BSA A65 clutch slip possible cause and remedy discussed followed by road test to confirm fix.

Yet another outing for this oil in frame, 750 cc converted BSA Lightning, following discussion regarding likely cause and work done to rectify the problem. Seven friction plates came out, but only six went in, as per original specs, but it is still very likely there is more area of friction material with the original six, than with the seven which were removed. It certainly put a stop to the clutch slip, in any case.

[@tonygriffiths2485]

I've been watching you for about 6 weeks now. That was the best and most rewarding ride I've been on with you. That lovely BSA twin sound under load, and you certainly tested the clutch alright, you made a lovely job of that amd all else you do. Cheers :)

[@paulhenshaw4514]

Thank you very much!

[@roeng1368]

I see those type of narrow clutch plates for Triumphs advertised in the magazines. Don't understand the reasoning behind them though. I had terrible clutch slip on the T90 after i did the conversion to allow the engine breathe into the primary chaincase, removing the crank seal, like the factory did in 1969. The multigrade oil i was using wasn't suitable for the clutch. A lot of slip and constantly tightening the clutch springs lead to the clutch being very heavy and the cable snapping on a regular basis.

[@piearm1271]

It’s amazing what people will fit, well found as that’s a peach of.a bike now.

[@paulhenshaw4514]

Thanks!

[@bigkraus1]

The advantage of the seven plate conversions actually work better with the Triumph motorcycles, which are a little bit more finicky with the clutches for some reason I went and bought brand new factory, clutches, and high-quality factory plates, and I’ve had no problems

[@billysolhurok5542]

I've run an A70 for many years. BSA installed a 21T engine sprocket,from the factory. A sensible upgrade,on this machine. I tried a 22T engine sprocket,and found I was slipping the clutch too much,for take off from a stop. Perhaps there were other factors involved,but I reinstalled the 21T. FWIW

[@andytheflyer]

I needed new plates on my '73 TR7RV so went for the Aerco 7 plate conversion. The new friction plates had much the same friction area as the old oem style friction plates and the 7 plate conversion is excellent with the recommended 650 springs. Why anyone could fit those narrow friction plates when the ones they took off were presumably the much wider oem friction plate width is beyond me. It's wonder the clutch even worked at all.

[@jd6549]

Paul the narrow clutch plates work on the stilleto heal principle. The smaller surface are should provide a greater clamping force and therefore less slip.👍🇬🇧

[@paulhenshaw4514]

What things should do and what they actually do are not always the same, and refitting the standard clutch plates, which the owner kept, did the job of stopping the clutch slip.

[@bsa_brummie7775]

Another good job done👍. I had the same issue on my T120 back in 2012. No names to be mentioned some so called improvements / products do not live up to the hype. All done in the name of profit!.

[@danielmcneil3004]

She sounds great now Paul. No slipping . Another repair done properly by Performance Classics. 👍. Owner will be happy. Cheers, Dan. ✌️🏍🇨🇦

[@paulhenshaw4514]

Thank you, Dan!

[@MarkNParker]

The narrow 7plate kits are by far the best I have used. Both my hotted bikes require them. One I use with 4 heavy race springs and an extra packer, that's the only way to hold its 97hp. The little 650 with ported head needed narrow friction plates with 3 heavy race springs to stop slipping under full load. The narrow plates are superior because they increase the pressure per square inch and move that pressure area out. I had tried many brands and types of plates. They are by far the best. The steel plates must be flat and racing clutch springs on a 750 3spring a necessity. The clutches are Triumph clutches and struggle with above stock hp.

[@paulhenshaw4514]

The reverse appeared to be the case with this machine. More friction area = more grip, less area can only grip more under much higher spring pressure. Snake oil. The seven slim plates slipped, the six original type plates don't slip in the case of this machine. All the plates in the seven plate clutch were newly fitted prior to the machine coming to me and the same plain plates were re used with the used original type friction plates I fitted and the clutch no longer slips..

[@MarkNParker]

@@paulhenshaw4514 I cannot really see why that is. That's just my experience. The Firebird has an old std clutch and the heavy springs and packer plate it would not grip, I sharpened a screwdriver and peeled that inner half of the friction lining off all the plates. I'm not sure what they are made of so wasn't going to machine them. I think it's just std lining material. Then it gripped. Usually people say they can run them lighter. I just wanted to explain what they were if you hadn't seen them before, and why they are like that. They are highly regarded. On the 883 the 3 spring would not do it, so I used a 4 spring centre. I used lots of different plates some glued themselves together, alloy ones expanded with heat to the point if you didn't get neutral when you stopped they would start to drag, then as they heated more and expanded it would drive off. It made the pushrod too short to hold the lift plate out. So I bought one of the narrow 7 plate kits, that just works like a normal clutch and disengages well. The extra plate does add friction lining. I had seen Harley plates like that and wondered about them. Main thing is you got it to grip. So that's good.

[@niallsommerville9941]

Well done. That's quite strange though, those look like they are for a lager hub. A dependable tacho would have been a useful diagnostic aid but your ears are well attuned. Nice choice of route, thanks.

[@garypotter1519]

Well, compared to when you first had it, that's like a different bike. What an improvement. 👍👍

[@ianyonok]

I have a pre-unit and a unit Triumph, plus 2 x late sixties A65s, all with those Norman Hyde clutch plates in. The unit Triumph is a Morgo 750 conversion, plenty of power, but no clutch slip. As you pointed out, 7 Hyde plates came out and 6 oem friction plates went in. I would guess that Norman's idea is that the grip is increasingly important as you move to the perimeter of the plate diameter. But I would always choose Hyde plates over the oem, they seem excellent to me and less chance of drag. Important to relieve the metal around each tooth, if necessary, to allow smooth plate movement past the burrs on the drum that inevitably build up. Almost a sloppy plate fit is good, but with sufficiently strong springs, usually screwed in as far as possible. Really like your vids anyway, Paul.

[@paulhenshaw4514]

Hi Ian and thanks. The clutch plates I removed weren't from Norman Hyde, though.

[@glaicogobbo4046]

Machine running flawlessly. Happy owner.

[@amelierenoncule]

WHY, indeed !? The only deduction I can, at this time make, is that the manufacturer made an elevated profit by doing so. One wonders [Me, that's who.], if they employs the same flawed thinking in making brake-linings ? I supposed it was prudent in not saying the companies name, but I wish that you would 'ave. A grande Public Service Announcement...and maybe life saver, too.

[@BilgemasterBill]

Why anyone would fit those narrow fiber clutch plates and NOT expect slippage is a bit baffling. I truly wonder why it was done. Only plates on the shelf? Some purported benefit? But she's chuffing along fine now. I gotta say that as I grow older I am warming up more and more to those dowdy old Beeza twins. Given my own dowdy temperament, I'd likely be perfectly content with the stock 650, but I imagine that 750 big bore might give it a bit more "Oompf!" to better cope with modern roadways, huh?

[@hermangibbs8163]

Great machine and ride. Thanks!

[@chrisjohnson4165]

All British bike clutches slip whenever there's some power going through them, even the Commando with a decent spring. I used to put ATF in my Commando chaincase, but still had to clean and rough up the plates every 6 weeks.

[@paulhenshaw4514]

Set up right, the clutches won't slip. I don't use ATF in any of mine. The clutch in this BSA doesn't slip any more, with 20 / 50 oil in the primary case.

[@chrisjohnson4165]

@@paulhenshaw4514 That's because the clutch can handle the moderate torque of the 650cc BSA.

[@paulhenshaw4514]

That BSA has a 750 conversion, also the clutch on my Trident with 850 Hyde top end doesn't slip, the clutches on our RE 500 and 350 racers don't slip and the clutches on my other bikes don't slip. It is down to putting them together properly.

[@shingerz]

Great quick ride that 👍

[@paulhenshaw4514]

Thanks 👍

[@victorterry]

Aren't they the clutch plates that come with the SRM aluminium pressure plate?

[@paulhenshaw4514]

I believe they possibly are.