I am wanting a ZF 6 speed for my 97 7.3 4 door short wide bed.

Where is the best place to find one? Maybe at Yard sale price

Anybody have a line on one I would appriciate hearing about it.

Thanks.

 

ZF6s generally aren't cheap.

I part out a lot of trucks, if I were to post up a ZF6 right now for $1300 I would wake up to a barrage of calls and texts from people trying to buy it.

Your best bet to find one cheap is either to buy it from someone who doesn't know what they have, or buy a parts truck and part the rest of it out and keep the transmission.

The second option would be the cheapest as you're going to need more parts from the SD than just the ZF6.

 

Id say parts truck, That way you can test drive it too, and make sure syncros aren't junk. you will need some SD parts as already mentioned. Then you can part out the engine and rest of the superduty. it will be a couple thousand dollar swap, unless you find a super deal on a parts truck, and can make enough money back parting it out

 

Thanks guys, I have the close ratio 5 speed now 4:14 first I think it is, and with 3.55 gears for towing on the interstate,


When I load a tractor or something heavy on my Goose neck trailer, it's a bear getting took off without dropping into the low side.


But with my 28 ft enclosed trailer and race car, the 3.55's are great towing at 75 mph and 2100 rpm.


With the baby Swamps and 4 inch exhaust, cold air kit and TS tunes its a road beast.


I just thought the 6 speed and lower first gear would give me my low ration first and still basically have the same thing as I have now 2nd on through 6th. Second being close to my first gear ratio now.


Be like just adding one lower gear below my fist now for moving heavy loads.


I may just have to settle for a low ratio ZF 5 speed to replace this one. But I hate the wide ratio with the 3.55's

 

I have bought a few ZF6s both brand new (Yes, they still had a few last year), and reman from Joes transmission on Ebay. I also have bought brand new 271 transfer cases from them as well. Not sure if core needs to be like for like though.

The ZF5 is not as notchy of a shift as the ZF6 though.

 

How do you like your clutch? How's the pedal feel? I am looking at clutches for replacement in a few weeks. Thanks.

 

I'm going to list the gear ratios of the different transmissions, then I will explain what I did with mine.

ZF6
1st = 5.79:1
2nd = 3.30:1
3rd = 2.10:1
4th = 1.31:1
5th = 1.00:1
6th = 0.72:1
Rev = 5.23:1

ZF5 S5-42
Close Ratio
1st = 4.14:1
2nd = 2.37:1
3rd = 1.42:1
4th = 1.00:1
5th = 0.77:1
Rev = 3.79:1

ZF5 S5-47
Close Ratio
1st = 5.08:1
2nd = 2.60:1
3rd = 1.53:1
4th = 1.00:1
5th = 0.77:1
Rev = 4.66:1

ZF5 S5-42/S5-47
Wide Ratio
1st = 5.72:1
2nd = 2.94:1
3rd = 1.61:1
4th = 1.00:1
5th = 0.76:1
Rev = 5.24:1

I do a lot of heavy towing with my truck and I had the S5-42 Close Ratio with 4.10 gears. It was terrible trying to get a load moving from a dead stop, and even worse trying to back a load up without putting my t-case in 4LO. The S5-47 Close Ratio is much better for towing with the slightly lower first three gears and reverse, but still was hard in some spots to start from a stop like on a hill, and backing up. Plus, the S5-47 was only made in '96 and '97, so they are harder to find. So what I did was took an S5-42 Wide Ratio from a '92 F-350, 460 gas truck, and pulled everything out of the gas case, and put it in an S5-42 diesel case. This will only work with a 460 gas transmission. The small block gas ZF transmission internals will not work in a diesel case. The Wide Ratio was offered in a diesel transmission, but I believe it was only in the F-Super Duty. I have never seen one. The good thing about the 460 gas ZF Wide Ratio is there a lot of them out there to be had fairly reasonably priced. If you compare the ratios of the ZF5 Wide Ratio to the ZF6, you basically have the same trans minus one gear. I love the way it tows, and I really like the low reverse. It works very well for what I do with my truck, and you don't loose anything on the highway because 5th gear (OD) is basically the same. The only flaw I have found with the gas/diesel hybrid is the upshift from 3rd to 4th gear. There is a larger gap there with the Wide Ratio than any of the others, but the only time it really has any negative affect at all is when I am towing real heavy up hill, and have to make that shift. If I don't have too far to go until I can top the hill, or it levels out somewhat, I will just ride it out in 3rd. If it is a long pull and not too steep, and I know I can pull it in 4th, I will wind it way out in 3rd, make the shift, then get in it pretty good until my EGTs reach 1200*. By then I can back out of it a little to let the EGTs settle back down, and have picked up enough speed and have enough power with my mods to continue on in 4th until I can shift to 5th. Other than that, I love everything else about it. It may not be the ideal transmission for everyone, but for what I do, it works well. I think it would be great for guys with 3.55 gears, that tow occasionally, but don't want to sacrifice the lower rpms on the highway by swapping to 4.10 gears. The S5-42 Close Ratio trans and 3.55 gears are the worst combo there is for towing in my opinion. The S5-47 with 3.55s would be better, but like I mentioned earlier, the 47s are hard to find. Building one of these hybrid trans is not a bad job at all. You just have to make sure you get the input shaft bearings shimmed right when you you put it all in a different case. If you have never had a ZF apart before, I would recommend getting a ZF5 service manual and study it before you try it. I still think it would be easier and cheaper than swapping to a ZF6 though. When people ask me about doing a ZF6 swap in an OBS, I usually just tell them that I don't think the juice would be worth the squeeze. This is all just my opinion though, and what works best for me. I'm not saying that this is the be all end all of transmissions by any means, because it may not work as well for others as it does for me, and others may not like it as much as I do. Just thought I would share the experience I have had with mine, and put the info out there as an option.

 

With the s42 I will assume someone did the swap. A S47 or like ReBuild said putting 460 guts in your case would be a MUCH better solution than Trying to find a ZF6

I sell ZF6s as fast As I list them for $2,000

 

Sorry, just now getting back on this. I have been busy with other projects.


My South Bend clutch has been great, I bought the 900 ft lb single disc.


Peddle effort is fine, maybe a slight bit more than stock.


The problem I have had with it is, with my truck being geared so tall in 1st gear, I have slipped it so much it chatters when I try to take off smooth now. I don't see that as a problem with the clutch though.

 

Update, Sorry (old thread)


I have found and bought two ZF6 speeds, I know the shafts are going to be different lengths, one shortened and one lengthened.


But what about going to the ZF 6 speed with the 5 speed transfer case?


Are the shafts the same or is something required to mate my case to the 6 speed.

 

Thanks for the info Bill, I appreciate it...........

 

The ZF5 and ZF6 output shafts are different, so you need the SD tcase, which I believe has different yokes so now you need custom drive shafts too. That's a lot of work for a .71:1 difference, or a .07:1 difference if you do a gas/diesel hybrid.

In the end, your towing capabilities will be much better off with a gear swap to 4.10s or at least 3.73s.

 

ZF6 VS ZF5 S5-42
3.55 rear gear, 2000 rpm with 33 inch tires
3/21/17

FZ6 FZ5
1ST 20.55 FDR 9.56 MPH ZF5 14.69 FDR 13.37 MPH
2ND 11.72, 16.76 ZF5 8.41, 23.35
3ird 7.45, 26.37 ZF5 5.04, 38.98
4th4.65, 43.08 ZF5 3.55, 5 5.33
5th3.55, 55.33 ZF5 2.73, 71.96
6th2.55 77.03

As you can see, if you drive the FZ6 as a 5 speed it’s basicallythe same as The FZ5 but 5.08 MPH faster in O.D.
I can live with this as I run 75 + on the interstate with my10,000 lb enclosed trailer most times.
But it will also act as if it were a 5 speed with a LL 1stgear to move my Backhoe and big tractor without slipping the clutch.
This will be a win win deal for me.
I have yet to see this info in all the searching I havedone. I hope this will help someone looking for info make their decision on atrans swap.
If my truck had the ZF5 S5-47 I’m not sure the extra overdrivewould be worth the swap, but for me and the S5-42, it’s a no brainer.

 

Sorry about the numbers jumbled up, It was good in Word document but didn't copy paste for crap.

 

I'm just saying that the ZF6 swap requires so much more work and $$ than just swapping your S42 for a S47, or putting 460 gears in your S42 case.

One thing I also haven't seen mentioned yet is that the ZF6 physically will not fit in an OBS without modifying the trans tunnel. So add that to needing a new tcase and drivelines.