OK, since it's called an E350 Super Duty, I'll post it here and see what comes up. Please I only want to hear from people who actually know something, not some crap about how E Series are some off brand or Red Headed stepchild made with left over parts etc.

Here's what I have: 2008 E350, 5.4L, 4R75, 3.73 rears, 265/75R16 tires.
It came stock with 225/75's, I went with taller front springs and 265/75 tires to get the look I wanted. This is also my first Automatic transmission EVER.

I understand that I changed my rear end ratio to the equivelant of 245/75 16's with 3.58's when I did that. Other than the speedo being 8% off now, I haven't noticed a difference in daily driving.

This weekend, I pulled a 2,500# trailer,10,500# gross combination weight, without problem on some huge hills in B. C., lots of power, even up 8- 13% grades.

Some of my questions:
1) Am I doing any damage to my transmission with the changed gearing?

2) Can I correct the speedometer and how?

3)Should I change fluid more often with this set up? I intend to change it every 30-35K.

4) Have I changed shift points by doing this and what does that mean to the operation of the transmission?

5) Is the 4R75 a good transmission and up to the job in a 13,000# GCW vehicle?

6) How do I know when the troque converter is locked and should I drive that way whenever possible?



Thanks

Bob

 

Dpn't worry about it, I post about my E350 here all the time.

4R75?
Are you sure you don't have the 5R110 TorqueShift?
Thats what the 5.4 trucks got in 08, and thats what the V10 and 6.0 vans had for that year too.

The tire change should not hurt it.
You can have it reflashed with a tuner or at a dealer to correct the speedo and shift points.

Do you have a tow/haul button, or an O/D off button?

 

Yes 4R75. O/D button. 5 speed was an option.

 

No, there won't be any damage.

On my old 1995 F-150 I had a 4R70W automatic. I upgraded to 31X10.5X16 tires, about 3 inches larger than stock. I drove truck about 200K miles like that, without ANY transmission issues. I did tow, up to about 4000 pounds.

At 30k I did have the rear seal fail, but that was on stock tires and was an easy fix.

 

Vans are cool. I want to find a late 70s/80s Econoline 250 cargo in good shape...