The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: Thomas on May 07, 2023, 06:09:33 PM

Title: Cracked rocker arm shaft
Post by: Thomas on May 07, 2023, 06:09:33 PM
Hi all,

The exhaust rocker arm shaft of my 1937 Model 9 cracked between its keyways and the keys are sheared off. I have no clue how to get spares. Can somebody help? Or is it possible to let the hardened shaft be welded in a skilled workshop? Can the shaft be detached from the arm and then machined in a lathe?

Cheers, Thomas
Title: Re: Cracked rocker arm shaft
Post by: phutton on May 08, 2023, 01:04:34 PM
Hi Thomas,

The overhead rockers are common to all 500 and 600cc models from 1932 to 1938, so there may be some in our Used Parts stock. Unfortunately, we are heavily involved in setting up a new store with racking, security etc and sorting out the new stock we acquired a few months ago. However, do get in touch with Paul Knight add add your requirements to his list.

PH
Title: Re: Cracked rocker arm shaft
Post by: Thomas on May 08, 2023, 01:22:00 PM
Thanks, Paul, I've sent him a message. Thomas
Title: Re: Cracked rocker arm shaft
Post by: Thomas on May 08, 2023, 06:05:29 PM
BTW: I know at least one fellow Beamer who also has cracked keyways in his rocker shaft. I asked Chris Fisher if can make them by reverse engineering using correct materials. With CAD it's a simple enough engineering task. Are there other club members interested in this?
Title: Re: Cracked rocker arm shaft
Post by: Thomas on June 22, 2023, 05:43:36 PM
Unfortunately, there was no help from the club side for the cracked shaft. But I have found a very smart solution. Because the shaft is hardened one cannot weld it in a regular way. I found a laser welder closed by who did an excellent job. Here is the result.
Title: Re: Cracked rocker arm shaft
Post by: singleminded on June 24, 2023, 10:36:41 PM
Well done for finding a solution Thomas..Something for us all to take note of..Thanks
John