The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Liakos1982 on 05.04. 2015 11:03

Title: Rapid Loss of Clutch Adjustment
Post by: Liakos1982 on 05.04. 2015 11:03
Hi All,

New to the forum and BSA's in general. I have a 58 super rocket which I have been slowly gaining comfort around.

I have gone on a few short rides this year so far, mostly in the countryside so very little city riding.

When returning home on both rides I experienced rapid degradation of the clutch adjustment. The bike started dragging with the clutch totally engaged. I took the slack in the handlebar adjustment.

Where should I focus my attention to solve this problem? I have read that it might be an issue with pushrod wear, but I was always cautious to have a fair amount of play 1/16-1/8 of free play on the clutch cable. Thanks for this insights!
Title: Re: Rapid Loss of Clutch Adjustment
Post by: bsa-bill on 05.04. 2015 11:43
Before going any further have a look at the clutch actuating arm on the top of the gearbox, it should be very near to 90 degrees to the clutch cable when the clutch is disengaged (handlebar lever pulled back)
adjustment is in the gearbox under the oval cover.

If that's is fine and the cable run has no snag points then you maybe have to look in the clutch
Title: Re: Rapid Loss of Clutch Adjustment
Post by: terryg on 05.04. 2015 12:17
Remove the clutch operating pushrod, accessible through the plate on the gearbox outer cover, and check that the ends are hardened. If they are not then premature wear could be the cause of your problem. It's easy enough to harden the ends in a flame, provided the material is correct
Take care if the pushrod has been fitted in two parts with a ball bearing in between. In this case you might end up taking the primary cover off too.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: a10gf on 05.04. 2015 12:22
Welcomed aboard, an introduction post (& pictures) in Bikes, Pictures & Members always appreciated.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: Triton Thrasher on 05.04. 2015 12:43
The nut nut on the timing side end of the mainshaft, which holds the kickstart ratchet pinion on, may have come loose, allowing the shaft and clutch to move toward the drive side.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: duTch on 05.04. 2015 15:06
 My handlebar adjuster vibrates loose(slack) if it's not locked in place...maybe keep an eye on that (has a similar symptom)
Title: Re: Rapid Loss of Clutch Adjustment
Post by: beezermacc on 05.04. 2015 20:09
The problem is most likely caused by uneven set up of the springs. If you sit in traffic with the clutch lever pulled in the clutch plates should separate fully so that there is little or no friction between the plates. If the clutch isn't pulling off evenly there is 'drag' on the plates which causes friction and heat and warps the plates which causes more drag etc. As the plates warp they drag even more until there is so much drag you can't hold the bike back and you have to stall her on the brake. Because the plates are warped the clutch is all out of shape (like a stack of buckled 45 r.p.m. records) and the pressure plate is forced further out so you will feel that the clutch lever at the handlebar goes slack. When the bike cools down and the plates flatten out again the clutch lever resumes its normal position. This can seem weird until you realise what has happened. What you need to do is remove the primary cover and check that, when the clutch lever is pulled in, the pressure plate is spinning flat when spun by the kickstart. You'll probably see the pressure plate 'kicking out' when you swing the kickstart - remember to do all this with the clutch lever pulled in; you can even tape or bungee it to the handlebar. To get the pressure plate to spin evenly you'll need to tighten the spring nearest to the point where the pressure plate is kicking out. Most of us, being aware of the inadequacies of the A10 clutch, tend to engage neutral as we come to rest so that we are not heating the clutch up.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: muskrat on 05.04. 2015 21:06
That's an excellent description of what happens beezermacc.
I use a cable tie to hold the lever in and turn it over with back wheel in 4th gear (plugs out) and a dial guage on the pressure plate. 5 thou or less runout is good.
Cheers
Title: Re: Rapid Loss of Clutch Adjustment
Post by: East_Coast_BSA on 06.04. 2015 04:57
Kicking the bike into neutral when coming to a stop is almost a given.  The clutch is dry so it doesn't take long to get warm and drag.  If you sit long enough at a stop the bike will start to creep with the lever pulled in all the way.  Also when the basket gets worn, it gets "notches" in the perimeter slots from the fiber plates slapping back and forth.  These slots don't allow for the plates to fully separate and it makes matters worst.  If you do take the side cover off, take the clutch cover off and make sure that the clutch retaining nut is tight.  I know someone who didn't put the tab-lock back on and the nut slowly walked off.  Every time he pulled in the clutch, he was taking out the free-play from the loose basket before he actually start to push the plates themselves.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: Liakos1982 on 07.04. 2015 16:51
Should there be a ball bearing between the rod and the clutch lever? I took the rod out, it's in one piece, the primary side looked better, but the other was not horrible. The clutch adjuster screw looked pretty worn though, it didn't appear like those two should be touching directly...
Title: Re: Rapid Loss of Clutch Adjustment
Post by: morris on 07.04. 2015 21:10
Hi Liakos, If the rod is in one piece it's ok. Some people cut it in half and put a small bearing ball between the two halves to adjust the total length. I personally prefer the one piece shaft.
There's no bearing on the lever or the clutch side
Big chance that the clutch is loose on the shaft as EastCoast suggested. Maybe a good idea to take off the primary cover anyway to have a look. If you have never opened it before, now is the time. You may find some surprises in there.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: trevinoz on 07.04. 2015 22:23
There should be a ball in the adjuster screw. I have seen a few where the ball has dropped out and the end of the screw becomes pretty horrible.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: wilko on 08.04. 2015 03:18
Your cable is about to bust.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: duTch on 08.04. 2015 09:16

 Yeah Wilko- I always have that feelin' on the Guttzi, not so far on the Beeza...but knew something made me do that earlier comment..
Title: Re: Rapid Loss of Clutch Adjustment
Post by: madsens on 08.04. 2015 12:15
hi
I had a similar problem - due to missing slack the rod must have kept grinding away... and the ball on the adjustment screw was ground totally flat  *problem* - I bought a new rod and new adjustment screw with ball at De Groot (Draganfly can also deliver)
The rod in my box has been cut by p.o. and fitted with a ball in middle, and is working nicely again - this time with a bit of slack... *red*
rgds
Joergen
Title: Re: Rapid Loss of Clutch Adjustment
Post by: terryg on 08.04. 2015 12:26
That's a good point about the slack.  Even the Haynes manual cautions against too tight an adjustment of the cable, recommending 1/16 inch play.
Title: Re: Rapid Loss of Clutch Adjustment
Post by: Liakos1982 on 08.04. 2015 19:36
Although I have yet to take off the primary (am waiting for a new gasket) I am fairly convinced it was clutch adjuster screw, as it was quite mangled. I have ordered a new one, a pushrod, gaskets.

Should I be concerned about the ground components (possibly the ball bearing as well) rattling around in the gear box? How would you suggest that I deal with this?
Title: Re: Rapid Loss of Clutch Adjustment
Post by: Triton Thrasher on 08.04. 2015 21:38
Can the ball bearing even reach the gearbox?
Title: Re: Rapid Loss of Clutch Adjustment
Post by: beezermacc on 09.04. 2015 08:27
I still think you should investigate the spring tensions. Any overheating of the push rod will probably be due to spring imbalance. It really is worth spending a bit of time getting this right as most clutch problems start with spring tensions problems. Previous posts regarding slotted baskets are also true and worth investigating. Clutch baskets are cheap and should be replaced if slotted; don't bother filing the slots!