Regear or buy another truck

XMR · February 13, 2023

18 Sierra sle with 5.3 think it’s 3.08 gears, 6” lift 35x12.5r20. First time buying a Gm truck and I’m starting to regret moving from ford. My 18 f150 with a 5.0 10speed and 35s had no issue towing or driving. This truck has issues doing even 70-75. I just deal with that but towing my canam defender is seriously depressing. Can barely do 65, 66-75 and it’s running 3k rpm and will not upshift what’s so ever, for an around 4500 load with the trailer that’s kind of ridiculous. I would like to be doing 75-80, but usually we run 2 sxs’s per truck which I won’t even attempt right now. I’ve had the truck since November, can’t go smaller on the tires. I actually use the truck off-road going to parks and getting around my buddies property where we keep the bikes. Should I even bother with spending the money on a regear or should I just bite the bullet and buy another truck? Other than the lack of power the truck seems to not mind the load. But I’m not trying to be limited to like 55 mph with two sxs’s on the trailer. Did I buy the wrong truck? Btw trucks in Texas, my local highway is 75 mph. I’ve thought about just buying and old diesel as a tow pig but I have enough stuff to work on, don’t feel like maintaining another vehicle. I would like to keep the truck, it’s nice to have a lighter 1/2 ton in the group.

JimCost2014 · February 13, 2023

42 minutes ago, XMR said:

18 Sierra sle with 5.3 think it’s 3.08 gears, 6” lift 35x12.5r20. First time buying a Gm truck and I’m starting to regret moving from ford. My 18 f150 with a 5.0 10speed and 35s had no issue towing or driving. This truck has issues doing even 70-75. I just deal with that but towing my canam defender is seriously depressing. Can barely do 65, 66-75 and it’s running 3k rpm and will not upshift what’s so ever, for an around 4500 load with the trailer that’s kind of ridiculous. I would like to be doing 75-80, but usually we run 2 sxs’s per truck which I won’t even attempt right now. I’ve had the truck since November, can’t go smaller on the tires. I actually use the truck off-road going to parks and getting around my buddies property where we keep the bikes. Should I even bother with spending the money on a regear or should I just bite the bullet and buy another truck? Other than the lack of power the truck seems to not mind the load. But I’m not trying to be limited to like 55 mph with two sxs’s on the trailer. Did I buy the wrong truck? Btw trucks in Texas, my local highway is 75 mph. I’ve thought about just buying and old diesel as a tow pig but I have enough stuff to work on, don’t feel like maintaining another vehicle. I would like to keep the truck, it’s nice to have a lighter 1/2 ton in the group.

Scan your QR code in the door jamb on the drivers side , then look for GU4, that is the RPO code for the 3.08 rear end.

CamGTP · February 13, 2023

Put some 3.73's in it and it will be a world of difference. Trucks with more gears in the transmission need less gear to do the job.

Trucks with a 6 speed will still want gearing when it comes to heavy ass rims and tires like you have. Find a 3.73 diff from a junkyard or something and then re-gear the rear end. Will be cheaper this way. Then tune it for the gear change.

swathdiver · February 13, 2023

3 hours ago, XMR said:

18 Sierra sle with 5.3 think it’s 3.08 gears, 6” lift 35x12.5r20. First time buying a Gm truck and I’m starting to regret moving from ford. My 18 f150 with a 5.0 10speed and 35s had no issue towing or driving. This truck has issues doing even 70-75.

The truck you chose was set up for highway cruising, not towing it seems. Then you made it worse with the lift and 35s. Regear for 3.73s and have it tuned to match and you won't miss that Ferd.

XMR · February 13, 2023

Think 3.73s will be enough? Or should I go up to 4.10s or higher? I don’t mind spending the money on gears and a tune, I just don’t wanna spend the money and it still suck at towing.

KARNUT · February 13, 2023

With less than 20ft lbs of tq difference and about 40 Hp. The difference should be negligible. The ford probably had deeper gears. Where it makes its peak plays a role too. Gearing is the problem. That’s not the trucks fault. Another misconception is you need lift and big tires to go off road. I worked off road on pipelines most of my life with only bfgs. Sure some people like the look. The old saying goes you have to pay to play. The cost is 411s or 456 and gas mileage, front end parts etc etc.

diyer2 · February 13, 2023

You bought the wrong truck to tow with then made it worse with the mods. Gear choice 373 will better and more suited for highway speeds, 411 will raise rpms and may keep it in a better power range. 456 I wouldn't do.

The only way to know is try it.

XMR · February 13, 2023

I guess I’ll start pricing out gears, I’m not planning on pulling more than like 6500 with two bikes, gear, spare parts, and tools. I wouldn’t think that would be to much for a half ton, we don’t even have hills around here. Anyone on 35s with 3.73s or 4.11s have any issue towing this weight? I also don’t really care about gas mileage, I daily a service truck.

swathdiver · February 13, 2023

10 hours ago, XMR said:

Think 3.73s will be enough? Or should I go up to 4.10s or higher? I don’t mind spending the money on gears and a tune, I just don’t wanna spend the money and it still suck at towing.

This is my daughter's NHT Sierra with 3.73s and the 6.2 motor. It's been running the lift and tires for ten years now without issue and can pull a house down still. She hauls hay with it sometimes and it effortlessly pulls trucks out of the mud when they're out playing in the woods or on the beach. The taller tires (35s) have reduced the axle ratio to being akin to 3.42s.

Someday we'll regear it to 4.10s so the gearing will be more or less back to stock 3.73s with the 35s. We talk about going to 4.56s which would be akin to 4.10s but if she goes to 33 inch tires or removes the lift than that would be an additional expense.

Silverado4x4 · February 13, 2023

As others have stated those 3.08 gears are for highway driving then you really killed it by adding the 6" lift creating alot of wind drag at highway speeds then you added the way heavier tires, regear to a 3.73 or a 4.10 in both front and rear and you will be good. With 3.08 gears and 35" tires your truck is really running about a 2.83 gear that's why it's a dog. It's not the trucks fault.

Edited February 13, 2023 by Silverado4x4