Going from 410 to 373 gears in 08 F350 DRW?

[trkworm2]

Hey Guys,

Fairly new to the sight and diesels for that matter. Obviously like all other owners, I am looking for better milage out of my 08 DRW. Will I get better milage by switching from 410 to 373 rear gears, and not lose my towing ability?

I have seen others discuss with older models, 6.0's and 7.3's, but have not found any threads on same topic for 6.4's.

I tow a 30" Fiver, not too heavy, but will trade up to bigger and heavier at some point, so I don't want to kill towing ability.

Many thanks

[sanman28]

Originally Posted by trkworm2

Hey Guys,

Fairly new to the sight and diesels for that matter. Obviously like all other owners, I am looking for better milage out of my 08 DRW. Will I get better milage by switching from 410 to 373 rear gears, and not lose my towing ability?

I have seen others discuss with older models, 6.0's and 7.3's, but have not found any threads on same topic for 6.4's.

I tow a 30" Fiver, not too heavy, but will trade up to bigger and heavier at some point, so I don't want to kill towing ability.

Many thanks

Not going to kill it, but you are dropping revs down about 100 rpms if you have 31" tires. if you have 33's or 35's your looking at about 150 rpms. Id leave it be and straight pipe it with a tuner. Thats more bang for your buck. I looked at going from 3.55's to 4.11's and it was going to be 2k all said and done. Tuner and pipes are 1200

[trkworm2]

I am running stock tires, just put new wheels on, stock size though, so whatever they are 265/70/R17's I think. I am through 4 gears inside of 35mpg with the 410's.

I have to imagine that if I can stretch that out a bit, so I can run 70-75 at around 2000 rpm, that I'd have to get better milage. Right now I am at about 22-2300 RPM.

I do have a Bullydog GT, DPF Back pipe, and S&B CAI, but all of that has made little difference in economy. I do get a little better milage towing, by about 1 MPH. That is only about once a month though.

Thanks

[Antonm]

If its your daily driver then do the regear for the milage and deal with the small reduction in towing performance for the 10% of the time you tow. If its not your daily driver and you mainly use it for towing the leave the 4:10's in there (getting a better tuner and delete the DOC/DPF will get you better fuel mileage). I also have an 08 DRW that I use for towing (not my daily driver), and it has the tow boss package with 4:30 gears. Since I tow an 18K pound toyhauler, the 4:30 gears really allow me to get the thing moving from a stop and climb hills, wouldn't trade them for anything when the trailer is hooked up. And unloaded on the highway I get a little over 14 MPG at 75 mph (and around 9.5 to 10 towing 18k at 70 mph) would probably get a little better if I'd slow down a bit (those are DOC/ DPF deleted mpg's).

[trkworm2]

I am definately going to do the DPF delete when I hit 100K. I am sure that'll make a huge difference. As for tuners, I have tried two and neither have made much difference.

That is why I was thinking taller gears or tires for a little better mileage on my daily driver.

Thanks guys,

[kingranch89]

that bullydog you got is trash sell it and get h&s

[trkworm2]

Thanks,

I've heard that the SCT and H&S are the bomb, with more custom tunes giving better economy. I don't have to worry about performance, and I don't race, so I was just looking for a little of both.

Honestly, I had the Ford factory reflash 11b23 done, and what a nightmare. They tune these things down if you stop in to check air pressure at the dealer, and man what a slug. Be that as it may, the best I can do is 17-18 at 65mph on the highway unloaded and no head wind, or 10-11 towning with my Fiver which only weighs around 10K loaded. If I jump up to 70 mph mileage drops to 13-14. I am not used to driving like ole Granny Alfred.

As I am new, the SCT and H&S was a bit pricey for me, and not really wanting to spend time with updates and custom tunes, I just wanted a little help. Yea, I know, near rear gears is going to be expensive, but then so will new larger diamater tires.

Thanks again,