Forum Discussion

Americamper's avatar
Americamper
Explorer
Mar 31, 2021

new Ford 7.3 gas with 3.55 axle ratio, does it work?

Anyone have the new Ford 7.3 gas with 3.55 axle ratio? If so does it work out for a 2500# TC?
  • mellow wrote:
    https://youtu.be/le_CdRGAmvg

    Video of the 7.3 with 3.55 gears towing 24K through the Rockies.


    Personally, I have a deep seated emotional objection to driving a big block motor down the road at 4,500-5,000 rpm..........moped maybe, big block, nope.
  • jimh425 wrote:
    Just fyi, my 4.30s kill MPG over 65. Yes, 4.30s are pretty high, but still, they have a huge impact even on cruise control. The RPMS are much higher. In case you didn’t notice, I have 6.4 diesel.

    And six speed tranny?
  • If it were 1978 and all I had was a 3-speed automatic transmission, I would have to say the 3.55 is a bad choice if you want to tow or haul much.

    HOWEVER it is not 1978 and the truck comes with at least a 6-speed transmission if not a 10-speed. The numerically lower axle ratios really "punch up" in this day and age due to the fact that there are more available gears to better match the load being towed.

    I don't know what the fascination is with being able to roar up every hill in top gear. It does not make sense to me. You're leaving a lot on the table for when you're not towing or hauling.

    On a 6-speed, you run in 4th when towing and 5th and 6th are for when you're not towing.
  • Absolutely amazing this is even a point of discussion.
    A 5.4 under the hood of a F250 would haul a TC around at highway speeds without significant issue.
    Guess it depends what you want your 0-60 and 1/4 mile trap times to be with a camper in the bed...
  • Just fyi, my 4.30s kill MPG over 65. Yes, 4.30s are pretty high, but still, they have a huge impact even on cruise control. The RPMS are much higher. In case you didn’t notice, I have 6.4 diesel.
  • Right, with the ten speed tranny this will be fine. I think I would go for the 3.73, but that’s me.
    Will you be towing anything behind the TC?

    What is your goal for the 3.55 ratio?

    IMO rear end ration has very little effect on mpg. Driving habits will have a greater impact.
  • I don’t but if it has the 10 speed transmission my guess is it would be fine even on mountains if it is rated for enough payload. Ford would probably have no advantage in producing a combination that can’t haul 2500. So, I’d look to see what payload it’s rated for.
  • Americamper wrote:
    Anyone have the new Ford 7.3 gas with 3.55 axle ratio? If so does it work out for a 2500# TC?


    I don't have one, but I would say no, especially if you also plan on towing anything or driving in the mountains.

    Flat ground, no towing, a TC which actually weighs 2,500 lbs and plenty of time to get where you are going, probably OK.

    I once drove two new F350 SRW V10 gasser Fords. One had 3.55 gears and the other had 4.30 gears. The 3.55 was a dog; the 4.30 was a rocket. I got out pulled by a 4-cyl Camry on I-65 in downtown Birmingham in that 3.55 truck.
  • Huh?

    Umm yeah, I mean, it’s got more than enough snort to haul around a TC.