6-speed manual trannie

[Papabear]

i was wondering will a 6-speed manual tranny for a 7.3 psd will fit on a 7.3 IDI or does anybody know of a way to get more gears behind an IDI without to much BS because i wanna go bull low but i also want good tall highway gears for fuel ecnonomy. I was contemplating a 6-speed manual with a 2 speed slave box behind the tranny and a 2 speed rear-ends with a divorced transfer case as i want to be able to be a 6x6 on demand and just lock up the tandems this truck will be worked in severe conditions once it is built. unless anybody has any better ideas. skies the limit


Thanx

 

[FordGuy100]

I know of only one guy who did it, and last I heard he was selling his truck. He is a member here...havent seen him in a while. Anyways, the 6spd swap was very intracit, there was a lot of modifications and one off pieces. IMHO its not worth it for the 6sp, a ZF is good enough.

Geez man, with all those overdrive's you could be idling along at 70mph . I dont think it will work though....a tranny plus transfer case plus overdrive box will probably make the driveshaft angle a little excessive, but I guess you could rig something up to fix that.

If'n you got enough money, that I would say go for it...but there will be a lot of modification involved. And if you do decide to do it, take lots of pics and tell us how you did it.

 

[Diesel JD]

Brownie box or roadranger would get it done cheaper but it would still require a lot of fabrication and such. Justin is right about the ZF 6, Jaybee did it but he's in the custom automotive business or some such professionally. He had kids, needed a crew cab or more family friendly vehicle, and the 7.3 dropped a valve. Don't know if its worth it or not, your call.

 

[discbrks]

A ZF-5 with a 3 speed brownie would give you 15 forward gears and 3 reverse. That set-up wouldn't be very hard at all to build.

 

[LCAM-01XA]

How about just an underdrive unit behind the transmission, then a divorced T-case? With a regular ZF5 and factoring the low range of the T-case that's 20 forward gears, with them bigass tires you got on that truck you only need like 3.55 rear gears and you're in the nice and comfortable 1400rpm range when flying down the freeway - engage the underdrive for in-town, throw in the low range off the T-case when you get off the pavement.

 

[JPR]

It is easier swap with the two wheel drive, but can be done even with a 4x4. The issues with the 6 speed are:

The 6 speed has a different input shaft (1.375 vs 1.25) and output shaft (24 spline vs 31 spline). So a custom clutch disc will need to be made. The old transfer case can not be used, so the 6 speed transfer case will need to be installed. This means loss of the speedometer drive, so you will need to modify the instrument cluster to hold a 92 speedometer.

The 6 speed clutch slave must be used, however it uses a different size pressure line so and adapter must be made up to splice idi line to the 6 speed line.

Fab a new crossmember and an adapter plate for the two upper bell housing holes which do line up.
Add an automatic transmission cooler and lines.

 

[RLDSL]

If youare really need ing that many gear combinations, you would be better off with a zf5 and a 4 speed brownie with a diviorced transfer case behind it.
The zf and brownie would give you 20 possible gear combinations. use the search feature in this section for brownie and auxiliary for some recent threads. I'm getting ready to do an install of a 3 speed brownie box behind a zf5
If you needed SERIOUSLY heavy duty you could get a twin countershaft unit and get in in an air shift box, keep in mind, it would weigh a BUNCH and the extra countershaft would contribute to friction losses

 

[Agnem]

The only way it would be worth it is if you have a free 6 speed in excellent condition sitting in your garage. Otherwise, pay the two grand and buy a gear vendors to go behind the ZF. Your time is probably worth a good bit to you, and Jaybee had a lot of machining into his ZF6. The six speed doesn't buy you anything, and in fact you'd end up with less gears than if you got a commercial add-on GV or US Gear.

 

[69dieselfreak]

i think a twin counter shaft trans is a little too heavy for our trucks and the input shafts are huge and adapting a clutch and the clutches desinged for those trans are heavy as hell and id think ud be robbing a bunch of horse power trying to turn those things
in this case ud might as well buy a single axle tractor and put a pick up bed on it and there you go it all ready set up

 

[RLDSL]

i think a twin counter shaft trans is a little too heavy for our trucks and the input shafts are huge and adapting a clutch and the clutches desinged for those trans are heavy as hell and id think ud be robbing a bunch of horse power trying to turn those things
in this case ud might as well buy a single axle tractor and put a pick up bed on it and there you go it all ready set up

I couldn't agree with you more, but I took one look at the setup he has figured up for axles already, and it's obvious that he's already figured out that this rig is going to spend most of it's horsepower trying to get out of it's own way, might as well give him all the options Besides, his wife already gave him permission

There are some lighter duty single countershaft air shift four speed auxiliaries, keeps the cool factor up and the weight factor under 400 pounds Only problem is those single countershaft jobs are really hard to find in an air shift. That's what i really wanted, but I finally gave up when a good deal on a 5831 with the right gear combination popped up for sale close enough to where shipping wouldn'nt kill me

 

[MARQ2277]

ZF 5 speed and gear vendor would be the ticket and it would all bolt up without a bunch of bs. I used a gear vendor behind an M22 muncie in a 66 El Camino, and it was worth every penny.

Marq
________________________________________________

 

[Diesile]

I hope the GVs are stronger than they were in '88 or so.

My unmodded 6.9l twisted a main shaft in two after about 60k miles

GV offered no credit towards a repair or new unit.

 

[towcat]

I hope the GVs are stronger than they were in '88 or so.

My unmodded 6.9l twisted a main shaft in two after about 60k miles

GV offered no credit towards a repair or new unit.

they've got stronger units now.
i do find it hard to believe that they didn't do anything for you. I have quite a few trucks that babysit with GV's in them. any of them with over 100k on the odo with the GV has broken the GV. The factory has been very accomodating in selling me rebuilt units as long as I sent in the broken one with all the broken parts. I think they are currently supporting the "type P" units. Those of you reading do bear in mind the trucks are running at 10k gross and 20k gross combined daily.

 

[MARQ2277]

Wow. I hope they are stronger. They sure bragged about handling all this horse power when I bought mine. If course, horse power is one thing, twisting torque is another.

Marq
______________________________________
1990 Ford F-250 4X4:
7.3 IDI with 120K on the clock:
ATS Turbo with waste gate:
Stage One Injectors (Oregon Injector Service):
Complete Return Fuel Kit (Oregon Injector Service):
DB2 Pump, cranked up with Cold Advance wired permanently on:
4” down pipe, 4” straight through exhaust stopping between cab and bed (no **** on my stuff):
Torque Converter Lock Up Switch (On/Off/Lock-Up):
E4OD Line Pressure Controller (adjusted to fast/firm shifts):
4” lift w/Rancho shocks:
Big Fat Tires on custom rims:

Tows 1985 fully loaded heavy 28 foot RV (my house) everywhere:

 

[towcat]

Wow. I hope they are stronger. They sure bragged about handling all this horse power when I bought mine. If course, horse power is one thing, twisting torque is another.

Marq

there is a huge difference when you are talking about a company truck vs. your own ride.