Theoretical Q about Model A Clutches

ahoogakev

ahoogakev

Member
Hello A Gang; I have a theoretical question about clutches please, I believe all modern clutch disks have springs in the center, to help smooth out the engagement when you step off the clutch, and probably to lengthen the life too...but I believe the original Model A clutches did not have those springs, they were "solid"... so my question is, would there be a noticeable difference, in how an original Model A clutch would feel in real-world use, compared to our modern ones with springs? Or would they feel the same? Would they wear out faster? Questions, questions! Thanks a lot! Kev
 
Springs were introduced at some point.

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I always thought that the springs in clutch plates were a service part and not original fit, and in my opinion only, not based on anything other than my own feel, that the spring clutch plates are a bit smoother on engagment.
 
Those springs are called "dampener springs" , and began to be used in clutch discs in the early 1930's.

By about 1935, the only company using a non-dampened disc was Hudson, and that was really a different animal, being a cork-faced "wet-clutch".

The purpose of the damper springs in the clutch hub is to promote smoother engagement.

Old-time solid-hub clutches can tend to "grab" or chatter on engagement, particularly if the driver has the engine speed "up" a bit, and is trying to gently "slip the clutch" to get the vehicle moving; it will tend to do a series of "bunny-hops"...

The "modern" clutch disc has two spring elements to it: the four to six damper springs around the hub, and the flexible springy metal core of the disc.

Modern clutches will probably engage more smoothly; service life will depend on the lining material used and the habits of the driver... in general, the less time the clutch spends "slipping", the longer the linings last.

When I'm driving any stick-shift vehicle, I try as much as possible to synchronize engine & driveshaft speed to minimize slipping the clutch.

For getting the vehicle under way, I will usually goose the throttle, and as the engine is coming back to idle, I am letting the clutch out and letting the inertia of the engine & flywheel get the vehicle moving, then when I've felt the clutch "hook-up" (positively engage), I step on the accelerator and go. This is easier with old torquey long-stroke engines then it is with modern short-stroke cars...

Aside from changes in friction material, there really haven't been many(any?) improvements in clutch design since the "cushion-plate / damper-hub" clutches of 1935, such as Bruce pictured in reply #2...

I cannot think of a reason NOT to use the "modern" type clutch disc in a Model A, unless you are going for an absolutely authentic restoration.
 
Not quite Model A, but I first heard about BUTTON clutches about 15 years ago. I still can't understand how having just a few circular buttons for a clutch can be better than a full circular lining?

For those not familure with the button clutch, just type it into Google or ebay and see what they look like. Seems to me that claiming a button clutch is better would be equivelent to removing 80% of the brake lining length and claiming it's better.
 
I have had A's with both types and have not noticed any big difference. I cannot tell which type it is until I look. I did have a rivet fail on one with springs letting the springs loose. Makes driving 100 miles home a challenge.
 
I have the "Later style" clutch disc in my Model As. I think they are less prone to chatter and have a little softer feel on engagement. You can use the clutch disc from a later Flat Head V-8 Ford, clear up to 1948 or may be 1949. The splines are the same. You just have to get the correct outside dia. The V-8s used 9, 10 and 11 inch.
 
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