Hello, Just looking for some thoughts on pulling hills with 3.42 gears.I'm going back to a pop-up TC @ 1800 lbs dry weight.The trucks I'm looking at are the Chevy and GMC 3500's SRW 4x4, standard bed, crew cab, with the 6.6L diesel.Their payload rating in 4185 lbsThey only come with a 3.42 gear option but have a 10 speed Allison transmission. And I like the 20" wheels just for the looks. Do you think this will be an issue hauling up mountain roads and interstates (East Coast) at closer to 3000 lbs fully loaded? Or should I look at the other competitors with a 3.73 option? TRANSMISSION & AXLEThanks for the adviceType: Hydra-Matic 6L90 six-speed automatic (6.6L gas) Allison® 10L1000 10-speed automatic (6.6L diesel) Gear Ratios (:1): 6L90 10L1000 First 4.03 4.54 Second 2.36 2.87 Third 1.53 2.06 Fourth 1.15 1.72 Fifth 0.85 1.48 Sixth 0.67 1.26 Seventh -- 1.00 Eighth -- 0.85 Ninth -- 0.69 Tenth -- 0.63 Reverse 3.06 4.54Final Drive Ratio: 3.73 (6.6L gas)3.42 (6.6L diesel)

I don't think 3.42 will be an issue with one of the newer diesels. Worst case, it will downshift going up mountains. On the other hand, my 4.30 gears never downshifts but runs at a lot higher RPM using more fuel even when empty.If I was you, I'd look at the tire capacity of the sizes for the brands you like. You may find the 18s to be a better choice for a SRW. I'm assuming you are talking about SRW since you mentioned 20s.

Thanks, the 18” wheels are standard and the 20” are a add on option. If I go with the 20’s it’s only for looks. I know I’ll sacrifice some MPG and some of the gear ratio. I’d love to have them if it’s not a huge trade off.

LL8 wrote:Thanks, the 18” wheels are standard and the 20” are a add on option. If I go with the 20’s it’s only for looks. I know I’ll sacrifice some MPG and some of the gear ratio. I’d love to have them if it’s not a huge trade off.Those 20's will also decrease ride comfort. Less sidewall.

jdc1 wrote:Those 20's will also decrease ride comfort. Less sidewall.Negative.

@LL8… You do realize that the truck(s) you’re talking about are rated to tow like 20klbs or more, right? A new Duramax won’t even work hard with a popup TC on it. An old diesel won’t either. Heck nearly any HD pickup gas or diesel from the last 20 years will haul your camper very competently.

3.42 gears for TC | Good Sam Community

jimh406
Explorer III
May 26, 2022
I don't think 3.42 will be an issue with one of the newer diesels. Worst case, it will downshift going up mountains. On the other hand, my 4.30 gears never downshifts but runs at a lot higher RPM using more fuel even when empty.

If I was you, I'd look at the tire capacity of the sizes for the brands you like. You may find the 18s to be a better choice for a SRW. I'm assuming you are talking about SRW since you mentioned 20s.
LL8
Explorer
May 26, 2022
Thanks, the 18” wheels are standard and the 20” are a add on option. If I go with the 20’s it’s only for looks. I know I’ll sacrifice some MPG and some of the gear ratio. I’d love to have them if it’s not a huge trade off.
jdc1
Explorer II
May 26, 2022
LL8 wrote:
Thanks, the 18” wheels are standard and the 20” are a add on option. If I go with the 20’s it’s only for looks. I know I’ll sacrifice some MPG and some of the gear ratio. I’d love to have them if it’s not a huge trade off.

Those 20's will also decrease ride comfort. Less sidewall.
Grit_dog
Navigator
May 26, 2022
jdc1 wrote:

Those 20's will also decrease ride comfort. Less sidewall.

Negative.
Grit_dog
Navigator
May 26, 2022
@LL8… You do realize that the truck(s) you’re talking about are rated to tow like 20klbs or more, right?
A new Duramax won’t even work hard with a popup TC on it. An old diesel won’t either. Heck nearly any HD pickup gas or diesel from the last 20 years will haul your camper very competently.
ssthrd
Explorer
May 26, 2022
My new to me camper has an advertised UVW of 1675 lbs which when loaded translated to 2800 lbs at the scale. I also pull a 14000 lb 5er. Neither bothered my 2018 at all. My door sticker says 3470lbs, so much less than the ones you are looking at. Towed in the mountains all over North America and of course my 6 speed downshifted of the steepest grades, but was never stressed. The 10 speed should carry/tow like a champ.

No worries. Load up and go camping!
valhalla360
Navigator
May 26, 2022
Even if the loaded truck camper is 3800lb, the drivetrain will hardly notice it.

Worst case, it will drop down a gear or two and run at roughly the same RPM that the higher (numerical) rear end would run at.

Assuming the tires/wheels don't degrade the payload, you should be fine.
BurbMan
Explorer II
May 26, 2022
I wouldn't sweat it, my truck also has 3.42 rear with 6 speed transmission and handled the Lance fine, also pulls the new 13k 5er fine too. Rear axle is more critical with gas engines and older 4 speed transmissions that had wider gear spacing.
JRscooby
Explorer II
May 26, 2022
Do you think they would put in as only choice of ratio something that would not be satisfactory at GCVWR?
Politicians might shoot themselves in the foot like that, car manufactures much less likely, IMHO.
mellow
Explorer
May 26, 2022
I know on the Ford side the new 10 speeds made the 7.3 gasser a very viable puller with either 3.73 or 4.30 (better suited for heavy).

I always direct people to this very long thread on gearing on the 7.3: https://www.ford-trucks.com/forums/1665685-numbers-dont-lie-3-73-vs-4-30-explained.html

Forum Discussion

3.42 gears for TC

About Travel Trailer Group

Related Content

3.42 vs. 3.73 gears.......

3.42 or 4.10?

2009 Tahoe 5.3L 4WD 3.42 Gears

F150 3.31 gears vs 3.55 gears

2014 Silverado 3.42 or 3.73