When Good Clutch Disks go Bad

[apbright]

Hey folks,

I bought my Model A about a year ago, at which time it had about 2500 mi on it since engine rebuild, and I have put about 5000 mi on it since. Last Friday, half way home from work while stopped at a traffic light, I noticed I couldn't fully engage the clutch - gears would grind when trying to put it into gear, even though the clutch pedal was fully on the floor.

I double-checked that there wasn't anything underneath the pedal, pressed triply-hard on it, but it still wouldn't fully disengage. In order to get home, I had to jam it into 1st gear, causing the car the lurch forward, while a sound came from the transmission that would have drowned out the industrial revolution. Rough treatment, I know, but it got me home.

Suspecting I had a clutch problem, I stripped the drive train down, and when I finally got the pressure plate off, a clutch disk with a dislodged spring fell out as in the attached picture.

So - the question is - am I right for feeling a little bit other-than-happy that what presumably was a fancy-new clutch disk 7500 mi ago popped a spring and caused me (so far) 6 hours of greasy hands and swearing in the garage?

Interested in all views as always.

Best,

Andrew

[big job]

Yes I would be happy to find that rather than going through all that and findin nothin
wrong.

[BRENT in 10-uh-C]

There is two things that need to be checked first before this goes much further, --and please understand that any defect is not necessarily the fault of your engine builder or parts vendor. Things do break, ...but let us discuss some things first.

The disc needs to be placed onto the input shaft or two live centers to check lateral runout. Often times, a bent/warped disc will cause this. It is not all THAT common but it does happen. Therefore look at the clutch hub area and see if the hub area shows signs of damage. I suspect it will however it also needs to be determined if this is a newly manufactured disc or a rebuilt one. It is also possible this is a new hub and it prematurely wore but I have only heard of one other person discussing this and I did not get to inspect the disc to see the damage. Again, there are many new discs installed each year and this is not something we hear a lot about so I suspect this is an isolated incident. I do hate it for you but you probably just need to install a good replacement and go enjoy many more uneventful miles of driving.

[montanafordman]

If I am not mistaken there are some clutch disks that come with a lip along each side of the length of each spring, presumably to help prevent the same thing from happening. It doesn't look like your disk has much holding the spring in there.

[zzlegend]

Ditto. I have heard of this before. Maybe one like this next time. Just a thought.

[smtichy]

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Originally Posted by BRENT in 10-uh-C

There is two things that need to be checked first before this goes much further, --

Maybe a 3rd thing ... Is there a "Made in China" label somewhere on that disc? More and more I see a lot of really cheaply priced new parts out there, and have been questioning the quality and durability of this stuff.

Really, it would be interesting to find out where that disc was made ...

[BRENT in 10-uh-C]

Originally Posted by smtichy

Maybe a 3rd thing ... Is there a "Made in China" label somewhere on that disc? More and more I see a lot of really cheaply priced new parts out there, and have been questioning the quality and durability of this stuff.

Really, it would be interesting to find out where that disc was made ...

I think we are getting a little "ahead of ourselves" here. Make no mistake about it that I am a very strong proponent of US Manufacturing however the offshore items can be equal to, --if not greater quality than what we are willing to produce here!!


Now, let's go back to discussing the clutch disc itself. The clutch disc that the OP shows is just like the unit that many suppliers sell, ...and I feel this unit has proven that it can be reliable. Again, how often does this very topic come up here where the disc has failed? I have enclosed some pictures of a unit I just removed from packaging. It is basically the same unit that many dealers sell so let's look at it a little closer.

With regard to this new disc, I think when you look at the total design of this hub & plate, you will see that "flange" is not needed. First off, if the input shaft that the hub spline is riding on is truly perpendicular to the flywheel, those springs should not need any type of "flange" to hold them into place. Second, if you look at the plate construction, you will see those windows for the spring are actually a smaller diameter than the spring itself. Therefore they really cannot fall through the window unless there is some force pushing them out at an angle. The splined hub and the driven hub both have notches on the ends that keep the springs indexed and inline. Therefore only something that is out of line can cause the springs to be forced out of alignment.

Now, I really did not want to publicly say anything before about the OP's failed clutch disc but when I initially looked at that clutch lining, my initial thought was either the disc is warped, --or the input shaft is not in alignment with the flywheel face. Look closely at the outer edge of the facing and see where there appears to be more wear. I think this would be indicative of the input shaft not being truly perpendicular with either the pressure plate or the flywheel surface. Then once engaged, the plate would force (clamp) the disc to run in direct alignment with the flywheel. If the input shaft were not in the same alignment, the constant bending motion could create premature wear on the clutch disc hub. Again, being able to examine everything more closely would likely offer an exact reason but at this point, I am not so sure we should be faulting the design or the manufacturer.

.
.

[Tom Endy]

A number of years ago the Nova Company produced a quality clutch for the Model A. It featured the little "grabbers" that secured each spring in place on both sides of the disk. Unfortunately they went out of business.

For a number of years suppliers have been carrying clutch disks such as the failed one in the question post. I have seen quite a few of them fail with one or more spring falling out of the slot. It is usually a premature clutch failure.

I refuse to install one. I made it a point to look for used Nova clutches at swap meets and managed to collect several. As long as the thickness is in spec they were good to use, and I did.

A couple years ago Bratton's began carrying a clutch similar to a Nova. I have seen several of them installed. They look to be a good quality clutch disk.

Part number 11400, $30.75

Photos show a Nova clutch, a poor quality clutch without spring retainers, a Bratton quality clutch, and an original Model A clutch without springs.

Tom Endy

[zzlegend]

Good pics. Thanks Tom. I agree with your statement.

[gweilbaker]

Could that outer wear be from the spring in that area?

[BRENT in 10-uh-C]

Originally Posted by gweilbaker

Could that outer wear be from the spring in that area?

How did it get there without scarring the disc lining up in the center? Also, there generally is not enough air gap between the plate/flywheel and the lining to get something as big as that spring through there to reach the outside.

[BRENT in 10-uh-C]

Originally Posted by Tom Endy

I have seen quite a few of them fail with one or more spring falling out of the slot. It is usually a premature clutch failure.

Since this surfaced, I have engaged in a couple of e-mails about this from a few concerned folks and I still stand by the same statement as I told them. How often have we discussed this on Fordbarn about springs coming out of the clutch disc? I am sure there have been some failures in times past as Tom has suggested however has anyone ever determined exactly what was the contributing factor on those that failed? If someone would take the time to take detailed pictures of the damaged disc, I for one would like to see it up close.



BTW Tom, I am curious about that last picture of the disc without any springs. While I have not researched it, I was understanding the original discs sans the springs were only used on AA's, and later on the 'N' series tractors. Is this true --or were they really used as a Model-A passenger car plate? If so, was it used during a certain period of time or a particular application??

.

[Gold Digger]

I ran into this same problem a few years ago and found that a 40 series John Deere tractor had the clutch spring retainers built into it and used it. Still running strong since 1969.

[apbright]

Thanks folks for all of the comments. In the end I put it down to a suspect quality clutch disk, and have since replaced it with one from Snyder's. It looked most similar to the one labeled "Bratton quality clutch" in Tom E's post, so I'm hoping it's a good one.

I added a few additional pictures, of the pressure plate, a close-up of the pressure plate, a close-up of the failed clutch disk, and the flywheel. To my eyes, the other springs in the clutch disk were also on their way out too. I didn't see anything wrong with the pressure plate or flywheel, although I can accept that finer precision tools than my eyes would really be needed to verify they're perfect.

Someone wondered why there were no scars from the dislodged spring. In fact, there were very severe scars on the clutch disk, albeit on the opposite side from the one I took the photo of. It also left scars on the flywheel, which are just visible in the picture.

In the end, the event gave this previously automotive-illiterate Silicon Valley Engineer the ability to say he fixed a clutch disk, and I'm just enjoying the pride in being able to say that for the first time.

[van Dyck]

Are the top two shims installed between the clutch housing and the engine block? They need to be there to establish correct alignment of the transmission input shaft (on which the clutch disc rides) to the engine crankshaft.
Also, using a straightedge across the pressure plate surface, check for cupping or bowing. Pressure plate surface must be flat. Wouldn't hurt to check the flywheel surface too, however the flywheel is less likely to cup or bow.

[Tom Wesenberg]

I would use a palm sander on the flywheel and replace the throwout bearing. Normally I never replace a good part, but I see signs of rust on the bearing. Was this engine washed down with water and left to dry? The stains on the pressure plate kind of indicate dampness and maybe? a stuck disc at one time.

[Great Lakes Greg]

Thank you van Dyck for answering a question I was going to ask. Those shims are apparently very important for shaft / flywheel alignment.

[apbright]

Shims between clutch housing and engine block... hmm... Given that I don't know what you're asking about, I'm going to say "No."

Will read-up on this one.

[Terry,NJ]

FWIW, I recently "Refreshed" a engine and installed it in my coupe. The Gasket kit had a thin paper FW housing gasket. I tightened the FW housing and checked the gap of the "Ears" at the top of the FW housing with a feeler gauge. The gap I got was .010. The old engine had a homemade gasket that was over .020, but was not shimmed, period. The bolts had been tightened against the engine block. Therefore the FW housing was in a warped condition. Upon reinstallation of the old engine, (A Couple of issues with the "New" engine) I maintained this shim and the first thing I noticed was that it vibrated a lot less (still some) when letting off the gas or down a hill. Clearly, these shims are necessary for proper alignment of the of the clutch vis a vis the input shaft of the transmission. The FW housing and the bellhousing (two Piece) is an engineering flaw that has been corrected over the years since the model A days. It's too flexible and requires a gasket to seal (the rear cam bearing), what should of been sealed in another way.
Terry

[Bob C]

Here is a link to Bratton's shims. http://www.brattons.com/product.asp?...=any&PT_ID=all

Bob