Clutch failure survey

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ChickenPinz
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Clutch failure survey

Post by ChickenPinz » Tue Jul 07, 2020 6:48 pm

This is a survey to find out about member clutch failures, and their likely causes. It's inspired by my recent clutch failure, which mimics another's failure less than a week later which had the same combination of events: original 40yo clutch + overspeed. My goal is to understand if the overspeed failure only occurs on old (or original) clutch discs, or has been known to happen on new clutches as well.

The two clutch failure cases I know of so far are 40yo clutch + overspeed.

Please weigh in on any clutch failures you've experienced. Include the age of the disc as well as the operating conditions that might have led to its demise.
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IMG_20200705_123223 (Large).jpg (284.17 KiB) Viewed 874 times
And....the likely overspeed event: https://drive.google.com/file/d/1upzfaO ... sp=sharing
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VinceAtReal4x4s
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Re: Clutch failure survey

Post by VinceAtReal4x4s » Tue Jul 07, 2020 8:56 pm

What do you mean by "overspeed"?

I had an almost new clutch fail once because the friction material cracked in one spot. The symptom confused everyone, which was it suddenly catching with no ease-in on take off. It was always assumed it was hydraulic and I went nuts bleeding and rebuilding that system for so long.
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ChickenPinz
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Re: Clutch failure survey

Post by ChickenPinz » Tue Jul 07, 2020 11:21 pm

If you watch the linked video, you'll see exactly how to overspeed one. Simply descend down a hill in low-range and 1st gear with the clutch disengaged. Top speed is 10MPH in low-range + 1st gear per the Operator's Manual. If we presume that's 4500RPM, then coasting down a hill at 20MPH will spin the clutch disc at 9,000RPM.
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VinceAtReal4x4s
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Re: Clutch failure survey

Post by VinceAtReal4x4s » Wed Jul 08, 2020 2:21 am

What was in the video was very tame compared to what I've done countless times in all kinds of 4x4's so I didn't see anything that could likely cause a mechanical issue. It seems like you were in a higher gear than 1st low range or the engine braking would have slowed you down more, unless you released the clutch, or was it already worn out by the time that was filmed? I can't hear your engine rev up so it seems more like you were rolling neutral for a few seconds or maybe its the distant audio plus my crappy laptop audio Im using at the moment.

(And I assume you meant clutch engaged and not "disengaged", which means the clutch would be disconnected, allowing the engine and trans to spin independently.)

The clutch isn't going to slip and wear until you depress the pedal to disengage it. It's plenty strong enough to stall the motor, as well as slow a loaded Pinz down with engine braking while descending steep grades in low gears, regardless of rpms.

New or old parts probably doesn't matter much. Some parts, as stated in my example above, are just defective or not made as well as others. There is nothing unique about the design of it, or the Pinz's overall driveline function that would make the clutch-wear scenario any different from any other 4x4.

By the way, if you rev your motor to 9000 rpm you are asking to destroy it. That should never need to happen.
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Joeri
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Re: Clutch failure survey

Post by Joeri » Wed Jul 08, 2020 11:21 am


ChickenPinz
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Re: Clutch failure survey

Post by ChickenPinz » Wed Jul 08, 2020 1:06 pm

Thanks for adding the explanation thread that further clarifies what this survey is about.

Still, I'm curious to hear of anyone's story of them personally experiencing an over-rev clutch failure on their Pinz. Just trying to gauge how common it is, and what role the age of the disc actually plays -- based on data, not conjecture.
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VinceAtReal4x4s
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Re: Clutch failure survey

Post by VinceAtReal4x4s » Thu Jul 09, 2020 2:13 pm

I don't mean to discount your survey but this is ultimately about an operating error. There's just no reason any 4x4 would need to rev up like that, engine or clutch, unless a driving error was made. Mistakes happen... I once rolled a 712 over several times, so I know!

There's also no way to know how old a clutch is. Could be 45 years old or could have been replaced with the exact same part 15 years ago. Only someone who bought a Pinz new could know, and no one here is in that boat to my knowledge although Dave and the GG is pretty close. :?
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ChickenPinz
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Re: Clutch failure survey

Post by ChickenPinz » Thu Jul 09, 2020 2:33 pm

Again, the goal is to determine if older clutch discs are more fragile than newer ones. This will help guide folks in their preventative maintenance and spare parts decisions.
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Texas710
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Re: Clutch failure survey

Post by Texas710 » Wed Jul 15, 2020 12:00 pm

I have not suffered a clutch failure (yet) but am having a hard time with this notion of over-speed.

I am a noob and pretty well self taught on driving a manual but it seems that coasting with the clutch disengaged (petal to the floor) is not the proper way to go down a hill or use a clutch. Not sure if this would be pinz specific or not. Hell, I don't even like to disengage the clutch at a light, would rather drop it in neutral.

ChickenPinz
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Re: Clutch failure survey

Post by ChickenPinz » Wed Jul 15, 2020 10:19 pm

No one said it was proper technique.
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4x4Pinz
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Re: Clutch failure survey

Post by 4x4Pinz » Sat Jul 18, 2020 8:01 pm

replied to your other post with our experiences

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