Adjusting Pressure Plate Fingers / Clutch & Flywheel Info

[Tom Wesenberg]

Original Thread
https://www.vintagefordforum.com/for...-plate-fingers

Anytime you install a new pressure plate or are chasing the cause of clutch chatter, you need to check to be sure all 6 pressure plate fingers are at the correct height and even with each other. I made this simple tool to make the job quick and easy. I just use a bolt and two nuts through a piece of aluminum channel, and lock the bolt head 11/16" from the face of the aluminum channel. If the bolt head has markings, I file them smooth. This picture shows a pressure plate from Little Dearborn, that I installed for a club member a few years ago. Being a bit off of 11/16" isn't critical, but having all 6 the same measurement is critical.

I made a hands free similar tool that beeps when the correct height is reached. You can see the picture and description in the "Homemade Tools" section.
https://www.vintagefordforum.com/for...homemade-tools



Homemade Tools Clutch Adjuster.jpg

[Mitch]

Important Clutch Disc Warning!

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[AL in NY]

Question.....Can you make pressure plate finger adjustments with the pressure plate still in the car?

[Mitch]

Yes

[Mitch]

Specs for lightening a flywheel


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[tbirdtbird]

Original Thread

I was the second member to sign up here on the VFF nearly 2 years ago, and Mitch's mission from the outset was to provide a forum with a breathe of fresh air. Meaning, politeness, solid experience from professionals, and to avoid myths and untruths and armchair advice so often found on other forums. He is also committed to having each and every Model A owner have the best possible experience with their cars, whether it be in driving, repairs, or anything in between. He is truly passionate about the Model A hobby, and as a professional mechanic himself, and Model A owner, brings a boatload of priceless experience to this forum.

Every now and then an important topic arises which presents an opportunity to once again stress the flaws in certain products out there. This is in response to a recent thread by Dennis.

Turns out there are 2 different clutch discs on the market. One should not even exist, and should be avoided like the plague, because the springs are not held captive and can and will pop out. This is really not good, unless you enjoy separating your engine from your bellhousing/transmission to fix the problem, that never should have existed. Mitch himself has had to make these repairs to cars that were worked on by unsuspecting buyers.

I am posting a picture of the correct type to buy, which in this case comes from the Bratton catalogue, although some, but not all, of the other vendors do carry them. Please notice the inset clearly shows how the springs are held captive and CANNOT pop out of place. This is the way clutch discs have been made since time began. Whomever manufactured the other type without captive springs should be re-assigned to manufacturing toothbrushes

Figured out how to lighten it
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[old31]

Thanks tbird, good info.

[Dennis]

Thanks Tbird. If I may add to this, call the vender and request a picture of the clutch disc before you order it from them.

[Jwmckenzie]

I assume the purpose of the spring is to take up initial torque when the clutch is engaged. How does it work? How is the spring activated by the friction surface?

I need to learn something today...…..

[BudP]

This might help to understand the principles of a clutch (not Model A clutch but the principles are there). https://www.howacarworks.com/basics/...r-clutch-works

[Jwmckenzie]

So my question is more specific to how the internals of the clutch disk work. So let me be more specific.

How is the spring connected between the friction part of the assembly and the hub?
If I had an old one I would cut it apart, need to put that on my Swap Meet list.

[carolinamudwalker]

Are the clutch plates from" Fort Wayne Clutch" captive? I installed mine before being educated.

[Mitch]

Good question Jon

Think of the center hub that splines onto the input shaft as a separate assy than the clutch friction plate. I believe the washer holds the two pieces captive and allows the inner hub to pivot. (not positive on the washer part) Then there are stop pins so it only goes so far


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[tbirdtbird]

Think of the center hub that splines onto the input shaft as a separate assy than the clutch friction plate.

That is the key, they are indeed 2 separate assemblies. The springs are pushed by the friction plate (think flywheel) , and then they in turn push on the center hub which is connected to the tranny input shaft

[tbirdtbird]

Hmm, I just read thru that older thread from the related topics that Mitch reminded us of about Ft Wayne clutch. Now I am very confused as to what they actually sell, since the pic varies from what one buyer said he got.

Brent's reply to look at an original Model A disc almost falls outside the current discussion because Ford used no springs at all, everything was solid.
To me, you have to be either solid , or have captive springs. Having springs that are not captive should be avoided like the plague, just ask the many who have had a spring pop out and jam up the whole works

[Tom Wesenberg]

I agree about the captive springs. Also note that there is also another thing that cushions the engagement, and this even applies to the original with no springs. Look closely at the metal disc where the clutch linings are riveted, and notice the disc is slightly wavy to help cushion the engagement.

When I first bought my 29 Tudor, it shook like a paint mixer every time I let out the clutch from a dead stop. I tried slipping the clutch and other things, but finally had to take the thing apart. I replaced the disc with a new one I bought at a swap meet, even though the one coming out was almost new. I also installed a good used pressure plate, even though the one I removed looked perfect. I also used my 1/4 sheet sander to lightly sand the flywheel. Then I also dialed in the flywheel cover. Now it engages as smooth as an automatic transmission.

[Steve Plucker]

Can you post a photo of the "bad" type of clutch disc?

Thanks.

Pluck

[Mitch]

Can you post a photo of the "bad" type of clutch disc?

Thanks.

Pluck

On this one the springs are not held captive
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[Mitch]

image_15435.jpg

[rheacox]

Adjusting Pressure Plate Fingers

Original Thread

What would be considered an acceptable tolerance when adjusting pressure plate fingers? I had suspected something was off when reassembling everything after putting the new engine in and recently the clutch started to chatter. Turns out none of the adjusting nuts were staked and all of the fingers were around 3/16”-1/4” … way off the 11/16” that they should be. The kicker is the note that came with the pressure plate said “DO NOT ADJUST” …

Anyway, I made up a tool to gauge the depth, was shooting for 11/16 (.6875). The tool came in at 0.692, not bad. I have a couple fingers adjusted to 0.692+0.004-0.000. Is that close enough or should I aim for a tighter tolerance like 0.002? Is there a spec for this?

[Patrick]

The spec is .002". Its not too hard to get with the unit on a bench but is tricky when in the vehicle so its my opinion that the .002" is more of a guide line in that situation.

I just turn a piece of stock to the dimension I want and then make the adjustment so each arm has the same drag. Then I tap each arm a few times gently and check/adjust them again. This is when the thing is on a bench.

When in the vehicle I just check for the tight arm and use a long .0015" feeler strip and adjust the rest to a fairly tight drag.

I'm kinda of the opinion that a chatter can come from a few issues.
Oil/grease where it shouldn't be but I don't see that very often
Finger adjustment
flywheel issue
bellhousing/clutch cover alignment

[rheacox]

Well then I'll shoot for 0.002", thanks! It is a bit of a pain in the car. Wish I'd thought about it before when it was on the stand. Oh well, should be able to finish it up tonight without too much hassle. I'll hook the pedal back up, work the fingers a few times and recheck before locking everything in place.

I'm 90% sure one or more of the fingers moved since none were staked and that's whats causing the chatter, they definitely weren't all at the same depth upon inspection last night. It was butter smooth when the engine first went in.

[rheacox]

Got it all buttoned up last night and boy is the clutch smooth again. Patrick, I do see what you mean about the 0.002 being more of a guide line in the car... tried to be a consistent as I could but between variations in holding the gauge I'm probably closer to +/-.004 but the clutch is smooth and I'm happy.

Went with the full belt and suspenders routine (nuts staked and loctited), let's see em back off now