BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
JRC Engineering dealers
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Geoff
Geoff
Westfield, Indiana, USA
Posts: 222
Joined: August 2001
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
43 registered members (57nortonmodel77), 202 guests, and 203 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Stew Dempsey, JoeBrown, Bart223, Duckster, IDG1
10174 Registered Users
Top Posters(30 Days)
Lannis 93
reverb 91
Stuart 71
koan58 67
Popular Topics(Views)
552,321 mail-order LSR
Forum Statistics
Forums34
Topics66,586
Posts645,483
Members10,174
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
BSA M20 Gearbox Help Request #34268
02/04/08 12:38 pm
02/04/08 12:38 pm
Joined: Aug 2001
Posts: 3,913
Houston Texas
Britbodger R.I.P. Offline OP
In Remembrance
Britbodger R.I.P.  Offline OP
In Remembrance
Joined: Aug 2001
Posts: 3,913
Houston Texas
A friend of mine's (yes - I does has friends RicB :p )M20 is sitting dormant because of gearbox problems. He would love to get it back on the road so I said would ask the BSA experts who resides on this board.

Unfortunately don't know the specifics of the problem but, for starters anyway, wondered whether the M20 shares the same gearbox internals as other Beeza's.

Any help/advice would be much appreciated.

Thanks in advance

beerchug

Support your #1 BSA Forum and our favorite sponsors

Check out BSA on e-bay: BSA Parts in UK, BSA Motorcycles in UK, BSA Parts in North America, BSA Motorcycles in North America

 
 
Re: BSA M20 Gearbox Help Request #34269
02/04/08 1:27 pm
02/04/08 1:27 pm
Joined: Aug 2001
Posts: 288
The land of pleasant living
Z
Zimm Offline

BritBike Forum member
Zimm  Offline

BritBike Forum member
Z
Joined: Aug 2001
Posts: 288
The land of pleasant living
Bodger:

Before he gets too deep into the box, make sure the clutch is spot on, unless absolutely sure the problem is in the box. Mine will fail to downshift if the clutch isn't right.

Getting it right includes making sure there is full movement of the clutch rod. Little stuff like the lower adjustment matters. Mine had wear in the clutch lever fulcrum point. Once I made a little bushing and installed it, it worked a lot better.

Zimm

Re: BSA M20 Gearbox Help Request #34270
02/04/08 1:41 pm
02/04/08 1:41 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

BritBike Forum member
Alex  Offline

BritBike Forum member
Joined: Sep 2002
Posts: 7,813
Seattle
Malcom, while the M20 box is very similar to the B31/B33/A/A10 box, the internals do not interchange. Still, M20 boxes and spares are not exactly rare, having been used on the vast quantities of WM20 as well as M33's, M21's and not quite as common M23&24.

Nice thing, though, they are dead-*** simple and very rugged in all areas except perhaps the cases, which seem to get broken a lot.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: BSA M20 Gearbox Help Request #34271
02/04/08 2:14 pm
02/04/08 2:14 pm
Joined: Aug 2001
Posts: 3,913
Houston Texas
Britbodger R.I.P. Offline OP
In Remembrance
Britbodger R.I.P.  Offline OP
In Remembrance
Joined: Aug 2001
Posts: 3,913
Houston Texas
Thanks Zimm, but think his problems go deeper than the clutch.

And thanks for the info on the internals Alex. Now I'll start looking for source of parts once I find out what he needs.

BTW, he is a local flattracker and has a really nice Trackmaster BSA twin (amongst his huge collection of British and other bikes) that he races from time to time. Will try and post a photo when I get home.

beerchug

Re: BSA M20 Gearbox Help Request #34272
02/04/08 3:34 pm
02/04/08 3:34 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

BritBike Forum member
Alex  Offline

BritBike Forum member
Joined: Sep 2002
Posts: 7,813
Seattle
Oooh, yea. Bodger, Domiracer will prolly have everything you need. If they don't, Draganfly certainly will.

Mmmm, trackmster.

Cheers.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: BSA M20 Gearbox Help Request #34273
02/04/08 5:04 pm
02/04/08 5:04 pm
Joined: Aug 2001
Posts: 157
P
Pat Offline
BritBike Forum member
Pat  Offline
BritBike Forum member
P
Joined: Aug 2001
Posts: 157
I have a spare BSA 4speed trany, casting no. AM 65-3394. One of the guru's will tell us if it's an M20 one.

Re: BSA M20 Gearbox Help Request #34274
02/04/08 5:23 pm
02/04/08 5:23 pm
Joined: Aug 2001
Posts: 3,913
Houston Texas
Britbodger R.I.P. Offline OP
In Remembrance
Britbodger R.I.P.  Offline OP
In Remembrance
Joined: Aug 2001
Posts: 3,913
Houston Texas
Thanks Alex and Pat for the additional info bigt .

Pat,

Any idea what you want for the gearbox if it is the correct one?

P.S. Hope to see Dave Valden (the guy with the M20) this weekend and will pass on the info.

Re: BSA M20 Gearbox Help Request #34275
02/05/08 3:45 pm
02/05/08 3:45 pm
Joined: Aug 2001
Posts: 157
P
Pat Offline
BritBike Forum member
Pat  Offline
BritBike Forum member
P
Joined: Aug 2001
Posts: 157
I'd like $80 plus shipping for the tranny. First gears are worn but everything else is good. Comes with the clutch, worn but the plates are there.

Re: BSA M20 Gearbox Help Request #34276
02/05/08 6:44 pm
02/05/08 6:44 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

BritBike Forum member
Alex  Offline

BritBike Forum member
Joined: Sep 2002
Posts: 7,813
Seattle
Pat, you can identify the box by the fact that the clutch actuation lever is attached to the center of the outside cover on M-20 gearboxes. Somewhere around the end of the war they changed the lever to rotating a shaft coming in the top center of the cover inside a banjo-shaped smaller casting. This later type was also used on rigid and plunger B-series bikes. Later B and A-series boxes have a rotating shaft coming directly into the top of the cover near its joining face with the inner cover.

And speaking of which, I forgot about the plunger and rigid B-series, which used essentially the same box as the M-20 but with different ratios. Many parts from one of those boxes could interchange...but the gears themselves are different.

Cheers.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: BSA M20 Gearbox Help Request #34277
02/05/08 7:25 pm
02/05/08 7:25 pm
Joined: Aug 2001
Posts: 157
P
Pat Offline
BritBike Forum member
Pat  Offline
BritBike Forum member
P
Joined: Aug 2001
Posts: 157
Thanks Alex. Had to go look at pics to check your meaning but see that my tranny is the later type with the clutch arm on the top of the side cover. There is a no.8 stamped on the tranny case, top left side above the sprocket, does this give any indication as to model, ratio, etc? Won't fit my C10 anyhow!


Moderated by  Allan Gill, Jon W. Whitley 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.6.1.1
(Release build 20180111)
Page Time: 0.045s Queries: 14 (0.009s) Memory: 1.0540 MB (Peak: 1.2385 MB) Zlib disabled. Server Time: 2018-04-25 00:48:54 UTC