I'm looking at purchasing a new truck right now and the one that I am looking at has an axle ratio of 3:08. Currently I drive a Suburban with a ratio of 3:42. Am I going to notice a great deal of difference when towing a trailer with the new truck. The new truck is a GMC Sierra All Terrain. I'm not too up on this and knew that someone here could help.
Question about axle ratio for trucks
- Thread starter swanee
- Start date
cuzzinolaf
Well-known member
You'll get better gas mileage when you're not towing.. that I know. I'm not sure about a difference. What size tires are on your current truck... and what are on the new one? How much weight are you towing? Enclosed type trailer?
polarisrider1
New member
A truck with 3;08 ratio can barely pull itself down the road. The 3:73 is what is in my truck and works great. Mileage suffers a bit. I did have a suburban with a 454 and 4:10 gears, it pulled everything at 7.5 to 9 miles per gal.. The 3:42 should be a decent all around ratio.
I am usually pulling an enclosed (steel) trailer with 3 very heavy commercial 72" Toro mowers. Right now with my Suburban it takes a bit to get up to speed and I do have to allow plenty of room to stop. I'm not using an e-brake. In the winter I pull two Revs on an open trailer.
polarisrider1
New member
oh we are doing "new" math. That makes a 454 a 7.4 liter and the 6.0 liter a somewhere around a 360-365 if a 350 is a 5.7 liter.
polarisrider1
New member
Yes you will notice a great deal of difference from a 3:42 to a 3:08. The 3:08 is what the dealers get stuck with to get fleet MPG's higher. They usually get stuck with X amount of these so they can get some "Real" trucks on the Lot that can actually pull themselves and a sizable trailer down the road. After all, isn't that what trucks are suppose to do? My dealer says he has to take 3 neons and other junk "whoosey cars" to pacify EPA reg's. to get the public what they really want, Real trucks. I had a chev. 1/2 ton short box with a 305 with 3:08 gear ratio with a 3 speed stick I installed 33 inch ground Hawgs on it with no lift. I never used 3rd gear. The truck could not maintain speed in 3rd. sad.
I agree. My guess is the new truck would have more hp and torque than the suburban but I would be very consered about that gear for towing.
All 2010 trucks come with a 6-speed trans. The 6 speed with 3.08 gears is DEEPER in every gear than the 4 speed with 3.73 gears. Notice that 5th gear in the 6 speed is essentially the same as 4th in the 4 speed.
6 speed
1st: 4.02 x 3.08 = 12.38
2nd: 2.36 x 3.08 = 7.27
3rd: 1.53 x 3.08 = 4.71
4th: 1.15 x 3.08 = 3.54
5th: .85 x 3.08 = 2.62
6th: .67 x 3.08 = 2.06
4 speed
1st: 3.06 x 3.73 = 11.41
2nd: 1.75 x 3.73 = 6.52
3rd: 1.00 x 3.73 = 3.73
4th: .70 x 3.73 = 2.62
4 speed
1st: 3.06 x 3.42 = 10.46 edited
2nd: 1.75 x 3.42 = 5.99
3rd: 1.00 x 3.42 = 3.42
4th: .70 x 3.42 = 2.39
There is more to gearing than the differential. You must include the trans gearing to know the final gear ratio.
All Terrain Dash
I have a 2010 GMC Sierra E. Cab SLT Z71 All Terrain with a 3.42 ratio. You can no longer get a 3.73 ratio unless you get the Max Trailering option with 6.2L engine. 3.08 is the default factory ratio, you can order a 3.42 as a no-cost option but the 3.08 ratio will be the predominant one you will find because people want fuel economy.
The reason for the higher ratio's is fuel economy and meeting fuel economy standards. My 2010 GMC with the 3.42 is averaging 18.5 mpg at only 2500 miles. I searched high and low to find the 3.42 because like some I was stubborn and wanted only another 3.73 but I never got better than 16.5mpg with the 3.73 and 4-sp trans in my 2008. I did drive a 3.08 truck and could not really tell, it was very powerful (315hp gas / 326hp E85) with lots of get up and go. I settled for the one with the 3.42 for the 3.42 but for all the other options it had, SLT and new color paint.
6 speed
1st: 4.02 x 3.08 = 12.38
2nd: 2.36 x 3.08 = 7.27
3rd: 1.53 x 3.08 = 4.71
4th: 1.15 x 3.08 = 3.54
5th: .85 x 3.08 = 2.62
6th: .67 x 3.08 = 2.06
4 speed
1st: 3.06 x 3.73 = 11.41
2nd: 1.75 x 3.73 = 6.52
3rd: 1.00 x 3.73 = 3.73
4th: .70 x 3.73 = 2.62
4 speed
1st: 3.06 x 3.42 = 10.46 edited
2nd: 1.75 x 3.42 = 5.99
3rd: 1.00 x 3.42 = 3.42
4th: .70 x 3.42 = 2.39
There is more to gearing than the differential. You must include the trans gearing to know the final gear ratio.
All Terrain Dash
I have a 2010 GMC Sierra E. Cab SLT Z71 All Terrain with a 3.42 ratio. You can no longer get a 3.73 ratio unless you get the Max Trailering option with 6.2L engine. 3.08 is the default factory ratio, you can order a 3.42 as a no-cost option but the 3.08 ratio will be the predominant one you will find because people want fuel economy.
The reason for the higher ratio's is fuel economy and meeting fuel economy standards. My 2010 GMC with the 3.42 is averaging 18.5 mpg at only 2500 miles. I searched high and low to find the 3.42 because like some I was stubborn and wanted only another 3.73 but I never got better than 16.5mpg with the 3.73 and 4-sp trans in my 2008. I did drive a 3.08 truck and could not really tell, it was very powerful (315hp gas / 326hp E85) with lots of get up and go. I settled for the one with the 3.42 for the 3.42 but for all the other options it had, SLT and new color paint.
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cuzzinolaf
Well-known member
I have 4.10s in my diesel and wish I had 3.42s. At 65mph I'm running just under 2000 rpm. Would love for it to be less than 1500 with some higher gears. I don't tow more than 3000lbs.
techsledder
Member
Whoa, a stump puller Cuzz!
@ swanee > My '09 F250 diesel is getting higher 18mpg's with the 3.73 @ 70mph and unloaded. This winter will be my litmus test on the fuel mileage with vehicle finally being closer to being broken in. Current trips to Indian River MI from MKE I have produced 14mpg through the U.P. while pulling my 5000lb ski boat and a full truck. Look into the new 2011 Ford diesel maybe... Peterson's off road was reporting a 4-5 better MPG than the old 6.4L in mine. It too has a 6 speed tranny.
cuzzinolaf
Well-known member
LOL. It is my first diesel and I didn't know any better. I wish I would have known what I know now. Saying that I get 16.5 consistently with driving around town, to work, etc. I'm hoping I can get 18+ on the way to the UP.... and 14 towing a trailer. <fingers crossed>
On my 06 Dmax I have the 6spd with the 3:73 rear end. I pull a 38 ft Montana fith wheel up to the Hodag and got 14 mpg running about 60 mph. Running empty at that speed I consistantly get 20-21 at 1500 rpm. Running 70 on the freeway I can get 18 mpg at 1750 rpm. Last year pulling my two place enclosed out to Wyoming, at 75 mph pushing a strong head wind it went down to 10 to 12..ouch... Still the best truck I ever owned.
oldguy
Member
I just traded in my Dura-Max for a 2010 Silverado with the the max towing package and the 6.2 liter gas engine with 405 hp. It is rated to pull 10400 lbs and that is just about what my skid steer and trailer weighs. The truck came with a 3.73 gear ratio and the 6 speed tranny. This vehicle is very comparable to the Dura-Max pulling the trailer up to 70 mph. The Dura-Max had more staying power in the hills. Mileage has been 16mph freeway and 14-15 around town, not towing anything. I would recommend the 6.2 liter if you don't want to shell out the big bucks for a diesel and still want plenty of power for towing.
I would hook up & demo with trailer. I like 3.73 GM rear end but the new trucks have been downsized for better MPG. You just won't know until you try it. I would not buy without towing demo & I no idea what they did in new tranny gearing & is difficult to know. Good question.
anonomoose
New member
I am not sure that te rear end makes as much difference as when we all ran around with 4 speed transmissions. With 6 speed jobs, you can drop the drive down a notch and wind the motor some and still end up with a pretty good pulling machine.
For those of you who are pulling with 6 speed trannies, I would try dropping it down a gear and seeing how this does on gas mileage. It is okay to wind the motor in the 2400-2700 range and still get good mileage. And if you drive without pulling something the newer lower geared rear end will let you eek out some extra miles to the turnip....
Just remember that the engineers dropped that rear end down for a reason and they also knew you would be pulling things, so perhaps you guys should read your manual a bit and see what they recommend. It isn't alway wise to use the high gear when towing.
For those of you who are pulling with 6 speed trannies, I would try dropping it down a gear and seeing how this does on gas mileage. It is okay to wind the motor in the 2400-2700 range and still get good mileage. And if you drive without pulling something the newer lower geared rear end will let you eek out some extra miles to the turnip....
Just remember that the engineers dropped that rear end down for a reason and they also knew you would be pulling things, so perhaps you guys should read your manual a bit and see what they recommend. It isn't alway wise to use the high gear when towing.
go for it its on the lot and they will deal.
Drop down a gear or two and spin it up.
Hunt around and find the dyno charts for
that engine and i promise you will be
surprised how high the rpms are for peak torque.
I spun my 454 at 4500--5000 for thousands of
miles yanking 6000-7000 lbs.
Drop down a gear or two and spin it up.
Hunt around and find the dyno charts for
that engine and i promise you will be
surprised how high the rpms are for peak torque.
I spun my 454 at 4500--5000 for thousands of
miles yanking 6000-7000 lbs.
anonomoose
New member
Wow...that's cranking the rpm's....Not sure I would recommend that for "miles and miles"...but short distances wouldn't worry me.
What was wrong with your truck you had to run a big block at that rate to pull a measily 6-7k? That son-of-gun should have sailed that load along fine without the fuss...unless you did mountain work!