4 speed to ZF 5 speed swap

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G. Mann

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New guy here, just found the forum and joined. Arizona truck, 85 long bed 6.9 with 372,000 miles 3rd owner, new set of injectors and IP recently, still running strong.

:confused: I have a ZF 5 speed and a Gear vendors OD I want to put in. The Gear Vendors is a no brainer that replaces the carrier bearing mount, however I'm hoping someone here has experience with clutch selection for the ZF. I hit the parts books and find clutches with 1 1/4 X 10 spline clutch but the pressure plates are all 2 bolt on 4 pattern. The 6.9 flywheel is 2 bolt on 3 pattern. Someone here know what clutch to use? :dunno

BTW. I presently have a 12 1/4 clutch on the 4 speed and a single mass flywheel [even have a spare flywheel] would like to stay with the bigger clutch size with the ZF 5 speed.

Have a DNE 2 [Doug Nash overdrive, if anyone is interested in that let me know]:thumbsup:
 

The Warden

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Welcome aboard!

I've done the swap, back in 2005.

Is your truck a 4x4 or a 2 wheel drive? If it's a 4x4, all you should need is the clutch assembly, floor pan insert (the T-19 floor pan insert MIGHT be usable, but you'd need to spend some quality time with a BFH modifying it to fit around the back of the ZF), and a crossmember...if it's a 2 wheel drive, IIRC you need to shorten your driveshaft and use a custom U-joint as the ZF's output yoke is bigger.

The T-19 clutch will not work with the ZF5, at least not without extensive modifications. The ZF5 flywheel is about double the thickness of the T-19 flywheel, and while I don't remember if the input shaft itself is the same diameter or not, the sheath that the throwout bearing rides on is wider on the ZF (i.e. a T-19 throwout bearing won't work; found that one out the hard way after wanting to put a T-19 greasable t/o bearing on my truck).

I used a LuK 12" clutch with a single-mass flywheel, that I got from here(part number 07-131FW). Been working absolutely beautifully for me over the last 2 years!! BTW, I would recommend the Kevlar pilot bushing, and you may as well replace the rear main seal while you're in there.

Regarding the Doug Nash unit, I might be interested...where are you located, and how much are you asking for it?

Hope this helps a bit...good luck!!
 

TBigLug

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This is a good question.... IMO because I want to do the same thing lol. Minus the Gear Vendor. In a 2WD all you should need is a shortened driveshaft, flywheel, clutch, custom u-joint? Do I have that right?
 

G. Mann

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OOOps.. duhhh a senior moment.

I forgot to state the obvious. My 85 is a 2 wheel drive.

Thanks for all the info and links. Still not clear however, do I have to buy a new flywheel to get a clutch that will work with the ZF 5 speed?

The T 19 jackshaft is 1 1/8 th X 10 spline, the ZF 5 spd. is 1 1/4 X 10 spline so it's a given the clutch disk won't interchange. Same for the throwout bearing, internal diameter is bigger on the ZF, also the clutch fork has to be changed. That I've got covered so far [it's only money at the parts counter, right?].

Question that I still can't answer is, Can I just buy a 12 inch clutch that will fit my present 2 bolt on 3 pattern 6.9 flywheel, or do I ALSO have to now buy a new flywheel [heavier] with the 2 bolt on 4 pattern to fit a 12 inch clutch to the ZF 5 spd?

I'm wanting to gather all the parts before I tear down so it's an "in and out" rather than a "down and wait" [and wait and wait].

Also, regards the rear trans mount on the ZF, is it the same as the T19? Same location and mount? Or is there an issue there that will bite me when I try to put it all back together?

I spoke with a fellow who sells gear vendors a lot and according to him, it's possible to use the rear housing on a 4X4 ZF in a 2 WD and mount the GV unit directly to the back of the ZF, eleminating the GV carrier bearing mounting which is "less than perfect" he says. According to him, the GV unit would then mount directly with the adaptor instead of a transer case. :dunno Anyone ever done this kind of swap? I would have to tear down the trans and rebuild it with the 4X4 rear case housing so more time and money. Would like to hear from someone who has actually done one.:hail
 

The Warden

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Thanks for all the info and links. Still not clear however, do I have to buy a new flywheel to get a clutch that will work with the ZF 5 speed?

The T 19 jackshaft is 1 1/8 th X 10 spline, the ZF 5 spd. is 1 1/4 X 10 spline so it's a given the clutch disk won't interchange. Same for the throwout bearing, internal diameter is bigger on the ZF, also the clutch fork has to be changed. That I've got covered so far [it's only money at the parts counter, right?].

Question that I still can't answer is, Can I just buy a 12 inch clutch that will fit my present 2 bolt on 3 pattern 6.9 flywheel, or do I ALSO have to now buy a new flywheel [heavier] with the 2 bolt on 4 pattern to fit a 12 inch clutch to the ZF 5 spd?
Yes, you need a new flywheel. The ZF flywheel is the same diameter, but it is almost double the thickness of a T-19 flywheel. Take a look at the first picture I attached. I don't know if a 2 bolt on 3 pattern clutch exists that would fit the ZF, but based on the thickness difference alone, I would strongly recommend just replacing the flywheel. Besides, this will make it easier to find clutch parts in the future.

Also, regards the rear trans mount on the ZF, is it the same as the T19? Same location and mount? Or is there an issue there that will bite me when I try to put it all back together?
I'm honestly not certain. There IS a difference in how the 4x4 T-19 is mounted to the crossmember, although after looking at the two crossmembers as compared to each other, it looks like the ZF mount COULD have been put on the T-19 crossmember without any difficulty. However, I'm like you in that I wanted to have all my ducks in a row, so I had a ZF crossmember (actually, turns out it was for an E4DOA :rolleyes: but it worked anyways) ready and just went and swapped them without trying to fit anything to the T-19 member. Look at Picture #2...the rubber mounts on the T-19 crossmember are for a second metal piece, that the actual tranny mount goes onto (no picture of that piece, sorry). I didn't measure height differences, and it looks like there ARE slots in the T-19 crossmember that the ZF mount could go onto. Again, I'm not sure...IMHO it'd be best to have a ZF crossmember handy, and if you want to make the T-19 member work, you'll have a backup to keep you from being off the road too long in case it doesn't work. If you can make it work, please report back! :)

I spoke with a fellow who sells gear vendors a lot and according to him, it's possible to use the rear housing on a 4X4 ZF in a 2 WD and mount the GV unit directly to the back of the ZF, eleminating the GV carrier bearing mounting which is "less than perfect" he says. According to him, the GV unit would then mount directly with the adaptor instead of a transer case. :dunno Anyone ever done this kind of swap? I would have to tear down the trans and rebuild it with the 4X4 rear case housing so more time and money. Would like to hear from someone who has actually done one.:hail
Well, if you're going to do that, the ZF will need to be completely rebuilt...as towcat has demonstrated in past posts, when the ZF is put together, the rear housing is the first thing that goes on...so, if you want to replace it, the tranny has to be completely disassembled. It might be better to sell the 2WD ZF and buy a 4x4 tranny.

I'm wondering if your Doug Nash unit can be modified to work on a 4x4? :D

BTW, the last three pictures...the first two are an illustration of the differences in the floor pan inserts. In the second picture, the T-19 floor pan insert is sitting on top of the ZF, with about 3/4" left to go before the lip makes contact with the main floor pan. The last picture is of the pilot bearing that was in my T-19...and you can see what condition it's in. And, that's why I recommended the Kevlar bushing instead. :)
 

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G. Mann

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A pic is worth a thousand words , thanks!!

This is exactly the kind of information I hoped for when I posted this thread.

Pretty easy to make the $$ decision $$ on the new flywheel now that I've seen them side by side. [still payday painful, but necessary]

Looks like I will be doing some sheetmetal work to seal up the doghouse over the ZF but I can do that. Helps loads to know what to expect.

I'm going to take a gamble on the trans mount and "try " to stick with the T19 mount.

I see why you recommend the pilot bearing .. ouch! that one is trashed.:puke:

I think for now, I'll just go with the GV arrangement I have which is the complete unit that mounts in place of the carrier bearing. The mount seems kinda mickey mouse but maybe it will hold for a while. In the mean time I'll take a serious look at building up a ZF5 / GV using the 4wd rear case /adaptor. [I'm still not convinced that will work :dunno ] Always better to have a running truck than a project. [make that "another project" in my case].

Regards the Doug Nash unit, it's presently configured to bolt up behind a C 6. I'll bet there is an adapter available that would put it right behind your 4X4, if you go looking in the right place. I think it's supported by US Gear now?

Thanks again for all the pics!!!:thumbsup:
 

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I'm following this one very closely and gathering good info from it too. A T-19 to ZF swap is in my near future also - in the Turbo-ed truck in my signature.

One other option on the flywheel that I am seriously considering is the DMF to SMF conversion. From what I've read the DMF can be disassembled and drilled to insert six 3/8" grade 8 bolts & lock nuts to secure the two pieces together - thereby converting the DMF to an SMF. I have a useable DMF and pressure plate, just need a new cluch disk.

Anybody got more info on the DMF to SMF conversion process - particularly with good pictures like what TheWarden has posted here?
 

towcat

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I'm following this one very closely and gathering good info from it too. A T-19 to ZF swap is in my near future also - in the Turbo-ed truck in my signature.

One other option on the flywheel that I am seriously considering is the DMF to SMF conversion. From what I've read the DMF can be disassembled and drilled to insert six 3/8" grade 8 bolts & lock nuts to secure the two pieces together - thereby converting the DMF to an SMF. I have a useable DMF and pressure plate, just need a new cluch disk.

Anybody got more info on the DMF to SMF conversion process - particularly with good pictures like what TheWarden has posted here?
I'd do a search here concerning the flywheel conversion. Iirc, there's mixed results from a few people who have done it. The worst case was the bolts sheared off. That trans is far from user friendly in the R&R dept.
 

G. Mann

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ZF 5 and flywheel situation

Since I'm the new guy on this block perhaps someone else knows how to search the archives about doing a flywheel conversion on a DMF to a SMF.

I've heard the ZF 5 is "sensitive" to power shocks thus Ford/IHC came out with the dual mass. I've also seen stacks of dual mass flywheels at the local clutch wholesaler that were all trashed and far as I can find out NO ONE rebuilds them. In fact, Arizona Clutch and Brake, [my local good guys] tell me they can't get parts to rebuild them, which makes the DMF a very expensive "one shot and yer had" . If the conversion really works, I wonder why someone like these folks aren't all over it.

Anyway, I will follow with great interest what you find. Likely could come up with a few "cores" to experiment with if I chat with the right folks back in the shop. [ie. quitting time, cooler in the truck "happens " to have a supply of the beverage of choice] ;Sweet

Having had a good hard look as the DMF I don't see a good place to just bolt it together, so I join TowCat in taking a hard look at how it's to be done. If it fails, murphys law says it would happen loaded, halfway across a railroad crossing, in front of a truckload of hazmat, at rush hour, across the street from a school for blind kids, and a DOT branch office while the local EPA chief was visiting. -cuss :eek:

BTW, any ideas on what I should do with the T 19? It's a good trans I just want the overdrive feature, thus the change.
 

The Warden

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I forgot to mention, the ZF flywheel in my picture is a single-mass unit. I've been running it for only 10K or so miles (my truck isn't my DD), and have had absolutely no problems. The biggest known concern with the SMFW is extra gear rollover noise at low engine RPM's, but IMHO it isn't a huge deal...especially when comparing prices between a single-mass and a dual-mass flywheel.

BTW, I took a LOT of pictures during my tranny swap (a friend was in an auto tech class, so we had access to a lift, tranny jacks, etc, but this also meant that he was the only one allowed to turn wrenches), and I plan to do a write-up on the job to submit as an article...just, I haven't had any time in the last 2 years *sigh*
 

towcat

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Since I'm the new guy on this block perhaps someone else knows how to search the archives about doing a flywheel conversion on a DMF to a SMF.

I've heard the ZF 5 is "sensitive" to power shocks thus Ford/IHC came out with the dual mass. I've also seen stacks of dual mass flywheels at the local clutch wholesaler that were all trashed and far as I can find out NO ONE rebuilds them. In fact, Arizona Clutch and Brake, [my local good guys] tell me they can't get parts to rebuild them, which makes the DMF a very expensive "one shot and yer had" . If the conversion really works, I wonder why someone like these folks aren't all over it.
the search feature on this site actually works compared to some others. try entering "lucky mod" or "converted dual mass flywheel". "lucky mod" iirc was named to the guy who did the conversion here first.
there's reasons why the DMFW fails prematurely. The largest is bad injection pumps and/or bad injectors. A pump on its way out will put out some really funny pulses and the flywheel will try to compensate for it.
 

G. Mann

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Thanks for the link Lucky

Now that I know someone has at least done it, the next question is, how long does it last? Is this a permanent good fix, or is it gonna bite me down the road and make me wish I had spent the $$ for a solid SMF?

Anybody out there been running one of these for a few zillion miles? I like the idea of the cost of 6 grade 8's over a new SMF. Question is, will they take the hammering that comes through the flywheel/clutch on the long term? Every DMF that I have seen has really been trashed when you look close at the springs and rubber dampener pucks on the back side...

Any thoughts on those issues ? :dunno
 
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