The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: Thomas on November 01, 2020, 11:18:00 AM

Title: Crank bearing size and suppliers
Post by: Thomas on November 01, 2020, 11:18:00 AM
Yesterday my footrest hanger had a fatique break. It may be connected with my girder spring vibrations/resonances. I meanwhile presume that my crank bearing could be worn and dismantling the motor should be on the plan. Sometimes one briefly stand on the footrests for relaxation while driving. Better not to think about what can happen. What main bearing for my 1937 Model 9 do I need? Is it one or two and where do I get them from?

Cheers, Thomas
Title: Re: Crank bearing size and suppliers
Post by: VicYouel on November 01, 2020, 12:09:56 PM
We will soon be stocking new foot rest hangers and other parts for foot rests.
Vic
Title: Re: Crank bearing size and suppliers
Post by: Thomas on November 01, 2020, 01:12:27 PM
Very good, Vic! I already found a pair of hangers in the shop but I am not sure if they fit.  Maybe I let it be welded. 

Because I never took a Sunbeam motor apart I would appreciate every helpfull information. Is there a back issue of the Beaming magazine or any other text that might cover what I am going to do?

Cheers, Thomas
Title: Re: Crank bearing size and suppliers
Post by: shorrog on November 01, 2020, 05:53:28 PM
Hi Thomas
There is a pretty good description of a 1927 rebuild in the shop https://marston-sunbeam.org/sunbeam_shop17/instructions/381-rebuild-of-a-1927-model-90.html


I am not sure of the differences between this and yours but it may help.
Graham
Title: Re: Crank bearing size and suppliers
Post by: Thomas on November 01, 2020, 06:28:05 PM
Great, thank you! I am confused, though, about the shipping. The shop website says "Free Shipping" while this is supposed to be valid only for memebrship applications. What is right?
Title: Re: Crank bearing size and suppliers
Post by: shorrog on November 01, 2020, 06:53:16 PM
Hi Thomas
The shipping rates were incorrectly set. I have now set them up for Europe and the rest of the world.
Hope that's ok now.
Graham
Title: Re: Crank bearing size and suppliers
Post by: Thomas on November 01, 2020, 07:05:15 PM
Very well, Graham, I just ordered it.
All the best, Thomas
Title: Re: Crank bearing size and suppliers
Post by: Thomas on November 01, 2020, 08:22:40 PM
BTW: I noticed that I'll get a disk with the text. A simple download would make things easier and faster. Cheers, Thomas
Title: Re: Crank bearing size and suppliers
Post by: Rick Parkington on November 04, 2020, 09:16:32 AM
Hi Thomas, I think you are correct about the footrest. If it is similar to the 1937 250cc model with the later type frame the footrests are completely different to earlier models.
I also had one break too - the only time I have seen it happen on an old bike - I Mig welded it and although I can usually weld things together successfully this time the footrest broke again easily. I remember the material seemed granular material - like cast iron. Perhaps bronze welding would work better - I can't remember how I fixed it now and the bike is long gone but just bear in mind it may be a bit more difficult than just a normal welding job.
Cheers Rick 
Title: Re: Crank bearing size and suppliers
Post by: Thomas on November 04, 2020, 09:33:02 AM
Thank you, Rick!

Yes, I noticed the strange material, too. There's even a small thread in it. I guess, I will let it be done by a professional welder in my neighborhood. Do you have any idea about the main crank bearing size?

Cheers, Thomas
Title: Re: Crank bearing size and suppliers
Post by: singleminded on November 04, 2020, 10:40:10 AM
I woulkd hazard a guess to the material being wrought iron, it brazes very easily. the join should then be strong enough for normal use..Welding can make the joint brittle, but a specialist can advise better than me.
Title: Re: Crank bearing size and suppliers
Post by: Rick Parkington on November 04, 2020, 11:20:41 AM
Hi Thomas, it looks to me like that has already been brazed without success. Bronze welding is a different process and may be better - I had a 1961 Triumph with a side stand that had been extended with a 2" piece bronze welded in and it was incredibly strong - even leaning the bike over onto it to lift the rear wheel.
Not sure about wrought iron Singleminded, I thought it was weldable - hence being used for gates etc and I don't think it has that sort of grain but as you say hopefully an expert welder could advise.
I can't help with the bearing size I'm afraid - I've never stripped a late engine and my bearing catalogues are postwar - but I know that the drive side mainshaft is a larger diameter than the early models so obviously the two bearings will be also but the timing side shaft is the same, so I guess this uses the MC22 bearing like other Sunbeams.
cheers Rick   
Title: Re: Crank bearing size and suppliers
Post by: singleminded on November 04, 2020, 10:06:47 PM
Sorry Rick I think i should have said malleable iron..John