Got a little more rv so, I replaced my 3.73 rear end with a 4.10 on my 2K 5.4 auto SC SB. Took a 1200 mile fishing trip to International Falls, MN and beyond. Got 17 mpg compared to 16. I like it a lot better. Doesn't downshift on every bump in the road. Love this site.

 

Did you change gears on spedo and odometer as well?
If not your odometer shows 1 mile, when it actually makes 3.73/4.10=0,0909
Meaning your calculated 17 mpg is actual 15.4

 

I understand there is no speedo gear on my 2000 f250. It's all electronic. At any rate the speedo is still dead on as it was before. I was more afraid of the shift points. If they changed, it was for the better.

 

I take it that was without pulling a trailer... but still thats really good... man your gonna make me wish I didnt order the V10 with that kinda milleage, my 6 banger super shorty F150 barely gets 17 on the hwy!

 

The PCM gets its speedo info from the ring gear (actually the tone ring on the ring gear). The speedo will always be accurate no matter what gear set it is changed to.

It will be off when the tires are changed to a different size.

 

Did you swap the gears yourself? Im looking at replacing my 3.73s, with probably 4.56 or 4.88s, Im running 285s on it (33s) and it pulls a little week. I will probably also have the tranny rebuilt once I get my POS Honda straightened out.

 

I'd go with 4.56s if I was you. 4.88 might be too steep for 33's.

 

I know my limitations. No I had it done by an outfit called ring and pinion. They have done stuff for me before so I know they are good.

 

No BigPapi I did not do it myself. I know my limitations. I had it done by Ring and Pinion in Waterford MI. (they did it cheaper than I could buy the gear set.

 

Going from 3.73s to 4.10s isn't much difference. I would have gone right to 4.30s. Check the speedo with the GPS I highely doubt its off.

 

I prefer 4.10 gears too. I go from sea level to 4500 ft in 40 miles allot and they fit the bill perfectly. You don't mention tire size so I guess your stock.

 

I have been told on mine to go from the 3.73's to 4.30's.. Should I go lower? or is 4.30's ok?
Are they hard to do yourself on this vehicle.. I have rebuilt motors and such but haven't had the pleasure to tackle a rear end yet.. Just a shade tree backyard mech... Thanks..

And MC9. Hope I get improvements like that...

 

Thats good mileage, I have a 04 reg cab 5.4 3.73 gear with 285's and the best I ever got was 15 with no load, only mod is a K&N filter and I thought I was doing good.

 

I actually got 18 once, going across TEXAS with a tailwind. I run commercial ta's 235 85 16. I always figured if I can hear my tires I am not going to get good mileage.

 

I actually got 18 one time going across Texas with a tailwind. I run Commercial TA's stock 235 85 16. I always figured if you can hear your tires you are not going to get good mileage.