Dismantling the chain case

Started by Thomas, September 28, 2017, 08:11:43 PM

Previous topic - Next topic

0 Members and 2 Guests are viewing this topic.

Thomas

Here are two pictures with more details and a scale.
1946 BSA C11
1937 Sunbeam Model 9
... and a scratched Hyundai
(MSCR member)

Thomas

Always great input, Steve!  :) The case is open. As with my first try, the upper part is difficult to lift and I can not get it entirely out of the frame. But it's enough to dismantle the wheel.
I was afraid of damaging something. Better some careful steps with the help of experienced colleagues instead of rushing into a mess. I hope my dull questions do not tiring somebody but I still need to learn everything. Look what I found in the lower part. A battered nut and a broken washer...  ??? The nut had a little fight with the chain. I have no clue where these parts are coming from.

Very welcome advice for the rear spindle and the bearings. I wanted to open it, indeed, and will try to find some time during the weekend.
Thanks again and cheers, Thomas 
1946 BSA C11
1937 Sunbeam Model 9
... and a scratched Hyundai
(MSCR member)

Greybeard

#2
Hello, Thomas.
The screw identified by the yellow arrow is an adjustable oil feed from the chaincase onto the chain. I've blanked mine off as given the distances it get used for, there is no need for it.
Hidden behind the tip of the yellow arrowhead, directly below the upper red screw, is (or should be) a matching one that secures the front end of the lower half of the chaincase.
Once that is undone the lower part of the chaincase should pull away quite easily. Both of the screws fasten into a captive nut brazed/welded onto the inner part of the chaincase. I had to reattach one of mine as it had come adrift at some point and a simple nut was used. Now, that was a challenge to get to! The top half of the chaincase takes quite a bit of juggling to extract from behind the various frame tubes but it is possible - there again, so is a Rubik cube  :-\

If you dismantle the rear wheel and it's bearings you may well find that the bearing carrier has broken - see the attached pic. The threaded end of the tube is a weak spot. Once it breaks, the tapered bearing is unsupported and there is nothing you can do to adjust it further. It's a common problem with the design. I had to machine new carriers for both my front and rear wheels. Replacement ones are unobtainable from what I found out.



Steve
1916 Triumph Model H
1926 AJS G8 500cc ohv
1937 Sunbeam Lion 500cc
1937 Ariel 500cc
1949 Matchless G80S
1952 BSA A10 Golden Flash
1953 Matchless G9
1953 BSA B31
1961 Matchless G80
1961 AJS M31 De Luxe 650cc
1961 Panther M120 650cc
BMWs R100RT - R80 - 1960 Earles fork R60
1960 Rover P4

Thomas

Hi all!

While thinking about dismantling the rear wheel I wonder how to open the main chain case. I disconnected the two screws indicated by red arrows in the attached picture but nothing moved. Do I miss a certain bold, stud or screw? And what's the knurled screw for indicated by the yellow arrow?

Cheers, Thomas
1946 BSA C11
1937 Sunbeam Model 9
... and a scratched Hyundai
(MSCR member)