I guess the exact amount of oil in the front forks of my 1965 B40F doesn't matter too much? I noticed in an enjoyable article by Paul Greenfield in the Feb issue of The Star that he put in 190 cu3. My BSA Instruction manual (I'm not 100 per cent sure it's for the correct year of bike) says the same: 1/3 pint (190cc) in each leg. But my Haynes Unit Singles manual says 1/4 pint (which is 118cc.)
I guess it doesn't matter too much, as long as it's something like that - is that right?
Phil.
I don't think the exact amount is critical - better tot have a bit too much than too little. If you vastly overfill then you will be prone to leaks.
An old mechanic told me many years ago that the B40 forks were quite crude and he suggested that I put 20cc more than the specified amount and also to use some thicker oil to try to improve the damping. Remember that one of the important jobs of the oil is to lubricate the fork bushes - you don't want these running dry!
Hi,
The BSA manual service sheet 426A:
https://www.bsaunitsingles.com/Archives/Owners_Manuals/C15%20&%20B40%20Service%20Sheets%20Book%2000-4082%20x.pdf
Best wishes...
Thanks Bess.
I thought I'd replied to Adrian but the reply doesn't show - no idea why, maybe finger trouble at my end. Anyway, what I said was: as I understand it, taking apart the forks is a bit of a specialist job, needing special tools, so perhaps not a good idea for a beginner like me - maybe if the forks are working okay then, other than changing the oil, it might be better just to leave well alone?
But then I haven't yet looked at the service sheets Bess kindly sent.
Phil.
Hi Phil,
Fork rebuilds are not to difficult, the tools can be made if you have the inclination and people here will guide you.
I would put the bike on the main stand, grab the bottom of the forks around the wheel spindle and rock back and forth. If there is play in the sliders (not the head stock) which you consider too much embark on a rebuild.
Changing the oil is always good and viewing the oil condition will give you an idea of the internals health.
Best wishes...
Many specila tools are made for these sort of jobs, but it is usually possible to manage without them. Ingenuity.
Mick
Thanks Mick, that's encouraging.
And thanks Bess for the service sheets! What a collection!
Phil.
Hi,
You are welcome :) :).
Regards...
I believe the main tool you need is the tool to un screw the retaining ring that holds the forks together. I made mine out of a piece of tubing, ground some of the end off to leave 2 prongs that engage in the cut outs in the retaining ring. I then welded some " handles " onto the tube so I could turn it.
There is a video on youtube showing someone removing the bushes and showing the tool and its dimensions he is using. I don't think it is a B40 but some very similar forks of another BSA.
I will say that 1. The forks are very basic and when mine had new bushes I still got a bit of knocking through them on rough roads.
2. I use 10/40 oil in mine to try to improve the damping a bit but to be honest it doesn't make much difference,3. If you drain the oil out of them, it usually looks very dirty after only a short amount of time ( true also with modern bikes!)
Thanks Adrian. That's useful for future reference. I've just felt for play, as per Bess's post, and there doesn't appear to be any, so I guess at this stage I'll just change the oil. Phil.
the Haynes manual specifies less than the BSA service sheets for the B31 as well. I followed the BSA measurements and the forks respond well. Measure how much you drain from each fork as a start...
Hi,
The Haynes manual (ISBN 0 85696 127 2) has contradictions,
The routine maintenance section states capacities B25SS, B25T, B44, B50SS, B50T, B50MX - 2/5 pint 190 cc. (1/3 pt is 190cc, 2/5 pt is 227 cc)
The recommended lubricant section states C15 & B40 models 10w/30 1/4 pint, B25 & B50 models TQF 1/4 pint. All the rest 10w/30 1/3 pint.
The fork section states All models 1/3 pint SAE 20
??? ::)
From distant memory, I think I used a screwdriver and a hammer - gently!
Mick
Mick, cant see how you could get away with a screwdriver and hammer. The collars are usually tight and the cut outs to engage in the proper tool are deep in the collar. I know some people try to remove them from the outside gripping the collars with a rubber strip and stilsons but I am also aware a lot of the collars got damaged trying to remove with incorrect tools!