Going 40s... New concerns...

[Pescatoral Pursuit]

and will likely rarely even use the last two trans gears at high way speed.

For anyone interested in real numbers and not made up speculation;

With factory diesel gears on 40s the engine does 1600rpms and happy to stay in 8th at 70mph, and shifting down to 7th does 2000rpms.
The "Current MPG" bow dropped precipitously when going from 8 to 7 leading me to believe the engine was not being overworked at highway cruising speed.

It also appears I've picked up .5 mpgs combined.

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[Rusty PW]

For anyone interested in real numbers and not made up speculation;

With factory diesel gears on 40s the engine does 1600rpms and happy to stay in 8th at 70mph, and shifting down to 7th does 2000rpms.
The "Current MPG" bow dropped precipitously when going from 8 to 7 leading me to believe the engine was not being overworked at highway cruising speed.

It also appears I've picked up .5 mpgs combined.

You have 40's on now?

Did you correct for tire height?

 

[Pescatoral Pursuit]

Did you correct for tire height?

Yes and yes.

 

[Rusty PW]

Yes and yes.

What was your corrected tire height?

I lost about 4 mpg going with 37's. I won't see an auto shift to 8th until 65 mph. Rpm is around 1,600.

 

[Pescatoral Pursuit]

What was your corrected tire height?

39.8 IIRC

 

[Lynn_F]

I daily drive and moderately off road with 40's and 3.73's. It drives like a dream...not quite as much pep as stock tires but still moves pretty quick. I had money set aside to re-gear and opted not to do it.

 

[Pescatoral Pursuit]

For starters your pinion angle is probably awful with a 5.5” lift. Upgrade to a 1350 drive shaft drive shafts or carry spare u joints

I think the pinion angles are okay.
I haven't lived the rear yet but will adjust accordingly.
Went from 3.5"to 4.5" springs plus 1" spacers while I decide on which full length coil springs to get.

I came here for the pictures of 5.5" lift with 40's and am disappointed...

Here ya go!

 

[Pescatoral Pursuit]

When the tires were put on we put 37 psi. The tread pattern showed it could use more so yesterday went to 40psi up front and 38 in an empty bed. Milestar Pats M/T 02.

Ride wasn't terrible before, but has smoothed out significantly.
I don't know if I'll keep it this way and risk wearing the crown out prematurely even though it's on the marks, there doesn't seem to be extra rubber there.

440 ft. lb. torque

Those are rookie numbers, m'lad.

Look into gears to bring the RPM's back down

You meant back up, right?

I don’t know, but I’m excited to see what you do!

I came here for the pictures of 5.5" lift with 40's and am disappointed...

Pics with a new paintjob!

 

[Sandevino]

Those are rookie numbers, m'lad.

Yup. My Cummins N14 makes three times the torque at idle.

 

[BearDog]

RCV in front. Chromoly in back. Truss both ends.

Freakin' send it!! ?

 

[Pescatoral Pursuit]

Yup. My Cummins N14 makes three times the torque at idle.

Talking about the EcoD.

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