Author Topic: No BSA topic but Sunbeam  (Read 120 times)

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Offline ThomasC11

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No BSA topic but Sunbeam
« on: July 14, 2019, 01:50:51 pm »
Hi all!
Has anyone ever had a "stuttering" front brake, i.e. when the brake is applied, the fork swings at the rhythm of the wheel rotation? That's exactly what I'm experiencing right now with my Sunbeam with girder fork. I have sanded the brake shoes, the drum is round and everything else is as it should be. I changed the two wheels against each other but the stuttering continues. No answer in the respective Sunbeam forum, so I ask here.
Cheers, Thomas
1946 BSA C11
1937 Sunbeam Model 9
... and a dented Opel

Offline Owen

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Re: No BSA topic but Sunbeam
« Reply #1 on: July 14, 2019, 01:53:43 pm »
It's usually an oval drum, worn wheel bearings or girder fork bushes?
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11
Anyone want a B20 in need of a lot of tlc

Offline MilitaryRon

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Re: No BSA topic but Sunbeam
« Reply #2 on: July 14, 2019, 03:10:53 pm »
Any of those ! And, or play in the head stock/steering stem bearings. Ron

Offline timsdad

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Re: No BSA topic but Sunbeam
« Reply #3 on: July 14, 2019, 06:00:09 pm »
Agreed. Also, did you adjust the brake hard on before you tightened the wheel spindle up, Thomas?

Ray
Just a motorcyclist.

Offline ThomasC11

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Re: No BSA topic but Sunbeam
« Reply #4 on: Yesterday at 07:12:26 am »
Thanks for your replies, Guys!

I do not believe that the drum is oval. I interchanged the two wheels (possible for a Sunbeam) and had the same effect as before. In addition, I carefully checked the drums by softly applying the brake which doesn't stop the wheel unevenly. The wheel bearings seem to be fine, too. No play in both wheels. Ray's hint is interesting, though, and I will check it tonight. I also will check the fork bushes and the steering stem bearings again. Look also nice, though. Because I already checked everything I now run out of ideas, indeed. But yes, I will enter my worksho tonight and perform monograde Ayurveda again.  ;D

Cheers, Thomas
1946 BSA C11
1937 Sunbeam Model 9
... and a dented Opel

Offline timsdad

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Re: No BSA topic but Sunbeam
« Reply #5 on: Yesterday at 08:28:21 am »
When I've removed a wheel, to fit a new tyre or whatever, I always fit the wheel loosely, connect everything up, speedo drive, back plate stay if there is one, and the brake. I centralise the brake by pulling it on hard between spinning the wheel and then hold it on hard while tightening the wheel spindle. This makes sure the brake shoes are concentric to the drum and wheel, otherwise some vibration may be felt when braking. Works for me!


Ray
Just a motorcyclist.

Offline ThomasC11

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Re: No BSA topic but Sunbeam
« Reply #6 on: Today at 02:02:44 pm »
Hi all! For now the price seems to go to Ray. I followed your procedure and adjusted the brake before tightening the wheel spindle (and filed chamfers to the shoes). Here we go, the stuttering is gone. So, thank you for this advice. I now wonder what in details happens when doing that. I thought the two shoes centralise automatically.
Best, Thomas
1946 BSA C11
1937 Sunbeam Model 9
... and a dented Opel

Offline timsdad

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Re: No BSA topic but Sunbeam
« Reply #7 on: Today at 03:02:18 pm »
It's how I've tightened a wheel spindle since the 1960s, Thomas, following the guidance of a wise old motorcyclist who lived near me. These old boys who helped me out in my teenage years were generous with their knowledge so I try to do the same.

I assume it gets the two shoes central in the drum and takes up any tolerance in the axle and fork bottoms before they're tightened. I'm glad it's sorted out.


Ray
Just a motorcyclist.

Offline ThomasC11

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Re: No BSA topic but Sunbeam
« Reply #8 on: Today at 03:49:22 pm »
Yes, Ray, it’s great to see how the good old knowledge is passed on by tradition, isn’t it?
Thanks again, Thomas
1946 BSA C11
1937 Sunbeam Model 9
... and a dented Opel

Offline MilitaryRon

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Re: No BSA topic but Sunbeam
« Reply #9 on: Today at 04:32:59 pm »
Well I've never heard this one! But nothing ventured and all that. I'm riding out to our club meeting tonight on my 5SW. So I slackened the wheel spindle nuts, clamped the front brake lever tight on and re-tightened the nuts........I'll find out if it's any better later!  Cheers Ron