using 5th gear.

[briney]

now, i've got a 77 2wd f100. i'm in the process of fitting a cummins. i am looking for more usable gears than the t-18. also,an overdrive would be nice. the truck is 4400 empty. some times i tow another 4500-odd behind it. am i better off with 2.75 diff gears and direct top, which with my 31's will give me 1900 odd at 65 in top. or should i keep my 3.25's, and use an overdrive ? i was led to believe that towing in o/d does bad things to transmissions. any assistance will be much appreciated.

[heep70]

I tow in OD unless I am climbing a steep hill. I believe Advance Adaptors has a nice OD that fits inbtween the bell and the tranny.

Here is the tech link. http://www.fordification.com/torque-splitter.htm

[71 LONG BED]

i was led to believe that towing in o/d does bad things to transmissions. any assistance will be much appreciated.

I believe that's slushboxes (automatics) only. They get realy hot.

[heep70]

I tow in OD unless I am climbing a steep hill. I believe Advance Adaptors has a nice OD that fits inbtween the bell and the tranny.

Here is the tech link. http://www.fordification.com/torque-splitter.htm

Just to clarify, the OD in the auto I use in my PSD.

[Thunderfoot]

I had a 94 Dodge with the Cummins with manual 5 speed O/D and towed all the time in O/D, pulling a 9,000+lb trailer with no problems... It had 3.50 gears... My 03 D-Max has an Auto with 3.73 gears and I do the same with it, no problems.
I think that the 2.75 gears are not going to be enough to get the load moving unless you use a granny gear then after that it still would be a workout on the other gears...

[averagef250]

The ZF 5 speed is a great tranny. The Ford T-19 4 speed was made in close ratio version in the mid 80's.

Towing in 5th with a cummins NV4500 is not a good idea. NV4500's are not stout enough for the 5.9 and 5th gear fails in every one of them eventually towing or not. The 5.9 will tow anything in overdrive with the right gears and minor mods. Just because the engine will do it doesn't mean the tranny will take it.

[briney]

so is there anything i can use that will stand up to it ?

[Thunderfoot]

The ZF 5 speed is a great tranny. The Ford T-19 4 speed was made in close ratio version in the mid 80's.

Towing in 5th with a cummins NV4500 is not a good idea. NV4500's are not stout enough for the 5.9 and 5th gear fails in every one of them eventually towing or not. The 5.9 will tow anything in overdrive with the right gears and minor mods. Just because the engine will do it doesn't mean the tranny will take it.

Me and my buddy’s must be lucky... or the NV4500HD makes a difference... I heard of some issues with some nut on the 5 gear backing off that was some assembly issue that some had...
I put 80,000 miles on mine (4X2 dually) from new before I sold it... never an issue with it or the truck in that time...
My buddy used them from 94 to 2000 (trucks were 94-97 with the fuel turned up) for excavation work towing a backhoe and crawler (up to 32,000 total GVW) every day in 4x4 rigs and never had a problem...

I'm no trany expert; all I can go by is what I have been around myself... Been lucky I guess
From what I have seen I would think one behind a 4BT would be no problem…

Don’t want to start anything here as I only have only been around about 10 Dodge Cummins trucks directly to judge from, so let me know what it is in them that has problems…

[averagef250]

My business is Manual Transmission Service. I could sell rebuilt Cummins NV4500HD's all day long if I could find enough good cores.

I build atleast 2-3 standard NV4500's/week and usually sell one torque king NV4500 to someone that's broken several NV4500's in thier work truck.

Every NV4500 I've touched over 100K miles has needed a new mainshaft and 5th gear. A good friend owns a performance diesel shop. His bread and butter is 94-98 12 valve work and 4BT 6.5 chev replacements. Every truck he turns up has tranny issues shortly thereafter. The NV4500 is not beefy enough for 800 lb/ft.

I've got a whole shelf devoted to broken NV4500 parts.

[rjewkes]

i know that tthe 97 F350 i towed to the crew wih did better with the od turned off.

[Thunderfoot]

Thanks for the info Dustin, sounds like we were really lucky...

On Briney's 4BT project; what would you suggest as a "trans" and "rear gear" setup for his truck that might have around 9,000lb from time to time total CGVW (truck and trailer) with 31" tall tires??

[briney]

i have been looking at transmission options while i wait for some engine bits to turn up. i can buy a good used nissan cabstar 5 speed, with a sbf pattern bellhousing for around au$1200. then i need to buy a hd clutch, shorten the tailshaft, convert to floorshift, get the speedo to work, and the list goes on. i have looked at the ranger o/d. with my t-18 it will give me 6 usable gears with a 27% o/d. ( same as cabstar. ) i already have the T18 working in my truck, and the list of mods is short. the only drama i see with the ranger is the whole 2 stick thing. the last thing you want when trying to get something moving is to take a long time shifting. i had thought about some sort of vacuum motor to shift the ranger. with an electric switch on the gearstick along the lines of an old 2 speed diff switch. any suggestions ?

[briney]

anyone ?

[MaxKlinger]

i had thought about some sort of vacuum motor to shift the ranger. with an electric switch on the gearstick along the lines of an old 2 speed diff switch. any suggestions ?

I really like that idea, actually. Either use a pneumatic cylinder or a solenoid to shift from direct drive to O/D. I'm sure it's doable. We did the same thing on our Formula racecar at school.

The question is, (and this goes for all you guys with O/D boxes) do you shift in and out of O/D while you're accelerating? Or do you just use your T18/NP435/what-have-you normally and then shift into O/D when you get some speed in 4th?

If I put an O/D box in my truck, I imagine I'll just shift from Direct to O/D after the T18 is already in 4th. The first four gears (especially with granny) should be good enough to get loads moving. That way you woudn't be shifting both boxes all the time and it wouldn't be so bad to have two shifters.

[averagef250]

You used to be able to get the rangers vacuum and air shifted. A friend has an air shifted ranger in a chevy dually with an isuzu 6BD turbo and sm465.

It works nice when it works. He's had to replace and re-engineer the shifting mechanism several times to keep it working.

He's well over 400 HP with the 6BD and the ranger's doing fine. He usually splits 2nd and 3rd even empty.