Gear Ratios

[BRDof3]

Need some quick info from the towing gods on this forum. What is the difference between gear ratios of 3.73 and 4.2? Just wondered which was better for towing vs. better mileage while not towing.

Thanks!

 

[kc5grw]

3.73 better for mileage
4.2 better for towing

The lower number ratio results in lower engine RPM for the same vehicle speed.

 

[BRDof3]

3.73 better for mileage
4.2 better for towing

The lower number ratio results in lower engine RPM for the same vehicle speed.

I thought it was a better ratio, though I wasn't sure, nor understood why.

Thanks!

 

[kc5grw]

A gear ratio of X, more accurately stated as X:1, means that your driveshaft is rotating X times for every 1 time that your wheels rotate. So for a 3.73 ratio the driveshaft turns 3.73 times for every 1 wheel revolution.

 

[bama_ed]

Need some quick info from the towing gods on this forum. What is the difference between gear ratios of 3.73 and 4.2? Just wondered which was better for towing vs. better mileage while not towing.

Thanks!

And now, your prayer having been answered, the gods demand a sacrifice of some sort!

Bama ED

 

[Thumper_ehhhhh]

If your looking to buy a new tow vehicle and want to get whats best. My oppinion would be 3.73 if you are a ocational tow'r. If your going to go full time I would get the 4.2 . Yes 3.73 is better for milage. I just dont want you to think you have to get the 4.2 to tow.

I happened to get the 3.73 in my suburban for that reason.

 

[ftwildernessguy]

3.73.......3.74........whatever works for ya.

 

[des1954]

My gears were stripped many, many years ago!

 

[bigdisneydaddy]

It definitely depends on the vehicle and what you are towing. I have had vehicles with the 4.10 and some with the 3.73 and in a 1/2 ton GM truck I prefer the 3.73 since it keeps the RPM's down a little more and stays plenty well into the power on the 5.3, you cant tow in Overdrive pulling a high profile trailer with these trucks anyways (unless you want to visit the transmission shop)
The 4.10 also netted me a little worse MPG when I wasn't towing 95% of the time.

So it all depends on what you will be doing with the vehicle.

 

[kc5grw]

Remember that mileage will also depend on the engine. I had an F250 supercab with a 460 attached to a 5 speed manual and 3.73 rear-end. I got 10 mpg in that truck towing or not (unless I really started putting my foot into, then towing mpg dropped considerably)

My F350 CC dually diesel 6 spd manual has 4.10 gears and gets me 15-17 without the trailer and about 9.5mpg average towing(11,000 lbs fifth wheel).

 

[LarryJ]

It definitely depends on the vehicle and what you are towing. I have had vehicles with the 4.10 and some with the 3.73 and in a 1/2 ton GM truck I prefer the 3.73 since it keeps the RPM's down a little more and stays plenty well into the power on the 5.3, you cant tow in Overdrive pulling a high profile trailer with these trucks anyways (unless you want to visit the transmission shop)
The 4.10 also netted me a little worse MPG when I wasn't towing 95% of the time.

So it all depends on what you will be doing with the vehicle.

Your experience is a little different than mine and a lot has to do if you are looking at a gassers or oil burner. In the Ford line for the 7.3L diesel the 3.73 is standard on the SD's except the duallys and because of the torque/HP curves do well. In my Van they only offered either a 3.55 or 4.10 and I have the latter and can still get almost 18+ not towing if I keep the speed just under 60. There is also in the 7.3L verison a 4K difference in the rated GCWR 16K vs 20K. I always tow in OD, but I don't have a stock tranny so I'm not worried there, but the 4R100 in the 7.3L was a weak link if you added any power above stock.

Larry

 

[ftwildernessguy]

 

[LONE-STAR]

I always buy 4x4's and put a little wider and taller tire under them. On my old 7.3 diesel it had 3.73 in it and pulled like a train even with 35" tall tires . But like a idiot I wanted a new truck a few years ago and got a 6.0 diesel 4x4. Again I put taller and wider tires on it. Well it was ok not towing but the 6.0 did not like the taller and wider 35" tires. With the taller tires it had knocked my gear ratio down around a 3.55. So I regeared to 4.30 the truck now tows much better. According to the numbers with the 4.30 and 35" tall tires this puts me somewhere between a 3.73 and a 4.10 about a 3.90.

Now on my wifes dodge diesel with the 5.9 and a 6 speed no matter what size tire I put on it (with in reason) the 3.73 gear still pulls great. I sure wish I had my wifes motor in my truck.

 

[kc5grw]

Now on my wifes dodge diesel with the 5.9 and a 6 speed no matter what size tire I put on it (with in reason) the 3.73 gear still pulls great. I sure wish I had my wifes motor in my truck.

I can't remember the show, maybe TRUCKS!, but they recently put a 70's Ford crewcab body on a dodge 5.9 manual tranny rolling chassis. Like you I'd love to have the 5.9 under the hood of my F350.

 

[LONE-STAR]

I can't remember the show, maybe TRUCKS!, but they recently put a 70's Ford crewcab body on a dodge 5.9 manual tranny rolling chassis. Like you I'd love to have the 5.9 under the hood of my F350.

That would be a sweet ride . I have heard of guys putting the 5.9 in there superdutys but I also heard the price tag is $14,000 to $20,000.

 

[bigdisneydaddy]

That would be a sweet ride . I have heard of guys putting the 5.9 in there superdutys but I also heard the price tag is $14,000 to $20,000.

I know a couple of guys with older Ford that have 5.9's in them, in a perfect world the Cummins would be available in all 3 trucks brands (Dodge, Ford and GM)

I also run a larger tire (285) on my Duramax, it ends up with a better final drive than the stock 245's, IIRC I am running about 1850 RPM at 60 MPH and right around 2000 at 70 MPH, which is why I run around 65 MPH mostly. I couldn't tell you what ratio is in my truck because there wasn't an option that year. The ratio is much less relevant on the diesels due to their torque, after driving my 99 1/2 ton and then driving the diesel I notice a huge difference, the torque of the diesel makes it feel like a much smaller truck.

 

[kc5grw]

Actually, if I had my way I'd have a C7 in my truck.
http://ohe.cat.com/cda/files/378797/7/LEHT3462-07 HR P1.pdf

From my freight driving days and experience with Cat and Cummings I always preferred the way the Cat engines drove much better than the Cummings.

 

[bigdisneydaddy]

Actually, if I had my way I'd have a C7 in my truck.
http://ohe.cat.com/cda/files/378797/7/LEHT3462-07 HR P1.pdf

From my freight driving days and experience with Cat and Cummings I always preferred the way the Cat engines drove much better than the Cummings.

Well..... now you went and opened it up to the larger ones, that changes everything.

I saw a Dodge power wagon a few years back that had a Detroit 6V92 that was straight piped, you could hear it coming a mile away.

 

[kc5grw]

Wow. Not sure that would be my choice of engine to squeeze into a power wagon. Now if I could fit a C15 into my truck.

 

[LONE-STAR]

You know the first company to put a CAT(diesel motor) in a 1 ton truck is going to sell like crazy. At least it would in my part of the world.