Zf5 clutch issues help appreciated

[rooster]

So the zf swap for me has been a constant battle. I swapped it about a year ago from a guy in cheyenne. Guy said it was in great shape and the price was decent so I proceeded to take it and put it in my bronco. The clutch that I had at the time was an old 3 finger style but was bassicly brand new so I went with it. Well I had several issues on was what was supposed to be a great test drive, first off I had grinding issues on pretty much every gear. And then the clutch would grab bassicly as soon as you let up on it which is super annoying and makes it hard to shift. My uncle and I rebuilt the tranny. I also bought a new slave and master cylinder and got it all bled . Put the tranny back it and still the clutch will only disengage when completely pushed in, and grabs as soon as you release it even a tiny tiny amount. So I thought I had a clutch issue so I took it out again and put a new clutch in it, if I remember right it was for a late 80s early 90s f250 with a 5.8l . Put the clutch on , re bled the slave and line which no air came out... put it back together and STILL the clutch only releases if you push it all the way completely in, and grabs hard after letting it out the smallest amount. So in the middle of my axles swap I decided I would pull it out yet again and try to fix it. It's like the slave needs to be spaced out... something is wrong. Forgot to mention I also got a new flywheel for it for a early 90s 5.8l.

Any suggestions? Ideas? I am so frustrated with this thing and it needs to be fixed now cause I'm not going to take this thing out again unless I absolutely have to. The way it is now is super annoying and hard to shift. Not to mention hard on the clutch and the whole drive train.

Thanks

[Digger]

So the zf swap for me has been a constant battle. I swapped it about a year ago from a guy in cheyenne. Guy said it was in great shape and the price was decent so I proceeded to take it and put it in my bronco. The clutch that I had at the time was an old 3 finger style but was bassicly brand new so I went with it. Well I had several issues on was what was supposed to be a great test drive, first off I had grinding issues on pretty much every gear. And then the clutch would grab bassicly as soon as you let up on it which is super annoying and makes it hard to shift. My uncle and I rebuilt the tranny. I also bought a new slave and master cylinder and got it all bled . Put the tranny back it and still the clutch will only disengage when completely pushed in, and grabs as soon as you release it even a tiny tiny amount. So I thought I had a clutch issue so I took it out again and put a new clutch in it, if I remember right it was for a late 80s early 90s f250 with a 5.8l . Put the clutch on , re bled the slave and line which no air came out... put it back together and STILL the clutch only releases if you push it all the way completely in, and grabs hard after letting it out the smallest amount. So in the middle of my axles swap I decided I would pull it out yet again and try to fix it. It's like the slave needs to be spaced out... something is wrong. Forgot to mention I also got a new flywheel for it for a early 90s 5.8l.

Any suggestions? Ideas? I am so frustrated with this thing and it needs to be fixed now cause I'm not going to take this thing out again unless I absolutely have to. The way it is now is super annoying and hard to shift. Not to mention hard on the clutch and the whole drive train.

Thanks

It definitely sounds like the clutch is not fully disengaging. 3-finger pressure plates are not compatible with the hydraulic clutch system as I understand it, so stick with the diaphragm spring type.

Tell us a little more about your setup. What year is your ZF?(identified on the side of the trans) What slave and master cylinders are you using? There were two different systems with different bores and they are incompatible with each other. What hose / connectors are you using to connect the master and slave?

[rooster]

Thanks for the quick reply, the zf is a 92 , and I ya I did replace the clutch with an 11' for a 90s pickup with a 5.8l.
I haven't even found anything online that is similar to my issues and I am lost on what to do. Tired of throwing money at it

[rooster]

Also the slave and master I bought were for a early 90s pickup with a 5.8l , which should be a zf tranny the line was the original that came with the transmission

[Digger]

Also the slave and master I bought were for a early 90s pickup with a 5.8l , which should be a zf tranny the line was the original that came with the transmission

There is not a single cutoff year when Ford switched between the two hydraulic systems and it varies by model. I use a F250 XLT with 5.8l for reference. The 1991 system is older and the 1993 is the newer. 1992 is mostly listed by itself on OreilyAuto and I don't know particulars.

Older systems used the larger 7/8" bore master with the hydraulic outlet facing forward and the black, larger quick connect.

Newer systems used the smaller 18mm bore MC with the hydraulic outlet facing downward and the gold, smaller quick connect.


From Eck's and my experience, I would replace your slave cylinder and re-bleed the system. The hydraulics are reliable, but difficult to bleed. I did some investigation when I pulled by trans because my slave worked perfect when pulled, but then won't bleed out. Like you, I could not get any air out, however the clutch would not fully disengage. If you examine the slave carefully and pay attention to how the system works, you realize that in normal operation the hydraulic fluid pushes the seal forward against the piston and when hydraulic pressure is released, the piston pushes the seal back.

The problem that occurs when bleeding sometimes is that in a semi-bled system, the piston cannot fully return the seal and negative pressure forms behind the seal and it draws air into the system. You could hear it on my truck. You will never be able to get the air out. The best course of action is to start by gravity bleeding the system as much as possible before beginning to bleed with the pedal. I also bled slowly, avoiding rapid releases of the pedal that would draw air in or worse, cause the seal to tip in the slave bore.

[Eck]

Just make sure that your master and slave are from the same donor/year and you could hopefully verify the specs of each to confirm what Digger is saying on bore size. Sounds like maybe you need first to replace the pressure plate with the diaphragm pressure plate and see if that'll fix your issue.


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[Digger]

For reference

[rooster]

So I was wrong the zf is a 93 , the master is the newer style you described . And I did buy a new clutch for with the diaphragm style pressure plate. The master cylinder is the newer style you described with the line coming out the bottom, and the line has the gold style quick connect.

I did gravity bleed the system wheni took it out this time ,and let about 2 reservoirs of fluid run through the system ,never letting the master be able to suck air, at first alittle bit of air did come out of the bleed screw in the form of bubbles but they stopped after letting some fluid pass through. ,
If it would be easier to go buy another new slave maybe I should, the previous time I tried this I used a vacuum bleeder, a power bleeder, and the conventional way with a helper, as well as gravity and it seemed like the gravity method was the only one that worked.
My pedal isnice and firm, but I have very little throw it seems like in my master cylinder before it bottoms out.

[Digger]

My pedal is nice and firm, but I have very little throw it seems like in my master cylinder before it bottoms out.

Hmmmm. Do you have pictures of the pedal assembly and where the MC is mounted? Are you sure the MC is bottoming out or is the pedal running out of travel? Maybe you and Eck could compare pedal ratios.

[Jesus_man]

Where did you source your slave? I bought one from autozone, o'reilly etc.. and it was a bear to bleed and failed in less than a year. The next one, was perhaps from BC broncos, which I didn't have the issues with. Finally, I had my tranny rebuilt and had him get me a slave and it's been good since.

[rooster]

I bought all the parts at orielys ,
I assumed the same thing thinking that maybe something was getting bound up on the pedal so I actually made it adjustable, but it is still bottoming out inside the master and seems limited in travel. I will post some pictures soon. Out of town at the moment

[Jesus_man]

I'd start with a new slave from a reputable tranny shop or Bronco Vendor of your choosing.

[Eck]

I bought all the parts at orielys ,
I assumed the same thing thinking that maybe something was getting bound up on the pedal so I actually made it adjustable, but it is still bottoming out inside the master and seems limited in travel. I will post some pictures soon. Out of town at the moment

Where are you located? If you aren't too far, I would be happy to help you for a couple of hours trouble shoot some things (I have spent days trouble shooting mine and it is frustrating to say the least). Sometimes a fresh approach or set of eyes can do wonders.


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[rooster]

I am just south of Platteville, also thank you I really appreciate the offer

[rooster]

It seems that all the parts that I have for the zf , slave, master, line seem to be correct. I am wondering if maybe there is a difference in flywheel thicknesses, I am running an explorer 5.0 and I bought a flywheel for a 90s ford pickup with a 5.0 so I would have the the right imbalance. And the clutch is for a 5.8l and it's an 11" with finger style pressure plate. My brother works for ford so I will see if he can get me a decent deal on a Motorcraft slave.

[rooster]

It seems that all the parts that I have for the zf , slave, master, line seem to be correct. I am wondering if maybe there is a difference in flywheel thicknesses, I am running an explorer 5.0 and I bought a flywheel for a 90s ford pickup with a 5.0 so I would have the the right imbalance. And the clutch is for a 5.8l and it's an 11" with finger style pressure plate. My brother works for ford so I will see if he can get me a decent deal on a Motorcraft slave.

[Digger]

It seems that all the parts that I have for the zf , slave, master, line seem to be correct. I am wondering if maybe there is a difference in flywheel thicknesses, I am running an explorer 5.0 and I bought a flywheel for a 90s ford pickup with a 5.0 so I would have the the right imbalance. And the clutch is for a 5.8l and it's an 11" with finger style pressure plate. My brother works for ford so I will see if he can get me a decent deal on a Motorcraft slave.

That shouldn't matter. The hydraulic system is self-adjusting. If were over-traveled, you would be leaking fluid.

[rooster]

Do you think It's possible that I got a slave for a m5OD for some reason? Or would this even bolt up to a zf5


I'm trying to think of everything

[Digger]

Do you think It's possible that I got a slave for a m5OD for some reason? Or would this even bolt up to a zf5


I'm trying to think of everything

Later slaves were fairly universal. Same unit for M5OD-R1, M5OD-R1HD, M5OD-R2, ZF5, and possibly Mitsu or whatever came behind the 3.0L Vulcan engine

[Eck]

So you're still using the finger style pressure plate? I would be tempted to change that to the diaphragm style and see if it makes a difference...


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[rooster]

Dang I was hoping that might have been my problem

And No sorry eck I messed that up, it is the diaphragm style pressure plate, I think I am going to go ahead and have my brother order a new slave for me though from ford since he gets a discount.

Right now I have the zf supported by a tranny jack and a few bolts holding it to the engine for easy removal and reinstall, every time I change tweak something I bolt it back up and have a helper push in the clutch while I rotate the yoke by hand, and still as soon as the clutch is let up even the slightest amount I can no longer turn the yoke. Just like it has been doing while I was driving it. I've bled the entire assembly multiple different ways while it was out, and all have produced this result. So like digger said the slave must have some kinda negative pressure pulling in air, hopefully the new one will get me going...

[rooster]

I will take some pictures tomorrow when I get back in town

[rooster]

Ok so I took the clutch back out to reference it against a clutch I had for an 89 5.8l that also had a zf behind it and everything measures out to be identical between them so I highly doubt it's the clutch.

Here is how I made the master adjustable, I cut the head off and 3/8 bolt and drilled a hole in the center of it the same size as the clutch rod. Then I welded them together and on the pedal is a hiem with the right female threads for the bolt. The rod have 1.5 inches of travel in the master cylinder.
My brother will be getting me a new slave from ford today, any tricks to bench bleeding the hole system while I have everything out?

[Digger]

You mentioned that your MC does bottom out, but is the piston returning all the way to the "home" position?

- What's your pedal ratio? (Pedal to pivot distance / MC rod to pivot distance)

When I installed mine, I had to make sure the pedal ratio was set so that the MC had full travel, then put a travel limiter on it to prevent damage. This way the clutch has maximum travel.



I just thought of something else: Is your firewall flexing? I've seen this happen before.

[rooster]

The rod goes into the master 1.5 inches before it bottoms out and and yes it does return all the way out and does not stay on the floor, when I took it out the pedal felt nice and firm, you could feel resistance the moment you pushed it in vs it being spongy. The firewall does flex a little bit but I know the pedal has maximum throw and is bottoming out now from the master before it hits the floor. How did you make your travel limiter, that sounds like a great idea

[rooster]

Decided to put the new slave in from ford ,I gravity bled the crap out of itand put the tranny back in . Then I used a vacuum bleeder and bled the system several more times. Finally I had a firm clutch pedal .I had my dad come help me and we did the same test as before.as he would push the clutch in I would turn the yoke as he slowly let up on the pedal until I could feel it grab. It now grabs towards the top of its throw instead of right at the bottom. I won't know for sure until I drive it but that is still a little ways out.

Thanks for everyone's help on this!


Also is anybody else's clutch pedal real hard? Mine is super firm, more so than my superduty with a 6 speed. Must be the pressure plate, just wondering if that is common on these things?

[Justin]

You mentioned that your MC does bottom out, but is the piston returning all the way to the "home" position?

- What's your pedal ratio? (Pedal to pivot distance / MC rod to pivot distance)

When I installed mine, I had to make sure the pedal ratio was set so that the MC had full travel, then put a travel limiter on it to prevent damage. This way the clutch has maximum travel.

Any tips on how to do this? I'm planning to replace the stock clutch pedal with a brake pedal, but an not sure if the stock spot for the linkage will give the right throw.

[Kinder]

I didn't plan as usual, but I also used a brake pedal and came right off the factory pivot point and straight at the firewall. Besides my problems with poorly made slave cylinders it has had great travel and I adjust the engagement point with a threaded sleeve.

[Digger]

You mentioned that your MC does bottom out, but is the piston returning all the way to the "home" position?

- What's your pedal ratio? (Pedal to pivot distance / MC rod to pivot distance)

When I installed mine, I had to make sure the pedal ratio was set so that the MC had full travel, then put a travel limiter on it to prevent damage. This way the clutch has maximum travel.

Any tips on how to do this? I'm planning to replace the stock clutch pedal with a brake pedal, but an not sure if the stock spot for the linkage will give the right throw.

If you mount your clutch MC near where every one else does, you should be okay. You just want to double check that the pedal is not limiting the clutch MC's travel by where you attached the pushrod. An easy way to do this is measure the MC's stroke length while its on the bench, then measure the pedal travel from where it should normally rest to where is contacts the floorboard.

Pedal.jpg

Dividing the pedal stroke by the MC stroke will give your ideal pedal ratio. Pedal ratio is B divided by A, as shown above.

[Eck]

Here are the instructions that BC Broncos includes with their ZF kit. I have used these to get mine measured and adjusted. The last page is not from BC but useful information if you need to add a pedal stop or need to figure out something more custom than what the rest of us have typically done in placing the Master Cylinder.