Clutch pedal sticking after new clutch - Ford Bronco Forum
 
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post #1 of 10 (permalink) Old 05-10-2017, 03:25 PM Thread Starter
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Clutch pedal sticking after new clutch

Hi all,

For starters, in 2012, I converted my '81 to a hydraulic clutch and an NP-435 transmission. When I did, I installed an entire clutch kit (flywheel, clutch, pressure plate, throwout bearing, and pilot bearing). The clutch worked beautifully, and I've been driving it for 4.5 trouble free years, and probably have 25,000 miles on it.

A few weeks ago, I installed the new engine that I built (build thread here: Performance 300 Build).

With it, I again installed an entirely new clutch kit and flywheel.

However, after about 200 miles on the clutch, it has really started to stick. When I press the pedal to the floor, there's a groaning/creaking in the first inch or so of travel when I let off the pedal. Sometimes it binds so badly that the pedal doesn't even come up at all and it will just stay on the floor. I have to pull on it with my foot to get it free.

Here's the weird thing though.

There is no binding when the engine is off. It's nice and smooth.
It works perfectly the first 5 minutes or so that I'm driving and has plenty of travel and is nice and springy.
It slowly starts to get stickier and stickier the longer I drive. After 20 - 30 minutes of driving, it becomes really difficult.

Any ideas? I've never dealt with an issue like this, and I can't figure it out. It's becoming downright dangerous.


March 2016 FOTM
1981 Bronco. 300 I6. 450cfm QuickFuel 4bbl. BFG A/T KO2 32x11.5" tires. NP-435 trans. EFI exhaust manifolds. 2.5" Exhaust. DUI performance ignition. Redhead steering box w/ Saginaw PS pump.
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post #2 of 10 (permalink) Old 05-10-2017, 04:18 PM
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Off the cuff, it sounds like a bad or improperly installed clutch pressure plate/diaphragm/basket.
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post #3 of 10 (permalink) Old 05-10-2017, 06:36 PM Thread Starter
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I'm pretty certain it was installed correctly, and lined up with a clutch alignment tool. It's a fairly straight forward procedure.





As for being bad, I suppose anything's possible. From what I'm reading though, symptoms of a bad pressure plate are usually clutch slippage, not engaging, etc. Could something with the pressure plate cause it to hang up on the return?

Everything works great aside from the sticking. It shifts really nice, disengages/reengages perfectly fine, etc.
Something just feels like it's sticking when the pedal is released from all the way down. If I push it down only 80% or so, everything's fine.


March 2016 FOTM
1981 Bronco. 300 I6. 450cfm QuickFuel 4bbl. BFG A/T KO2 32x11.5" tires. NP-435 trans. EFI exhaust manifolds. 2.5" Exhaust. DUI performance ignition. Redhead steering box w/ Saginaw PS pump.
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post #4 of 10 (permalink) Old 05-12-2017, 05:50 PM
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If I had to guess, I'd guess that the clutch release bearing is either shot, misaligned, or both. You "should" be able to tell if you lightly press on the clutch while the engine is running. If you feel the clutch pedal pulsating up and down, you'll know.

My guess involves the assumption that you've installed an external slave cylinder with a stock-type fulcrum ball, clutch fork, and a slip-on/slot-type clutch release bearing. Of course, you could also have a bent clutch fork (but wtf would have bent it?).
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post #5 of 10 (permalink) Old 05-16-2017, 12:00 PM Thread Starter
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Hey flomaster, the clutch release / throwout bearing is brand new.
I suppose it could be misaligned, but I'm not sure how, as the install is extremely straight forward. Just face it the right way, put the fork around it, and slide it on the input shaft. But... things do happen. Either way, no pulsating when I lightly press on the pedal.

You're right in the assumptions with the external slave, fulcrum ball, and fork/bearing. Most of that wasn't touched though, except for taking the fork off so I could put a new release bearing in. As said, before the new clutch, I've been problem free.

The issue also comes and goes. I actually had an almost completely issue free drive to work this morning. The pedal was nice and springy like it should be. But, I know that it'll only be a matter of time before it starts sticking again.


March 2016 FOTM
1981 Bronco. 300 I6. 450cfm QuickFuel 4bbl. BFG A/T KO2 32x11.5" tires. NP-435 trans. EFI exhaust manifolds. 2.5" Exhaust. DUI performance ignition. Redhead steering box w/ Saginaw PS pump.
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post #6 of 10 (permalink) Old 05-17-2017, 01:01 AM
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Well, assuming that you're using the correct clutch fork, and all internal parts are assembled and functioning correctly, could the outside of the clutch fork be coming in contact with something (exhaust maybe)?
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post #7 of 10 (permalink) Old 05-17-2017, 12:14 PM Thread Starter
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I don't think it's anything external (exhaust is on the opposite side of the transmission) since really all I did was pull the old engine out and put the new engine in. Nothing really with the transmission except loosen the mounts to give me some wiggle room. Plus, the issue is only while the engine is running.

I really have no idea. Thanks for the brainstorming/suggestions though.

Oddly, it seems that over the last few days, it's been going away. There's still a small amount of binding, but it doesn't stick like it was. Hopefully it stays away. If not, I may have to go pick the brain of a tech at a local transmission shop.

It's a lot of work to pull it back apart, and I'm not really even sure what I'd be looking for. Everything looked correct before I put it in.


March 2016 FOTM
1981 Bronco. 300 I6. 450cfm QuickFuel 4bbl. BFG A/T KO2 32x11.5" tires. NP-435 trans. EFI exhaust manifolds. 2.5" Exhaust. DUI performance ignition. Redhead steering box w/ Saginaw PS pump.
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post #8 of 10 (permalink) Old 05-17-2017, 11:10 PM
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Spitballing here...

Well, process of elimination in mind, I guess it could be a bad pilot bearing. Do you have a roller-bearing type pilot bearing, or the bushing-type? If it is, the noise would manifest itself when the difference in speed between the flywheel and input shaft is the greatest.

The roller bearings are better at reducing friction, but the bushing type will save your input shaft if it does die.

Edit: Keep in mind that just because a part is new, it does not mean that it is any good. I've had new parts fail out of the box, and this includes name-brand stuff.
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post #9 of 10 (permalink) Old 05-19-2017, 05:48 PM Thread Starter
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I used to roller bearing type pilot bearing. But, I can't logic out a way it'd make the clutch "stick" if it was bad. There's no noise, just a rub/friction when I let the clutch out. Sometimes very little to no friction, sometimes a lot.

And yeah, parts can definitely be bad. I'm just hoping it's something I can get to without taking the transmission out.


March 2016 FOTM
1981 Bronco. 300 I6. 450cfm QuickFuel 4bbl. BFG A/T KO2 32x11.5" tires. NP-435 trans. EFI exhaust manifolds. 2.5" Exhaust. DUI performance ignition. Redhead steering box w/ Saginaw PS pump.
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post #10 of 10 (permalink) Old 05-19-2017, 06:51 PM
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Forgot about the sticking part. Guess you're going to have to take it apart and find out. Bummer.
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