Axle ratios

[brnzbk]

I've been looking at new F350's SRW and everything I see has the 3:55 gearing. My intent was to get the 3:73 but apparently I would have to special order it. So my question is: How much am I actually giving up (uphill pulling) going to the 3:55 over the 3:73? The largest fiver we are considering is the Cedar Creek 36 CKTS, about 12K unloaded with a GVWR of 16.5K. If we get that particular one a dually would probably be a better fit and most of them on the lots have 3:73, I'm just not sure we are going to go that large.
Is there a noticable difference between those two ratios when towing?
I know its' a tough question to answer, so many variables, but just a general opinion or practical experience with these ratios would be helpful.

[jnphobe]

If you can find a dealer to order one as fleet you can get 3.73 gears in a SRW it is a fleet only option

[Cummins12V98]

brnzbk wrote:
Thanks for the replies and valuable information.
I'm going to the dealer on Monday or Tuesday and talk to my sales guy and see what we can put together. I've got my eye on a couple of trucks on the lot, one is a SWR 3:55 and the other is a DRW 3:73, we'll see what happens.

If you think about the future the DRW is the way to go. Every one goes to a larger RV.

[brnzbk]

Thanks for the replies and valuable information.
I'm going to the dealer on Monday or Tuesday and talk to my sales guy and see what we can put together. I've got my eye on a couple of trucks on the lot, one is a SWR 3:55 and the other is a DRW 3:73, we'll see what happens.

[Javi1]

As someone who has pulled the same 12K 5th wheel with both a '12 F250 with the 6.7 and 3:31 gears and a '15 F350 with the 6.7 and 3:73 gears... there is no comparison between the two.. Yes the 3:31's will pull the trailer down the road and at 65mph it will take all but the higher overpasses without down shifting. But get that sucker on the secondary roads and that ain't the case. Even here in relatively flat Texas my F250 spent a lot of time in 5th and a good bit in 4th when the speed limit was 55mph.. The F350 don't.. And here's the kicker.. my fuel consumption went down when I started pulling with the F350.. don't know how it would pull with 4:10's but I expect it would get rolling a bit quicker and downshift a lot less, but cost more in fuel. So, I'm not gonna try them unless I pickup a much larger 5'er and a F450 or F550.

[The_Mad_Norsky]

Another agreement on the 3:55 in the SRW Ford.

That new Ford diesel puts out a massive amount of torque and power.

Go for it!

[NC_Hauler]

rjstractor wrote:

Cummins12V98 wrote:
Ok now which one of us is "Dumb" or "Dummer"

Me like the 4:10's

But it's not an apples to apples comparison- the Ford transmission has lower (higher numerically) ratios is all but sixth gear, so in the first five gears the final drive ratios of a Ford with 3.73 axle gears are very close to that of a Ram with 4.10s. At any rate, the 3.55 ratio that the OP has should move his trailer rather nicely.

Agree the Ford with the 3:55 gearing should do just fine....

[rjstractor]

Cummins12V98 wrote:
Ok now which one of us is "Dumb" or "Dummer"

Me like the 4:10's

But it's not an apples to apples comparison- the Ford transmission has lower (higher numerically) ratios is all but sixth gear, so in the first five gears the final drive ratios of a Ford with 3.73 axle gears are very close to that of a Ram with 4.10s. At any rate, the 3.55 ratio that the OP has should move his trailer rather nicely.

[NC_Hauler]

Cummins12V98 wrote:

NC Hauler wrote:

BenK wrote:
About 9% diiference in torque

Less torque if going from 3.73 to 3.55

More torque if going from 3.55 to 3.73


If MPG is higher in your have to have list...get the 3.55's

If performance is higher on your have to have list...get the 3.73's


I'll always chose performance over MPG...opinions vary...

I for one, agree with you on this Ben....course I'm one of those "dummies" that has a 4:10. I do almost all my towing in the mountains though.

Ok now which one of us is "Dumb" or "Dummer"

Me like the 4:10's

I said that because someone else couldn't understand why someone would want a 4:10...thus the reason I said it the way I did.....I think we're both pretty doggone smart:)

[Cummins12V98]

NC Hauler wrote:

BenK wrote:
About 9% diiference in torque

Less torque if going from 3.73 to 3.55

More torque if going from 3.55 to 3.73


If MPG is higher in your have to have list...get the 3.55's

If performance is higher on your have to have list...get the 3.73's


I'll always chose performance over MPG...opinions vary...

I for one, agree with you on this Ben....course I'm one of those "dummies" that has a 4:10. I do almost all my towing in the mountains though.

Ok now which one of us is "Dumb" or "Dummer"

Me like the 4:10's

[ggardne2]

Unless you buy a truck with 20" tires I would stay with the 3.31 ratio, I tow with an F-350 6.7L SRW with the truck maxed out on weight and truck rarely if ever will come out of 6th gear unless pulling a significant grade. Normal freeway grade changes such as overpasses are no problem and the truck will pull them in 6th gear.

[Lynnmor]

BenK wrote:


Less torque if going from 3.73 to 3.55

More torque if going from 3.55 to 3.73

If performance is higher on your have to have list...get the 3.73's

BUUUUUTTTT................. He CANT get the 3.73 in that truck.

The 3.55 will do just fine.

[NC_Hauler]

BenK wrote:
About 9% diiference in torque

Less torque if going from 3.73 to 3.55

More torque if going from 3.55 to 3.73


If MPG is higher in your have to have list...get the 3.55's

If performance is higher on your have to have list...get the 3.73's


I'll always chose performance over MPG...opinions vary...

I for one, agree with you on this Ben....course I'm one of those "dummies" that has a 4:10. I do almost all my towing in the mountains though.

[BenK]

About 9% diiference in torque

Less torque if going from 3.73 to 3.55

More torque if going from 3.55 to 3.73


If MPG is higher in your have to have list...get the 3.55's

If performance is higher on your have to have list...get the 3.73's


I'll always chose performance over MPG...opinions vary...

[Javi1]

If I had that trailer I'd be looking at DRW... 3:73 is kick butt for pulling with the 6 speed.... 3:55 is better than the 3:31 in fact with that trailer the 3:31 will keep you in 4th or 5th at any overpass