Engine RPM's @ speed

[RumPunch]

So as I drive my Bronco and become more familiar with it I have a few questions. I can count that my A4LD is shifting through all gears and into overdrive but I question engine RPM at speed. Truck has 31" tires and is running 3.73 gears. I seem to be around 2400 RPM @ 60 mph. Does this seem a little high to anyone or no? Is it right on the money. Raises question if I was to go with a lower gear for off road, 4.10-4.56 , would I then be 3k + @ 60..?

 

[franklin2]

According to the calculator in this link, 2400 is a little high. What tach are you using? It could be suspect.

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

purperformance.com

The overdrive ratio for the AL4D is .75 to 1.

If you plug in 1 to 1 for the transmission gear ratio, which is 3rd in your transmission, you do get 2425 rpm at 60. Are you positive you are in overdrive?

 

[RonD]

Yes, +1, reads like its in 3rd gear not OD

1st is not a gear, first shift is to 2nd, then 3rd, then OD

Did the shifter you use have the P R N O D 2 1, so 7 detents

 

[RumPunch]

@franklin2 I will take it out for another drive to verify shift count and rpm as soon as I get a chance.

@RonD yes factory auto shifter so correct on detents. If I am following correctly I should only count 3 shifts right?

 

[2011Supercab]

Also try downshifting from overdrive to drive at speed to see if it actually downshifts.

 

[RonD]

Yes, 3 shifts; 2nd, 3rd, 4th

 

[RumPunch]

So I can confirm that the truck will shift into all gears 100% although it's a very subtle shift into overdrive, I definitely do not notice it every time. Once up to speed I can pull the shifter from O to D and feel the downshift and RPM's rise although not very much maybe 1-200 rpm depending on speed.

 

[2011Supercab]

At 60 mph it should change about 400 rpm, I think you're feeling the torque convertor lock up.

My 2011 with 30" tires and 3:73's runs at 2000 rpms at 60.

Not sure of the overdrive ratio on mine 5 speed auto.

 

[00t444e]

It should feel like 4 shifts. 1-2, 2-3, 3-3 locked, 3 locked- 4 locked. Sounds like the converter is locking in 3rd but it isn't shifting into overdrive.

 

[RumPunch]

I would have to agree. Didn't realize TC locked in 3rd? If that's the case then I would agree.