Zf6 swap?

[Mattc2066]

I currently have the ZF5, after i put 3.55 gears in the rear i want to do a swap to a 6 speed manual. Would this be a hard/involved job? Is there any fabrication or adapters needed? Any info is greatly appreciated. And no i dont have a practical reason for it other that spreading out the load of the 3.55's a little bit more so its not as doggy, and i just like 6 speed manuals.

 

[franklin2]

As time goes by things change, but I remember a old thread on here where a guy did it, and it was major work. And then the late model transfer case had to be used with it, they changed the shaft size and spline count on the output of the zf6.

 

[u2slow]

The zf6 gives you a basement gear. Not much else compared to the diesel zf5.

As I understand it, the problem with that trans on the idi is they did away with the thick adapter/spacer and built that thickness into the bellhousing. Now add in the IDI to ZF adapter and now there's a spacing issue.

 

[snicklas]

Is it a lower 1st? I thought 1st and "high" (5th or 6th) was the same, and it gave you one in the middle.

I've never driven a ZF-6, so I don't have any in person experience. But, there are a couple people that have done it, and they said it is not worth the time an effort, since they basically gained nothing. They both said, they should have just done a ZF-5

 

[Farmer Rock]

Isn't the truck in question an f super duty? With the 5.13 gears you have now, it has a really low 1st and reverse. If you want better mpgs but still want more low end gearing for a heavy truck, I think 4.10 would be the ticket. I personally think 3.55s in that heavy of a truck is not going to leave you happy when it's said and done. If you go 4.10s, you won't have the need for a lower gear.
Just my $0.02



Rock

 

[BrandonMag]

I currently have the ZF5, after i put 3.55 gears in the rear i want to do a swap to a 6 speed manual. Would this be a hard/involved job? Is there any fabrication or adapters needed? Any info is greatly appreciated. And no i dont have a practical reason for it other that spreading out the load of the 3.55's a little bit more so its not as doggy, and i just like 6 speed manuals.

Hard/involved? Depending on your definition of what "hard" is, the answer to that question is either yeah or YES!
Fabrication/adapters? Yes and yes. It's been awhile, so very specific details escape me, but the ZF6 is a completely different animal than a ZF5. Different bellhousing bolt pattern and (I'm pretty sure) the 6 is a larger transmission overall.

None of this is to say it's impossible, but considering what you stand to gain from this swap, it just ain't worth the effort... with one big BUT! If you enjoy wrenching and your primary motivation is the challenge of taking a project like this on to complete it for the satisfaction it will bring, then I say HELL, YEAH! Do it and post pictures (or a YouTube video). We'll all benefit from your experience.

 

[u2slow]

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[bigdog]

My 86 6.9 two wheel drive cab and chassis has a burg warner 4 spd with 3.55. I have thought of installing a ZF5 in this truck. Seems like there is a lot of conversation on the subject. Can anyone let me in on the pro's and or con's and what will be needed to make the swap to the 5 spd?

 

[IDIBRONCO]

You won't gain anything in the towing category. How I describe it it that you basically have an overdrive and a half with this set up. You'll get lower RPM going down the road while in overdrive so you should get better fuel mileage. I also prefer the way that the ZF5 shifts over the way that a four speed does, but that's just personal. As for what it takes, the transmission, at least a clutch plate if not the pressure plate too, maybe an entire SMF conversion, you can reuse the four speed trans cover plate (in the floor) but you won't be able to screw the shifter boot down to the floor. Since I've only done this in 4X4 trucks, I don't know about the rear yoke and U-joint on the back of the transmissions. A con would be the higher ratio first and reverse(maybe) gears. You'll have to slip the clutch more in reverse. I almost always put mine in 2 Lo for backing up.

 

[franklin2]

My 86 6.9 two wheel drive cab and chassis has a burg warner 4 spd with 3.55. I have thought of installing a ZF5 in this truck. Seems like there is a lot of conversation on the subject. Can anyone let me in on the pro's and or con's and what will be needed to make the swap to the 5 spd?

The overdrive is great. I gained 3 more mpg going from a c6 to a zf 5. If you figure how long it would take to get payback with the better fuel mileage, it will be a long time. But there are other benefits I didn't realize till after I did the swap. Running down the highway it's very easy to keep up with traffic without thinking the engine is going to blow up. And it is so much quieter in the cab. And just think how much longer the engine will last now it's not turning all those rpms.

I found the best way to do this is buy a donor truck. A junkyard wants $800-$1200 for a transmission. And then you need other odd bits to get it in place. I found a wrecked donor for $1000. Got the tranny and everything I needed except the SMF conversion. I then was able to sell my good c6, the transfer case from the donor, the wheels from the donor, and I got some spare parts I have used from the donor like the tailights, the wiper motor, etc. All that brought the cost way down for the swap.

 

[ttman4]

As time goes by things change, but I remember a old thread on here where a guy did it, and it was major work. And then the late model transfer case had to be used with it, they changed the shaft size and spline count on the output of the zf6.

ZF5 to ZF6 swap.
I saved the link & write-up but now can't find it,.....and only going off old timer memory.
IIRC several yr ago (10-12-15) couple guys on here fab'ed an adaptor or something for the top 2 bolts. Seems IIRC the bottom 4 were the same. The adaptor plate is left out. The spline shaft on ZF6 is shorter but same spline. And I don't remember what all has to do for starter etc, etc.

Like I say, this is only off of old memory. I may be way, way off on the whole thing/project.

 

[franklin2]

I definitely remember the zf 6 setup upsetting the tried and true "any Ford transfer case will bolt up to any Ford 4x4 transmission". They will except the zf 6. Don't know about the later automatics either.

 

[u2slow]

The 02ish nv271 I have is 31 spline (presumably from auto) and fits a ZF5.

 

[Mattc2066]

Thanks for all the info guys. I have decided to keep the ZF5 as it sounds like there wont be any significant benefit. I will be going with 3.55 gears though. I am not ever going to tow with this truck. It is a weld rig amd never has anything over 2,000 lbs on it and regularly has less than 1200 lbs. 90% or more of my driving will be on the interstate doing 70 mph and i want the lowest RPM possible as i will be going pretty far at those speeds. Im not concerned with being able to haul @ss from light to light in town. If its a slow starter from a stop i am perfectly happy with that if it gets better MPG at 70+ mph and doesnt bang off the rev limiter at 68 mph. The 5.13 it has now is just ridiculous for my purpose of a 90% + interstate truck.

 

[u2slow]

For 3.54 in the Dana 80 you need a different offset carrier.

3.73 normally does too, except the factory ford version fits the common 4.10-5.38 carrier.