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Discussion Starter #1
Alright fellas, I'm stumped; for the last few weeks my ZF6 has been making this screeching or creaking noise, almost like someone opening a door, or running fingers down a chalk board, when I push the clutch in and then let it out; I first noticed it when the truck is not running, and it's just awful; you can hear it in the cab; so I had my wife hope up in the driver's seat and move the clutch in and out, and it is crazy loud screech under the truck, and sounds like it's coming from the transmission itself

when I first heard it, I thought it was the pedal itself, so I hit it with some lube and still had the noise, so that's when I poked around some more to find it at the actual transmission (or so it seems)


my truck has 125K on it and what's stumping me is the transmission shifts smooth in all gears, no grinding, no slipping clutch, no kicking out of gear, no symptoms of failure at all and the fluid level looks fine at the slave cylinder; what could this possibly be???

I also hear some rattling when I go over bumps, and when I'm slowing to a stop below 10 mph; this happens both in and out of gear; maybe this is related...maybe not

has anyone had this issue before??? just looking for some insight before I go to the shop and drop big bucks unnecessarily

thanks
 

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Throwout bearing going bad.
DENNY
 

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Discussion Starter #3
would a throwout bearing make a screeching noise when the truck isn't running? the just happens when the clutch pedal moves in and out. It's not constant like a throw bearing noise when the clutch is engaged...so that wouldn't be my first guess.

Some amplifying data to this mystery was this morning. Got in the truck and pushed the clutch in and no noises, and smooth as butter. After driving 20 mins to work, I turn off the truck and work the clutch pedal, and the creaking/screeching noise during pedal movement is back. Also, I've noticed in the past, after I've been driving a while, the clutch pedal is less smooth when I'm letting it out. It's almost like a ratcheting feeling when trying to let the clutch out slowly.
 

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You can try lubing the pivot points on the clutch pedal but if it is coming form the tranny I would say throwout bearing. Just to be clear you hear the noise before you have started the truck?
DENNY
 

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If its not the pedal linkage then you probably need to pull the trans out. My guess is throw out bearing or clutch pressure plate.
 

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I have had that noise come from both the pivot point and the pressure plate. I had to change the Pivot ball in the bellhousing for one and a new clutch assembly for the other. The sliding of the throw out bearing on the transmission neck could also cause the noise you describe. Either one requires pulling the transmission

I have been able to grease the pivot point and reduce the noise before

Any senior members want to clarify this on these transmissions PLEASE do.
 

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Discussion Starter #7
You can try lubing the pivot points on the clutch pedal but if it is coming form the tranny I would say throwout bearing. Just to be clear you hear the noise before you have started the truck?
DENNY
yes and no; when I hop in the truck in the morning and push the clutch in before starting, there is no noise; however after I've been driving the truck around, starting and stop the engine, the noise gets pretty loud; but yes, it happens when the truck is off (most noticeable), and when it's running (less noticeable due to engine noise), but definitely when the engine/tranny are warmed up
 

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Discussion Starter #8
alright fellas, I took a video this time so you can tell me your thoughts and no guessing as to my description of the noise. Again, it doesn't do it when its cold. Got in the truck this morning and quiet as a churck mouse, then after driving for about 45 mins, it has the horrible screech. Heres the video.

 

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Try lubing every pivot point you can find (under dash) If that does not work you have to pull the tranny.
DENNY
 

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If it gets worse after driving I would bet its under the bell housing, whatever the problem is. Things inside the cab should not get hot.
DENNY
 

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I'm guessing the throwout bearing is going bad. Also the fingers on the pressure plate are probably dry causing the screeching when they move across the face of the bearing. I'd recommend you pull the tranny and replace the clutch and throwout bearing.
 

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Discussion Starter #12
well, sounds like either way the tranny will have to be pulled; I don't have the knowledge when it comes to tranny to pull it out and then diagnose so I'll have to take it to the tranny shop; what could I expect to pay out the door for clutch and throw out bearing replacement??? possibly pilot bearing too...?
 

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I had a similar noise back in the day. I don't remember exactly what I lubed up, but it was one of the friction points under the dash. I remember pulling the spring on the pedal and lubing the ends where it rubs against the holder...that was after I lubed the various pivot points. Bottom line, it's probably something related to the pedal assembly.

Have a helper stick their head under the dash and then under the truck to confirm where the noise is coming from. My $0.02 says it's coming from the pedal assembly.
 

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Discussion Starter #14
if it was from the pedal assembly, wouldn't it always do it? my noise only comes when the tranny is nice and warmed up, and sounds like metal on metal almost
 

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You would think so but it is worth taking a can of silicone spray and hitting any moving part outside of the tranny.
DENNY
 

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Discussion Starter #16
well, new LuK clutch kit installed, and STILL exact same noise and same symptoms; what else could this be? slave cylinder creaking as it goes in and out after warming up? the pedal assembly does make some noise, but the nasty screeching noise is from the bell housing; could removing the pedal spring help maybe? any negative effects to that?
 

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Did they find any issues with the parts they replaced? Did you replace the throwout bearing? Did you lube all moving parts outside the tranny before you tore it apart?
DENNY
 

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I really have to ask, who did the clutch replacement? They did not say anything about the noisy clutch? Would have been a good time to eliminate a few things.
Bill
 

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Discussion Starter #19
so, I took it back to the shop and had them come out and listen to it when it was nice and warmed up; he used a stethoscope to pinpoint the sound which apparently is coming out of the slave cylinder; he thinks that over time it has worn a groove in the cylinder and when it warms up and expands, then it makes the loud squeak noise; he is going to replace that free since he didn't diagnose it properly the first time; he ordered the Luk slave and master cylinder prebled kit; we'll see if that fixes it

in other news, the clutch is great; nice and smooth (when its cold), and super soft; soo soft that I took the pedal assist spring out to make it not want to stick to the floor; I've read about alot of guys doing this with aftermarket clutches like the South Bend and LuK so I figured I'd give it a try for a while
 

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Yep, a clutch slave that was worn could easily sound like that. Glad you finally got it figured out.

I removed the assist spring after putting in a SB clutch and the pedal stuck to the floor at higher rpms (on the drag strip - not good). Seems like the centrifugal force on the pressure plate would make it stick when revved up. Been without the spring for years now.
 
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