The Ford Barn

JayJay · 10-02-2023, 08:37 PM

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.

Fullraceflathead · 10-02-2023, 11:26 PM

1.123 is exactly what 3 of mine measured.

Richard Knight · 10-02-2023, 11:32 PM

I have ground a couple hundred in a winona-van norman grinder. Always ground to 1.125. + or - .002 is just fine.

BRENT in 10-uh-C · 10-03-2023, 05:14 AM

Quote:

Originally Posted by JayJay

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.

If only the replacement clutch linings were a uniform thickness!!

What do you suppose a thicker/thinner lining does for that number?

.

JayJay · 10-03-2023, 11:25 AM

Quote:

Originally Posted by BRENT in 10-uh-C

If only the replacement clutch linings were a uniform thickness!!

What do you suppose a thicker/thinner lining does for that number?

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".

BRENT in 10-uh-C · 10-03-2023, 12:03 PM

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Quote:

Originally Posted by JayJay

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".

Yes. FWIR, I absolutely hate setting up to grind a flywheel with a stock pressure plate anymore.

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.

Richard Knight · 10-03-2023, 04:05 PM

Gee I wish I had seen
that print 40 years ago! The final step of checking and adjusting the fingers is what counts.

10-02-2023, 08:37 PM	#1
JayJay Senior Member Join Date: Jan 2020 Location: SF Bay Area Posts: 1,079	Pressure plate mounting surface to flywheel surface distance 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 San Francisco Bay Area ------------------------ 1930 Murray Town Sedan 1931 Briggs S/W Town Sedan

10-02-2023, 11:26 PM	#2
Fullraceflathead Senior Member Join Date: May 2012 Location: Chillicothe, Missouri Posts: 1,176	Re: Pressure plate mounting surface to flywheel surface distance 1.123 is exactly what 3 of mine measured. __________________ "If I asked people what they wanted they would have said faster horses." -Henry Ford "Primitive technology is not a design flaw" 1928 Ford Model A Roadster Pickup 1930 Gordon Smith Air Compressor 1941 Willy's Pickup 1960 Thunderbird-For Sale 1964 Buick Riviera 2x4 425 1965 Pontiac GTO, 455 Super Duty 2004 Dodge Ram SRT-10, V-10 Viper 1977 Charger Jet Boat,460 Ford,Jacuzzi Jet Front Engine Nostalgia Dragster,Supercharged 296 "Fullrace Flathead" Ford Engine Build up on DVD ask

10-02-2023, 11:32 PM	#3
Richard Knight Senior Member Join Date: Mar 2021 Posts: 130	Re: Pressure plate mounting surface to flywheel surface distance I have ground a couple hundred in a winona-van norman grinder. Always ground to 1.125. + or - .002 is just fine.

10-03-2023, 04:05 PM	#7
Richard Knight Senior Member Join Date: Mar 2021 Posts: 130	Re: Pressure plate mounting surface to flywheel surface distance Gee I wish I had seen that print 40 years ago! The final step of checking and adjusting the fingers is what counts.