Clutch advise needed

[GreenSnakeDoc]

I've got the tranny and bellhousing out and need to put a new flywheel/clutch in. I've been told that my coaxial slave cylinder/throwout bearing is a McCloud product and need to know if this part will work with both a diaphram and a lever type pressure plate. Thanks for the knowledgeable responses I'm sure to get.

[Jimi G]

Originally Posted by GreenSnakeDoc

I've got the tranny and bellhousing out and need to put a new flywheel/clutch in. I've been told that my coaxial slave cylinder/throwout bearing is a McCloud product and need to know if this part will work with both a diaphram and a lever type pressure plate. Thanks for the knowledgeable responses I'm sure to get.

The McLeod hyd throwout bearing will work with either type of clutch plate. jimig@standardtransmission.com

[GreenSnakeDoc]

Thanks jimi g. I just received a flywheel from Jegs that only works with a diaphram style pressure plate. The flywheel # is 317-FWFM116", if this means anything. Jegs specs are 28 Oz. external balance, 11" clutch, and 164 tooth.
Trouble is its 13 1/4" O.D. where the old one is 14" O.D. I don't think my starter motor pinion will engage it, and the outer diameter of the old 11" clutch disk will rub against all of the holes near the O.D. of this f.w. I think this could allow cracking making the f.w. dangerous. I'll have to count the number of teeth tonight. Any opinions or advice?

[patrickt]

Originally Posted by GreenSnakeDoc

The flywheel specs are 28 Oz. external balance ... Trouble is its 13 1/4" O.D. where the old one is 14" O.D.

If you replace your externally balanced flywheel with a different sized flywheel (even though it is still externally balanced) you might encounter engine balance issues. Aside from the starter motor pinion issue, I would be very hesitant about changing my flywheel size on the balance issue alone.

[CobraEd]

I believe that all 351s use the 28oz balance. Only the newer 5.0s use the 50oz. However, the 28oz flywheel comes in both a 157 tooth or a 164 tooth version. Either one will work, but the bellhousing must have dual positions for the starter to allow it to fit. Otherwise the flywheel must match the opening in the bellhousing for the starter.


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[GreenSnakeDoc]

Thanks for the suggestions guys. I'd like to know exactly what 28 oz. imbalance means. An extra weight located towards the O.D. has more effect on balance than the same weight in the middle. Maybe the automotive engineers have an 'understanding" on this and use the terms "28 oz." and "50 oz." to simplify the nomenclature. From doing a little work with gears, I've learned about a term called "diametral pitch". It's basically the spacing between adjacent gear teeth. Whenever two gears mesh, they must have the same diametral pitch so each tooth on one goes into the gap between teeth of the other. A designer can take the diametral pitch number and the number of teeth he needs on each gear for the reduction ratio to get the pitch diameter of each gear and the center spacing.

[CobraEd]

diametral pitch????

I think that you need to worry about that only if you are below the equator where the coreolas effect is reversed! Most American cars are built to be sold ABOVE the equator!!!!


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[patrickt]

Ford changed the external balance for small blocks in 1980 from 28.2 ounces to 50 ounces. I believe the flywheels look the same, but you can not switch them without throwing your engine way out of balance. Trust me, you don't want to do that. What I am not clear on is whether or not there are aftermarket flywheels that are a different size, yet still maintain the proper external balance needed for your engine. I would think that if you held your new flywheel up against your old flywheel and there was an obvious size difference then there would be a corresponding balance difference as well -- but I don't know. That was one reason why I stroked my 428, it did away with the external balance issue.

[Jac Mac]

Originally Posted by GreenSnakeDoc

Thanks for the suggestions guys. I'd like to know exactly what 28 oz. imbalance means. An extra weight located towards the O.D. has more effect on balance than the same weight in the middle. Maybe the automotive engineers have an 'understanding" on this and use the terms "28 oz." and "50 oz." to simplify the nomenclature. From doing a little work with gears, I've learned about a term called "diametral pitch". It's basically the spacing between adjacent gear teeth. Whenever two gears mesh, they must have the same diametral pitch so each tooth on one goes into the gap between teeth of the other. A designer can take the diametral pitch number and the number of teeth he needs on each gear for the reduction ratio to get the pitch diameter of each gear and the center spacing.

28oz or 50oz imbalance should be correctly stated as 28 oz/inch.
The 28oz/50oz is actually the weight that would be placed on a 1" radius from the centerline of the crank main bearing journals if that was physically possible.
As its not a smaller actual weight of metal is placed at a larger distance from the centerline- from memory I think it goes : 28oz[/i] @ 1" radius, 14oz @ 2" radius, 7oz @ 4" radius, 3.5oz @ 8" radius etc.

50 @ 1", 25 @2", 12.5@4", 6.25@8" etc,

Im sure some genius will correct me if wrong, but thats how I understand it.

""" Not sure I ' Learnt ' anything from the correolius example above though

Jac Mac

[GreenSnakeDoc]

I counted teeth today. Do you know how hard it is to count over 100 teeth when the flywheel is in a thick plastic bag? 157 is the number, which goes against the listed spec of 164. I can't use it with my existing iron bellhousing, but I wouldn't mind finding an aluminum one to save weight. Maybe aluminum ones use a 157 tooth flywheel? And the clutch diameter, wasn't 10" or 10 1/2" a size for a lot of Ford vehicles?