OD worth the $ ?

[u2slow]

Imho, the C6 is the issue. I had similar frustration with my diesel TH400 suburban. What you can optimize in terms of rpm and speed (by axle ratio) comes at a direct trade-off to pulling power.

Where I got to in the end was a 4spd manual swap and a ratio change to 3.21(from 4.10). I was then getting about 6mpg better, and had more torque off the line due to the 6.55 first gear.

With your 285/75 the tire is a bit shorter than the 235/85, so starting in 2nd is probably easier to get rolling. But with the 75`s the engine will spin over a bit faster at speed.

Check again. 285/75 is positively the taller tire.

 

[Old Goat]

Check again. 285/75 is positively the taller tire.

You may be correct on that.
I was thinking of the 245/75 which I have.


Goat

 

[Brian VT]

What's a comfortable highway speed with the ZF5?

 

[Rdnck84_03]

My '97 powerstroke with a zf5 and 4.10 runs somewhere around 2100-2200 rpm at 65, honestly never pay that much attention to the tach in this one i justshift by feel. On I believe 235/85/16.

My '99 powerstroke with zf6 and 3.73 runs about 1900ish rpm at 65. I think the o/d ratio between the 5 and 6 are really close believe the 5 is a .76 o/d. Don't remember exactly on the 6.

 

[Rdnck84_03]

With your 285/75 the tire is a bit shorter than the 235/85, so starting in 2nd is probably easier to get rolling. But with the 75`s the engine will spin over a bit faster at speed.

Honestly empty it takes off fairly easy in second except for I am pretty sure the trans input shaft bearing and pilot are worn so it shutters if you try to slip it at all. So I usually do rolling stops any time possible or if I have to completely stop, use 1st to roll about 4' then grab 2nd.

James

 

[Nero]

My zf with 4.10 runs about 2200 at 65 as well. Really starts to wind out at 75-80

 

[u2slow]

I got to drive a 4wd IDI/ZF/3.54 truck for a couple years. Excellent all-purpose truck; offroad, highway, whatever.

 

[ROCK HARVEY]

I have a zf5, 4.10 4x4 with 35” tires. I definitely could not live without that 5th gear. 70mph is only 2100rpm in my truck.

If I didn’t have holes in the floorboards and missing door seals, I’m sure it would be a lot quieter on the freeway!

 

[Rdnck84_03]

My zf with 4.10 runs about 2200 at 65 as well. Really starts to wind out at 75-80

I'm not sure where the top is on that one, it is mostly a tow pig. I have never been on the interstate with it. It is stock except I was told by po that they put bigger injectors in it. No idea what they are, but I'm guessing by the way it feels they are 160cc 30 over. It runs too good to pull them to have them tested.

James

 

[Black dawg]

I got to drive a 4wd IDI/ZF/3.54 truck for a couple years. Excellent all-purpose truck; offroad, highway, whatever.

I recently went to 354 in my truck but with t19 and us gear od. Now if I can just find a wide ratio zf this thing will be how I want it. It is a much more driveable pickup now.

 

[franklin2]

I went from a c6 to a zf 5 speed and changed nothing else. I gained 3 mpg with just that swap. And I was surprised how much torque the c6 left on the table.

I had a steep gravel driveway and with the c6 it would start out ok, but then the truck would stop and I would have to keep revving the engine to get it to move, and be careful not to spin in the gravel. After the zf swap I just put the truck in 2nd gear and let out the clutch. It just crawled right up the driveway without hardly touching the throttle.

The reduced highway noise is great. I was trying to figure out payback on the swap with the better fuel mileage, but the reduced noise and higher speeds made it worth it whatever it cost. In my case I found a wrecked donor, and after I sold off the c6, the spare transfer case, wheels and other various parts, I did not have much money at all in the swap.

If you want a automatic, I recommend the E4OD. Yes it needs a aftermarket computer to run it, but it's a much more efficient transmission and the aftermarket controller gives you the neat options that the newer trucks have, like tow/haul modes and manual downshifting with a button.

 

[Brian VT]

Should I grab these off CraigsList until I can decide what I want to do?

1994 E4OD Automatic Transmission was in a Diesel 7.3L 4x4 selling as a Core $100

Rear Ends 10.25-355 gears $275

 

[IDIBRONCO]

(I probably should have bought an F150 gasser).

But then you wouldn't have gotten to meet all of us cool guys and gals.

Is there any option for a lockup converter for the c6?

No, but you can use one of these to help reduce the slippage.

You must be registered for see images attach

Imho, the C6 is the issue.

I agree.

What's a comfortable highway speed with the ZF5?

In my Blue truck, I can easily cruise 75-80 with no issues (except or the cars with red and blue lights on them) and no turbo.

I got to drive a 4wd IDI/ZF/3.54 truck for a couple years. Excellent all-purpose truck; offroad, highway, whatever.

This is the set up I have in my Blue Truck with 235/85r16 tires. It's great except a little weak when towing.

And I was surprised how much torque the c6 left on the table.

This is why I say that the C6 make an IDI feel doggy.

 

[IDIBRONCO]

Should I grab these off CraigsList until I can decide what I want to do?

1994 E4OD Automatic Transmission was in a Diesel 7.3L 4x4 selling as a Core $100

Rear Ends 10.25-355 gears $275

That's up to you. The E4OD will most likely have to be rebuilt. That's costly, but shouldn't be more than the Gear Vendors you were looking at. You'd still have to buy an aftermarket controller too. The 3.55 rear end(s?) would be a start, but you'd still need to find the front end in order to use 4X4. I'm not saying don't get them, but you would probably be better off (in my opinion) to decide which route to go and then stick with that one. For your usage, I don't think that you'd need both an overdrive and the 3.55 gears since you don't see highway usage very often. Again, in my opinion, I think that you should go the E4OD route and keep your 4.10 gears. That way, you'll still have better acceleration in stop and go traffic. I also feel that would be the way I would go if I was in your shoes. I think that you'd be happier getting rid of the C6. Don't get me wrong, I love a C6 transmission, just not behind a IDI.

 

[Brian VT]

Thank you. I value your opinion.
I agree that the E4OD does look like it will suit my needs better than the C6.
Except that the reason I sold my modern vehicle and bought this old truck was to get away from computers and electronics.