Oddball transmission ideas

[Booyah45828]

I have you going 90 at 3000 rpm in direct with 235/85r16 tires and a 5.13 rear axle.

Here is the gear/speed calculator I use. I find it pretty interactive. Best to probably use it on a computer vs a phone.

https://www.blocklayer.com/rpm-gear.aspx

Nevermind, I had mine in km/h

 

[ISPKI]

S-series internationals would have them all as well. Essentially any IH from 83 when the IDI came out to about 94, when the T444e/powerstroke took over. I'm not all that sure on parts interchanges with 404/446 stuff.

Best bet would be to get a donor vehicle, and swap like for like. I'm sure you could find something cheap for sale that's rusted out. You might even prefer the heavier duty IH over the superduty

Yeah thats the route im looking at. I have seen plenty of older medium duty trucks being retired and stripped for parts around me. Even looked at an older F-700 for 1000$. Thats just too big for what im doing. I will still need to fit it onto some trail heads and still want it modern enough that I can find parts for it.

So, single shaft vs double shaft transmissions... Are all overdrive medium duty transmissions double shaft? is that where the 6+1 comes from?

 

[ISPKI]

Nevermind, I had mine in km/h

Hah! I think the only way this truck will hit 90 is if I drive it off a cliff!

The old dog cruises at 65-70 comfortably enough as it is right now. Might be able to hit 80 but id rather not find out.

 

[subway]

So, single shaft vs double shaft transmissions... Are all overdrive medium duty transmissions double shaft? is that where the 6+1 comes from?

No, but like I mentioned. The single shaft overdrive medium duty transmissions are not very common. Before I found my eaton fuller I was looking at the 5 speed overdrives from a duece truck. It is also possible to order the gears to make a eaton fuller overdrive but that can be a bit of work piecing parts together.

It took me close to a year to find my transmission but it should outlast the truck. The loads I am putting on it are a joke compared to what it can do.

Another option is to just run large tires so you don't need overdrive with 3.55 gears.

something else to think about, you wont be speed shifting these big transmissions. They have a lot of rotating mass and shift normally just fine but could not match as fast as my ZF could shift if I was pushing the limit.

 

[Booyah45828]

Yeah thats the route im looking at. I have seen plenty of older medium duty trucks being retired and stripped for parts around me. Even looked at an older F-700 for 1000$. Thats just too big for what im doing. I will still need to fit it onto some trail heads and still want it modern enough that I can find parts for it.

So, single shaft vs double shaft transmissions... Are all overdrive medium duty transmissions double shaft? is that where the 6+1 comes from?

The 6+1 is single countershaft, as are most MD 5 and 7 speed transmissions. They're more often found as direct models vs OD ones in my experience. Your twin countershaft units are more of your HD transmissions, and will have 8 speeds plus. They'll have 4-5 speeds in the main box, and then 2-3 speeds in a splitter box bolted onto the back of the main. Your twin countershaft transmissions are more robust, but they will be pretty tight between the frame rails of a pickup, and will likely require floor pan mods to make it fit.

The 6+1 is called that way because it has 6 synchronized gears, with first being unsynchronized, kind of like a granny gear. It being synchronized will allow you to shift it like a zf5, or any other pickup truck with a manual. I'm not aware of any twin countershaft transmission that are synchronized. So with those you'll have to double clutch or float gears.

 

[ISPKI]

Got it, very interesting info. My truck is running and driving just fine with an E4OD that was rebuilt in 2013. Sometimes it blips into limp mode but goes away if I shut the truck off. It also shifts a little funny sometimes. Might be alot of issues that I am still hunting down.

Sourcing a donor truck will take some leg work. Basically have to find a possible donor, check the numbers on the trans. Look them up and verify gear ratios... I dont mind slow shifting, like I said, this truck is work duty only. I have no interest in trying to race it around or anything like that.

 

[ISPKI]

I have a local person with a DT466 mated to some kind of 10 speed transmission. The DT466 is blown but I am curious what kind of 10spd would have come mated to it? ive found some info on Eaton 10 speed dual range transmissions and it looks like many of them have a .74 OD but it also has air input lines which im not sure about.

 

[Booyah45828]

10 speed would be a twin countershaft unit. The air lines are to operate the splitter. Get a tag off the transmission and you can determine the gearing. Some had OD, some didn't.

 

[Old Goat]

When I was working, we had some RTO-910 I think they were. They had the OD as I remember.
On the side of the shift lever is a air shift knob. In the down position you are in the low range. 1st thru 5th. When you are ready to go to 6th, pull up on the knob, you are now in the high range, and go to 1st which now becomes 6th gear and onto 10th gear.

We had a lot of the DT466 engines, they ran good, and don`t remember having much trouble with them, but they will put out a lot of thick white smoke when a Turbo lets go... That was a fun day.


Goat