Hi all, I looking at buying a 1997 Ford F-250 7.3 PSD 4x4 - has 4:10 rear axle,
I want to tow a double axle trailer and I would like to know how hard it is to change the rear axle to a more fuel efficiant 3:73 or 3:55. Can someone tell me which would be the better axle for towing and what is involved in switching out the axle, do i need a different differential or can I just replace the pumpkin? Please let me know.
Thanks in advance,
Jim

 

For towing you'd want the 4.10s. Changing out the gears is just that... Changing out the gears. But, it'd cost you in the range of $1500-2000 to get them done (both front and rear).

 

To put in a new set of gears it will be about $700 per axle. Now there is a cheaper alternative. You can go to a salvage yard and find a 10.25 with a 3.55 or 3.73 axle ratio. For the front you only have to find a pig in the junk yard with the matching ratio. Just simply swap the axles themselves. You may have to do some spindle bearings or brakes on the rear axle, but as long as the axle is sealed and it wasn't trashed before it came in the inners are usually fine. The u-pull-it yard I go to an axle costs $45 and for $10 more they will cut it out of the vehicle and carry it up to your truck. A friend of mine just did this exact thing on his 97 F250 and it was only a few hundred dollars for the whole thing.

 

Hi, and thank-you both for the response. You say the 4:10 would be better for towing a double axle car trailer. Some folks say a 3:55 or a 3:73 would be better for towing, ie better fuel mileage. Can someone explain the merits of the better axle ratio for this 97 F-250HD 4x4 PSD. It as the 4:10 gears. But I want to understand why the 4:10 is a good axle for towing over the 3:55 or the 3:73. It would save me some money not having to do the swap. Please let me know if you can.
Regards,
Jim

 

Good grief, this has been answered in any of the threads on this subject you've posted already. Maybe if you ask it enough you'll eventually get the answer you want.




This is as plain and simple as anyone can make it.

The 4.10 gears are better for towing because the lower gearing can get the load moving better. They will cause your mileage to drop while going down the road because of the higher engine rpms.

The 3.55 or 3.73 gears are not as good for towing because it gets heavy loads going much slower. While cruising empty your mileage will be higher because of [drumroll]lower engine rpms[/drumroll].


You're towing a tandem axle car trailer, probably rated to 7k lbs I'll bet. At most its 10,400 lbs. You don't need 4.10 gears to pull that, its not a loaded 30' gooseneck My advice don't buy the truck. I shudder at what other questions may ensue.

 

a lot of people have even gained mileage when empty with 4.10's vs 3.55's

 

Maybe on a gasser... But on a diesel? Hell no.

 

oh, I didn't know that... thanks for the info