Clutch CW Questions...

[joemathews]

So you are supposed to disable the clutch start switch under the pedal, and put the car in neutral whenever possible to avoid having the clutch in...all in order to prevent crankwalk. But when you have the clutch pedal pressed down, the clutch is not engaged...so wouldn't it cause LESS stress on the crankshaft if you had the clutch pedal IN more? I guess I'm a little confused about this...especially the clutch start concept.

[TurbosR4me]

People disconnect their clutch start switch so they dont have to do a cold START with the clutch in. Especially when u have a heavy lb pressure plate, its really hard on your thrust bearing when u have 2600 lbs pushing on your crank when there is no oil in your engine.

You should also try to keep your clutch disengaged if your at a long stop.

[joemathews]

Yea, I've heard that several times. It still makes no sense to me. If you have the clutch pedal in, the clutch is out. This means that no part of the clutch is engaged with any part of the crankshaft. If the clutch pedal is NOT pushed in, the clutch is obviously engaged when you start the car. So what I don't understand is why it is better to have the clutch engaged upon starting the car (thus having stress directly on the crankshaft before oil has begun to circulate effectively) than starting the car with the clutch IN, waiting 10 or 15 seconds, then engaging it (by then oil should be working its way to where it should be).

I just don't see why it is supposed to be better for the crank if you start the car with the clutch engaged. Doesn't make sense to me. Does anyone else see this paradox? Help me out here, Kevin...

[ashah000]

I see what you are talking about... but I dont have an awnser.

[kjewer1]

To dissengage the clutch you have to overcome the pressure of the springs in the clutch pressure plate. With a 2600 pound plate, thats 2600 pounds. When you push in the pedal, this is what you are doing. So you are pushing the clutch plate/flywheel towards the block with 2600 pounds of force to release the clutch. THIS is what puts the pressure on the thrust bearing, not the clutch itself. When your foot is off the pedal and the clutch is engaged, the 2600 pounds of pressure is simply the plate clamping the disc to the flywheel, but there is no pressure on the plate/disc/flywheel towards the motor. Hope that helps.

[MiTsUsPyDeR97]

I had the understanding that is the pedal is pressed the the pressure plate is not applying pressure to the clutch plate therefore there would be no necessary force on the flywheel. But then on the other hand, if you have it rigged to start w/out the pedal being depressed and the car in nuetral then there is also no extra force being exerted. I think I have confused myself now........

[JoeWagon]

The stuff that holds the clutch has to push against the engine to pull the clutch out.

Do you know what a flywheel puller is? To pull the flywheel, you have to hold the engine in place. To hold the engine in place when you pull the clutch away from it, its 2600 pounds.

[kjewer1]

The pressure plate wont be applying pressure to the disc, but you have to push on the release fingers to release the disc. That pressure is whats pushing on the whole plate/disc/flywheel assembly, towards the block.

[MiTsUsPyDeR97]

Got it. Thnx for the clarification.

[joemathews]

So why is there not the same force of 2600 lbs applied to the flywheel/crankshaft assembly when the clutch plate is engaged? It seems to me that if it takes 2600 lbs to push the clutch plate off of the flywheel when you DISengage the clutch, then when the clutch was engaged, it would be exerting the same 2600 lbs to lock up to the flywheel. Thanks for the explanations guys, but I guess I'm just dense or something...still not seeing it. Here is a visual of the clutch engaging and disengaging by the way (put up strictly for Kevin's benefit, of course )...

http://auto.howstuffworks.com/clutch3.htm

[RattlesnakeGST]

Its been my experience that its totally random.. youre gonna get it or your not...

[joemathews]

Have you read any of this thread besides the title, man? Cars are machines, and when there is a problem with a machine, it is due to something failing, something putting pressure on someplace it is not supposed to. This always has a cause; it is not merely bad luck. I refuse to believe that CW is random, because it doesn't seem to me that mitsubishi just happened to build some engines with a time bomb feature to cause the crank to go haywire at a certain time. As Kevin preaches, CW will happen if you give it a chance to by failing maintenance, having your oil filter back off, etc...my goal is to make sure that I have done everything in my power to prevent it from happening. If it happens anyway, so be it, but I will know that I've done as much as I can to prevent it.

[JoeWagon]

It's like a spring. Springs don't have pressure on anything unless you pull them. There's no pressure on the block until you push in the clutch.

[kjewer1]

I didnt read the link (nice comment, lmao ) but let me break down the 2 scenarios.

With the clutch pedal up and the clutch "engaged." The pressure plate puts 2600 pounds of force in the direction of the flywheel to clamp the disc between the two. The flywheel, disc, and pressure plate have no force on them either toward the block or away from the block. That whole assmebly just sits there, with the only force being exerted by the spring clamping the disc.

Now, to disengage the clutch. The driver puts the clutch pedal down. Through the pedal assembly, rod, master, hydraulic lines, slave, slave rod, and throwout fork, the fingers of the spring are pushed in toward the motor to lift up the pressure plate off the disc (those fingers are on a pivot point on the plate, so pushing the fingers toward the flywheel pulls the friction part of the plate away from the flywheel, and disc). Now, to overcome the 2600 pound spring pressure, you have to exert some decent force on those fingers. That will push the whole plate/disc/flywheel assmebly TOWARD the block as well. This is where the pressure on the thrust bearing comes from! Its trying to keep the crank in place, while there is a strong force coming from the clutch pedal action.

Its important to note though that there is some leverage in those long fingers, so it doesnt take the full2600 pounds of force to overcome the 2600 pound spring. What the actual force required is, I dont know. But its up there. 1000 pounds at least I would assume.

I hope that helps explain it. I think the key is in remembering that the clutch can have 2600 pounds of clamping pressure but the whole assembly itself just free floats on the end of the crank. Until you step on the clutch pedal.