Author Topic: Clutch cable & adjustment  (Read 336 times)

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Brown975

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Clutch cable & adjustment
« on: 10 April, 2020, 02:31:31 »
Evening all, been working on my 1960 A10 golden flash today as ive had an issue with the clutch since ive owned it and i thought enough is enough.

Since total restoration it has spent most of its life in a heated garage with little use and when it was restored, new clutch plates and clutch cable were fitted along with many other new items. The main issue has always been the bike creeps in 1st gear with the clutch fully engaged and i can never find neutral when its idling so riding it is a pain.

When i recomissioned it for the road, all oils were changed. When riding, i found i was having clutch slip when pulling under load in 4th mainly. That issue was fixed by some adjusting of the clutch cable at the handle control by putting in some more slack. However, the bike still has its same annoying issues mentioned.
What ive found:-
1) my clutch arm on the gearbox sticks out past the casing almost at a 30degree angle and is not parallel to the casing.
2) my clutch cable is around 51.5inches outside diameter.
3) the clutch springs look to have been adjusted so around 3 or 4 threads of stud stick out past the 6 nyloc adjusting nuts.
Here's what i think.. the clutch cable is too long so they have compensated by adjusting the gearbox clutch lever to take up some adjustment as when the lever is parallel, i run out of adjustment at the handle bar.
I also think the lever is then at the incorrect angle losing some mechanical leverage/advantage. I also think the springs are too tight. So what i plan on doing is:-
1) buy a 48inch clutch cable
2) adjust it all correctly with the lever parallel at the gearbox and ensure i have 1/4 inch play at the lever
3) Adjust the springs.
Any further advice or any issues with my plan or my diagnosis please offer your advice.
Thanks, Adam.

DAVE BRADY

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Re: Clutch cable & adjustment
« Reply #1 on: 10 April, 2020, 08:43:33 »
Good morning Adam,

It sounds like the clutch plates are not separating properly causing drag.
When you have adjusted everything is there still a bit of slack in the cable?  At the lever there should be about and 1/8".
I believe that the arm should be parallel when the lever is pulled in so max. mechanical advantage is gained when the springs are compressed the most so that is probably correct.   
When the adjusting the arm clearance to the push rod, do not tighten it, just let the adjuster come in to contact with the rod and then back it off so you can just feel a bit of play, perhaps 1/2 a turn.  This is so that when running there is no pressure on these parts.  If there is no play then the rod is trying to push the plates apart causing slip especially as things warm up and expand a bit.
Adjust the cable after doing the other arm/rod clearance.
The clutch itself may need a bit of inspection.  Although new plates were fitted was this just friction plates or plain plates as well?  Often the plain plates are over looked and over time they can distort and once no longer completely flat will cause problems such as difficulty in getting neutral.
Are there grooves and burrs on the centre and drum where the plates fit.  This can cause problems with the plates getting stuck or not moving freely.
Is the pressure plate flat?  This is another part often over looked and it does have a bit of a hard life over the years.
Are the springs all the same length and strength? Having the same amount of thread showing should be a starting point for adjustment and each one will need to be tweaked to get the pressure plate lifting square - providing the plate is flat.
Spend plenty of time adjusting the springs.
Sorry if this sound a bit simplistic but this is how I would think it through.

Dave.

JulianS

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Re: Clutch cable & adjustment
« Reply #2 on: 10 April, 2020, 10:35:04 »
Unfortunately the BSA swinging arm 6 spring clutch (not to be confused with the 6 spring plunger/rigid clutch which is completely different) is notorious for slipping and dragging. Many owners over the years have suffered with this.

BSA cured it by fitting the 4 spring Triumph clutch.

idie

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Re: Clutch cable & adjustment
« Reply #3 on: 10 April, 2020, 11:28:13 »
I have a six spring clutch on both my B33 and M33 and my son has one on his Shooting Star. None of them give any trouble. I don't know why as so many people do have trouble with them. Maybe I have been lucky, I just make sure that they are set up correctly. I do use ATF in the chaincase instead of the recommended SAE20 oil. This I find doesn't help with drag.