Hi guys,
I bought my C15 a month or so ago, and found that when it came to tdc, kicking it over the clutch would slip.
I fitted new friction plates and springs, having soaked the plated in 20sae oil for several hours.
At first it improved the kicking over a bit but that didn't last, and now it's slipping again.
I have 140 ml of atf in the chain case, and now have the new springs tightened as far as they will go while allowing just enough freedom for the clutch to disengage when required.
At tdc I can stand on the kick start and the compression will hold my full weight for a good 15 to 20 seconds.
If I jump on it the clutch slips.
I keep thinking there's too much compression??
Your thoughts would be appreciated.
Late Addition, I've checked for wet sumping by draining, no problem found.
When it is running, there's no smoke whatsoever even when I throttle it.
Timing is spot on, as is valve clearance etc, oh and clutch cable and push rod are free with slack movement.
Oil is clearly being pumped around evidenced by the return to the oil talk and oil to the rockers.
Mike.
Check there is sufficient clearance between the clutch centre screw and the pushrod. Screw in the centre screw until it touches the end of the pushrod then back it off 1/4 turn before locking the nut.
Expect to re-adjust soon after fitting new plates as they bed in.
Are you doing this with the primary cover on or off?
Hi cdsdorset, thanks for the reply. it's with the cover on.
Rupert,
I assumed since there was free play on the clutch lever, there'd be free play on the push rod.
Anyway, I'll do as you suggest and see what happens.
Thank you both for your interest.
Mike.
Hi Rupert,
An instant fix!!
I backed off the screw as you suggested, and now I can put my full weight on the kick start and a little jump has it spinning over without clutch slip.
I guess now I ought to be thinking of backing off the new clutch springs.
Anyway thank you for your advice, very much appreciated.
Mike.
If not done as Rupert said, the rod and screw can be worn shorter. Had to replace on a newly bought B44 trials bike.
Pleased its sorted easily. Clearance on the cable at the handlebar lever but no clearance on the pushrod inside the engine probably indicates that the lever inside the engine was resting against the inside of the outer cover. I'd be tempted to back off the clutch centre screw two complete turns to move the lever away from the cover then adjust the cable slack at the handlebar to give correct s clearance in the system.
Hi Rupert,
Not such good news.
I went to start the bike today and guess what, the clutch is slipping on kickover again.
I've undone the adjust screw so it's loose and left it like that, tried kicking it, clutch still slips.
The springs and friction plates are brand new, is it possible the smooth plates are at fault?
Other than these plates, I'm at a complete stand still for not knowing what else to try.
Regards,
Mike.
Further to my last mail, I've now stripped the clutch and found two of the plain plates showing clear signs of bluing, and a third looking so polished I could nigh on see my face reflected in it.
I've ordered a new set of plain plates as a matter of course, so time will tell if this is the end to the slipping saga.
Regards,
Mike.
Hi,
Warped plain plates can cause problems during use but unless they are very bad, should allow the engine to be turned over without slipping.
Put all the plain plates together and hold them between finger and thumb of both hands at 180ยบ and squeeze one side and then the other. There should be minimal rock and no obvious gaps. Even new ones may not be perfect.
Dave.
Hi Dave,
I'll have a look tomorrow and do the test you describe.
The oil I originally soaked the new friction plates in was Halfords 20/50 Classic for older vehicles, is it possible it had non friction additives in it?
I'm currently soaking them in ATF which looks considerable thinner than the 20/50.
Mike.
Hi,
I would wash all the oil off the plates and start again. There is no real reason that I know of for soaking friction plates in oil. I think this comes from the old cork inserts and not the bonded friction material.
Any engine oil will be non-friction and whilst it can be used in a primary it is best if it does not get on the plates. The amount that goes in the primary is enough for the chain to run in it as it goes around and splashes to where it needs to be and the rotating clutch tends to fling the oil away from the plates.
ATF is my preferred primary lubrication.
Dave.
Dave.
Hi Dave, many thanks for your input on this slipping problem.
I've never owned a British bike before or worked on one, so I'm guided by what I read.
So many times I've read about soaking the plates, which I must add has seemed counter intuitive to me. Now to read you thoughts makes me think I should follow my own common sense in future.
I'll deep clean the friction plates today and rebuild the clutch. I can easily test it with the cover off and let you know the result.
Thanks for your help thus far.
Mike.
I've never heard of soaking plates. While we refer to these as "wet" clutches they are not truly wet. The plates stay reasonably dry as centrifugal force flings the oil off and the primary oil level is set below the plates. I would be cleaning the plates in petrol or brake cleaner before assembly.
Hi Limeyrob,
Believe it or not, I've read whole strings of debate as which oil to soak them in, some saying how you should avoid oil with modern additives.
I've already washed the oil off in watch cleaning fluid (I'm a watchmaker) that strips most oils etc.
I'm also going to go over them carefully with a blow torch, not aggressively so but just enough to burn off any residue.
Ultimately, if I have to, I'll buy a new set and be done with it.
Thanks for your interest.
Mike.
Hi Mike,
I think the blowtorch is not needed and there could be a risk of damaging the friction material. I reckon the watch cleaning fluid will be enough. Give it a go and see how it is.
Dave.
You can sand the friction plates on a flat surface to get the scorched layer off. The scorching is carbon and its slippery.
The clutch has been reinstalled and thus far no slipping.
The only thing that might happen is residue coming out of the plates under compression. It's unlikely given how I washed them, but anything is possible.
I have to say before I close how grateful I am to the forum and all the help and suggestions, all very much appreciated.
Mike.
If the plates seem to be in acceptable condition they shouldn't slip if there is enough pressure pushing them together. Therefore if they slip its likely due to insufficient pressure, caused either by mechanical obstruction of some sort - eg the lack of clearance on the centre screw - or insufficient pressure from the springs.
The springs collapse with age and use, therefore fit new ones to remove that variable.
Another mechanical obstruction which should be checked for is that the spring cups are not bottoming in the clutch centre when the pressure plate is fully home.
Hi Rupert,
Well here we are a good few days later and the clutch is as solid as rock.
No slipping whatsoever, springs are screwed down to the screw head and first coil showing.
Engine starts first kick every time which is a joy.
Next job is to stop the damn sump cover from dripping. I fitted new gaskets with Hematite but still I get a weeping drip forming on one of nuts, and it's driving me nuts. It only drips two to three times a day, but there should be none. The rest of the engine is dry, after much effort, so I'll not rest till I have this last one nailed.
On a different point, what's the view with fitting indictors. Do many of you guys fit them?
Regards,
Mike.
Hi,
Indicators a must these days. We have them fitted on our 4 BSAs.
Dave.
Hi Dave,
Thanks for your input.
I kept thinking about how does anyone know what move you're about to make without indicators.
I read that the hand signal for turning right is with your left arm pointing upwards at a right angle with a clenched fist. I find it hard to believe anyone out there would know what move you're implying, certainly not turning right!
I'll get a set of blinkers on order.
All the best,
Mike.
Hi,
I reckon that most drivers will think you are just waving to someone. Consider that turning right across the on coming traffic, taking your hand off the throttle and not covering the front brake to indicate
is a recipe for disaster. I think that turning right like this is the most dangerous manoeuvre.
The signal that you mention is not in the Highway Code so will not be taught to any road user.
There are three for motorcyclists.
Left arm straight out - intending to move to the left or turn left
Right arm straight out - intending to move to the right or turn right
Right arm move up and down - intending to slowdown or stop.
Not to mention the life saving 'over the shoulder' look and the use of mirrors.
Both hands are best kept on the handlebars and I fitted 'push to cancel' switches so there is not fumbling for the centre position, especially with winter gloves on.
Dave.
I can say from first hand experience, the life saver look over the right shoulder saved my life.
About to turn right from an A road down a lane to my house, I did the look, and got the shock of my life, as a 52 seater coach overtook me with such a rush of wind that near blew me over in the road.
Just one second into the turn and yours truly would not be here typing this!
I've not ridden a motorbike for twenty odd years. Back then it was all Jap stuff ending on a Yam FJ 1100.
Now I have this little all black C15 bought a month ago, getting it ready for my relaunch onto the road.
At 78 I'm going to take it steady at first! ;D
Btw, was your indicators a complete packaged set?
Cheers,
Mike.
Hi,
No. I put the parts together myself. I think that Paul Goff does everything you need but it is possible to get some things a bit cheaper elsewhere. Use LED bulbs to keep within the wattage of the alternator. Fit an LED bright pilot bulb or use a dipped LED headlight for daytime running. LEd Stop/tail as well.
Dave.
I have 2 bikes on the road, a 53 Matchless and a 59 A10. I made the decision to make my own indicators for the A10 and they really make a difference. The Matchless runs battery total loss as its set up as a trials bike and while I ride it on the road locally I avoid busy roads because of the lack of indicators. I feel much safer in traffic on the A10 because of the indicators. My DIY set up is 6v with LED indicators (home made, soldered to boards) but with 5w incandescent bulbs for the left and right tell tales. I found these were necessary to get the flasher unit to work. The tell tales are std Lucas instrument lights fitted into drilled holes in the speedo / tacho mounting plate (its a Road Rocket bitza). You can get by with one instrument bulb if you wire in a pair of diodes.
the oil sump plate weep is a stinker to cure - on my C15 I have reduced it , but all 4 studs go into the open crankcase and I reckon the oil weeps round the threads and out , so try some silicone around the threads to stop this weepage
Led indicator set ordered. I decided on separate items as it gave me a better choice or components.
The leaky sump is a pain, in that it will be the third time I've had it in bits to stop the drips.
I've bought some high grade heat resistant acrylic gasket cement which came recommended to stop leaks...time will tell.
I'm toying with the idea of swapping the long two seater out for a single seat, I just like the look and getting my backside down just a tad lower, not that I'm short in the leg at 6 foot.
Thank you all for your interest and ideas, it makes it more fun to own one these old bangers. ;D
Mike.
I feel for you, its become so much more complicated. When I first rebuilt a BSA clutch (A C11G) there was only SAE 30 to go in the case and the Service Sheets to work to. In those days the clutch friction came as pads that you pressed into each plate, a right job as it was almost impossible to get them level. If you look in an old parts book you will see them still listed. They would be sold in a paper bag and looked like sweets! Unfortunately they were almost certainly asbestos which is why they worked so well.
The rationale then and the one I stick to even now, is that the oil level should be below the clutch and centrifugal force will for the most part keep the plates reasonably oil free. If they slipped you soaked in petrol and then sanded and gave the springs another half turn.
Good luck!
Jazzman,I hope your cure is permanent.
I had annoying kickstart clutch slip with a b31 and I found that the cure was to use the triumph unit 650 non slip oil ( sorry forgotten spec) and more importantly keep the primary oil level to the minimum that oils the chain ( splash )and no more.
Hi Eddie, well thus far it has not missed a beat. Every time I start it the clutch grip is very positive and that with the spring wound out so that the head and one turn of each spring is visible clear of the pressure plate.
A more irritating and frustrating battle going going on is with trying to make the bike oil tight. I have one last drip that refuses to stop...But I will get done come hat may.
Chears,
Mike.
Hi,
The lack of a gasket on the inner timing/gearbox cover seems to be the problem. After shimming the main shaft without a gasket there was a slight weep from the engine part so a strip and reseal and it is cured but now has a weep from the gear box section. Over the winter I will do it again but make sure it is flat on a piece of toughened glass. The main shaft bush may have to removed to do this but it should be worth the effort.
Dave.