unusual clutch issue

[greenskeeper]

So about 20k miles ago, right before I bought my truck the clutch, flywheel, fork, hydraulics, etc where replaced at a ford dealership by the original owner.

Within the last 10k miles or so, the clutch has gotten "grabby" to where it will shake the truck when engaging from idle. Adding throttle only makes the shaking worse.

The weird part is that when the truck is cold and not driven too far, it seems to be at it's worse.

Last night we were running around town, and after about 45 minutes of driving the clutch didn't grab or shake the truck at all.

This morning when cold it went back to being grabby again.

Most of my trips are under 10 miles so the truck never really warms up.

What the heck is going on here?

Contaminated clutch? No oil leaks.

Moisture getting into the bellhousing? I do go to the car wash often with the aggressive under carriage spray.

Unrelated to the clutch itself?

 

[Thewespaul]

Sounds like you got some hot spots on the flywheel, two clutches and an engine ago in the shop truck I replaced the south bend with a Phoenix friction not because the sb was having issues but because of all the hot spots on the flywheel from launching at the track. It made backing trailers up a hill a nightmare and would rattle the teeth out of your head. Fresh clutch and flywheel fixed it up, but really just resurfacing would be fine. I know some people have revved up and slowly let the clutch out in third from a stop and made it better, but I would be worried about how much life that would take off the clutch.

 

[greenskeeper]

I thought about the "hot spots" on the flywheel, but I'm about as easy as they come when clutching, so for the last 20k miles it's lived an easy life. When I bought the truck it has less than 2k miles on the new clutch and components and drove without this issue.

 

[Thewespaul]

Hmm, well I’ve had a similar issue with a 460 that had a zf behind it. Clutch was fine but the input shaft had a lot of side to side play, and made it feel like a brand new clutch had hot spots on it. If your zf is high mileage it may be the issue

 

[greenskeeper]

Hmm, well I’ve had a similar issue with a 460 that had a zf behind it. Clutch was fine but the input shaft had a lot of side to side play, and made it feel like a brand new clutch had hot spots on it. If your zf is high mileage it may be the issue

The transmission has 254k miles on it, so it's very possible it's the input shaft. I'd hope that when Ford did the clutch for the original owner they would have taken a look at the input shaft on the transmission while it was out.....who knows.

 

[greenskeeper]

Removed starter since there is no inspection port on the zf6, also took a look with the slave cylinder removed

From what I can see with a mirror, nothing is out of the ordinary.

I am currently using a heat gun to blow hot air into the clutch area (with pedal to floor) in case it is moisture related.

Who knows....if this does nothing then I'm going to keep driving it as is until I get the motivation to pull the transmission/transfer case and investigate further.

 

[greenskeeper]

After all that, turns out it was the connection at the clutch pedal with the master cylinder rod.

A heim joint fixed the problem as there is zero play in the clutch pedal action now.

 

[Thewespaul]

Interesting, glad it was a simple fix

 

[FarmerFrank]

Glad you found it. I had a similar issue in a 90 bronco when I was 17. Got so bad you could hardly pull out. Found 2 bellhousing bolts left and they were finger tight, every time I pushed in the clutch I was moving the transmission back 3/4"... Last guy must have used his biggest screw driver to tighten them.


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[NO_SPRK]

so my clutch did the same thing after washing the engine. bell housing on zf6 is very tight... not much breathing room. if you washed some junk on the clutch it would almost feel like it slipped. id try slipping the clutch a little and see if it goes away. that helped me. now i have a south bend clutch and havent had any issues. except at 50k on it the damping hub is already sloppy

I thought about the "hot spots" on the flywheel, but I'm about as easy as they come when clutching, so for the last 20k miles it's lived an easy life. When I bought the truck it has less than 2k miles on the new clutch and components and drove without this issue.