Crank Walk - Good read...

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Crank Walk - Good read...

Postby MrOizo » Wed Dec 01, 2004 10:37 am

Stolen from www.supraforums.com... about how when you start your car you shouldt push the clutch in as the crank shifts and when you do that first thing, say in the morning, there is very little oil against where the crank sits and wears...

Hey everyone,

I've had a lot of people ask me why the crank walked in my motor, so after a bunch of investigation, I believe I know why it happened to Sean and I at nearly the same time.

Our aftermarket, and even the stock pressure plates pull considerably on the end of the crank when you press them in. Under normal driving conditions this is perfectly ok. But, under engine cranking conditions when you start your car it is not good at all. The reason for this is that the thrust bearing requires an oil wedge to protect itself. This oil wedge isn't there until adequate oil pressure is achieved once the car starts.

Both Sean and I have been tuning the AEM ECU for quite sometime now. He tuned his for about 2 weeks before I started. We both concentrated on the idle and driveability characteristics, and not startup. We spent quite a bit of time re-starting our cars. I probably restarted mine over 1,000 times and so did he. His crank walked about 2 weeks before mine did.

I don't believe it's related entirely to the aftermarket pressure plate, as I've run a stiffer pressure plate in my car since 1996 and this is the first this has happened. I also don't believe it's the fault of the AEM ECU. If you are tuning an AEM ECU, get the car to start quickly first, then concentrate on tuning. You can also add a switch to bypass the clutch safety switch so you can start it without pressing the clutch in. Some Toyota trucks actually came with this switch from the factory because cranks walked quite a bit in those trucks.

Hope this helps.

Take care,
Chris.


You can also add a switch to bypass the clutch safety switch so you can start it without pressing the clutch in. Some Toyota trucks actually came with this switch from the factory because cranks walked quite a bit in those trucks.
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Postby Rollux » Wed Dec 01, 2004 12:43 pm

Haha, a clutch safety switch!! Obviously to stop dumb Americans starting their car in gear and then sueing Toyota for spilling their coffee on themselves. :lol: :lol: :lol:

Mind you, a few JDM cars are coming thru like that too. Makes you wonder what the world is coming to :roll:
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Postby Dr-X » Wed Dec 01, 2004 1:28 pm

lol didnt realise any cars had clutch safety switches. Interesting read, though.
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Postby CozmoNz » Wed Dec 01, 2004 2:53 pm

2002+ subaru legacys (the preddy ones, single turbo), need the clutch to be held in before shell start...

its got preddy guages ^_^
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Postby Disco » Wed Dec 01, 2004 4:36 pm

New Hyundais have "engine immobilisers" (clutch safety switches) so the clutch has to be in before the car will start...

I sat in one for about 10 mins trying to start it until the penny dropped...
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Postby Dell'Orto » Wed Dec 01, 2004 5:08 pm

I've seen a fairly modded MR2 suffer from pretty catastrophic crank walk (like there is a nice kind :roll:) with having a heavy duty clutch, and that was on a fairly fresh motor too
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Postby FLAWLES » Wed Dec 01, 2004 5:43 pm

tractors have saftey switchs on there clutch peddals and the gear stic has to be in nutral aswell as the handbrake on

but as for the flywhell thing never realy thought of that, flywheel walk az there would be piss all oil there on start up and when you apply the clutch your moving the clutch ether down or sideways " pending on witch way it cranks over " thus losing some of the oil to the sump
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