88 would be madness. The 6 speed has more aggressive gearing than the old 4 speed so while 4.56 and 4.88 may have been the go to in the old days with big tires it's a lot "more" gear now with the 6 and especially 8 speeds.

Rme2513 · November 7, 2015

Old 700r4 tranny overdrive is .69 in OD new six speed has two OD gears sixth is .66 and firth is .85 so I see no difference other then when it down shifts the rpm want jump out the roof and like I said it's not about gas mileage with your truck it's about rolling on 37s and turning 130 ish lbs per wheel and tire it will a lot better on the truck and I know you will like it I have a k5 blazer 700r4 with 410s on 35s and it downshifts a lot on the highway if you want 4.55 get them all in saying is if it were me and what I use a truck for I would get 4.88. Ok I did some figuring at 60 mph with 4.55 rpm would be 1710 and with 4.88 1830. And if you had stock tires with 3.42 rpm is 1460 but keep in mind the weight diffrance roughly 200 lbs more to turn and while pushing the truck

seansharley · November 7, 2015

Truck looks sick man, you must do a ton of highway driving to justify wanting to regear, that expense is going to be huge. I would think some bolt on performance parts would be $$ better spent. Just my opinion

CAtaylor · November 7, 2015

Best bet and cheapest option would probably be swapping the rear axle. The front can be re geared no problem. I am sure there are some 14/15's with the 9.5" showing up at the scrap yard you could get pretty cheap. Pull an axle, ship it to someone for the work then have a 1hr install when you get it back., IMO. With the 37's I would go 4.88. I ran 4.56 on my 14 with 35's and it was great but with 37's and extra weight I would have wanted more gear.

Adding power to the truck with that much load on the transmission would probably crater it pretty quick. Re-gear and you would be amazed at the difference it will make. After that is done, if you still want more, add power.

crushNchowda · November 10, 2015

w those tires and a 9" lift you effectively have a 2.73 rear lol!

seansharley · November 11, 2015

Best bet and cheapest option would probably be swapping the rear axle. The front can be re geared no problem. I am sure there are some 14/15's with the 9.5" showing up at the scrap yard you could get pretty cheap. Pull an axle, ship it to someone for the work then have a 1hr install when you get it back., IMO. With the 37's I would go 4.88. I ran 4.56 on my 14 with 35's and it was great but with 37's and extra weight I would have wanted more gear.

Adding power to the truck with that much load on the transmission would probably crater it pretty quick. Re-gear and you would be amazed at the difference it will make. After that is done, if you still want more, add power.

Isn't it a 9 3/4 with the 6.2.?

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crafferty · November 11, 2015

Isn't it a 9 3/4 with the 6.2.?

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Yes and if we are splitting hairs it is 9.76" (who knows why they decided on that number). He was just saying swap the 9.76" with a 9.5" and then you can regear it real easily.