I have a BSA 4 spring clutch I'd like to use on my '67 Lightning.
The springs I happen to have with it don't seem right.
Does anyone know the specs for the 4 spring clutch springs, length, bind length, number of coils, strength, wire thickness?
How about the spring cups?
Thanks, I can't find it in my manuals.
Hi,
Hope this helps:
Best wishes...
:) :) :) :)
That's quite interesting because I have cast around and can't find any springs of that length. I bought "BSA A50/A65" clutch springs and they gave me a lot of grief until thanks to Julian I found out that they were too long. Gave me serious problems. So having measured I cut them down to size and all now seems to be OK.
None of the suppliers appear to sell the correct ones, the nearest that I can find are the late Aerial springs and even they are 42mm
I have just measured a new "A65" spring 43.6mm, that's a lot of extra length. It could go a long way toward explaining why fitting the new springs can be such a painful experience.
I shall be more than happy to have these points challenged and my knowledge updated.
Mike 8) 8) 8)
Hi,
Here's the 3 spring clutch details, they are specified at 46.03mm length, suppliers mixing the part numbers up?? I can imagine they also supply the wrong working coils and spring rate.
Draganfly offer, Clutch spring set (Sold each) for Triumph BSA A50,A65 (1966-72), and Triumph 650cc Unit construction models, with 3 spring clutch. 1.76"x.66", 10 coils of .107" wire. Not as BSA spec.
In the past I also had no end of trouble with the valve springs ::) ::)
Best wishes...
:) :) :)
I spoke to Drags about this. The guy kindly measured and basically they appear to nothing anywhere near as short as 39mm. That's where I got the info about the Aerial springs. Trying to put a 46mm spring into the space for 39mm is never gonna work successfully. But it does go some way to explaining the amount of times this problem is broached here and on other sites.
Mike 8) 8) 8) 8)
Right! Thank you, that is very helpful!
Bess, Can you tell us where that list is from? A parts or repair manual for a certain model and year?
The springs that came with the used clutch have a free length of 1 5/8" and I would say 7 working coils. Coil bound at @13/16"
I bought some by part number 68-3236 from a vendor and got 4 Kibblewhite springs measuring @2"!
They coil bound at @1" which is roughly the spring cup size.
It would be great to have some authentic BSA ammo to educate these vendors.
Hi,
The 4 spring clutch specs came from 1962-65 workshop manual, the 3 spring came from 1966 to 1970. There is a 1971 manual, basically the same as 1966 to 1970 with an up-rated spring rate of 121 lbs.
Best wishes...