6.2L w/ 3.23 or 3.42?

ajensen383 · December 23, 2017

OK, so looking at possibly getting something new... I am torn between the 3.23 or the 3.42 with the 6.2L.. ..when I ordered my 2011, I wrestled with the same decision on whether to go with the 3.73 or 3.42..I went 3.73 with the max tow, and couldnt be happier...I love the way it will hold 6th gear pretty much anywhere I go unless its a really steep grade, even then it only comes out of lockup..Very rarely does it ever downshift to 5th, I love that about my truck..

With these new ones with the 8 speed, my biggest concern is the downshift factor with the 3.23 since in 8th gear it will be at a very low rpm...My wife has a 2014 tahoe with the 5.3 and 3.08s and it constantly downshifts at the hint of a grade, or even a stiff head wind..lol.. I hate driving it because of it ... I feel if I get the 3.23 I will be in the same boat.... but maybe not I dont know..

I know due to the 8 speed, even the 3.23 will "feel" stronger than my 2011 throughout the rest of the gears, its just being in 8th that concerns me

So has anyone driven both the 3.42 and 3.23 and have any insite on how they drive on the highway??

For what I tow, open car trailer with a 3500# car, either should be fine to tow with...Im more concerned with daily driving and trips with the downshifting

swathdiver · December 23, 2017

I can't see a downside to going with the 3.42 over the other. Get it and like the 2011, you'll never regret it.

i82much · December 23, 2017

always get the steeper factory gears. the mpg benefits are negligible, the performance benefits are not.

some comments from a gm engineer that may be of interest:

http://media.gm.com/media/us/en/gmc/vehicles/sierra_hd/2012.detail.html/content/Pages/news/us/en/2012/Aug/0817_gmc_differential.html

swathdiver · December 23, 2017

Wait a second! I just reread this post, are you going to part with that Victory Red truck? That's the kind of vehicle you pass on down to your kin, like a favorite rifle or pistol!

seamus2154 · December 23, 2017

I have had 3.42's and 3.73's in the prior generations and can't say they are a good comparison. BUT I have had the 5.3 LT in this platform and had 3.08's and 3.42's With the 5.3 and the 3.42's were needed, and both always needed to downshift with the 6 speed often. Hated those trucks especially for towing. Have no reservations with the 6.2 8 speed and 3.23's. It is a whole other animal. I am on my second Denali with this combo and the motor and trans are awesome and I tow a similar weight as you stated. (Zo6, open trailer 5700 lbs). The gearing and torque make it my ultimate tow vehicle with no drama or constant downshifting like the 6 speed. I feel no need for 3.42's. Now I am sure if I had alot more weight and didnt care about fuel mileage 3.42's may be needed and wanted. Depending on your speed it will stay in 7th or 8th. But if it needs to drop to 7th or 6th it is not such a big drop that you will notice like the 6 speed. It is definetly designed with towing in mind. Its a pleasure. I also get 15.5 towing at 74 mph which is diesel territory! 21-23 mpg under 80 mph not towing. Have no worries, it is VERY different from the 6 speed. Go drive one. With all the great deals don't let the 3.42's be a deal breaker for you. Good luck.

Nanotech Environmental · December 23, 2017

13 hours ago, ajensen383 said:

OK, so looking at possibly getting something new... I am torn between the 3.23 or the 3.42 with the 6.2L.. ..when I ordered my 2011, I wrestled with the same decision on whether to go with the 3.73 or 3.42..I went 3.73 with the max tow, and couldnt be happier...I love the way it will hold 6th gear pretty much anywhere I go unless its a really steep grade, even then it only comes out of lockup..Very rarely does it ever downshift to 5th, I love that about my truck..

With these new ones with the 8 speed, my biggest concern is the downshift factor with the 3.23 since in 8th gear it will be at a very low rpm...My wife has a 2014 tahoe with the 5.3 and 3.08s and it constantly downshifts at the hint of a grade, or even a stiff head wind..lol.. I hate driving it because of it ... I feel if I get the 3.23 I will be in the same boat.... but maybe not I dont know..

I know due to the 8 speed, even the 3.23 will "feel" stronger than my 2011 throughout the rest of the gears, its just being in 8th that concerns me

So has anyone driven both the 3.42 and 3.23 and have any insite on how they drive on the highway??

For what I tow, open car trailer with a 3500# car, either should be fine to tow with...Im more concerned with daily driving and trips with the downshifting

If you're only occasionally towing a car trailer, the 3.23 should be fine with a 6.2, especially with the 8 sp.

Here's the thing- I find it interesting that you're concerned about the truck downshifting when the the load increases a bunch. Yet, when you think about it, if you go with a lower gear, say a 3.42 or a 3.73, it's kinda like driving with the trans in 7th(give or take) all the time, vs with a higher gear, and you can never upshift. You'll always be running higher rpm than necessary when in lower load conditions.

Some of the info in that GM article a couple posts up isn't quite accurate, especially about fuel mileage. Lower gears will cause fuel econ to drop much more than .2 or.3 mpg.

elKrusto · December 23, 2017

I had a 15 Denali with 6.2 and 3.23 gears best mileage I could average was around 13.4 liters per 100 km

I now have a 17 SLT 6.2 with 3.42 gears and my mileage is usually around 12.9 liters per 100 km

The 3.42 gears does hold hi gear longer and tow better, and ya...it feels much better when I hammer down the "go " pedal, lol

i82much · December 23, 2017

1 hour ago, 3beejay3 said:

Some of the info in that GM article a couple posts up isn't quite accurate, especially about fuel mileage. Lower gears will cause fuel econ to drop much more than .2 or.3 mpg.

they were quoting a gm engineer. no one on this forum knows more than that engineer about this topic.

and, even assuming the difference is twice what he suggested, it still ain’t much.

Get the steeper gears.

ajensen383 · December 23, 2017

3 hours ago, 3beejay3 said:

If you're only occasionally towing a car trailer, the 3.23 should be fine with a 6.2, especially with the 8 sp.

Here's the thing- I find it interesting that you're concerned about the truck downshifting when the the load increases a bunch. Yet, when you think about it, if you go with a lower gear, say a 3.42 or a 3.73, it's kinda like driving with the trans in 7th(give or take) all the time, vs with a higher gear, and you can never upshift. You'll always be running higher rpm than necessary when in lower load conditions.

Some of the info in that GM article a couple posts up isn't quite accurate, especially about fuel mileage. Lower gears will cause fuel econ to drop much more than .2 or.3 mpg.

Yep, thats exactly what its like...Is rather have it running a few hundred more RPM rather than constantly downshift , upshift, downshift, upshift driving down the highway, its annoying as hell..give me a few hundred more RPM and im happy.....

My 2011 with my stock wheels and tires with the 6.2 and 3.73, i have gotten 20.0 MPG highway if im not hammering on it...on a nice highway cruise i can easily get around 19MPG....20MPG if im keeping it under 65 and light on the throttle....In my everyday driving, usually rural back roads and some highway im usually between 15-17 ...

The ratio difference between the 3.73 and 3.42 is more significant than the 3.42- 3.23 is, so thats why im wondering how it is on the highway

Im old school, and i usually like the deepest gear i can get, but its alot harder to finding a 3.42 truck comapred to the 3.23s...Its tough because I like the Z71 front ends way better than the regular LTZ chrome front , plus I hate woodgrain interiors, but I do like having the "fast" truck.

truckguy82 · December 23, 2017

I don’t know why gm even offers the 3.08 or 3.23

whats the point, with afm you’re not going to see any better efficiency

i82much · December 23, 2017

if it weren’t for the kids i would run around in a nice solid lifter small block with a muncie and 4.56 gears, so 3.42 with a frickin’ 8 speed seems like a no brainer.

KARNUT · December 23, 2017

I’m with you on every but the solid lift, you can have that, hydraulic roller for me.

Sent from my iPhone using Tapatalk

ajensen383 · December 24, 2017

59 minutes ago, i82much said:

if it weren’t for the kids i would run around in a nice solid lifter small block with a muncie and 4.56 gears, so 3.42 with a frickin’ 8 speed seems like a no brainer.

LOL...Thats actually the exact set up in my 1970 Nova...Solid roller 383 , Muncie 4 speed and 4.56 gears in a 12 bolt...4,000 RPM at 65mph

i82much · December 24, 2017

yeah i went hyd roller on the hot rod. saves time, which i need because of the kids!

65 gto, 505 ia2, m23 with 3.54 strange s60.

ajensen383 · December 24, 2017

13 hours ago, i82much said:

yeah i went hyd roller on the hot rod. saves time, which i need because of the kids!

65 gto, 505 ia2, m23 with 3.54 strange s60.

Nice... How do you like the M23..I was considering upgrading the stock muncie for the M23..what ratios did you go with?