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11-06-2019, 06:33 PM | #1 |
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Join Date: May 2010
Location: Suth'N Maine
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Clutch chatter....
an interesting problem came up on an episode of "garage squad" were some clutch chatter was due to improper machining of the flywheel resulting in high spots on half the face of the flywheel.
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11-06-2019, 06:43 PM | #2 |
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Join Date: May 2010
Location: Coral Springs FL
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Re: Clutch chatter....
Gosh, no excuse for that. I wonder what the best method is for machining a flywheel? Lathe, milling machine or something else?
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11-06-2019, 07:20 PM | #3 |
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Join Date: Jul 2019
Location: Southern Oregon
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Re: Clutch chatter....
There are many different ways to resurface a flywheel but, it should be done by mounting the flywheel by it's crankshaft surface. That surface, of course needs to run true.
I'm not a automotive machinist but, I have machined many Cummings flywheels and SBC, race flywheels. I made fixtures to bolt them onto my lathe. Always checking for run out, before machining. Over heating a clutch, can create hard spots, on the cast iron surface and if you turn them, you have to deal with that. If you grind them, it's not as big a deal.
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Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline |
11-06-2019, 08:14 PM | #4 |
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Location: Qld, Australia
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Re: Clutch chatter....
I use an old crankshaft ,cut off at the start of the rear main, hold it by the rear main part and clock it up in the 4 jaw,then bolt the flywheel to it.
Lawrie |
11-07-2019, 03:03 AM | #5 |
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Join Date: Apr 2015
Location: Sweden
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Re: Clutch chatter....
The thing is if the flywheel has hard spots on it taking a very light cut on a lathe will give you a surface that still has the hard spots...the cutting bit on the lathe will flex between the soft and hard material.
So you either have to cut through the hardspots to get a perfectly flat uniform surface doing it in a lathe...or you need to grind it. I have a flywheel grinder...with a diamond grindingwheel itīs faster and produces a perfect surface every time. |
11-07-2019, 03:17 AM | #6 |
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Location: Southern Oregon
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Re: Clutch chatter....
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Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline |
11-07-2019, 08:48 AM | #7 |
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Location: Sweden
Posts: 3,045
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Re: Clutch chatter....
The problem isnīt that the bit canīt cut through the hard material.
Itīs that the load on the lathe is different when the bit hitīs a hardspot it moves away under the increased load. Even a $250 CBN insert at high speed does this...then it depends on how bad your hardpots are... Same goes for grinding if you just go hard at it and donīt let it spark out at the end... |
11-07-2019, 12:36 PM | #8 |
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Location: Southern Oregon
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Re: Clutch chatter....
Murre,
It sounds like you know the trade and yes, that's true, that's why I said usually. When turning, it can also make a difference where the hard spot is as, surface speed changes, as you go across the surface.
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Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline |
11-07-2019, 01:27 PM | #9 |
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Join Date: May 2010
Location: Long Island, NY
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Re: Clutch chatter....
You really need a "dedicated" Flywheel grinder, this is the sole reason this machine exists, it puts the correct "scalloped" finish on every wheel and compensates for the "hot-spots".
Since a grinding wheel (stone) is used it will at least "flatten" any high spots. A tool that uses a blade generally speaking is not all that good for resurfacing these wheels! Most "flywheel-grinders" use a constant fluid supply during the procedure! They also all mount the flywheel from the flange to maintain good parallelism! Thanks, Gary in N.Y. P.S. Here's a shot of an ass'y just machined, balanced, and indexed for the plate! You can clearly see the "scalloped" finish!
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11-07-2019, 02:19 PM | #10 |
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Join Date: Jul 2014
Location: Iowa
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Re: Clutch chatter....
At our machine shop we have a "flywheel grinder" designed for the job. We resurface all flywheels to remove evidence of wear. It does reduce clutch chatter, of course, but that is a product of the original torque tube design which transfers rear axle movement to the motor mounts and clutch linkage. Practice in operating the clutch pedal will help, but that chatter is an artifact that will always be with us.
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