Formumites
As you know, I have been looking for friction plates for the clutch on my 1968 Starfire
Well, I ordered a set and they arrived.
With 8 drive lugs they looked the part, unfortunately they don't fit.
Schoolboy error . . . .I bought "BSA B25 friction plates", rather than measuring the old plates and trying to find replacements
The clutch I have takes plates that are;
ID; 3 3/8" or 93.34mm
OD; 5 11/16" or 135mm
10 drive lugs
Can anyone tell me whether this is a standard B25 clutch or, as I suspect, it's from another bike
I've added a couple of pictures of the clutch and an old plate
All the unit BSA singles from C15 to B50 used the same clutch plates. From Feked's web site, the correct 10-lug plates have an OD of 134 mm and an ID of 93 mm. At face value, it looks as though the plates you bought are correct for a B25. It would be interesting to know what the OD and ID of the clutch assembly you have measures?
Quote from: Spaceman on 11 Apr, 2023, 17:07
All the unit BSA singles from C15 to B50 used the same clutch plates. From Feked's web site, the correct 10-lug plates have an OD of 134 mm and an ID of 93 mm. At face value, it looks as though the plates you bought are correct for a B25. It would be interesting to know what the OD and ID of the clutch assembly you have measures?
I added the OD and ID in my original post
The clutch I have takes plates that are;
ID; 3 3/8" or 93.34mm
OD; 5 11/16" or 135mm
10 drive lugs
The "BSA B25" friction plates I bought were a millimetre or two larger OD and only had 8 lugs, as you see, my cluch has 10 lugs.
A positive is that, it looks as thougth I am going to be able to get Surflex plates . . . . OK, they're £15 a piece, but, at least they should be right
So a standard B25 clutch!
Quote from: Spaceman on 11 Apr, 2023, 19:00
So a standard B25 clutch!
That's good news.
When googling B25 friction clutch plates, many results are 8 lug discs
I ordered the wrong thing
Well it means I can get some decent replacements
Thanks
I agree with Spaceman the BSA Unit Single clutch from 1959 to 1970 was fitted with the 4 plate clutch. That has 5 plain plates and 4 friction plates with the rear-most plain plate against the Hub and the friction plates sandwiched between. So starts and ends with plain plates. I agree with Janner it should be a 10 lug friction plate. Perhaps worth checking the springs to see if they are equal length and to become compressed and distorted. Also worth checking the Chainwheel where the friction plates slide the slots can wear with a wavy edge and cause clutch drag. This can be levelled up with a file, but will increase the slot size and increase the rattle. Other option replace the chainwheel.