Clutch arm spindle S/A A7

[Pete Gray]

Trying to get my 6 spring clutch operating smoothly and without dragging.
I've found that the clutch arm spindle is worn oval as is the housing giving quite a lot of lateral movement which is clearly reducing the throw of the clutch meaning I haven't been able to leave play at the lever.
Taken the g/box outer case off now I'm trying to think how the spindle can be made true so I can bush the case to a true diameter but it's a bit tricky with the shaft and lever being effectively one piece.

Any bright repair ideas our there or does anyone have a shiny new arm/shaft for sale ???

[chaterlea25]

HI Peter ,
New shiny SS clutch arm is available from SRM

HTH
John

[KiwiGF]

My machinest guy made the spindle round again but asked me first if I minded if he made a small indent in the arm end of the spindle so he could turn it between centres, I did not mind, then he also machined and bushed the gearbox casing to suit the smaller diameter spindle. It should now be good for another 60 years

I have a 6 spring clutch with new or near new parts and it works perfectly ...touch wood etc......

[Pete Gray]

Thanks for the replies
I enquired at SRM who don't have the A7 S/A spec spindle in stock - they've all gone and no plans for anymore due to cost !
I've got the casing and spindle with a local jobbing engineer who's going to sleeve and true up the spindle (I hope)
Ordered a stainless steel fastener kit from Lyford Classics which includes all the bolts, studs and screws etc for the gearbox so it should look pretty as well as having a working clutch.

[duTch]

 Pete, Lightning Spares also had them listed a couple of years ago, likely same source as SRM, maybe worth for anyone elses info..?

[chaterlea25]

Hi All,
Good job I got one for my RGS project so

John

[Pete Gray]

Well, despite my good intentions and the refurb'd clutch arm/spindle/bush I'm still struggling !!
It's acting as though the full action of the lever isn't sufficient to fully release the clutch plates, with no play at the clutch lever I could still do with another 2 mms of travel. But how can this be ??
I've fitted new springs and set the plates to run true using a Dial Indicator. It's running to within 0.010" which must be good enough ?
Not being very mathematical I can't decide whether the angle of the clutch arm affects the distance moved by the rod?

Looking for more inspiration please ..................

[muskrat]

G'day Pete, what condition are the slots in the chainwheel and center. The plates might be binding in the wear notches.
10 thou is good, 5 would be better.
Cheers

[bsa-bill]

l I can't decide whether the angle of the clutch arm affects the distance moved by the rod?

Yes it does Pete, same as brake arms.

The arm should be at 90 degrees to the pushrod when the clutch is disengaged ( drive disengaged )

as  well as the adjuster on the arm in the gearbox, the adjuster is splined onto the arm so more adjustmen there if wanted.

BUT from your mail you mention lack of travel, just might be worth a look at your handlebar clutch lever, there are a lot of levers being used that are not quite right in regard to travel

I've just taken some pics that might show what I mean better, distance between pivots on handlebar lever about 1 1/8 th inch and to help narrow down your hunt for reasons the clutch arm on my bike has 1 CM of travel (sorry to mix up metric and feets - just my age )

OOPs forgot to sat bottom pic is with the clutch arm pulled fully in (clutch disengaged)

[KiwiGF]

Pete, how much movement of the pressure plate  are you getting? From memory the plate only moves 60 thou at most on my 6 spring.

Also just to sure, when using the dial guage did you measure the plates movement in say 4 places at 90 deg to each other? Measuring the movement is important as the chain wheels rarely run true so you should measure movement so any lack of trueness does not affect measurements, so to start with the dial guage should be set to contact in all 4 places when clutch is engaged and then you have to pull the clutch lever in to check the 4 points all move out the same amount.

On my dial guage the needle would spin about 1.5 turns, but start from a different reading at each of the 4 point.

Difficult to describe in words!

[morris]

Did you run a feeler gauge behind the pressure plate with the clutch lever actuated?
I fitted new springs, spring cups and plates some time ago and found that, for the pressure plate to be true to the clutch plates, had to tighten some adjusting nuts about 2-3 turns more than the others. I adjusted it on sight, just ran a feeler gauge behind to check. No issue whatsoever.

[Pete Gray]

Still struggling big time ! Got the gearbox back together with the clutch arm spindle trued and bushed to a good fit.
Set up the clutch with no play at the lever and still the clutch drags.
The plates are running true checked with dial gauge but there just doesn't seem to be enough movement to disengage fully.

Once more I've stripped the clutch to look for causes - I had already filed all lumps out of the chainheel and centre grooves.
The plates are new surflex and are dry - should they be oiled ?
The chainwheel seems ridiculously loose on the double row ball race - not bearing play but 1/4" of free movement from back to front. Is this correct?
This photos show the chainwheel in situ with the bearing visible with the chainwheel at the back of it's play.

No doubt my best move would be a 4 spring replacement - Lyford show one at £280 + VAT but I really can't justify that cost ............. maybe.
Does the 4 spring unit fit directly without any other parts required - and is it a straightforward job ?

[bsa-bill]

can we establish how much travel the pushrod has at the clutch end then we could compare with the norm

[chaterlea25]

HI Peter,
Could you take some pics of the clutch arm, and the widgit inside the inspection cover that pushes the rod
the top lever and the adjusting screw should be at 90 degrees to each other for maximum lift
altering the pushrod length is probably best way of setting it all up,
This is because the modern clutch plates are much thinner than the originals

The bearing in the chainwheel often looks like yours !!!
Check thet the bearing inner race is a tight fit on the shaft adaptor
Most of the pattern ones produced in recent times are about 15 thou loose on the adaptor
When the clutch centre is bolted up it should dramatically reduce the play in the chainwheel

HTH
John

[trevinoz]

Pete,
             What is the fulcrum length of your clutch lever? (on the handlebars)
Mostly they are 7/8" which I find is not enough to release the clutch.
I use 1-1/16" levers and the dreaded 6 spring clutch works perfectly.

Trev.