Good afternoon,
Has anyone modified the very early 4 spring clutch to take an extra plate. 5 plates is standard but can an extra friction plate be fitted if the lip on the back of the centre is removed?
Dave.
from my poor memory i believe that is what the 7 friction plate conversion starts with.
apparently its a dunstall mod
Hi,
I have completed this mod. so now have a clutch centre with the lip removed, a friction plate inserted first and then plain, friction as usual. Although an extra plate is fitted it only results in one extra friction surface so a 10% increase in friction area. BSA thought that this would be worth doing so it should result in an improvement. Road test soon.
Dave.
hi dave,
i read your clutch is slipping with extra load. your better off with a REM COMMANDO centre converted to fit the tri bsa mainshaft and use a COMMANDO diaphram clutch.
Hi Eddie,
I have replaced the friction plates and springs so hopefully OK. All I need is a road test to confirm.
Dave.
Hello guys, advice wanted.
Have i got misplaced parts in my 4 spring clutch? I went from a 3 to 4 spring clutch, a 63 engine, bought last year a new old stock one never been used as i can see. Clean it out and greased the 21 rollers, and secured the bolts on the backside with a thread. There 6 steel and 5 drive plates. When mounting the pressure plate wich has the cups welded on ( not seen yet, only one with loose cups) mounting the springs 42mm long and nuts it takes lots effort to press the springs for mounting the nuts. Can't screw the nuts on til it protrude, it gets coilbound. Looks to me that the cups are 25 mm long they are to short, or the bolts are to short. My 3 spring clutch has cups 35 mm long and 50mm long bolts. Have i got a misplaced pressure plate here.
What you think?
Greets gup
Hi,
The pressure plate looks right as mine was spot welded like yours.
The spring length I have is 1 35/64" or 39.2907mm. The extra 2mm could make all the difference. Also, the first plate to go in is a plain plate that sits on a slightly raised step to give it a tight fit against the lip at the back of the clutch hub. If this first plate is not fully home then it could effectively add over 1mm to the stack of plates.
This 1mm plus the extra 2 on the spring means 3mm to compress to get the nuts started and 3mm to lead to being coil bound.
Dave.
Thanks for your replay Dave, i Will double check this. If the frist plate is sitting tight.
I checked the back plate and it is tight, see pic. According to the manual the spring length should be ok, but It says: normal setting is for the outer face of the nut to be flush with the end of the stud. I had longer studs squared one ,i modified to fit. Now i can normally push the nuts on to engage. Looks like the bolts came with the clutch were to short?
Have this lot on the bench and not yet mounted in the clutch wheel .
Am i right????
Have no info about the length of the bolts.
Greetings gup
Hi,
The spring length may have changed along with slightly deeper cups.
With the spring length as I mentioned and the standard cups and bolts, the nuts could be engaged quite easily.
It is interesting that there are always anomalies with BSAs and specifications could change mid year.
The main thing is that your clutch works.
Dave.
That's the main thing you're right about that. I only altered the bolts, longer ones. Checked the square lifting , put in first gear and rolled the back wheel.wen lifting it comes clear, and let go it cannot turned because had a bar through the conrods. The final test is the first run. I also discovered a hollow spot in the pressure plate (tape) it wasn't totally flat, with a bit of bending and a lot of fuss it's ok now. I'm accustomed that lots of new parts needs a bit of work for better fit. It's a shame really.
Needed some more time to lift a 4 four spring clutch then the 3 one, made a pointer for easy visibility.
Another question what sort of oil do you use in the primary? Something that won't affect the clutch? Read about sae 20, fork oil, atf? How do i know wich dopes shouldn't be in the oil.
Gup
Hi,
I use a mineral ATF. Many thousands of miles covered with no problems.
Dave.