The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: Steve_M90 on August 07, 2019, 09:56:35 PM

Title: Magneto fibre drive wheel
Post by: Steve_M90 on August 07, 2019, 09:56:35 PM
On my M90 with Lucas MS1-4 Magneto, the fibre drive wheel is stripped of teeth. Two problems: why and replacement. Dynamo turns freely and drive wheel is solid on the shaft. It is not perfectly flat, it is out of true by +-10 thou. So not sure if this is enough to be the cause, nothing else obvious. In terms of a replacement, they seem to be somewhere between rare and unavailable. There's one in an eBay auction. Dave Lindsley doesn't have any. Any thoughts? Has anyone considered reverse engineering, 3D printing?

Steve
Title: Re: Magneto fibre drive wheel
Post by: singleminded on August 08, 2019, 11:59:05 AM
Does your mag fibre gear have a clutch drive or a keyed metal boss in the middle..John
Title: Re: Magneto fibre drive wheel
Post by: singleminded on August 08, 2019, 12:15:41 PM
About £22 inc postage from Tony Cooper. He has them in stock  ph.01215592405
Or I have a spare secondhand one..John
Title: Re: Magneto fibre drive wheel
Post by: Steve_M90 on August 08, 2019, 03:44:53 PM
Mine has a keyed metal boss in the middle. Thanks for the details. Steve
Title: Re: Magneto fibre drive wheel
Post by: Steve_M90 on August 08, 2019, 08:57:43 PM
Tony has plenty - 20 year's worth he said!

His advice and that of David Lindsley is that the wear / failure is a result of bad design and the slightest mechanical misalignment or sloppiness in the set up. I've had two fails in three years so I wonder if I'm doing something wrong?
Title: Re: Magneto fibre drive wheel
Post by: singleminded on August 08, 2019, 10:23:03 PM
You may have to make up gaskets to get the gears in line when tightened..The mesh of the gears needs a little clearance without too much backlash. This needs to be checked at every tooth position in case the armatures do not run true.  John