Joined
·
9 Posts
I am considering running 37in. tires. I am concerned with loss of towing power and mpg. Should I regear? And if so what ratio? Thanks in advance.
Do I need to re-gear?
1 - 20 of 21 Posts
Joined
·
778 Posts
Uh... oops /ubbthreads/images/graemlins/biggrin.gif I still run 3.73s and I have no problems. No detectable powerloss.
According to This link, a corrected ratio would be 4.18s, so regear to 4.10s would be pretty close. 4.56 and 4.88 is just to high I think, that is unless you have a dually with 4.10s to begin with.
According to This link, a corrected ratio would be 4.18s, so regear to 4.10s would be pretty close. 4.56 and 4.88 is just to high I think, that is unless you have a dually with 4.10s to begin with.
[ QUOTE ]
Uh... oops /ubbthreads/images/graemlins/biggrin.gif I still run 3.73s and I have no problems. No detectable powerloss.
[/ QUOTE ]
oops is right! he has no listed power mods, so assuming a 3.73 factory ratio, add 37's, and you'll be wanting more than 4.10's!
Uh... oops /ubbthreads/images/graemlins/biggrin.gif I still run 3.73s and I have no problems. No detectable powerloss.
[/ QUOTE ]
oops is right! he has no listed power mods, so assuming a 3.73 factory ratio, add 37's, and you'll be wanting more than 4.10's!
Joined
·
691 Posts
I ran 36 12.50 radial superswampers on my truck for a while with the stock 3.73 gears and combined with my 6 speed.
It drove like dog poop. Steaming piles of it. So I took em back off and went back to 285s.
If you have an auto tranny and pull nothing you could get away with stock gears but it will take more felt power away then you think even with all the diesel torque.
I agree on 4.56s
It drove like dog poop. Steaming piles of it. So I took em back off and went back to 285s.
If you have an auto tranny and pull nothing you could get away with stock gears but it will take more felt power away then you think even with all the diesel torque.
I agree on 4.56s
Ok, so I run 35 12.50 Toyo MT's and I tow a 9,000lbs trailer. When everything was stock I was towing a 4,200lb trailer and could pass everything in sight going uphill (it was fun). I lifted the truck, chipped it, did the intake and exhaust at basically the same time I bought my new trailer. It now tows ok, but is not so great on the hills. I was thinking of going to 4.56 (I now have 3.73 limited slip). Will 4.56 work for me or should I go to 4.10? Also, what will this do to mileage? Improve it I assume since the motor will not have to work as hard to roll me down the freeway (correct?)
4.56 may be a little low for 315's, but where you drive is important also. do a lot of mountain passes and 4.56's would be beneficial. a lot of flat land running and 4.10's would be right. average highway speed is also important, you should be running about 2100 rpm's at cruise to attain the best performance/mileage numbers.
Cool, without the trailer 2100rpm puts me around 85-90mph (as I sit now). THAT is why I got such stinking good mileage on our last trip to WY without the trailer...
I tow mostly down the freeway at about 60-65 (with overdrive off this puts me at about 2500rpm) and on the state highways at 55 (not sure where the rpms sit then as I am spending my time watching for the morons that think I can stop on a dime and insist on pulling out in front to of me.
My wife does a lot of in town driving during the week which kills the mpg as I sit now. With 4.10's will I be able to get it to run like stock (with a chip) up the passes with the trailer? I like to maintain 60-65 up hill (and still have power to accelerate) without having to run 3200rpm and 25lbs of boost.
I tow mostly down the freeway at about 60-65 (with overdrive off this puts me at about 2500rpm) and on the state highways at 55 (not sure where the rpms sit then as I am spending my time watching for the morons that think I can stop on a dime and insist on pulling out in front to of me.
My wife does a lot of in town driving during the week which kills the mpg as I sit now. With 4.10's will I be able to get it to run like stock (with a chip) up the passes with the trailer? I like to maintain 60-65 up hill (and still have power to accelerate) without having to run 3200rpm and 25lbs of boost.
[ QUOTE ]
Cool, without the trailer 2100rpm puts me around 85-90mph (as I sit now). THAT is why I got such stinking good mileage on our last trip to WY without the trailer...
I tow mostly down the freeway at about 60-65 (with overdrive off this puts me at about 2500rpm) and on the state highways at 55 (not sure where the rpms sit then as I am spending my time watching for the morons that think I can stop on a dime and insist on pulling out in front to of me.
My wife does a lot of in town driving during the week which kills the mpg as I sit now. With 4.10's will I be able to get it to run like stock (with a chip) up the passes with the trailer? I like to maintain 60-65 up hill (and still have power to accelerate) without having to run 3200rpm and 25lbs of boost.
[/ QUOTE ]
Maybe not like stock & empty, but you should certainly be passing the gassers!
Cool, without the trailer 2100rpm puts me around 85-90mph (as I sit now). THAT is why I got such stinking good mileage on our last trip to WY without the trailer...
I tow mostly down the freeway at about 60-65 (with overdrive off this puts me at about 2500rpm) and on the state highways at 55 (not sure where the rpms sit then as I am spending my time watching for the morons that think I can stop on a dime and insist on pulling out in front to of me.
My wife does a lot of in town driving during the week which kills the mpg as I sit now. With 4.10's will I be able to get it to run like stock (with a chip) up the passes with the trailer? I like to maintain 60-65 up hill (and still have power to accelerate) without having to run 3200rpm and 25lbs of boost.
[/ QUOTE ]
Maybe not like stock & empty, but you should certainly be passing the gassers!
15 for the pair, the limited slip is in the carrier, so whatever setup you have now will not need to be changed unless you opt to do so. However, with that said, it would be a good time to consider adding a front limited slip too as the axle will already be apart.
[ QUOTE ]
I am considering running 37in. tires. I am concerned with loss of towing power and mpg. Should I regear? And if so what ratio? Thanks in advance.
[/ QUOTE ]
4.88's would be too low for 37's unless you're constantly hooked to 15,000lb trailer. I went with 4.56 with my 38's and I run about 150 rpm higher than stock at highway speed. I only picked up about .5-1mpg, but the truck is more fun to drive, accelerates stronger with less pedal pressure tows great. Do the gear swap..your tranny will thank you! If you tow often and heavy I'd probably go 4.56. If you spend a fair bit of time unloaded I wouldn't go lower than 4.30
I am considering running 37in. tires. I am concerned with loss of towing power and mpg. Should I regear? And if so what ratio? Thanks in advance.
[/ QUOTE ]
4.88's would be too low for 37's unless you're constantly hooked to 15,000lb trailer. I went with 4.56 with my 38's and I run about 150 rpm higher than stock at highway speed. I only picked up about .5-1mpg, but the truck is more fun to drive, accelerates stronger with less pedal pressure tows great. Do the gear swap..your tranny will thank you! If you tow often and heavy I'd probably go 4.56. If you spend a fair bit of time unloaded I wouldn't go lower than 4.30
Joined
·
423 Posts
From experience... I have 38's I had 4.88 gears... they sucked.. I just put in 4.30's much better! and I tow and tow heavy. Everyday.
I have 37" Toyo's and 4.88's. I tow 13000lbs of Weekend Warrior and it works great. RPM's are high when not towing and mileage sucks, but all I use this truck for is towing. I wouldn't change a thing. My last truck was a 7.3, 4.56 and 38" tires and it struggled with this trailer. In gearing, a little goes a long way! Also, big tires without regearing places a hughmungus strain on auto trannies, prepare to replace it if you tow heavy without proper gears. Chips and other performance items only compound the problem without the right gears, I've been there, done that! I think the cost of regearing should be factored into your budget when buying lifts, tires, etc! Just my opinion! /ubbthreads/images/graemlins/cool.gif
Joined
·
126 Posts
um with the 37's and stock gear ratio you will NEED to regear to keep the tranny cool and alive in 75-100k miles. I have 35's and upgraded to 4.30's and went overboard on the gear. i have now an effective 3.93 gear and my highway unloaded dropped from 18-14. do the 4.30's if you are going to run 37's and it will go back to stock ratio with stock size tires. pulling power in this config is nice and fuel mileage is nice too.
I have the big Rig setup 22.5s which are 36 "high and i can feel the difference tring to decide if the added highway drop in rpms is worth the lower bottom end I have 4:10s now and was told to go with 4;56s I don't presently tow much will get 20' enclosed trailer sone(I race bikes)what do you guys think
Joined
·
9 Posts
Sounds like 4:30 is the way to go. Any one else running this ratio with 37's?
1 - 20 of 21 Posts
