What's the rpm at highway speed

[benjiyam]

I,
I'm looking into buying a 1999 4 door, dual RW F-350 with 7.3L PS. I have test driven the truck and at 60MPH it is running at 2500 RPM , is this normal for that truck. It as a 4 speed automatic transmission. The truck only as 70 000 mile (110 000km)

Thanks,

Benjiyam

[Dave]

sounds about right for 4.10 gears. Does it have 4.10's or 3.73's

---

Last edited by Dave : 04-12-2007 at 11:44 AM. Reason: added ?

[Banshee34]

I run over 70 at 1999 rpm's???

[cblackb]

Yeah with the deep gears she's gonna be wound up decently high at highway speeds. I've got 3.55's or 3.73's I can't remember..but I run around 1800 at 65. Your mileage will suffer but it'll pull like crazy.

[MrJohnWayne]

I've got the same truck (except I have a 6 speed.) It has 4:10's. At 70 mph I'm running 2350 2400 RPM's

[benjiyam]

Thanks for your answers,

In conclusion with a 3.73 = 1800 RPM at 60 MPH

withe a 4.1 = 2300 RPM at 60 MPH

[Maintain]

Originally Posted by cblackb

Yeah with the deep gears she's gonna be wound up decently high at highway speeds. I've got 3.55's or 3.73's I can't remember..but I run around 1800 at 65. Your mileage will suffer but it'll pull like crazy.

With 4.10's and the stock 30-31" tires at 60mph with 4.10's you should still be just a tick under 2,000 RPM'S. Unless you have an OBS 10.25" rear axle - you have 3.73's from the factory.

Originally Posted by MrJohnWayne

I've got the same truck (except I have a 6 speed.) It has 4:10's. At 70 mph I'm running 2350 2400 RPM's

This sounds about right... HOWEVER the Auto will run lower RPM's then the 6 speed in it's final gear since the auto's O/D is .71 and the 6spd is around .8 something... The #'s might be SLIGHTLY off...

Originally Posted by benjiyam

Thanks for your answers,

In conclusion with a 3.73 = 1800 RPM at 60 MPH

withe a 4.1 = 2300 RPM at 60 MPH

My conclusion is that the truck has TINY tires on it - around 24" tall. Probably not.
The gears have been changed... to something as high as 4.56's. Possible.
You were driving around in 3rd gear (with O/D off). Most likely.

At 60 with a rear axle ratio of 4.10 with 32" tires in 3rd gear you'd be running 2500-2600 rpm's.

[95PDXLT]

Originally Posted by Maintain

At 60 with a rear axle ratio of 4.10 with 32" tires in 3rd gear you'd be running 2500-2600 rpm's.

Agreed

my guess is 4.10 in drive with a slighty larger tire than stock. I had an 89 7.3 with 4 speed manual no o/d and with the stock tires it spun 2600-2700 @ 60mph.

[PSDfan99]

i have a 99 and its got 3.73's and i can go 70mph at exactly 2,000 RPM

[cblackb]

Ok I got curious and went for a drive. At 70 mph I'm not quite to 2000 RPM and I'm running stock tire size of 265/75/16's. I think I do have 3.73's. Yeah you may want to verify that you're indeed in OD and not 3rd.