Diaphragm Clutch?

Can you check runout on the crank flange while you have the flywheel off?

Anyone have a spec for flywheel runout? The inner to outer difference seem rather odd to me though. I’d hope for perfectly flat.
 
I saw in one place spec was .001” per inch but I don’t know if that means from the center out (5”) or full diameter (10”).
 
I’m not sure how to explain this but I read somewhere that there should be some kind of spring between the 2 sides of the clutch disk to ease the engagement. I am not talking about the torsion springs that are around the center and actually look like springs. I’m talking about some kind of wavy metal sandwiched between the 2 wear surfaces. Anybody familiar with this?
 
This is the difference I found. I think it makes a difference.
 

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I would think so too Dick. I believe that I can see the “wavy metal” spring that I tried to describe between the wear surfaces on only one (I assume that’s the old one?)
 
Paul, I would certainly think that it should be perfectly flat all the way across the surface. After all, they grind them flat when they resurface them.
 
New flywheel: These days more than ever, new doesn't always mean good. I would think a good machine shop could tell you if the flywheel surface is good or should be perfectly flat. Those measurements not being flat makes me question it.
 
Dick said:
This is the difference I found. I think it makes a difference.
Click to expand...


It does. The wave spring between the fiber halves is the "marcel" spring and it does help with chatter and allows a smoother clutch action.



Also, to the O.P. concerning the flywheel. Yes it should be dead flat. A new flywheel that is not is incorrectly made and will not work as well as it should.


Having said this stuff, I find that most folks who are truly happy with a new currently offered clutch have purchased the Centerforce flywheel, pressure plate and disk. Seems like a very good product.
 
Marcel Spring, yes was the name I was trying to remember! I can’t imagine how a flywheel could help be perfectly flat unless it was “turned” on a lathe as opposed to “ground” or “surfaced” on a mill (granted, I’m not a machinist), or if it had worn that way. I can’t imagine how .005”-.007” could wear off in 10 miles no matter how bad things were slipping & chattering. I will be talking to Mac Van Pelt as soon as I can get him on the phone Monday morning.

I will get the flywheel off on Monday as well and check the runout on the crank flange. I need to determine if the .008” runout I am getting off the flywheel is due to the flywheel, the crank, or a combination of the 2. I know also (and shame on me for forgetting in the heat of the moment to check) that crud can get in between the flange and the flywheel. I got a chance to put a micrometer on the new disk and it is .305” I don’t know what spec is. I can see that “gauge plate” for the 10” clutch is .295” but that may not be the correct thickness for the clutch disc. I’m sure the info is readily available but I have not had the chance to go hunting for it yet (Model A Picnic today).
 
7RT-7521……. that was the deal on mine. The hole in it was wallowed out massively. Had to be welded up and redrilled to the correct diameter. The other end of that has a clevis on it that pivots on the release lever. Another place with a ton of play in it….. filled with weld and redrilled to the correct diameter for the pivot pin. And no more clutch chatter.
 

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I tried a diaphragm clutch (10") that was listed for a Y-block. The fingers interfered with the throwout bearing hub. According to Ft Wayne, no early Ford Trucks ever had a listing for a diaphragm clutch, and ones for Cars such as what I bought are made to clear the smaller-diameter release hub on cars.

I fought severe chatter on my F-1 for almost 3 years, tried adjustable finger PP's from 2 sources, new release hub, release bearing, to no avail. I measured less than 0.004" on the face of the flywheel, which is supposedly within spec. Finally I took the flywheel in to a different shop and had it surfaced again. Sure enough, the machinist said it had an obvious wavy pattern on it, which only took a 0.005" cut to clean up. Since then my clutch is smooth as butter.
 
Going back to Flat Top’s earlier post which shows the page from the service manual: the resolution is poor but it looks to me like it says 1 3/4” for a 10” clutch with a .295” “gauge plate” I don’t have a .295” gauge plate but I do have aa clutch disc then when fully compressed by the PP measure’s .295” so that should be spot on or at least very close to the gauge plate. That said, I measure 1.95” using a straight edge as shown in the picture. That’s quite a bit more than 1.75”. Thoughts anybody?
 
Sorry for the bad resolution… so with the clutch disc and PP fastened to the flywheel, measure from the top surface of the PP down to the finger surface/adjuster. Your looking for the following:

9” disc should be 11/16 ( disc is .340 thick)
10” disc should be 15/16 ( disc is .295 thick)
11” disc should be 7/8 ( disc is .365 thick)
 
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