4.10 vs 3.55

[ne buckeye]

Ok, I've been thinking about changing my gears from a 4.10 to 3.55's or 3.73 if the make them for my truck. what's the pro's and cons? I know my 4.10's pull better bet it kills fuel mileage.Alot of trucks have the 3.55's so it can'nt pull to bad. My truck is a 93 250 idi non turbo , I pull a 7000 pound pulling tractor

 

[towcat]

bad idea to go to 3.55's with the weight you pull. the tractor may be 7k, but how about the trailer and the pit stuff? You will be bogging the motor quite a bit between gears. imho, 4.10's are a little boggy, but 3.55's are unacceptable when pulling weight. anything load over 3k in weight is heavy in my book.

 

[david85]

The only time you notice the difference between different gear ratios is starting off. After that, the upshift happens later on relative to vehicle speed, so actuall pulling power is unchanged once you are rolling. I went from 4.10 all the way down to 3.08s and never regreted it. I pulled a load of hay on a 20' flatbead plus whatever we could heap up on the truck. Maybe that was 7000lbs, I don't know.

Steep inclines when pulling a heavy trailer and starting off are the only time I felt a difference after my swap.

3.08s have the advantage of having a similar final drive ratio in 2nd gear (C6) as 3rd gear with 4.10s. So in reality, once rolling, I had more flexibility for towing or running empty. Even at 50 MPH I can drop to 2nd gear if I want.

The question is, how often do you pull that load and at what speed? If you are at 50-55 MPH 4.10s are already ideal for a N/A IDI.

 

[RLDSL]

With that kind of weight behind it, you really do want the 4.10 if you are going to be pulling all the time. However, I see you are in Nebraska , if you do all of your pulling there, you could probably get away with a taller rear and still be able to pull, but keep in mind that your fuel mileage when loaded will most likely go down unless you can find a sweet spot in a lower gear. You don't mention what tranny you have, but on mine with a 5 speed and 4.10, pulling a 10k 5er even on flat ground, I get better fuel mileage running in 4th and slowing down, it;ll pull 5th just fine with power to spare, but having to keep it floored to do it, just inhales fuel, it does much better dropping a gear and letting it wind up a bit.
Obviously your empty mileage will go up with a taller rear. It's just a matter of what you need to do with it. If you plan on heading out across the Rockies with that load on, you'd probably kick yourself with a taller rear, unless you put some kind of auxilliary box on there ( Brownie, Gear Vendors, US Gear ) to be able to split the gears.

 

[supervert]

dont do it, i have 4.10 and 38"s and it sucks big time. i just got back from dirtbike riding in the sierra's and i could barely keep it going 55 and that was with only 2 bikes in the back and my truck weighs 7k. i am scared to even think about towing my toyota to the trails as soon as its done. i will be re gearing to something like 5.13's soon

 

[towcat]

dont do it, i have 4.10 and 38"s and it sucks big time. i just got back from dirtbike riding in the sierra's and i could barely keep it going 55 and that was with only 2 bikes in the back and my truck weighs 7k. i am scared to even think about towing my toyota to the trails as soon as its done. i will be re gearing to something like 5.13's soon

Turbo and a IC is what you need
I have no problems running I80 to Reno passing traffic loaded at GVW. Bad thing is I'm usually the fastest one in the pack

 

[icanfixall]

But gees towcat... You have the govenor married to your right foot all the time.... Yes... Someday I too will "see" the govenered rpm, just not any time soon.... Still babying the new motor some what....

 

[BigRigTech]

I pull 9K from time to time between the trailer and truck aboard it with 3.55's and a 5spd....It's a give and take thing...I went to 3.55's from 4.10's....I'd like the 4.10 acceleration but I like the lower rpm's at highway speeds that the 3.55's give....I can still drive 60mph in 4th and I'm not screaming the old girl too bad.

 

[david85]

dont do it, i have 4.10 and 38"s and it sucks big time. i just got back from dirtbike riding in the sierra's and i could barely keep it going 55 and that was with only 2 bikes in the back and my truck weighs 7k. i am scared to even think about towing my toyota to the trails as soon as its done. i will be re gearing to something like 5.13's soon

Trouble holding 55 MPH at 7000 lbs? I think somethings wrong. My truck would bump the governor with 4.10s (70 MPH) or with 3.08s (95+MPH) and that was before the turbo and still running a C6 transmission.

 

[Cheaper Jeeper]

Trouble holding 55 MPH at 7000 lbs? I think somethings wrong. My truck would bump the governor with 4.10s (70 MPH) or with 3.08s (95+MPH) and that was before the turbo and still running a C6 transmission.

It may not be as bad as think when you consider the 38"s...

38" tires are 5"-5.5" taller than the stock 235/85/16"s - which are roughly 31.7" tall. That's a 17% taller tire - which with 4.10 gears is the equivalent of stock tires and 3.50"s

On the other hand, even with the 38"s it shouldn't have a hard time maintaining 55...

 

[typ4]

But gees towcat... You have the govenor married to your right foot all the time.... Yes... Someday I too will "see" the govenered rpm, just not any time soon.... Still babying the new motor some what....

dude !!!! you better get that thing wound up, if you balanced it it will be fine, diesels are made to run on the governor , so get to it. I had 2 k on mine then letter rip. you need to make sure that a ridge doesnt build up from low speed lugging

 

[FordGuy100]

Agreed, he should be able to maintain 55mph. I'm thinking timing is a little retarded, IP is going out, or bad injectors.

 

[LCAM-01XA]

But gees towcat... You have the govenor married to your right foot all the time.... Yes... Someday I too will "see" the govenered rpm, just not any time soon.... Still babying the new motor some what....

Lol, ain't just him, last time I pulled the 30-footer I took the 4-hour drive from Columbus to Detroit in two hours and a half - pulled over 'round Delaware to turn the IP down a bit, told my pilot car keep on cause I'ma catch up with 'em, and from there it was all one hand on the wheel and the other on the CB and left lane and pedal to the floor Them pilot guys still ain't sure when exactly I flew by, but god bless the poor soul who had seemingly all the state troopers who were on duty that night ganged up on him on the other side of the freeway, he cleared US-23 for me for several counties ahead

 

[Mr_Roboto]

I had 3.55's in my old F350 wrecker. The only problems I had was starting uphill with a heavy vehicle on the back. I ran loaded to 14 - 16K and never had power issues once rolling.

If you have an automatic the torque converter will take care of the starts from a stop. I ran one of my old vans with 7.3 IDI / E4OD and 3.73 gears loaded to maybe 18K across the Alleghany mountains with very little problems (started to overheat about 2 miles from the mountain peak but the radiator in that van was junk).

 

[RKOCH]

Personally I run nothing higher than a 4.10 in all the rigs I have ever had. I want a truck to pull and work 65-70 mph is fast enough. Keep the RPMS @ 3000 and it will pull like a mule. If I need fuel milage I will drive my car.