The 6 spring clutch.

[A.t.d.c. 1.]

I have one of these on the 57 BB33 .I have searched the forum but, for the life of me I fail to see  how the clutch works, why have a corked plate at the rear and how is this set up ?? I understand about the outer ball race depth being fitted correctly in the clutch shell but should the steel plate touch, or if not then only when the front plates are engaged ..If you can tell what I am on about ..Please enlighten me Thanks.......... Rich.

[beezermacc]

The first plate that fits on the mainshaft is a very heavy solid steel plate (65-3872), then the chainwheel with its cork inserts, then a steel plate, then a driving plate with corks, etc, until the last plate which is the steel pressure plate. So the chainwheel is simply one of the cork plates with teeth and gets gripped in the sandwich when the clutch lever is released.

[A.t.d.c. 1.]

Thank you ...So should there be no pressure on the rear plates when the clutch is engaged ,lever out ?

[RichardL]

Beezermacc gave a great explanation of the assembly of the clutch, so I hope I'm not stepping on his toes by jumping in.

When the clutch is engaged (lever out) is exactly when the pressure occurs between all the plates and the chain wheel. Remember, the chain wheel, by virtue of the bearing design, has a degree of freedom which allows it to be pressed against the heavy steel plate on the gearbox side. When you grip the lever you are pushing the outer pressure plate away from the friction stack and, therefore, freeing the chain wheel.

Richard L.

[beezermacc]

When squeezing the lever in, the push rod lifts the pressure plate away froom the rest of the plates so the whole stack becomes free and the clutch slips. When releasing the lever, the springs put pressure in the cups which force the pressure plate onto the stack so the whole lot becomes solid and the clutch bites. Don't forget that the heavy back plate is solid and acts as the base of the sandwich and the pressure plate acts as the lid on the sandwich, all the other plates including the chainwheel are the filling. The plain plates spin with the clutch hub whereas the cork plates spin with the chain wheel. When squeezing the lever in the chainwheel and all the cork plates spin as they are driven by the primary chain but, because there is no pressure being exerted onto the plates, the plain plates remain stationary. Effectively, the cork plates are attached to the engine whilst the plain plates are attached to the gearbox. Drive can only be achieved when the springs are released, by the handlebar lever, to put presure onto the plates and hold the stack into a solid mass.

[A.t.d.c. 1.]

Thanks for the replies guys ...Things are much clearer now ..Rich.

[scotty]

The following animation shows what Beezermac and RichardL so eloquently stated

How Multiplate Clutches Work
www.youtube.com/watch?v=TcYsV063lk8

It's not BSA specific but similar

HTH

S

[A.t.d.c. 1.]

Excellent .Very clear responses ..I am going to like this site Thanks ....Rich.

[Topdad]

Hi Rich, unfortunately the 6 spring clutch isn't the best clutch produced by BSA    .The guys here have given you a pretty clear idea of how it should operate and I know that a lot of members use them successfully but alas not me.I sincerely hope it works well for you but if it is problematic I'd consider replacing it with a 4 spring unit which is far from being perfect but is more reliable. Hope you don't mind my input but I've seen people put off an otherwise reliable BSA's solely because of dodgy clutches. Best wishes and happy riding, BobH

[A.t.d.c. 1.]

Bob ...I have a 4 spring clutch on the A10 and that is sweet ....But I do have a further question in this area .. I removed the the clutch arm on the gear box to fix the slop in it ..It did seen at the time that the actuating part did not look to be in the correct position ..and I would ask, how is the splined adjuster  fitted in relation to the operating arm...as fitting it just guess work at the moment ?..Thank you .Rich ..

[muskrat]

G'day Rich. It should be placed like any other lever. At rest it should be a bit more than 90 degrees to the push rod and when actuated it should move just through 90 degrees. Same for the lever to cable.
Cheers