37s on stock 3.73 or 4.56

[dirtyduramax05]

ive been running the stock gears for years and i get good fuel mileage with this set up but i do pull skidsteers and a two car trailer loaded and i was wanting to see what others are running and what yall think of 4.56 and how much high way mileage will i loose and how much pick up will i see on bottom end

 

[SKNKTNK]

I would like to know the same thing. I'm running 38" tires but I get horrible mileage. 8 in town and 12 fwy

Sent from my SCH-I535 using Tapatalk 2

 

[duramaxdiesel]

I've got 37's on my LB7 and I towed quite often with it. Mileage was actually better seeing as I was always on the highway. In town from stoplight to stoplight and just getting around was no problem. That being said, the truck was tuned. Stock tuning I wouldn't even think of it. I thought I'd have to get 4.56's but the truck does great with the stock 3.73's. This is just my observation.


Nick

 

[Hot COCOAL]

Well, I can't imagine a re-gear would hurt either of you guys

Keep in mind that my truck has the 6sp trans, but I'm quite happy with my choice to alter the gear ratio.

I am running 4.11's w/35's and I think I could've/should've gone to 4.56's and been good with them. The 4.11/35" combo still have plenty of MPH for 1/4mi runs, lots of low end grunt and still let the rpm's run under 1800 at 65mph.

I noticed a little bump in mpg, but not a significant enough amount that I would recommend a swap for economy gains, especially for a 4x4(2 axle's), although in terms of percentage my 1.4 mpg increase equated to roughly 10% yes I was getting an average economy of appx 14.8 mpg before and now I get about 16.2. Towing seemed easier all the way around too, easier on economy, easier to get to and maintain speed and slightly easier on the egt's as well.

Other placebo effects could possibly be:
A feeling of better throttle response
Less turbo lag, ie the gears get up and go faster, so will the turbo
Getting through the gears faster, less feeling like your pushing to run them out, if that makes sense, which yields
Quicker 0-60, ah hell, improved acceleration at any point really

Downsides include:
Cost, depending on how you go about it and the mileage on all the axle bearings, labor isn't cheap and neither are all the parts once they are in a collective pile.
Dialing in your speedo :rofl:
Potential for gear whine
Potential for future gear whine
Time and planning, that is if you can't afford to go and just have an axle or two built up done up right. I couldn't, it took me a year maybe more to get all my parts together (including the lift) and the rear end went out two months before I could afford it course, at that time I decided to add an eaton DETROIT trutrac to the list too...

If you're planning on keeping you're trucks and running those big tires guys, I personally believe it's a worthwhile investment, if younplan on getting rid of the truck w/in two years or so, I'm not sure I'd be willing to drop the coin and settle for smaller tires...

 

[mackthehack]

37's with 4.56's mpg's kind of suck. I do a lot of surface street driving not to much on the freeway. Been thinking of re gearing to 4.11's.

 

[Hot COCOAL]

37's with 4.56's mpg's kind of suck. I do a lot of surface street driving not to much on the freeway. Been thinking of re gearing to 4.11's.

Lol, yeah, but your truck is Ginormous :roflmao:

And you've got that really light solid axle swap helpin your economy too:joker:

I was told that the 4.56's would be more "performance" really heavy towing or sled pulling orientated and the 4.11's would be more for street/tow/daily when coupling them with 35"s

Which is why I went with the 4.11's in the end, but I had originally ordered 4.56's and then chickened out....can't say I'd be disappointed if I'd gone through and installed the 4.56's. I'm really happy with the way the truck drives now, and I doubt I'd be any less happy with 4.56's now that I've had the 4.11's although I really do think the 4.11's were the better choice, for me....

 

[Chevy1925]

im swapping to 4.56 gears this weekend. BUT there are a few good reasons they will work with me. highway wise, i hardly every go faster than 70mph. i dont know why but i like the speed and keeps me out of trouble with speeding tickets. i also mainly use the truck for towing now or long trips. Unless the samurai breaks, winter time is the trucks time to sit and enjoy the occasional weekend cruise. When i tow, you can tell its lugging along. Most people probably wouldnt notice it but if i try to cruise 60mph or 65 in 5th, egts start coming up t0 1000* and its really out of its sweet spot.

MPG right now, i get no better than 16 highway and 13-14 in town but i also have a FRP issue and an intercooler with a gapping hole in it. thats all getting ordered up today.

i put off gears for a loooooong time and was actually going to go to 4.10 gears when i could but the more i thought about it and what my truck is doing more of now a days, id rather go with the 4.56 for towing. i jsut kept putting more and more power at the truck for towing to overcome the lack of gears but there is only so much you can do to a motor to get bottom end grunt back in low RPMs.

 

[blk smoke lb7]

im swapping to 4.56 gears this weekend. BUT there are a few good reasons they will work with me. highway wise, i hardly every go faster than 70mph. i dont know why but i like the speed and keeps me out of trouble with speeding tickets. i also mainly use the truck for towing now or long trips. Unless the samurai breaks, winter time is the trucks time to sit and enjoy the occasional weekend cruise. When i tow, you can tell its lugging along. Most people probably wouldnt notice it but if i try to cruise 60mph or 65 in 5th, egts start coming up t0 1000* and its really out of its sweet spot.

MPG right now, i get no better than 16 highway and 13-14 in town but i also have a FRP issue and an intercooler with a gapping hole in it. thats all getting ordered up today.

i put off gears for a loooooong time and was actually going to go to 4.10 gears when i could but the more i thought about it and what my truck is doing more of now a days, id rather go with the 4.56 for towing. i jsut kept putting more and more power at the truck for towing to overcome the lack of gears but there is only so much you can do to a motor to get bottom end grunt back in low RPMs.

Isnt that going to hurt you for trap speed in the 1/4?

 

[Chevy1925]

Isnt that going to hurt you for trap speed in the 1/4?

Shit Scott, its been a 1.5 years since ive been back to a track :roflmao:. i dont know as 5th gear would fall under the power range she needed in order to keep pulling hard. between the fact i have one of russells sweet turbos now, will be fixing my leaky intercooler, have a good trans back in her, and its not 100* out i doubt ill loose much trap speed over my last time out . i believe ET should drop though right?

 

[blk smoke lb7]

Shit Scott, its been a 1.5 years since ive been back to a track :roflmao:. i dont know as 5th gear would fall under the power range she needed in order to keep pulling hard. between the fact i have one of russells sweet turbos now, will be fixing my leaky intercooler, have a good trans back in her, and its not 100* out i doubt ill loose much trap speed over my last time out . i believe ET should drop though right?

I hope it does.I was thinking of going the opposite way and going to 3.42 to equal the 6 speed over drive.Guess it all depends on where your last shift is before the the end of the 1/4.i will be paying close attention to the next time you hit the track though.

 

[mackthehack]

Lol, yeah, but your truck is Ginormous :roflmao:

And you've got that really light solid axle swap helpin your economy too:joker:

I was told that the 4.56's would be more "performance" really heavy towing or sled pulling orientated and the 4.11's would be more for street/tow/daily when coupling them with 35"s

Which is why I went with the 4.11's in the end, but I had originally ordered 4.56's and then chickened out....can't say I'd be disappointed if I'd gone through and installed the 4.56's. I'm really happy with the way the truck drives now, and I doubt I'd be any less happy with 4.56's now that I've had the 4.11's although I really do think the 4.11's were the better choice, for me....

It ain't that heavy.... Hahaha! What weighs the most is the 3/8" skid plate/control arm mount. That bitch must be atleast 300lbs. 4.56's are not to shabby from a dig or at certain higher speeds. A lot of low end torque with them.

 

[mackthehack]

im swapping to 4.56 gears this weekend. BUT there are a few good reasons they will work with me. highway wise, i hardly every go faster than 70mph. i dont know why but i like the speed and keeps me out of trouble with speeding tickets. i also mainly use the truck for towing now or long trips. Unless the samurai breaks, winter time is the trucks time to sit and enjoy the occasional weekend cruise. When i tow, you can tell its lugging along. Most people probably wouldnt notice it but if i try to cruise 60mph or 65 in 5th, egts start coming up t0 1000* and its really out of its sweet spot.

MPG right now, i get no better than 16 highway and 13-14 in town but i also have a FRP issue and an intercooler with a gapping hole in it. thats all getting ordered up today.

i put off gears for a loooooong time and was actually going to go to 4.10 gears when i could but the more i thought about it and what my truck is doing more of now a days, id rather go with the 4.56 for towing. i jsut kept putting more and more power at the truck for towing to overcome the lack of gears but there is only so much you can do to a motor to get bottom end grunt back in low RPMs.

70mph? Thats for old people... :rofl: You'll definitely get the low end torque back with 4.56's.

 

[Chevy1925]

haha i know. back when i was driving back and forth to flagstaff/phoenix every weekend when i was in college, thats where i got my best fuel mileage. since then i get in a mind set about mpg when ever i travel. im slowly coming out of that though since im not hurting for cash all the time like i was back then but i just stick with 70. after all, in a 4hr trip to the dunes, 5-10mph faster isnt gunna save me much time but it will kill my fuel mileage lol

 

[Chevy1925]

I hope it does.I was thinking of going the opposite way and going to 3.42 to equal the 6 speed over drive.Guess it all depends on where your last shift is before the the end of the 1/4.i will be paying close attention to the next time you hit the track though.

im thinking about running at the NHRDA opener. im going either way, just not sure if i wanna run. that will probably be the next time i run so ill keep you updated!

 

[mackthehack]

haha i know. back when i was driving back and forth to flagstaff/phoenix every weekend when i was in college, thats where i got my best fuel mileage. since then i get in a mind set about mpg when ever i travel. im slowly coming out of that though since im not hurting for cash all the time like i was back then but i just stick with 70. after all, in a 4hr trip to the dunes, 5-10mph faster isnt gunna save me much time but it will kill my fuel mileage lol

I know what you mean. I feel like it get the best mileage at about 80. But that could just be in my head movies. 70 is good for mpg's. i know my mpg's are going to change after I upgrade the turbo. Thinking about running this 472 that I have for a little while. And have Russell do his magic on my stocker and put my 475 over it. Then eventually ditch the 475 and run a set of 256's with the modded stocker.

 

[Hot COCOAL]

im swapping to 4.56 gears this weekend. BUT there are a few good reasons they will work with me. highway wise, i hardly every go faster than 70mph. i dont know why but i like the speed and keeps me out of trouble with speeding tickets. i also mainly use the truck for towing now or long trips. Unless the samurai breaks, winter time is the trucks time to sit and enjoy the occasional weekend cruise. When i tow, you can tell its lugging along. Most people probably wouldnt notice it but if i try to cruise 60mph or 65 in 5th, egts start coming up t0 1000* and its really out of its sweet spot.

MPG right now, i get no better than 16 highway and 13-14 in town but i also have a FRP issue and an intercooler with a gapping hole in it. thats all getting ordered up today

i put off gears for a loooooong time and was actually going to go to 4.10 gears when i could but the more i thought about it and what my truck is doing more of now a days, id rather go with the 4.56 for towing. i jsut kept putting more and more power at the truck for towing to overcome the lack of gears but there is only so much you can do to a motor to get bottom end grunt back in low RPMs.

SO MUCH WIN!!!!!!!

:woott:

:coolspot:

You deserve all of it man, congrats :thumb:

And it's about damn time:rofl:

 

[Chevy1925]

I know what you mean. I feel like it get the best mileage at about 80. But that could just be in my head movies. 70 is good for mpg's. i know my mpg's are going to change after I upgrade the turbo. Thinking about running this 472 that I have for a little while. And have Russell do his magic on my stocker and put my 475 over it. Then eventually ditch the 475 and run a set of 256's with the modded stocker.

gawd id love to put a couple 256's off to the side of my stocker. the work Russ does makes such an awesome improvement in the turbo! you may talk to him about that 75 as well if you can swing it. i know him and i have been talking about doing mine and finally doing that damn 80mm upgrade ive had sitting her.

SO MUCH WIN!!!!!!!

:woott:

:coolspot:

You deserve all of it man, congrats :thumb:

And it's about damn time:rofl:

lol thanks Jason. im definitly excited to see how quick she gets off the line now with the new gears. trans will need some time to learn though

 

[mackthehack]

gawd id love to put a couple 256's off to the side of my stocker. the work Russ does makes such an awesome improvement in the turbo! you may talk to him about that 75 as well if you can swing it. i know him and i have been talking about doing mine and finally doing that damn 80mm upgrade ive had sitting here.

I've thought about him doing work to the 75 as well. Shit! If I don't sell this 472, I'll have him do his magic and run it to see how I like it. Trips is as far as I'm going with the turbo set up.

 

[Hot COCOAL]

lol thanks Jason. im definitly excited to see how quick she gets off the line now with the new gears. trans will need some time to learn though

:hello:
I'm excited for you man:woott: I was duly impressed with mine and I only went from 3.73 to 4.11 on 35's

You still rockin 37's yeah?

On the trans, Can you reset the tapps? Would that help?

 

[Chevy1925]

:hello:
I'm excited for you man:woott: I was duly impressed with mine and I only went from 3.73 to 4.11 on 35's

You still rockin 37's yeah?

On the trans, Can you reset the tapps? Would that help?

yup! still on 37s. i wouldnt reset taps, ill leave it as is and let it learn as i slowly increase throttle increments. it may be different now with the defuel set right but i tried putting stock tires on my rig few years back for the track and it flaired, bucked and straight up gave me the finger the whole way down the track compared to the 37s.