gears / rpms

[5.0 Kid]

Hi everyone

My dad has 2001 explorer sport. He loves the truck. loves towing chevy's out of ditch with it. But he hates his gas mileage. after crunching some numbers, I think it doesn't add up. his diff says he has 3.73 gears, he has 255/70/16 tires, and at ~ 100kph, 60mph in over drive he is at 4000 rpm. Does this make sense to anyone.

 

[martin]

I'm not certain but I think the rpm's should be closer to 2200. Sounds like it's not shifting up for some reason, don't know why though. I'm sure someone else will post with some more useful information.

 

[Mac]

Sure sounds like it's not shifting as mentioned. You ought to be able to tell just from the sound if it's running that high. I've got the same diameter tires and with the 4.10 gear, only doing 2300 rpm at 70 mph.
Dave

 

[James86]

My 3.0 with a 4sp auto and 4.10" does 2200rpm at 60~ and 2800rpm around 70mph, and I have 225/75R15, or whatever was stock size.. don't recall the number

 

[85_Ranger4x4]

With 3.73's, 235/75-15's and a 3spd (third is 1:1) I was turning right about 2800rpm at 55mph.

How many times does it shift? My guess would be once, third would still be a much lower RPM than he is seeing. Mine was, and I had much smaller tires to boot.

 

[5.0 Kid]

The odd thing is when you press the over drive button, the little light comes on and says od off it goes up another 1000 rpm's

 

[exbass94]

OD gear ratio is 0.75:1. So given the tire size and axle ratio you gave, I calculated it out and at 4000 rpm, you would be going about 127 mph. Even if it's in 4th gear (1:1 ratio), you would be going 95 mph at 4000 rpm (assuming the torque converter is locked).
3rd gear is 1.47:1 ratio, which means you would be going about 65 mph at 4000 rpm. So apparently the transmission is never getting past 3rd gear.

 

[5.0 Kid]

Thanks for the info that makes sense. Does anyone know why its not shifting tho?

 

[exbass94]

I would try shifting down to the "2" position and see if anything changes. If nothing changes inspect the shift linkage and make sure it's working properly. It sounds like it's actually in the "2" position when you think it's in "D."

 

[06RangerXLT]

also, never trust the diff or tag. mine says LS 3.55 yet i have 4.56 locker

 

[5.0 Kid]

06RangerXLT did you change your gears? we never and we bought it off lease so I don't think they were changed, but could be possible. First thing Im going to try is what exbass94 said.

Thanks for the help guys

 

[adsm08]

Count the bumps when you put it in drive. Count off R, N, D. Drive it up the highway. Watch the tach for the shifts. The needle will drop when it shifts.

If it shifts more than once your trans is slipping.