I put in the spare tach senor I took off a truck at the salvage yard since my old one wasn't working, and had a question on the RPM's. At 60mph its reading at 2700 RPM, which seems really high to me, considering the truck has 3:55 gears, even with the C6. Could the sensor be off and give a bad reading, or is this right? Any thoughts?

 

what size tires? if your OD on the tires are 28-29" then ya, thats exactly right


this chart is in 1:1 gear at 60mph. 1:1 is 4th gear for the t18,t19, zf5 and zf6.... final gear on your c6 and 3rd in e4od.

 

and you sure they are 3.55's and not 3.73's or 4.10's?

 

the door tag from the donor truck and the axle tag on the truck now led me to the 3:55's. Truck has 30" tires on the back(215/85/16), so it looks like I should right at 2600RPM according to the chart, pretty close to what it seems to be reading. Thanks for the help oreo

 

a trans without overdrive today will kill ya at the pump.
you may want to look into gear venders,E40D w/pcm,or zf5 speed.
over time,you'll save $ if you plan to keep the truck around for any length of time,and drive often.
id drive a max of 40 mph if i had a 3 speed before i gave my $ to the oil co. not kidding either.

 

Im going to be converting to a zf5 and 4x4 in the spring, as long as I can find a donor truck with all the necessary parts. I hate having to piece together a project. That doesnt help me now, having to drive the truck cross country sometime this week, guess I'll just have to slow down as much as it'll kill me

 

My motorhome witch I do nothing but highway driving with hours and hours non stop has 3.54 and the 3 speed C6 and I love it that way! 2600RPM sounds about right judging from the sound of it when cruising @ 60mph. Gets ~11-13mpg depending on condition. On the coast of California this summer cruising at 100km/h (62mph) I got 14mpg out of it! 14mpg with a cottage on wheels! I run on 6, 215/85R16 tires inflated at 70psi for maximum fuel economy.

But for my application, I preffer NOT having OD for a non turbo motorhome, being...well a box on wheels, has a lot of wind drag, so keeping the engine revving up all the time is a good thing, it's not lugging, always has power on command, and it's the best automatic transmission Ford EVER made! So no worries about some silly sensors going bad and damaging the trans. when i'm at the other side of the country....


Plus nothing compares to the highway Roar of an IDI

 

And since the C 6 torque converter does not lock up, your RPM's will be a bit higher than what you would have with a manual tranny when the engine is under a load.

 

Would that chart apply to my truck? I'm running an automatic with the e40d, and 235/85/16's, I believe 3.55's and at 60 mph's with the OD on the rpm's sit at like 1500-1600 rpms. I can't get it any higher than 50 mph with the OD off, the engine is revving like hell at about like 1800 rpms but won't go faster.

 

that chart applys to every truck, car, semi made in the world. and like i said, its in your final 1:1 gear, for you thats with overdrive off. so turn your od off, get up to 60 and go from there.

 

can you word this entire statement in a different way please?
im interested in your problem,but can't make out what your saying really.

did you intend to say;
OD ON = 1500/1600 rpms @ 60 MPH
OD OFF (3rd gear.direct drive 1:1) = 2800 rpm @60 and feels like your hitting the governor?

if this is so,
why would you want to drive faster than 45/50 in direct drive anyway? because your towing or?
you can tow in OD unless she starts searching back and forth between 3/4.i don't share this problem with the 3.55's and shorter tires.i just let her find 3rd on the inclines and revert back to 4th when she wants at the top.

 

Something is wrong if the engine will not rev over 1800 RPM.

The stock upper RPM limit should be somewhere between 3300 and 3800 RPM depending on how tired the govenor springs are in the IP.

 

Thats exactly what I'm saying, when towing heavy loads I leave the OD off when in the city, and still off till about 60 mph on the freeway, then turn it on for freeway driving. but it only goes to about 1800-1900 rpm @ 60, not 2800 with the OD off.

It will rev over 1800, usually only when I punch it going up hill, but it rarely goes over 2500, and thats punching it hard at about 80mph. Never gotten it faster than that.

Even when I had the box filled with like 2500lb's, and a 6000lb trailer, punching it up steep hills in first gear going like 15-20km/h the rpm's barely touched 2000, and she was talking back on the quiet island road quite a bit.

 

When I load mine down, it rarely goes under 2000 RPM.

Run the tach up to 3400 and it usually drops in the next higher gear at about 2000 RPM.

With my engine setup, less RPM's would have the EGT's off the scale on the high end.

Then again, I am usually a lot heavier than those numbers.