what exactly happens when the clutch "burns up"? - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 12-17-2001, 10:27 PM
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what exactly happens when the clutch \"burns up\"?

Well, the subject is pretty much self explanatory. It's just that this exact thing happened to my friend the other day as he tried to pull somebody out. I was asked by another friend of mine, "What exactly happens when the clutch burns up?" and I didn't have an answer for him. I know a little about clutches and transmissions, like the functions of the flywheel, clutch disc, and pressure plate, so that might help you in explaining this to me.

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post #2 of (permalink) Old 12-17-2001, 11:07 PM
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Re: what exactly happens when the clutch \"burns up\"?

Blake, i'm not an expert but I'll give this my best shot...
When you start your Jeep up, your flywheel and pressure plate are moving/turning... when you let the clutch out, these two come together and grab the clutch disc which is sandwiched in between the two.. (disc is splined to the input shaft of the tranny). When using hard, such as pulling someone out or trying to get unstuck,plowing,etc. heat builds up, and the springs can no longer "hold" the disc and it starts slipping causing the smell from the heat/friction. Your disc is actually turning or slipping between the two instead of being held.

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post #3 of (permalink) Old 12-18-2001, 12:20 AM
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Re: what exactly happens when the clutch \"burns up\"?

The last reply is pretty dead on. A clutch is made up a relatively soft material, mostly asbestos, and when the pedal is let go too fast, under too much load, the engine is spinning far faster than the tranny and rear diff, as the clutch tries to 'mate' or join, the two, it heats up excessively, therefore 'burning' up. Too high speeds, and temperatures destroys the material designed to soften the impact. It works alot like brakes trying to 'mate' the wheel speed and the caliper speed. poof, gone.
So next time you go to use the clutch, there is very little material there, the pressure plate or flywheel may be damaged, therefore the clutch slips, or it is too thin too hold onto much of anything. burnt.


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post #4 of (permalink) Old 12-18-2001, 12:58 AM
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Re: what exactly happens when the clutch \"burns up\"?

Besides the fiber material of the clutch disk being worn down, all the friction surfaces will glaze over including the metal surfaces. That is why a proper clutch job includes machining the flywheel, replacing the clutch disk and pressure plate. The flywheel may still be perfectly flat but once it's glazed over a new disk will still chatter. Machining the flywheel takes that hard shinny surface off.

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