ok so i pretty much have my mine made up im goin to put a 5.9 cummins in my 87 f250 and i have found adapters to mate a c6 up to it. would my c6 hold up? or would it be better to put a 5sp behind it?

 

The c6 is a stout tranny but you are talking torgue the727 held up the thing you wont like is no overdrive and the cummins doesn't turn the rpm's an idi does . I personally would go with the ZF for the overdrive.

 

I vote for the zf or if ya dont want to do the standard tranny swap I'd go with the dodge tranny. nothing realy wrong with the C6 other than what starilt said... The thing that usually decides what tranny you use is usually how much money ya got...lol. I've read a bunch on cummins swaps and from what I hear people usually wish they had used the tranny off of the cummins just for ease of the install. A stock cummins dont rev as high as a idi or a power stroke so a gear set higher than 4.11's is usually the best, and will give ya the best millage.

 

I don't think the RPM difference between the two (which is from a max of 200 RPM down to absolutely NO difference) is going to matter because you are going to either need high rearend gears OR an overdrive with either engine.
I can't imagine going to all of the trouble to mount a ZF-5 to a Cummins when an NV4500 or NV5600 will bolt right up to the Cummins. Especially in your case as you will be converting to a manual from an auto either way.

The 727s put behind the Cummins had a VERY heavy duty and expensive torque converter to be able to take the low RPM torque. I'm not sure if there is a low-RPM TC out there made for this application. The IDI diesel TC might be, I don't know.

On the RPM thing my '91 Cummins will run right up to the governor at 3200 rpm as smooth as silk. My '94 IDI does not feel good over that speed anyway so there is NO WAY I would run it over 3200 RPM for ANY length of time. So to me it's a moot point.

Another option, which is what I'm going to do in the future, is use an Allison 545 (automatic), or similar model, out of a medium duty truck. They are 4-speeds with out overdrive so you still need a high-geared rearend or in my case 3:54s and 35-36" tires.
They are available pretty cheap as I've bought 3 of them for 250-350 bucks and they are really stout. These trannys are NOT the ones GM puts behind the Duramax (1000 series), they are a lot bigger and stronger. Not to mention simpler and HEAVIER. You DO run into problems with the 4wd. though because you'd have to run a divorced X-case.

 

would like a 6 spd alisson work behind it?

 

The C-6 works and is strong enough to handle the 5.9. I've had a C-6 behind an industrial 5.9 for over 12 years.

The real problem as already stated is the gearing. To be able to "really" use the torque of the 5.9, you either need overdrive with high gears, or better, double overdrive with high gears.

With 4:11 gears, no OD and stock 2500 rpm you will turn about 56 mph, with a gear vendor OD it'll barely do 75 mph. 2500 rpm is far from ideal, way out of the torque curve. You also have to rig up a vacuum regulator or go to a manual valve body.

With my 86, I figure the best overall setup would be 3:54 gears, overdrive trans along with the gear vendor overdrive. That would keep the engine in the torque curve and best fuel mileage range. Or just be happy running around 60 mph.

 

out of both the idi's i have driven neither of them feel bad at govener speeds my dads 7.3 feels like just fine at 3800 rpm and i wouldnt be afraid to turn it more, and my 6.9 feels just the same i wouldnt be afraid to put them on the rev limiter all day

 

You would stiill need to get a diesel bellhousing for the 4500. When I was researching this swap for my truck, several companies (Ford-Cummins, Destroked) recommended keeping the ZF 5 or 6 over the 4500 and the 5600. I like the gearing of the NV better and it seems like the iron case would be stronger, but they claim that it isn't.

There are adaptors and controllers available to run the Allison behind the Cummins. There is an article in Diesel Power (last month I think) about a Super Duty with a CR backed by an Allison.

Jason

 

DESTROKED: Cummins Conversions

Here is just about any thing you could want (Its just money).

 

The reason they are saying to keep the zf-5 is because it's already in the truck. The X-case is there the drivelines are there...it's easier.
If you're going to swap in a manual FROM an auto you'd be foolish to use the ZF-5, it's not as good as the New Venture trannys.
Maybe they just want to sell you the adapter parts. I think your feelings are right: there is NO WAY the ZF-5 is better/stronger than the NVs. They're definitely not perfect but they are the best.
Case in point- has anyone ever heard of swapping a ZF-5 into anything if it didn't have a Ford motor? NO! Have you heard of people swapping New Venture trannys into EVERYTHING? YES!

The best way to do a swap is to get a donor truck. The '94-early'98 trucks with manual trannys will ALL have the NV4500 and the better 12V Cummins with the Bosch P7100 in-line injection pump. The smart way to go is to get one of those as a doner.

 

To me the nv4500 and the ZF5 both have their downfalls.
The NV has been adapted and run in every thing alot of the reason for this is the bellhousing setup.
I like the seperate bellhousing setup better.
If money is no object the 6sp would be the way to go (I like gears though)

This ones for you dodge. What is involved in using a ford 205 or 1356 behind an NV 45 or 56 do you know what options is out there.
Does the NV 5600 have the integral bellhousing or is it removable.

 

GM used an integral bell housing on their NVs. Dodge used a removeable one. Dodge also had more of the gears synchroed than GM did.
Advanced adapters makes an adapter for putting a 205 on the back of the NVs but I don't know if they have one for a Ford. I didn't think about that but that might be another reason the "experts" recommend retaining the ZF. Good thinking!
I have absolutely nothing against the BW1356 but I would definitely prefer the 205.
The Dodge's NP241s etc. are just as good too but again the front output is on the wrong side.

I THINK the 5600 has a seperate bell housing as well but I don't know as much about them as they came in the 24V trucks and I kind of ignore them. I do know they had trouble with some of them pre-'01.5.
the cost of them is more than I like too so I've shyed away from them. I'm with you though, I LIKE GEARS!

 

Their is a co in your neck of the woods that modifies the ZF6 with a smaller input and output shaft to use it with a 7.3 or cummins and a 1356 to adress speedo problems.
I too like the 205 better but I have a 1356 case for the gearvenders and a double over has been bugging me can't help it. If I go this far though it will be something I will keep forever so putting out the money for a gv 205 adapter may have to happen.

 

Do you know who it is or where they're at?
I've tought of putting a PS 6-speed in my '94.

You want to hear a REALLY goofy idea?
I'd like to put an IDI turbo in an Excursion and install a 6 speed out of a doner SuperDuty.
It's weird but it would almost be a bolt-in. There'd be some electrical to figure out but nothing insurmountable. Then I'd only need the front out-put changed on the trans. Plus I could plumb the intercooler from the PS into the IDI.

If I come across an Excursion with a bad PowerStroke and/or trans. I'll probably end up with it.

 

With the Cummns swap, the transmission has to be relocated a bit. I can't recall how much though. So it doesn't matter.

The integral bellhousing of the ZF limits the ease of swapping to other brands. But where possible, the ZF is very popular for the gearing it offers, because it is cheaper to find, and much easier to swap since Ford hasn't changed output sizes and adaptor bolt patterns since the 70's.

Jason