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Duratec clutch suddenly won't disengage


Rattie

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I think I have this one on the ropes, but I thought I would share and get see if anyone had had the same issue before and if there are any better solutions.

Almost at the end of our trackday at Bedford on monday, I was heading up the pit lane to start one last session, when the clutch suddenly stopped disengaging. Got it out of first, but then couldn't get it back in. Could feel the syncro drag as I operated the lever. Got towed back to trailer, called it a day.

Upon inspection through the slot where the hose and bleed nipple stick out of the belhousing, everything looks OK, no fluid splashes or damage. No drop in fluid level in the M/C either. When the pedal is operated, the release bearing extends and operated the release springs, but not as far as I would expect.

So, after some thought I open the pedal box and find the pedal clevis (thin, welded on additional support) has snapped off at the weld. This allows extra movement of the clevis pin and hence the lack of disengagement travel.

Bit crap that. The weld has a nice fillet profile, but very little penetration into the thicker pedal steel.

So I've tacked itback myself and ordered a replacement.

What bothers me really though is the single sided clevis on the Wilwood M/C shaft, hance requiring the tacked on plate on the pedal itself. Would it not be a better plan to use a proper clevis "nut" on the shaft?

Has anyone changed over to this arrangement?

Martyn

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Uh oh... when I saw the title of your post, I thought you might be suffering the same problems I've had recently.  I'm mightily relieved for you that you're not!

I'd agree that a U-section clevis for the clutch m/c push rod would be a better design.   The brake m/c pushrod already has one.

I think CC have done it this way so that they can use the same clutch pedal for hydraulic and cable.

JV

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Hi John,

Yeah I saw your problem posts while searching for hints on mine. Scored flywheel is a bugger.

I've ordered a 5/16 Wilwood clevis from Rally Design, which may solve the issue once and for all, if it fits round the pedal lever. I'll update as and when.

Martyn

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Had more time to bleed and test the clutch over the weekend. It actually appears to have fragmented. It'll disengage for a short distance, then latch up, which I'm guessing is fragments of clutch getting wedged between the plates, randomly.

So, time for a full replacement in all probability. Damn

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Sorry John, I wasn't clear, it's not a time thing but a displacement thing. The hydraulics are working just fine. I've had my wife hold the pedal down for a minute and there was no creeping of the slave/bearing to the rear (I could see down the bleed/hose slot with a torch).

No the centre plate must have come apart. I see it happens a fair bit.

I'm currently trying to find out what exactly the difference is between the two AP cover plates that Caterham have used on different engines recently. Mine's a CP5905-1, but I see the Rover one was a CP5905-500 and yet people have been fitting that to Duratec cars, presumably without problems. Another thread I think

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Thanks, Martyn - I understand now. 

Re clutch covers, I asked Tony in Parts about which one I should use.  He recommended this one.  The code shown in the photo is CP5905-500.  He also recommended this centre plate on the grounds that my R400 has the 220bhp motor.  He went on to say that "there are various different specs of clutch that have been available and these parts can be used on other models".  

I don't know how different the CP5905-1 cover is.  No doubt Tony would advise you.

Hope you get it all fixed soon.

JV

 

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