The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: a101960 on 04.07. 2018 16:00

Title: Clutching at straws?
Post by: a101960 on 04.07. 2018 16:00
4 spring clutch (surflex plates) I have posted about the problem of what seems to be clutch drag after the transmission has warmed up before, but I am getting no where. Tried all kinds of things to resolve it with out any success. However, looking at the parts book I notice that it shows a friction plate as being the first plate, that is to say the first plate in the chain wheel,  (see picture). My clutch was assembled with a plain plate in this position. Is that correct, or should the plates be assembled in the order shown in the parts illustration?(http://) I have double checked everything. No burrs, or nasty nicks, and plates show no sign of warping. Fitted new springs cups and adjusters. SRM Ally pressure plate and radial bearing. To be honest don't no where to go next. All I know is once everything gets warm Neutral goes missing!
Title: Re: Clutching at straws?
Post by: JulianS on 04.07. 2018 16:12
Plain plate first.

That diagram not too helpful.

Below from owners manual.
Title: Re: Clutching at straws?
Post by: a101960 on 04.07. 2018 16:38
Quote
Plain plate first.
Parts book illustration as you say not helpful. I have been reading everything I can about these clutches, and just to muddy the waters Draganfly state that the number of plates varies can anyone shed any light on this? I have 5 friction plates and 6 steel plates.
Title: Re: Clutching at straws?
Post by: A10 JWO on 04.07. 2018 17:34
I have read that friction plate goes on first on A65's, so why different on A Series ?
Title: Re: Clutching at straws?
Post by: JulianS on 04.07. 2018 17:42
A65 up to 1965 have plain plate first 5 boned plates. Different design clutch from 1966. The drum does not have a lip as A10 4 spring and bonded plate bears on the chainwheel and it has 6 bonded plates.

Standard setup is 5 bonded 6 plain.

Some bikes were converted from 6 to 4 spring using the clutch parts from the Triumph 500 pre unit dynamo models. The drum was different in that it was designed to take only 4 bonded and 5 plain plates.
Title: Re: Clutching at straws?
Post by: A10 JWO on 04.07. 2018 17:48
Well done Julian, a font  *smile*
Title: Re: Clutching at straws?
Post by: scotty on 04.07. 2018 17:53
On my 4 spring I have 5 friction plates and 6 plain steel plates with a plain steel plate fitted first in the clutch drum
Title: Re: Clutching at straws?
Post by: a101960 on 04.07. 2018 18:29
Quote
On my 4 spring I have 5 friction plates and 6 plain steel plates with a plain steel plate fitted first in the clutch drum
That is exactly what I have got. What I can't get to the bottom of though is why it drags when it's hot. Gearbox gets a bit notchy at that point too and finding neutral becomes impossible. Both gearbox and clutch operate perfectly until then. This is the third time I have had it all apart and I can see nothing amiss. Clearly something must be wrong. I'll try oil instead of ATF this time, but I won't be holding my breath. Thank you everyone for your comments. Mean while I'm still tearing my hair out.
Title: Re: Clutching at straws?
Post by: RogerSB on 04.07. 2018 19:08
Last year I fitted the complete SRM clutch upgrade kit to my 1960 A10 GF and the instructions clearly stated plain plate first followed by friction and so on until all are used up - and there were 6 plain and 5 friction plates in the kit.

I also made myself up an assembly note for future reference. The illustration showing the assembly order is mine (so I hope I've got it correct) but the text is based on SRMs. I've made a picture file of it to attached here - if any help.
Title: Re: Clutching at straws?
Post by: chaterlea25 on 04.07. 2018 19:12
Hi All,
I would try gently heating the plain plates in an oven, start as low as the oven will go, 60-70 degC
take out the plates carefully and see if any have warped, then try maybe 90-100degC if they remained flat

Does the clutch lever go slack when the clutch gets hot? that would be a symptom of warping plates
A friend had a similar problem with one of his bikes, it turned out an adjuster was vibrating loose *lol*

The A10 setup with the plain plate in first is "a not too clever " idea !!
The spring pressure is acting against the plain back plate at a greater diameter than where it sits on the lip
tending to bow the plate
The clutch can be modified to the later A65 & Triumph setup, as I wrote up in this post
https://www.a7a10.net/forum/index.php?topic=9646.msg70166#msg70166

Last but not least  *ex*
Does your clutch have a solid or cush type inner drum?
Wear in the clutch cush drive components will cause slip or drag problems even though the unit looks perfect externally *warn* *problem*

John

Title: Re: Clutching at straws?
Post by: DuncanF on 04.07. 2018 20:18
Silly question, but are you SURE the clutch is disengaging squarely? I was sure mine was, but suffered the same grief. It was only when I put a dial test indicator on a stud and plate fixed to the primary case, that I found it wasn't. I mounted the indicator, and rested the end on the pressure plate with the clutch disengaged, then turned the engine over slowly. I had about 1/16" -1/8th" overall discrepancy. When I adjusted the spring adjusters one at a time, and confirmed it was spot-on square, was I happy. When the clutch gets hot and the plates swell, 1/8" is a lot. Voila, problem disappeared.
Title: Re: Clutching at straws?
Post by: KiwiGF on 04.07. 2018 23:01
4 spring clutch (surflex plates) I have posted about the problem of what seems to be clutch drag after the transmission has warmed up before, but I am getting no where. Tried all kinds of things to resolve it with out any success. However, looking at the parts book I notice that it shows a friction plate as being the first plate, that is to say the first plate in the chain wheel,  (see picture). My clutch was assembled with a plain plate in this position. Is that correct, or should the plates be assembled in the order shown in the parts illustration?(http://) I have double checked everything. No burrs, or nasty nicks, and plates show no sign of warping. Fitted new springs cups and adjusters. SRM Ally pressure plate and radial bearing. To be honest don't no where to go next. All I know is once everything gets warm Neutral goes missing!

I’ve no experience of the 4 spring clutch, but on a 6 spring the first plate is plain because the chainwheel has friction inserts in it, which effectively makes it the first “bonded/lined” plate. Having said that one can get odd mixes of parts with clutches and someone could fit plates in the wrong order deliberately, to overcome another problem, such as weak springs.

I assume you have not got the cheap “thin” plain plates, these don’t work well at all but unfortunately are in the aftermarket, supplied by the less reputable suppliers I guess.

It’s not uncommon for a clutch to be ok cold and drag when hot. This can often be fixed by adjusting the springs so the pressure plate lifts off “equally” (eg the same amount) at 4 points at 90deg. There is a bit of an art to this. It’s also important to have the minimum spring pressure such that you dont get clutch drag, but get maximum pressure plate movement. It’s surprising how much overly tightened springs can affect pressure plate movement. It seems the extra force to move the plate causes the cable to “compress” and the various levers take up more slack, resulting in less movement. I get about 080” movement on my 6 spring, but with over tight springs this would reduce to more like 050”.

Are the springs adjustable? If so, are you using a dial gauge to adjust the springs?
Title: Re: Clutching at straws?
Post by: Colsbeeza on 05.07. 2018 00:18
I have just replaced my entire 4-spring clutch (the one without cush), including a new Inner drum. Built up from parts sourced all-over. Not an SRM clutch though. The missus is still speaking, but she hasn't added it all up yet. When she does, I may be looking for accommodation elsewhere.
My new Clutch Wheel as well as the old one has the rivets slightly exposed, and not all evenly. There is no way a friction plate could engage that. I was going to grind them back but decided not to once I thought about it. *conf2* There would be no point in having friction pads on both sides of the first plate. However, having said that, a first friction plate would revolve with the chain wheel, so no rubbing would occur anyway. So I fitted a plain plate first as per the manual.
The Inner drum has the "stops" at the back, so it appears to be designed to prevent the first plain plate contacting the rivets on the chainwheel.
I agree that it was designed to have a plain plate first, but not a great design. As John suggested the pressure plate pushes on the outside of the outer plate, but transfers the forces onto the inner edges of the first plate - could cause buckling of the first plate.! The first plain plate first just clears the rivets sufficiently I hope. The new plates are thick (2mm), so hoping all will be well heat-wise.
I have also replaced the old steel pressure plate with a machined alloy one (I think made by MCA). With such a smooth surface, it was possible to get the plate balanced to +/- 10 thou with a dial gauge although it took about an hour. You may notice that one of the bolts is not visible. That's because it is black. I lost one and the replacement was different.
I am so confident that I have fitted the Clutch Outer Alloy Cover. Be riding it next week with luck.
Colin
Title: Re: Clutching at straws?
Post by: duTch on 05.07. 2018 03:20

 I've had no experience with the 4 Spring ones, and it may be irrelevant but they seem to have similarities to the Plunger 6 Springer which has a thicker plate at the back (I'd be guessing at the thickness though-maybe 2 or 2.5mm as opposed to 1/16" I think for the regular ones )   *dunno*
Title: Re: Clutching at straws?
Post by: a101960 on 05.07. 2018 08:29
Colsbeeza that is exactly how I set my clutch up, and it takes hours to do, or at least it takes me hours. A very frustrating procedure

kiwgf
Quote
I assume you have not got the cheap “thin” plain plates, these don’t work well at all but unfortunately are in the aftermarket, supplied by the less reputable suppliers I guess.
I presume, ( maybe wrongly) that I have good quality plates because the friction plates are surflex and for that reason I believe that good quality parts were used to assemble the clutch in the first place.

I am off to do battle again, I will bear in mind all of your comments and suggestions. I will let you know How I get on.
Title: Re: Clutching at straws?
Post by: Billybream on 05.07. 2018 08:45
When fitting the SRM Alloy Plate and Top Hat Radial bearing you would have shortened the push rod, did you harden the cut end.
Also worthwhile modification is to cut the push rod in half and insert a ball bearing.
Sure it will be something simple, best of luck with the refit.
Title: Re: Clutching at straws?
Post by: Colsbeeza on 06.07. 2018 10:51
Billy,
My pressure plate did not come with a ball bearing, but had a 1/4" steel cup in the centre. I presumed it was meant to have a ball bearing there, so I put a used steering head ball (don't throw anything away) in it anyway - greased to stop it falling out whilst assembling. For the pushrod,  I used a new piece of 1/4" Silver steel, as the old one was too short (my old Inner drum was only 30mm deep, not 35mm as it should have been.
I was a bit hesitant to cut the rod and put a ball in the middle, as with my luck it would fall into the gearbox if I withdrew the rod. So I didn't. The new rod was 297.5mm, and the old one was 292.5mm. No surprise really, as the new drum was deeper by 5mm.
I did try to harden the ends by heating to cherry red (Silver Steel recommended 770-790 DegC), checking for magnetism to ensure I was above 770 DegC, and quenching, followed by tempering. As I have never done any hardening before, I am not sure how successful it will be. It seemed hard by the file test. I used an old Honda alternator rotor for a magnet. It has a very strong pull, and I could not feel the magnetism easing. So quenched it anyway. *conf2* Then on tempering I am darned if I could see the colours going straw or any other colour, so dunked it anyway. It hissed a bit, so was at least 100 DegC. *dunno* Time will tell. Tubal Cain strongly recommends lots of practice to get good judgement - how true.!
Colin
Title: Re: Clutching at straws?
Post by: chaterlea25 on 06.07. 2018 15:48
Hi Colin,
After hardening, you need to polish the rod end back to shiny steel, then when you re heat you can see the colour changing

John
Title: Re: Clutching at straws?
Post by: KiwiGF on 07.07. 2018 04:20
Billy,
My pressure plate did not come with a ball bearing, but had a 1/4" steel cup in the centre. I presumed it was meant to have a ball bearing there, so I put a used steering head ball (don't throw anything away) in it anyway - greased to stop it falling out whilst assembling. For the pushrod,  I used a new piece of 1/4" Silver steel, as the old one was too short (my old Inner drum was only 30mm deep, not 35mm as it should have been.
I was a bit hesitant to cut the rod and put a ball in the middle, as with my luck it would fall into the gearbox if I withdrew the rod. So I didn't. The new rod was 297.5mm, and the old one was 292.5mm. No surprise really, as the new drum was deeper by 5mm.
I did try to harden the ends by heating to cherry red (Silver Steel recommended 770-790 DegC), checking for magnetism to ensure I was above 770 DegC, and quenching, followed by tempering. As I have never done any hardening before, I am not sure how successful it will be. It seemed hard by the file test. I used an old Honda alternator rotor for a magnet. It has a very strong pull, and I could not feel the magnetism easing. So quenched it anyway. *conf2* Then on tempering I am darned if I could see the colours going straw or any other colour, so dunked it anyway. It hissed a bit, so was at least 100 DegC. *dunno* Time will tell. Tubal Cain strongly recommends lots of practice to get good judgement - how true.!
Colin

Rightly or wrongly I was far less scientific than this, I just get the rod end red hot and dunk it in water, with no tempering done afterwards as there is no bending of the rod going on and I just want it glass hard, I’ve always done it this way without problems *dunno*
Title: Re: Clutching at straws?
Post by: Colsbeeza on 07.07. 2018 12:17
Thanks John,
Tubal Cain was a bit vague about polishing the rod end before tempering. Next time, I will polish it. Presumably the quickest way to keep it warm is to touch it to the motorised wire brush on my bench grinder.? Or some 1200 Wet & Dry.? Maybe autosol or Goddards Glow afterwards.? What do you use John.?
kiwigf - that is interesting. The books are of the opinion that the steel would be very brittle, thus the need for tempering. Given the relatively light load, perhaps it is not a huge problem if you quench harden only without tempering.?
Cheers
Colin
Title: Re: Clutching at straws?
Post by: KiwiGF on 07.07. 2018 13:23
Thanks John,
Tubal Cain was a bit vague about polishing the rod end before tempering. Next time, I will polish it. Presumably the quickest way to keep it warm is to touch it to the motorised wire brush on my bench grinder.? Or some 1200 Wet & Dry.? Maybe autosol or Goddards Glow afterwards.? What do you use John.?
kiwigf - that is interesting. The books are of the opinion that the steel would be very brittle, thus the need for tempering. Given the relatively light load, perhaps it is not a huge problem if you quench harden only without tempering.?
Cheers
Colin

I’ve not thought about it too much, but a push rod is not like a knife blade which is subject to being flexed or bent and where the steel being brittle would be a problem, so I’m thinking the rod end being brittle is not a problem in practice, and really what is wanted is a rod harder than the ball bearing, and tempering will soften the rod end, albeit maybe only a small amount if done properly.
Title: Re: Clutching at straws?
Post by: RogerSB on 07.07. 2018 16:15
When I had to make a push rod for a new SRM clutch last year I made one out of a length of 6mm dia silver steel purchased locally. After I cut it to the size required I heated both ends (one end at a time I will add) until glowing red and then quenched in ATF oil. In my ignorance I didn't temper the ends afterwards. I haven't checked the ends since fitting, as the clutch has pefrormed faultlessly - so I'm hoping a quench in ATF oil was good enough.
Title: Re: Clutching at straws?
Post by: JulianS on 07.07. 2018 16:51
Have used method described by RogerSB a number of times, never tempered and never had any problem after many many miles.

It is the method recommended in the instructions which come with the SRM clutch, the same method was recommended by Devimead back in 1982 when I first fitted their light alloy pressure with needle thrust bearing and shortened the rod.

Title: Re: Clutching at straws?
Post by: chaterlea25 on 07.07. 2018 21:27
Hi Colin,
I just use a bit of fine emery to get the steel colour back, nothing exotic
That said I have often just quenched the ends of the rod in water, touch with a file and see if it bounces off
Thats hard enough *ex*

John
Title: Re: Clutching at straws?
Post by: Colsbeeza on 07.07. 2018 23:57
Thanks John  (CL25), I wasn't sure that the 1200 grit may scratch the rod, inducing cracks. Looks like the books are aimed at perfection, whereas we just want to harden it.
Sorry John (a101960), we have hijacked your problem a bit with pushrod issues. Not sure whether any of this has helped with your clutch problem.
Colin
Title: Re: Clutching at straws?
Post by: a101960 on 08.07. 2018 08:03
Quote
Sorry John (a101960), we have hijacked your problem a bit with pushrod issues. Not sure whether any of this has helped with your clutch problem.
Colsbeeza Don't worry about that. It is all very interesting. As for my problem I spent the whole of yesterday resetting the spring tension ( a bit lighter) and pressure plate lift. Primary cover is not yet fitted, so I have not yet tried it out. Not sure if this is a good omen or not, but now when I turn the engine over with the kick start there is an audible clank when the clutch is operated and the plates "rattle" when the clutch is turning with the lever pulled in. Time will tell I suppose. Mind you it was far to hot really to be working in the garage, I was knackered by the time I had finished.
Title: Re: Clutching at straws?
Post by: duTch on 08.07. 2018 08:34
 I hope this one works for you- plates rattling sounds good to me, but....

 
Quote
..... Mind you it was far to hot really to be working in the garage, I was knackered by the time I had finished. 

 Just how hot was it ?? ...like enough to temper the pushrod ??
Title: Re: Clutching at straws?
Post by: KiwiGF on 08.07. 2018 08:44
Quote
Sorry John (a101960), we have hijacked your problem a bit with pushrod issues. Not sure whether any of this has helped with your clutch problem.
Colsbeeza Don't worry about that. It is all very interesting. As for my problem I spent the whole of yesterday resetting the spring tension ( a bit lighter) and pressure plate lift. Primary cover is not yet fitted, so I have not yet tried it out. Not sure if this is a good omen or not, but now when I turn the engine over with the kick start there is an audible clank when the clutch is operated and the plates "rattle" when the clutch is turning with the lever pulled in. Time will tell I suppose. Mind you it was far to hot really to be working in the garage, I was knackered by the time I had finished.

Can you give it a test ride before fitting the cover? I did that to establish roughly how far I could back the springs off before it started slipping. On the swing arm it’s best to put bolts temporarily into the front 3 holes before setting off.
Title: Re: Clutching at straws?
Post by: a101960 on 08.07. 2018 10:52
Quote
Just how hot was it ?? ...like enough to temper the pushrod ??
dutch easily hot enough to do that! It was so quite too, not a sound anywhere. There I was totally absorbed in the task of clutch fixing, and the rest of neighbourhood indoors watching the tele. Shame the bike was not road worthy otherwise I would have been out taking advantage of the empty roads.
Title: Re: Clutching at straws?
Post by: a101960 on 12.07. 2018 09:53
Well, the clutch is back together again, and last night I went for a test ride after spending forever and a day setting the clutch springs up. Not much improvement. Now, a question about the chainwheel bolts. Mine are loose and wobble about all over the place. Should they do that? or should they be reasonably rigid? Do I need to buy a new chain wheel? It has occured to me that maybe this is where my problem might be, and my reasoning for this is that the bolts are relying on spring tension to keep them central, and therefore are potentially likely to move about as the spring pressure changes causing the clutch adjustment to alter as the clutch is operated. I can't see any other reason for the clutch behaving as it does due to misalignment of the springs as they compress and release. Just a thought as everything else checks out OK.
Title: Re: Clutching at straws?
Post by: JulianS on 12.07. 2018 09:59
The bolts are like that, they just fit loosley through the centre drum.
Title: Re: Clutching at straws?
Post by: a101960 on 12.07. 2018 13:38
Quote
The bolts are like that, they just fit loosley through the centre drum.
Ah well, pretty much as I thought, any thanks Julian. Nobody can say that I am not trying! Got to explore every possibility. Leave no stone unturned and all that.
Title: Re: Clutching at straws?
Post by: Angus on 12.07. 2018 14:32
Note quite the same but could be worth a try. When I first had the A10 the clutch actually locked up a couple of times and would not disengage. Pulled it apart and put it back together again fine until warm. The second time I spent ages with forum help going through everything trying to find what was wrong. I ended up using an old set of roller bearings I had, even though the ones in there measure the same (Vernier gauge not a micrometre).
I would try removing one roller just to see if it is because it is all to tight when warm.

PS it is still fine.

See https://www.a7a10.net/forum/index.php?topic=8389.msg59326#msg59326 (https://www.a7a10.net/forum/index.php?topic=8389.msg59326#msg59326)
Title: Re: Clutching at straws?
Post by: a101960 on 12.07. 2018 15:27
Quote
I would try removing one roller just to see if it is because it is all to tight when warm.
Angus, thanks for your suggestion. I will check that out, whatever it is that is going on is clearly very obscure (at least to me) so anything is worth investigating. I have nothing to lose, and much to gain.
Title: Re: Clutching at straws?
Post by: duTch on 13.07. 2018 03:33
 I just remembered.... dunno if it was Angus'issue or someone elses ,  but maybe check the length, as the issue of which I'm thinking was 1/4" long rollers (6.35) instead of 6mm long- that's enough difference to make a difference...  *conf2*