Question 3.73 vs 3.55

[hntnv]

I am in the process of purchasing a new truck, and have noticed on the 08 and 09 F-350's there is 2 different gear options. I am looking for the Pro's and Con's of both. My 2002 had the 3.73's and it always pulled like a mule. My truck spends most of its life hooked up to trailers. I have a 28 foot bumper pull toy hauler that I pull whenever possible. Will the 3.55's pull as well as the 3.73's that were in my old truck? I would hope that when empty the 3.55's would get better fuel mileage, although the 6.4's aren't as efficient as the 7.3? What would you guys recommend? Thanks for the help. There is always lots of info available from you guys!!!

 

[BIG JOE]

As you said.. the 3.55s may get you better MPGs.. empty. But the 3.73 are real good for pull'n. And because you pull alot of stuff ? I'd go with the 3.73s.. In the long run, I think you'd be happier ?

I know I sure like my 3.73s..

Joe

 

[JLDickmon]

x2

 

[Zookie400]

i have 3.55's but now that my truck is seeing more towing time than empty, i am looking to go down to 3.73. with the 3.55s its a little sluggish off of a stop, and in the mountains it spends its life in 3rd rather than OD.

the 3.55's are nice for long straight empty stretches of highway

 

[Rusty74]

You should be fine. I pull the passes here in Colorado with a 2008 F-350 SRW, 5W and boat and have no problems at 60 - 70 mph. There is only 4% diffrence, it will make a diffrece if you go with a larger tire in the future.

 

[hntnv]

Thanks again for all of the info.. I have been without my truck for about a month now and am getting a little antsy. Looks like I better stick with the 3.73's. The 09 had 3.55's and alot more money, the 08 is 10,000 cheaper and probably a better fit... At least that is what my wife says.......

 

[patrickc]

A happy wife.... equals a happy life! hahaha...

 

[BIG DUTY]

Im not sure about the exact conversion but, with 3.73 gears and a 35" tire is it similar to a 3.55 and stock tires? I had stock tires and switched to 35" tires and barely noticed a difference in performance.

 

[yukondiesel]

Mileage can actually suffer with higher ratios, since the engine won't work in its most efficient torque range, resulting in more "pedal" to do the work. This manifested itself as lugging the motor and generating a lot of diesel smoke (pre-dpf) which equals wasted fuel.
Higher ratios can also keep the transmission from shifting into the next gear, effectively reducing the final ratio, depending on the speed of the truck. so the short answer is: " it depends". Good luck...Joe

 

[DaveBen]

I have been running trucks since 1970 and I would think 3.55 would be way too tall. As yukon said, you would be out of the power band and lugging it. Stick with the 3.73.

Dave