Re: 1962 BSA DBD34 Gold Star restoration (making progress)
Andy, I cannot pass up $50-100 CB400f parts bikes when I find them.
I made some time this weekend to install the clutch and timing plate.
Original clutch and primary
New clutch and primary
I did this in several stages and I started by installing the clutch and cush drive without the back primary cover so it is easier to align them with a straight edge, as suggested by Dave Kath on the Britbike.com forum.
I made a crude, but effective, tool to tighten the cush drive nut from a 2" washer, large nut and some 1/4" square stock. Four pieces of square stock were welded to the back of the washer to correspond with the four slots on the cush drive nut. I can now use a socket and a torque wrench to tighten the cush to the correct tolerance. The factory service and Haynes manuals suggest tightening the cush with a drift and hammer! I did not want to pound on my new crankshaft end. SRM offers a nice nut driven cush drive nut, but I chose to re-use the original.
Homemade service tool
Cush drive (without washer, replacement still on order)
Aligning clutch basket (chainwheel) with drive sprocket.
Shimming
I used three different straight edges and checked alignment with the gearbox pushed forward, in the middle and pulled all the back. The cush sprocket is .010" narrower (.2825") than the clutch basket sprocket (.2925") so I needed to account for the .005" difference on each side of the drive sprocket while shimming. I asked Pearson to throw in some shims with my clutch and I ended up shimming the drive sprocket out .027" and checked alignment again throughout the swing of the gearbox. All good.
Next, I fit and cut the primary chain to 70 links and left 1/2" chain play.
The closed end of the clip faces the direction of the chain travel.
With the shimming done, I installed the back of the primary cover and did it all over again.
felt washer
Sliding oil seal plate
bolts
adapter and woodroof key
clutch basket
clutch nut and plates
lifter, needle bearing plate, hardened washer and ball bearing
installed the lift plate and tightened the springs all the way down
Next, I fitted a 1/4" ball bearing and the original clutch push rod through the gearbox mainshaft. Obviously it is too long, so I cut it and left 5/16" of the rod protruding on the timing side (9 5/8" overall length). I heated the end to cherry and quenched it oil to harden it and keep it from mushrooming. Many suggest (including SRM) to quench in water, I have read the arguments on the Britbike forum and elsewhere chose to quench in oil. The clutch adjuster was replaced, tightened and I adjusted the cable. The clutch works beautifully and does everything it should and nothing it should not.
This is a dry run and not the final installation. I am still pondering machining down my transmission sprocket and rear wheel sprocket to fit a modern drive chain so I will need to remove the clutch again to do so. Once the drive chain is installed, I will safety wire the inner primary cover bolts, torque the cush and clutch nuts to spec, use a bit of loctite and oil the clutch plates and chain. And I still need to make the time to polish the primary cover.
ball bearing
original clutch push rod
The new timing plate was easily installed
I added the oil release ball to the timing cover and and installed that too.
It is beginning to look like a motorcycle!
I also painted the inside of the ugly ass front fender, polished the stays and installed them. The exterior still looks like crap and I really want a new clubman fender and stays but first I need to restore the speedo, rebuild the magdyno, new wiring harness, battery, rear chain and guard and install new valves and guides. Speedo will go out for restoration this week and am waiting for new bearings for the mag and dynamo so they can be serviced as well. Getting closer!
