In the market for a F250 SuperDuty 4wd, 6.2 engine & fifth wheel camper. I expect the trailer to be in the 10-12K range for weight.. Mostly midwest towing, but will see some mountains. What would the best gear ratio?

 

4.30

Denny

 

near top of towing weight.. 4.30 is best.

 

Run a search on this forum. There are countless posts on this topic.

Steve

 

You just want to watch this place burn to the ground, don't you?

GF

 

I'm still just waiting for someone to successful do a gear swap from 3.73 to 4.30 so I can buy one of the 1000's of pretty 6.2L/3.73 optioned trucks hanging out at dealerships around me.

 

Indeed. Amazing how few 4.30's are in dealer stock.

 

Ron94150 did a swap from 3.73 to 4.88 and then did a lift and 37's .. so it can be done just costs money.

 

I think that is a reflection of where dealerships and the manufacturer see the demand. Percentagewise, how many buyers even consider rear end gearsets? Not many I bet.

 

This is true but dealership sales people don't even know what a towing guide is and what difference it make towing with deeper gears. The last truck I used for towing with 3.73 gears was my 81 I bought used and rebuilt, after it's first major trip I changed it to 4.10 gears. When I ordered my 2013 the sales person tried to talk me out of 4.30 gears, he was informed that if my truck didn't have 4.30 gears I wouldn't take it.

Denny

 

I am not sure how to insure there are more knowledgeable sales people. Increasing demand might bring about that change, I don't know. So far it doesn't seem to be having an impact. I know I looked at literally hundreds of new trucks on dealer lots and never found a single 4.30.

Steve

 

The last time I found a trimmed out truck with 4.30 gears on a lot is when I found 2 at Crater Lake Ford in Medford OR in 2000, we took one back to Nebraska.

Denny

 

I was fortunate to find a 2012 this year with 4.30s. The only option s on the truck are ESOF and 4.30s.

 

if you put the shifter in 5th instead of 6th you in effect just switched from 3.73 to 4.30 gears. the only down side is a little less "grunt" in first gear.

 

Ehhhhhh ...... sort of yes, but not really. It's not just first gear that is effected. Given that the 6.2L engine develops an average torque of 390 ft-lb across it's power-band, the scenario you suggest would result in the 3.73/5th gearing actually giving a slight edge over the 4.30/6th gearing. So, I agree that you will find a "sweet spot" where the gearing will be effectively similar.

But that ignores the topic of how much gearing effectively allows one to "hold" a road speed, especially under load. May folks who tow (especially those who tow heavy loads) want to be able to maintain momentum uphill.
The 4.30 gearing returns a smaller spread of wheel rpm for every engine rpm.
Taller diff gears (lower numerically) offer a broader range of wheel speed per tranny gear, but give up a slight bit of force generation via lower torque multiplication.
Shorter diff gears (higher numerically) offer a greater wheel force generation effect for any tranny gear selected, at the expense of wheel speed.
So, when towing at or near GCWR limits, greater diff reduction gearing offers more ability to "hold" any given gear going uphill, whereas taller gears will cause a downshifts sooner, and more often.


For the OP, I would highly recommend the 4.30 gears for his stated intent of use.