So took my 21' boat to the lake and the e40d and 3.55 gears blow for towing. I couldn't hardly pull the trailer up the ramp and it shifts like crap

 

i got 4.10s on my new truck wish we could trade axles lol i miss my 3.55s

 

If i had a zf5 I'd be happier

 

My E4OD and 3.55s shift like crap. I haven't pushed it hard or anything, yet, but my 1st gear seems especially doggy. This is a big reason why my 5 speed swap is in progress.

 

I pushed mine really hard it was trying to pull a hill in d with the od button off had it to the floor and it won't down shift till it got down to 40mph and then it seemed to rev to high it's like it won't unlock the torque conventor in 3rd and when it does unlock it drops into 2nd and keeps it unlocked and revs to high

 

Yeah, I hate the way my E4OD shifts.

 

Some guys love them I don't get it

 

Do you still have your 52" tires on there? That will make those 3.55's way way WAY too HIGH a gear if you do. If the speedo hasn't been re-calibrated that will cause it to shift all screwy too.

 

Don't you mean that the 3.55's will make that far to high of a gearing? Conventional wisdom would tell you to compensate for oversize tires with a really low gearing like 5:1 or lower.

 

High, low whatever you want to call it. 3.55's wouldn't be bad for towing with stock size tires, but you seriously need to re-gear to 4.56's or more (higher, lower) so run tires that tall.

If you don't believe me, look at 427Fordman's setup. And he tows that with 3.55's and an E4OD just fine.

 

Yeah. The higher the number is, the "lower" the gearing is. It means more driveshaft rotations for every axle rotation.

 

Mine tows great with 3.55's and 33" tires... but I have stage I's and a PHP chip which help a TON!

 

if he has 52 inch tires the final drive ratio would be 2.52

 

I have 2 trucks
A stock cc swb f25e0 2wd with e40d and 3.55 gears and 343k miles. This truck tows like crap

A 97 cc swb 4x4 zf5 and Dana 60 with the 52 inch tires

 

You've got some issues somewhere, a 21' boat should be no problem at all, no matter what. Mine stock before any mods I pulled a 32' enclosed bumper pull trailer loaded all the time without problems. You ever done injector work on that truck? 343k is a lot of miles on stock ones.

The e4od never shifts great stock, but was majorly improved in mine with a valve body. Now it is as good as can be. Your power is down, that is why its trying to go to second at that speed.