Hey everyone,

I am new to the truck scene, and have been wanting to buy myself an older ford (85, 86 preferably) and I thought too look around to figure what I would get for mpg and found a lot of information about ratios and I didn't even really think about speeds. So I am more confused than when I started and I just want to get some advice from some owners of these trucks. I am looking at the 6.9 engine because that's what comes in those years, also I want a 4x4 and I want it to be diesel, obviously.

I was reading that you can change the ratios pretty easily, and I am competent in doing my own repairs so that's fine, but I also thought I read that you cant just change all of them, so If I buy a truck, I wan't to know what ratios I can change it to.

I live in Mass, so more than likely I will be on the highway and will go between 55 and 70.

Thanks Again,
Devin

 

Seriously guys, nothing!

Help me out !

What kind of transmissions options am I gonna get?

What kind of ratios options do I have?

Can I preform a 5 speed swap? If so what would my ratio options be?

 

probably 4 speed with 3.55s will run 70mph with 285s turning 2800 rpm with 12-13mpg.if you zf5 5 speed swap 5th will be useless with 355 for pulling 411 is what came in my 94,mine pull strong until a big hill.i get 13-15 mpg but i pull a landscape trailer 5 days a week

 

First of all, thanks for the reply, I was beginning to think that I was just going to get swept under the rug.

Also to get things straight,

in the years 80-86 there were two trannys offered correct?
c-60 I beilive which was a 3-speed manual
and t-19 maybe which is the 4 speed auto

That was it right?

Also I understood that the zf5's 5th gear would be 1:1 ratio and so isn't the 4th in the t-19 so swapping would really not matter as far as pulling power, that's more of a issue with the gear ratio of the 355's, but if my plan were to say get a zf5 and change to the 4:11 that would not be so bad on power, do I understand that correctly?

also like I said before, how do I know what gear ratios the zf5, t-19, & c-60 can take?

My main goal would probably to be bring the mpg down, I need a truck that I can use for wood, garbage and craigslisting. I have a utility/converted horse trailer 6x14 but It just has my tools in it and I belive it is about 2500 empty, so even if it was loaded with 1500 pounds of junk, I should still be fine I would think even if I did have the lower gear ratio.

If not call me out on it, cause I wouldn't want to under power so much that its worthless, but then again I really don't see myself moving the trailer, its just a work shop for me, and if the truck I get can't move it, I can always borrow one.

Sorry for the long winded comment

 

hmmm nothing, eh

 

Top gear on the 5spd is an overdrive.

You got your transmissions backwards. C-6 is 3 speed automatic and T-19 is 4spd manual.

Once you get past 60mph, your mileage will go down greatly just from wind resistance. However, lower rpms are good.

My 85 has 4.10s and runs 235/85R16s, for about a 32" tall tire.

My 90 has 4.10s as well with identical tires.

The 85 is an F250 regular cab long bed with a camper shell, it has a 4spd and a 6.9. The 90 is an F350 crewcab long bed with no shell, it has an E4OD (overdrive automatic) with a 7.3. Both trucks are 4x4.

If I keep the 85 at 55mph or lower it gets 19mpg. The 1990 gets almost similiar mileage at 60 (around 18). I'm sure it would get better if it had a 5spd instead.


I had a friend with an 85 that had a 4spd and 3.55s. Running the same tires I run he got better than 20mpg at 60mph. He claimed 25+ Not sure about the 25 figure, but I can see 20 easily enough.


Again, an important factor is speed, but RPMS are very important here. Sounds to me like 3.55s is what you'd want if you aren't going to change the transmission. A big reason I don't like to take my 85 past 55 is RPMs. I have no problem taking the 1990 to 70.


I usually am doing almost perfect driving for mileage. We don't have to stop too often and I do longer stretches when I drive. Again, mileage can easily drop by 20% or more between 60 and 70mph. I may reclock the 1990 at 65 eventually to see what it actually does, I do know it'll be lower.

 

Thanks for the reply

Yeah I guess I got em mixed up, that's good anyways, cause I wanted manual and I wanted the 4 or the 5 speed.

So does anyone know if when/if I get the zf5 can I swap to the 355 ratio? And am I gonna be severely underpowered as far with a load or with a trailer, or can I just baby it and be alright?

Also what about duallys, is that gonna kill my milage? Is that something I should stay away from, I see a lot of trucks have them and not sure if I should shrug it off or stay away?

---AutoMerged DoublePost---

86 Ford F-350 Diesel


What engine is this!?!???

 

on dually's I heard you can remove the extra wheels, does anyone know if that's true?


Also what would you guys say about the 7.3 engines, I am wondering incase I find a deal on a newer truck, I would really like an 86 or prior body style but if I have to I am just wondering if there were any major issues in either of the engines that anyone could point out to me?

Also what did the 7.3's come in for trannys?

Thanks Again,
Devin

 

I have a 85 F-250 6.9 and its my daily driver, it handles 70 at about 2,500 rpm no problem. Plus I get 20Mpg out of mine all day long. I highly recommend The 85-86 6.9s. Even in the mountains of Oregon with Radial tires I beat out all these other trucks

 

6.9's are great. i got 20mpg empty all day long. unfortunately blew a headgasket at 180k in the mountains. ran it for a while after that and it still ran ok most of the time. still 20mpg. it never let me down. It definitely didnt make for the fastest truck but with the 4 speed with granny 1st it would pull