F350: 4.30 or 3.73 Gears

I have 4.44's in my Ram 5500 CTD. It is fine for me since I usually keep under 65mph. I would not want 4.88's for highway use with a diesel. 4.30's in a gasser should be fine. If you drive faster or live in the plains, you may want lower ratios.

With such a light trailer why would you even consider 4.30. I towed my 15K trailer all over the US with 3.73 with no issues and I'm sure glad I had 3.73 when driving around without the trailer, which ends up being the majority of your driving.

Many years ago 4.30 gears would kill the top end in a diesel truck, but with today's double overdrive transmissions it's not really an issue. Where I work we have an F550 with 4.88 gears and it runs at 70 with no issues, maybe 22-2300 rpm.

Kayli's Papa wrote:
I really hate to enter in to this spirited conversation mid stream , but I am in desperate need of advice. I HAD a 2013 F-350 6.7psd 3.73 rear that towed my 15000# fifth wheel. It has been wrecked and now I am looking @ a 2016 F-350 or F-450 . My question is if I opt for 4.30 gears what will I gain /sacrifice over my 2013 in terms of fuel milage, top end etc.etc. I understand that I will have a better bottom end but at which cost.

I would greatly appreciate any advice or feed back that can be offered

When talking about diesel 3.73 gears are great because of the rpm operating range, 4.30 gears would kill your top end.

We've been discussing 4.30 gears in a gas motor not a diesel, gas motors make most of their power in the higher rpms unlike the diesel so the 4.30 gears are better suited for gas motors that are pulling loads.

Denny

Kayli's Papa wrote:
I really hate to enter in to this spirited conversation mid stream , but I am in desperate need of advice. I HAD a 2013 F-350 6.7psd 3.73 rear that towed my 15000# fifth wheel. It has been wrecked and now I am looking @ a 2016 F-350 or F-450 . My question is if I opt for 4.30 gears what will I gain /sacrifice over my 2013 in terms of fuel milage, top end etc.etc. I understand that I will have a better bottom end but at which cost.

I would greatly appreciate any advice or feed back that can be offered

Unless you plan to tow 30,000# the 3.73 has proven over the years to be the optimn gear ratio for Diesel engines. 15,000# will be no problem with the 3.73. If you are towing 25,000# or more 80% of the time then a 4.30 may be the best choice.

GM has consistently out pulled most with the 3.73. With a 6 speed transmission after 1st gear there is very little difference in performance between the 3.73 and 4.30.

You will suffer top end speed and mpg unloaded at highway speeds with the 4.30.

I really hate to enter in to this spirited conversation mid stream , but I am in desperate need of advice. I HAD a 2013 F-350 6.7psd 3.73 rear that towed my 15000# fifth wheel. It has been wrecked and now I am looking @ a 2016 F-350 or F-450 . My question is if I opt for 4.30 gears what will I gain /sacrifice over my 2013 in terms of fuel milage, top end etc.etc. I understand that I will have a better bottom end but at which cost.

I would greatly appreciate any advice or feed back that can be offered

I'm not seeing the mechanical difference in your second statement. Do you have a reference link or equation supporting it?

Bedlam wrote:
Something else to consider is that you are putting less stress on the transmission torque converter .

from a stop yes, moving no difference.

Also, if you are towing in 2nd overdrive 6th with the 4.30 you are putting more stress on that 6h gear clutch pack, then towing in 5th or 1st overdrive with 3.73 :)

Denny & Jami wrote:

Bedlam wrote:
Something else to consider is that you are putting less stress on the transmission torque converter or clutch on every initial start if you have a higher gear reduction in the axles.

That's also a very good point and another good reason to go with lower gears.

Denny

I agree with the lower gears helping remove some of the stress. Denny is towing very heavy, and needs the help of the 4.30 gears. I also agree that it is hard to compare the old C6, or E40D, to these newer 6-speeds. Gearing changes would be less noticeable, with the new tranny.

Jerry

Bedlam wrote:
Something else to consider is that you are putting less stress on the transmission torque converter or clutch on every initial start if you have a higher gear reduction in the axles.

That's also a very good point and another good reason to go with lower gears.

Denny