Hi. I'm rebuilding the QD hub of my 1970 A65 project. I have a question regarding the splined ring that bolts onto the back of the brake drum. The face of the ring doesn't press up against the rear face of the brake drum, there's a 35 thou space there. The ring is seated as far as it can go into the groove on the back of the brake drum. It almost looks like there ought to be a shim in there to take up the gap but there's nothing shown in any of the parts books that I've looked at. I did wonder if maybe I'd got a mid-match of parts from another BSA model but the only other QD hub I can find is for a 1950s A7/A10 and they seem to use the same splined ring and brake drum as my A65. I can't believe that the splined ring isn't supposed to bolt flush against the back of the brake drum, so does anyone have any ideas what's wrong please? I guess I could just make a 1mm thick shim but I'd rather do things correctly.
Thanks
Regards
Tony

Hello Tony.  The earlier 'Driving Flange' (BSA's description) used on plunger framed A7/A10's and pre unit singles was part no. 67-6101, plus the brake drum on those bikes incorporated the sprocket. Your A65 'Driving Flange' should be part no. 42-6019 (also same part on pre-OIF unit singles). My question is, have you either purchased a new Brake Drum or Driving Flange?

Isn't there a rubber seat that go between the drum and hub. It's there to keep dirt out. My B33 and Shooting Star have one.

The rubber sealing ring is fitted over the crinkle hub splines and is butted up to the hub. Tony is refering to a gap between the internally splined driving flange and drum.

Hi Ian. Thanks for replying. My project came as a collection of parts so I'm trying to put things together. My brake drum is the type that gets the sprocket ring bolted onto it (10 bolts). I think that the correct one for the A65. I've got two of those driving flanges - unfortunately they are both exactly the same. So do you think they are the plunger ones?
Finding the 'other' type (part 42-6019) as a secondhand part seems difficult- I guess I just need to keep looking.
Thanks again
Regards
Tony

I have an ongoing 1970 A65 Firebird project, which has the same rear wheel setup as yours. I've just looked at the driving flange and roughly measured approx 3mm thickness for the outer ring that bolts onto the drum. In respect of the drum, does yours have 2 cooling fins cast in?

Hi Ian. Thanks for checking your drum and posting the photo. My drum is the same as yours as far as the number of find goes. The problem with the driving flanges that I've got is that they don't seem able to go far enough into the recess in the back of the drum - the part of the plate with the holes through it sits 35 thou above the back of the drum when the plate is as far in as possible. The spigot of the plate seems to be held off the back of the drum by an angled section of the bearing bore.
Regards
Tony

Ok Tony, Please see attached. Is your setup of bearing, shim and circlip as per the drawing?

Hi Ian. Yep, exactly the same as the parts diagram you snipped.
Regards
Tony

Would you be able to post a picture of the drum bearing housing ?