[6pack] Worn pressure plate as the cause of clutch judder ?

[John Mitchell]

 Stan, I was wondering if when your were last reinstalling your 
transmission, you allowed the transmissions weight to hang on the input 
shaft, while you were getting things lined up?  I did this, and it 
caused the clutch plate to warp slightly, and gave the same symptoms as 
you describe.  I now use very long studs in place of the top 3 bell 
housing bolts so the tranny can hang on those until I get things lined 
up enough for it to slide together.  Just a thought.   John Mtichell   
76 TR6

Foster, Stan wrote:
> Dick, the pressure plate and clutch plate were both new and replaced at the
> same time (it was part of a TRF magic clutch kit). The flywheel was
> resurfaced.
>
> Clutch plate shows no sign of wear
> Flywheel shows a very slight sign of wear
> Pressure plate has a noticeable step in it.
>
> Understand your point about the disc straddling the step, not sure if can do
> that after installation though. Also understand your point about poorly
> installed cover plate. I'll be sure to check that on reassembly.
>
> None of this is going back in the car but I am still curious to know why this
> system failed after 400 miles..
>
> Stan
>
> -----Original Message-----
> From: Sally or Dick Taylor [mailto:tr6taylor at webtv.net]
> Sent: Thursday, March 06, 2008 2:54 AM
> To: Foster, Stan
> Cc: 6pack at autox.team.net
> Subject: Re: [6pack] Worn pressure plate as the cause of clutch judder ?
>
>
> Stan--- The clutch plate, counting both sides, has about .120 of lining
> on it before hitting the riivets. Altho we don't usually wear down a
> clutch this far, I have seen them worn down to where there was only
> about .030 of linng left, and the clutch did not slip. Having a step in
> the pressure plate of about 1/32 is not in itself a reason for the
> slippage. It should still "clamp". The problem most is likely from the
> clutch plate not fitting or riiding down inside this step. If a part of
> the disc is trying to ride the lip, it will slip and judder.
> Different diameter clutch plates could be the culprit here.  Variations
> of .125 aren't uncommon when going from one brand to another, and using
> the old pressure plate.
>
> I've never seen a pressure plate wear down like the one you have, but a
> step in the flywheel could cause the same judder that you feel. (That, I
> have experienced when changing to a different disc that was a little
> larger)
>
> A cocked pressure plate could also cause the slippage and judder, as
> with Seth's '76 TR. You'll want to be sure that it mates flush with the
> flywheel when installing. A few thin feeler gauges around the perimeter
> can come in handy as you tighten down the clutch bolts.
>
> I'd be interested in how you come out of this!
>
> Dick