When Should An EOD4 Shift Into OD

[u2slow]

I would just not use OD. Pretty simple.

 

[DirtyWood]

75-80? I don’t even drive my 68 Camaro or my Subaru wrx at 75-80mph. I’d never in a million years drive a 35+ year old 1ton truck at 75+. And people wonder why I get 25mpg. Slow down. It doesn’t really make up any real time and costs wear and tear, fuel and a wreck will be 10xs worse. In this particular case from the original post the island speed limit is 55. 55pmh with 35” tires is going to be very hard to do in OD. That’s the point of the post. Gotta turn OD off, get small tires or deeper gears. 4.56, or 4.88 is the correct gear sets for 35s.
I’d encourage everyone to look up gear and tire size charts and see original RPMS and how gears and tires effect RPMS.

I only drive fast on long trips. For every 100 miles driving 75mph instead of 55mph there is a 30 minute difference. So even a relatively short 300 mile drive would take an extra 90 minutes and that is not a negligible amount of time. Yes it is stupid to speed on an 8 mile trip to the grocery store but it does add up on longer distances. And yes you pay for that time savings,15mpg-17mpg, but my time is more precious than my money. The truck feels great at 75mph. I do find 25mpg to be a bit hard to believe as you are one of two people I've heard make that claim in 15 years of owning and being around Ford IDI trucks--not saying impossible but definitely an outlier.

 

[DirtyWood]

mine is 4x4 and factory tires size is 215/85/16 1994 F350 Dually 4x4

Yes dually trucks generally have the smaller tires but I'm fairly certain the OP's truck does not.

 

[YachtTech82]

75-80? I don’t even drive my 68 Camaro or my Subaru wrx at 75-80mph. I’d never in a million years drive a 35+ year old 1ton truck at 75+. And people wonder why I get 25mpg. Slow down. It doesn’t really make up any real time and costs wear and tear, fuel and a wreck will be 10xs worse. In this particular case from the original post the island speed limit is 55. 55pmh with 35” tires is going to be very hard to do in OD. That’s the point of the post. Gotta turn OD off, get small tires or deeper gears. 4.56, or 4.88 is the correct gear sets for 35s.
I’d encourage everyone to look up gear and tire size charts and see original RPMS and how gears and tires effect RPMS.

Yeah, 45mph speed limit on this rock. I have him driving with OD off for now, I haven't had a chance to experience what he's talking about yet.