Powerstroke vs IDI transmission question

[tgallmey]

My 1990 has a ZF 5speed in it and I was wondering something hypothetically. Lets say I found a good ZF 6 speed for a 7.3 PS would it mount up fine to my 7.3 IDI? Is anything Different

 

[CHKNFKR]

I cant say for sure whether or not the idi will bolt to a zf6, but even if it does it's still not a bolt on affair. The 6 speed is a taller transmission and will get into your tunnel. Most people throw on a 2" body lift to accomodate this on the obs psd trucks.

 

[tgallmey]

I cant say for sure whether or not the idi will bolt to a zf6, but even if it does it's still not a bolt on affair. The 6 speed is a taller transmission and will get into your tunnel. Most people throw on a 2" body lift to accomodate this on the obs psd trucks.

body lift is no biggy. I just wish I could do 70mph lol my truck has 410s and I dont wanna give em up lol just wish I had an extra gear at times

 

[Original_Ranger84]

Changing to a six speed wont get you any more speed, the final gear will still be a 1:1 ratio, but the gears up to it will be closer together so you will have a better selection of gears though.

 

[CHKNFKR]

Changing to a six speed wont get you any more speed, the final gear will still be a 1:1 ratio, but the gears up to it will be closer together so you will have a better selection of gears though.

Half true. The zf5 is already an overdrive transmission. The zf6 is also an overdrive transmission, both high gears are .73(i think) the 6 speed just gives you an extra gear to get there.

 

[huggyb1972]

What size tires are you running currently i was thinking about dropping down from 35's but was uncertain where I would top out at my govenor kicks in around 80 with a t-19

 

[Original_Ranger84]

Half true. The zf5 is already an overdrive transmission. The zf6 is also an overdrive transmission, both high gears are .73(i think) the 6 speed just gives you an extra gear to get there.

I didn't think most 6 speeds were overdrive transmssions. But yeah the extra gear will only really help in towing or racing kind of applications. because the extra gear isn't going past your original top gear.

 

[CHKNFKR]

I didn't think most 6 speeds were overdrive transmssions. But yeah the extra gear will only really help in towing or racing kind of applications. because the extra gear isn't going past your original top gear.

Yup. All the 5speeds and 6speeds are single overdrive.

 

[tgallmey]

I didn't think most 6 speeds were overdrive transmssions. But yeah the extra gear will only really help in towing or racing kind of applications. because the extra gear isn't going past your original top gear.

ah I c I didnt know that

 

[tgallmey]

What size tires are you running currently i was thinking about dropping down from 35's but was uncertain where I would top out at my govenor kicks in around 80 with a t-19

Im running lt235s and I wanna go up to 33s I wonder what speed Ill be able to run

 

[Original_Ranger84]

The 235/85's I assume? will only be about a 1/2" to an 1" taller then the tires your running now but wider and a little heavier. One thing I have noticed with my IDI (E4OD) is that they really don't have alot of speed to them. It has 3.73's and tops out around 85 - 90ish I think if its not towing anything.

 

[tgallmey]

The 235/85's I assume? will only be about a 1/2" to an 1" taller then the tires your running now but wider and a little heavier. One thing I have noticed with my IDI (E4OD) is that they really don't have alot of speed to them. It has 3.73's and tops out around 85 - 90ish I think if its not towing anything.

I have 4.10s I can do 55 at 2200 rpm lol I need to crank 70 mph out of her so I can drive 150 miles to see my girlfriend lol

 

[adsm08]

If you grab the 6 speed you might get away with 3.73s and not notice a difference in towing.

 

[CHKNFKR]

If you grab the 6 speed you might get away with 3.73s and not notice a difference in towing.

I know the idi and psds are compltely different animals but my '95 is sporting the zf 5 with a 3.55 rear. I only need first gear if i'm towing about 6000 lbs or more.

The point i'm getting at i guess is with a diesel, you don't really need much in the gear department.

 

[NMB2]

I ran both of my IDI's @ 2600rpm on the highway. Not an issue.