Pressure plate mounting surface to flywheel surface distance

JayJay

JayJay

Well-known member
Perhaps a tiddly point, but what is the pressure plate mounting surface to flywheel friction surface distance supposed to be? I've seen 1.120", 1.123", and 1-1/8" (1.125"). I suppose there is some leeway that can be taken up in pressure plate finger adjustment, but I'm having my flywheel surfaced and I need to tell the machine shop something. Before resurfacing it's currently a fat 1.125" so I suspect the pressure plate mounting surface will need to come down some.

I'm thinking of telling the machine shop to machine it to 1.121"/1.125" (that is, 1.123" +/- 0.002"). Does this seem reasonable?

Thanks in advance, as always.
 
JayJay said:
Perhaps a tiddly point, but what is the pressure plate mounting surface to flywheel friction surface distance supposed to be? I've seen 1.120", 1.123", and 1-1/8" (1.125"). I suppose there is some leeway that can be taken up in pressure plate finger adjustment, but I'm having my flywheel surfaced and I need to tell the machine shop something. Before resurfacing it's currently a fat 1.125" so I suspect the pressure plate mounting surface will need to come down some.

I'm thinking of telling the machine shop to machine it to 1.121"/1.125" (that is, 1.123" +/- 0.002"). Does this seem reasonable?

Thanks in advance, as always.
Click to expand...


If only the replacement clutch linings were a uniform thickness!! :rolleyes: What do you suppose a thicker/thinner lining does for that number? :eek:


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BRENT in 10-uh-C said:
If only the replacement clutch linings were a uniform thickness!! :rolleyes: What do you suppose a thicker/thinner lining does for that number? :eek:
Click to expand...
Thanks for the drawing, Brent. I had the same thought as you re: friction disk thickness. I suspect that adjusting the fingers helps compensate for varying disk thickness. I can't imagine a functionally significant pressure plate spring tension issue over a couple of thousandths.

Given that I'm already at 1.125"-1.126", I'm going to have the shop set the distance at 1.122"/1.125".
 
JayJay said:
Thanks for the drawing, Brent. I had the same thought as you re: friction disk thickness. I suspect that adjusting the fingers helps compensate for varying disk thickness. I can't imagine a functionally significant pressure plate spring tension issue over a couple of thousandths.

Given that I'm already at 1.125"-1.126", I'm going to have the shop set the distance at 1.122"/1.125".
Click to expand...

Yes. FWIR, I absolutely hate setting up to grind a flywheel with a stock pressure plate anymore. :o Several years ago I converted my machine over to use a 5" CBN cutter, and it is a 'pain' to index the flywheel for that flange. Therefore, anymore I do not machine the pressure plate flange on my flywheel grinder. Now I machine the disc surface first and remove it from the flywheel grinder. Then I use a crankshaft flange tool that I machined from a scrap crankshaft that I bolt the flywheel onto in the lathe. I just measure the depth and then use the trepanning method to quickly take the flange down to size.
 
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