The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Sam C on 17.08. 2015 09:40

Title: slipping clutch
Post by: Sam C on 17.08. 2015 09:40
All

For those that haven't picked this up yet: I'm very new to this. First bike, only learnt to ride a week ago, and bike is about twice as old as I am!

So bear with me.

I'm noticing that the clutch is slipping quite badly, which is a pain. Basically, opening up the throttle too quickly just causes it to slip... which is a bit hairy when trying to overtake anything!

So my questions are:

(1) Is there any sort of adjustment that should / could be made before simply replacing things.

(2) If there isn't / it doesn't work what is it I would replace - on a car I would just buy a clutch kit and fit it - on this bike there seems to be an array of different bits and I can't work out which to buy / what gaskets I'm going to need. Truth be told, until I take the clutch apart I'm not even sure I understand how it works.

(3) Even stupider question: I don't even know what type of clutch I'm likely to have (there seems to be 'four spring' or '6 spring' options... maybe even more?).

(4) Is replacing a clutch / adjusting the clutch a particularly involved or difficult process. I would happily do it on a car, just reading the Haynes, and I have done loads of work on older cars in my time (replacing engines, gearbox, ignition systems, clutches of course etc. etc.). So I am technically okish - a 'competent bodger' is probably a fair description.

(5) Is there anything I should consider from a safety point of view (e.g. some old parts have things like asbestos in them - do I need to worry about anything like that here?).

My bike is a A10 Golden Flash. 1959. 650cc. Swing arm.

Thanks all and apologies for daft questions. Maybe one day I'll be good enough to pass some of this stuff onto someone else that is starting out!

Cheers

Sam





Title: Re: slipping clutch
Post by: Greybeard on 17.08. 2015 09:51
First thinks: Is there too much oil in the chaincase? These clutches basically run dry. The small amount of oil in the case is there for the chain.

There should be a small amount of slack, (1/8") in the clutch cable.
Title: Re: slipping clutch
Post by: duTch on 17.08. 2015 10:14
 Hey Sam, settle down and grab a tinnie......Fair chance you have a four spring clutch..maybe..and in your favour.

 They are not difficult, first arm yourself with a sixpack, and a tin can to sit on...and drain the primary case- it can be messy so until you figure out a process, use a fairly sizeable catchtray....when it's fairly drained pull the cover (adding to the "process"), and all will be revealed...

 Now there is different ways you can do it from here; simply proceed with a "clutch spring adjustment", or unscrew all the adjuster screws diagonally and count each turn (not hard/ nor important-but advantageous), and have a look at what you have..also not hard, and a good thing to do....if you can, measure the thickness of the friction plates (the ones with stuff that's not plain steel)

 measure how much oil drained out...not so important (much- just a reference)...and note!
 Grab another six pack...and research "adjusting the clutch", really quite simple and everyone has a variation of it- just something you'll figure out, but don't be afraid to ask...

 I may be back in a few hours *beer*

 G-B's idea noted, but I'm going in deep....

Title: Re: slipping clutch
Post by: RichardL on 17.08. 2015 17:01
GB,

Wouldn't it be more accurate to say that our clutches "basically run wet in a controlled amount of oil"? I can't believe that running anything like dry was planned in the original design. I'm guessing that they ditched the early dome when they realized that didn't keep out the oil anyway, and the clutch still worked fine (for the era). Here is a place where my own limited experience with other motorcycle clutches comes in and leaves me wanting.  It seems to me that the wetness in our clutches provides a degree of smoothness in our takeoffs and downshifts.

Richard L.
Title: Re: slipping clutch
Post by: Triton Thrasher on 17.08. 2015 18:26
First adjust the clutch, exactly in the order that the manual says.

If that doesn't fix it, the springs can be tightened, the plates can be washed, or even replaced.


If the four spring clutch is "based on" Triumph clutch types, does anyone know if you can do the modifications to get an extra plate in?
Title: Re: slipping clutch
Post by: Greybeard on 17.08. 2015 18:36
...I'm guessing that they ditched the early dome when they realized that didn't keep out the oil anyway, and the clutch still worked fine...

My clutch has the domed cover. I suppose some oil dampness gets in there but not very much at all. You may be correct in saying the oil aids clutch action.
Title: Re: slipping clutch
Post by: a101960 on 17.08. 2015 19:22
Quote
First adjust the clutch, exactly in the order that the manual says.
What TT said. That is very important. I have a 4 spring clutch. If you are going to set it up you would be well advised to get yourself a dial gauge. I thought that my clutch operated quite well, but it was difficult to select neutral when stationary. Setting up the clutch plate adjustment with the dial gauge completely transformed the clutch operation. Selecting neutral while stationary is now easy, and the action is light with no drag or slip. You can get a gauge and magnetic stand here for under £20.

http://www.ebay.co.uk/itm/DTI-Dial-Indicator-Gauge-with-Magnetic-Base-Stand-Engineers-Clock-Stand/161019284441?_trksid=p2046732.m2060&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D16581%26meid%3D1839658744947729906%26pid%3D100040%26prg%3D7839%26rk%3D1%26rkt%3D4%26sd%3D161019284441%26
Title: Re: slipping clutch
Post by: bikerbob on 17.08. 2015 19:35
If your bike is genuine 1959 and has not been modified then it will have the revised 6 spring clutch fitted, the 4 spring clutch was fitted from 1960. As a start I would check that you have a small amount of play at the handlebar lever also the lever on the top of the gearbox should also have a small amount of play if either has no play then adjust until you have. The gearbox lever is adjusted by removing the small plate on the front of the gearbox inside you will see a nut with a central screw slacken the nut and turn the screw anticlockwise to give a small amount of play. If both have play then you need to remove the primary case and try adjusting the tension on the springs but it is really important that the springs are adjusted evenly as the plate must lift off squarely when you pull in the clutch lever as mentioned in the above post. If that does not cure the slipping then you may have to buy new friction plates.
Title: Re: slipping clutch
Post by: oldbeezageezer on 17.08. 2015 21:46
for what it worth Sam, I have the same bike as you and my clutch was dragging. No amount of fiddling with adjustment made very little difference.
I decided to check the clutch and that's when problems started.

You have to remove the foot rests. Not easy on mine and when I got them off found the splines on left side so worn which explained why the foot brake came on when any weight was put on the foot rest.

Get the foot brake out of the way

Drain the chaincase and remove the cover. You will need to get a new gasket for this for re assembly. General feeling is that silicon gasket goo may break away from the inside of any areas it used on and may block oilways or do other things which won't be good.

My bike had a six spring clutch and the chain wheel could be wobbled from side to side on the shaft. It had to come off which was easy as the lock nut wasn't that tight. The slots in the chain wheel basket where the 'fingers' of the clutch plates slide in and out were worn and burred causing the plates to catch and not operate cleanly.

The cork inserts were almost flush with the pates they were in. You can buy replacement corks and refit them. I suppose someone does that!

The clutch centre was also worn and the large splines that the inner basket slides on were scored and the ends chipped.

I noticed that the inside of the chaincase cover had nice circular scoring where the crankshaft cush drive nut was coming undone. My shaft has an additional 'lock' nut fitted. I have been told by other owners that it is because a split pin had not been fitted so the cush drive nut and the 'lock' nut are trying to escape.

Good news. The chain and main drive wheel do not show bad wear.

I weighed up my options and costed parts for a six spring replacement. A four spring complete replacement clutch was cheaper (£320) so I bought one from a company who assured me it was and would be correct for my bike. After it arrived and I tried fitting it the clutch centre would not go all the way on the shaft and the lock nut would only go on two threads. The taper on the new clutch centre was smaller than my shaft. I called the company and in fairness they offered a refund which I accepted. They then sent me a photo showing the clutch properly seated on a A10 and the lock nut fully secured. 

I then purchased a complete clutch from SRM with their own mods and finer adjustment screw. It is a bit dearer (£385) They also supply a fitting and set up guide, although I did need to clarify some of the wording on this forum. They also give a torque figure for the clutch lock nut which is not in the BSA service sheets or Haynes.

I have today, just finished the adjustments for 'proper' operation. so won't know how good it is until I put everything back together. SRM also do their own cush drive lock nut again with torque setting so I will probably end up getting one of those and replace mine.

You probably won't have the same problems as me but when you do, if you have to replace clutch/parts, don't re fit the chaincase cover until you have tested the clutch on the move. Otherwise its all got to come off again and running without oil in the chaincase won't hurt for testing.

I had an oil leak around the rocker box to cylinder head so thought I would do that while waiting for new clutch. Got it off but couldn't get box back on as the studs would not line up with the holes. Turns out three of them are bent. Waiting for new studs as I write. Should be here tomorrow.

What a101960 said about a dial gauge makes sense to true up the clutch lift and I think I will get one before I finish with the clutch.

Bit of a tale this but forewarned is forearmed as they say. Hope it helps.

As a bit of added info, as this is not enough, I have converted to 12 volt electrics and electronic ignition. I know that works and it starts easy peasy!

Good luck
Alan
Title: Re: slipping clutch
Post by: oldbeezageezer on 17.08. 2015 21:48
Sam
Check the thread 'wrong centre' Might be some info there for you.
Alan
Title: Re: slipping clutch
Post by: RichardL on 18.08. 2015 00:39
The cork inserts were almost flush with the plates they were in. You can buy replacement corks and refit them. I suppose someone does that!

I think you can now find the inserts online, but I couldn't when I was rebuilding my clutch in 2005. I called up a local friction materials supply house and asked for samples of the right thickness. About the smallest sample they could provide was enough to do the job, maybe twice over. The material was asbestos-free, so I just cut out the chips on my band saw and ground the corners to radii that fit. Still working after about 4,800 miles and one replacement of solid plates.

Richard L.
Title: Re: slipping clutch
Post by: duTch on 19.08. 2015 12:06

 I'm inclined to think that any oil that gets in against centrifugal force won't stay long before it's flung out by same centrifugals.....unless it's somehow sucked in through the bearing, and pumped out with same centrifugals  *conf*

 GB, my domed cover is really good at keeping the dust out of my spare basket on the shelf- amazingly convenient fit :! Too much involved in pulling it off everytime I feel like checking on things

  Geez O-B-1-Begeezas, no offence, but I hope no-one quotes that entire mammoth effort... *eek*
Title: Re: slipping clutch
Post by: Topdad on 19.08. 2015 14:03
My old plunger was a dry clutch and always stayed that way with the dome fitted . Re the dial gauge, as I like to be able to get neutral with ease it's very high on my want one list ,in the meantime you could use a piece of stiff wire to act as a pointer,I attach it to a nut on the barrel flange ,then position it  just over the clutch, pull in clutch, kick bike over and use to see how the pressure  plate behaves in relation to the pointer then adjust the springs to get it spinning round level. It really makes a difference as John says.
On mine I adjust the cable at the handlebar to loosen the cable right off to start the bike and once warm I tighten it up to enable neutral to be selected easy when coming to a halt .Once the bikes over the first start the clutch doesn't slip when riding but after everything cold it slips badly .  A job for the winter ! but til then nahhhhh. i'll ride . Cheers Bob
Title: Re: slipping clutch
Post by: worntorn on 19.08. 2015 20:08
My 63 A10 clutch was slipping badly a few weeks ago when I first tried the bike. It turned out that the primary was over full and the oil was quite dark in colour. A change to ATF type F put an end to the slippage.

Glen
Title: Re: slipping clutch
Post by: duTch on 20.08. 2015 01:58

When I adjust the clutch springs, I was using a hose clamp to hold the hand lever in (but I couldn't find it last time, so I utilized a special tool as per photo). .. Then I slip it in top gear and spin the rear wheel (as others also do) but just eyeball down the pressure plate. . is quicker than setting up the dial Guage. .. .  and works fine doesn't slip(since I put new plates in) or drag, and I easily get neutral at standstill *smile*
 [quote If the four spring clutch is "based on" Triumph clutch types, does anyone know if you can do the modifications to get an extra plate in?[/quote]
 Probably not Much help , but I don't know about the four springer, but I tried doing five friction plates in my Plunger; they fitted OK, but slipped a lot (as did four)because I couldn't get enough preload on the springs before they bound up, but with different Springs it might work. .
Title: Re: slipping clutch
Post by: Greybeard on 20.08. 2015 08:50
Where can I get me one of them special tools?

Looks like you have a very early petrol tank with speedo in the tank.
Title: Re: slipping clutch
Post by: Viking on 20.08. 2015 09:16
I have been “playing with” BSA & Triumph bikes from the 50ties since the 90ties
In general, the 4 spring clutch, is working well, (If all components is in good working order).

Slipping is generally caused by either weak springs or oil contaminated friction plates.

They can either be contaminated by using engine oil in primary cover, or seeping engine oil from the crank shaft housing, if the engine suffer from “wet sumping”.
To cure the problem:
A)   Replace the clutch plates with new high quality frictions plates. Or

B)   Wash the old plates in pure petrol, to wash off residue of oil.

(For a quick and dirty ( with fire hazard and great danger !! ) solution: pout ½ liter of pure petrol in to the primary cover, run the engine for 5 minutes with the clutch engaged. This wash off oil on the plates, and drain off the petrol, the add the proper amount of ATM oil)
BUT this quick and dirty. Requires a standby fire fighter canister !

Do not use engine oil in the primary cover, it contaminates the clutch friction plates and gives a slippery clutch.
I use ATM F type oil. Like CASTROL DEX II   mineral based automatic transmission oil.
Title: Re: slipping clutch
Post by: Greybeard on 20.08. 2015 10:01
Do not use engine oil in the primary cover, it contaminates the clutch friction plates and gives a slippery clutch.
I use ATM F type oil. Like CASTROL DEX II   mineral based automatic transmission oil.
I took that advice for my machine.
Title: Re: slipping clutch
Post by: oldbeezageezer on 20.08. 2015 19:42
I have just fitted a SRM complete clutch and say DO NOT use TQF, ATF or fork oil as they have antifriction additives which will cause clutch slip. Only engine oil 10/30 or 10/40. So I am going with their recommendations.

Haven't road tested it yet as still got to sort out correct footrest parts cos mine have duff splines.  Ran the bike on the bench and before fitting chaincase and the clutch operates well.

Alan
Title: Re: slipping clutch
Post by: Triton Thrasher on 20.08. 2015 20:07
SRM say some strange things.
Title: Re: slipping clutch
Post by: a101960 on 20.08. 2015 20:17
Quote
I have just fitted a SRM complete clutch and say DO NOT use TQF, ATF or fork oil as they have antifriction additives which will cause clutch slip.
Utter nonsense! I have used ATF in my primary chain case for over 14 years and my clutch has never slipped. What are SRM talking about? These are the same people that say they will not honour the warranty on a rebuilt engine if you fit an external in line oil filter. An automatic gearbox is full of clutches that is how they work. Same as they say use only mono grade oil. By the 1970s BSA recommended using multi grade oil in both the engine and gearbox.
John
Title: Re: slipping clutch
Post by: Johnny J on 20.08. 2015 21:03
"Do not use engine oil in the primary cover, it contaminates the clutch friction plates and gives a slippery clutch.
I use ATM F type oil. Like CASTROL DEX II   mineral based automatic transmission oil."


Sorry, but I believe BSAs own Instruction Manual before anything else, running engine oil without any problems what so ever...
Don't think every BSA owner since like the 40's has been driving around with a slippery clutch.
Title: Re: slipping clutch
Post by: muskrat on 20.08. 2015 21:06
I agree with John & TT. The worst thing to put in the primary is modern multi grade car engine oil. They have friction modifiers that will kill a clutch in no time flat. If I use oil it's a motorcycle oil for wet clutches (Castrol 4T)
Car automatics have a clutch pack just like your bike but one for each gear.
Cheers
Title: Re: slipping clutch
Post by: muskrat on 20.08. 2015 21:08
Johnny got in ahead of me.
Johnny, engine oil didn't have friction modifiers back then.
Cheers
Title: Re: slipping clutch
Post by: RichardL on 20.08. 2015 21:25
I'm no expert in this, at all. When I first rebuilt my bike and fired it up in 2006 (and knew even less), I had 20W/50 in the primary case, slightly modifying what Haynes was suggesting. The clutch worked, as far as I knew, fine. Then I changed to ATF, based on advice in the forum (I had yet to reach "Dazed and Confused" status back then.) I did notice the improvement. I'm too lazy to do A/B testing on it to relive the differences now that I've ridden an A10 some thousands of miles (in a circle around my house). What I would argue to those who may know better is that the oil or ATF that is being flung wildly around inside the chaincase somehow stays off of the clutch by centrifugal force or otherwise. I would be very surprised if the inside of the chaincase is not a dense blend of mist, droplets and streams of lubricant leading to "wet" clutch. 

Richard L.

 
Title: Re: slipping clutch
Post by: duTch on 20.08. 2015 23:30
 
 
Quote
Where can I get me one of them special tools?
   Trade secret-"pat. pending" *smile*

 Richard-that maybe moderately true about misting, probably best way to find out is remove the inspection cover while still running after a ride and have a bopeep. I suspect most oil would be flung linear to the chain. .. And only until the chain has flung enough that the level drops to bottom of chain level. .. *dunno2*
 Re: ATF- I don't want to turn this into an oil thread *shh*.. But only recently did I realize there are several different types of ATF- But which one best for P.chain and forks(recommended for both my bikes).. *????*
Title: Re: slipping clutch
Post by: Rocket Racer on 21.08. 2015 00:34

Wouldn't it be more accurate to say that our clutches "basically run wet in a controlled amount of oil"? I can't believe that running anything like dry was planned in the original design. I'm guessing that they ditched the early dome when they realized that didn't keep out the oil anyway, and the clutch still worked fine (for the era). Here is a place where my own limited experience with other motorcycle clutches comes in and leaves me wanting.  It seems to me that the wetness in our clutches provides a degree of smoothness in our takeoffs and downshifts.

Richard L.
Can't really agree with that; the primaries run beautifully dry...however the chain hates it and quickly becomes noisy. I ran dry primaries on a number of race engines and the only issues were chain related.
The oil is really only there to lube the chain and sprockets. However (again) the oil can contaminate the plates, typically where an engine has sat and cause slip and/or drag to an otherwise vaguely useful  clutch. A heavy oil  won't throw clear well, something I believe the lighter ATF does better.
On my race A10 I'm running a ventilated dry belt BNR clutch, no oil goes anywhere near the primary.

For a slipping clutch I would typically strip , clean and inspect so I at least knew how poked it was. I'd also probably refit it while I pondered how long I had to save up for a decent clutch.
I ran a 6 spring in my B33 for over 25 years quite happily and parts are readily available at least.
Sadly the 6 spring clutch was probably most suitable for a washing machine rather than a motorcycle. Not one of BSA's finest designs, but it can be kept serviceable.
Title: Re: slipping clutch
Post by: Johnny J on 21.08. 2015 01:01
Johnny, engine oil didn't have friction modifiers back then.
Cheers

Don't think there are any in the single grade Classic oil I use either...
Title: Re: slipping clutch
Post by: duTch on 21.08. 2015 04:36
Off topic, but;
 
Quote
Looks like you have a very early petrol tank with speedo in the tank.
I had no idea what it was off, but finally figured a while back that it's from a first model '46 A7 'Vertical Twin'- but recent discussion told me first A7 was '47, so now I just don't know  *dunno*
Title: Re: slipping clutch
Post by: Rocket Racer on 21.08. 2015 05:44
Off topic, but;
 
Quote
Looks like you have a very early petrol tank with speedo in the tank.
I had no idea what it was off, but finally figured a while back that it's from a first model '46 A7 'Vertical Twin'- but recent discussion told me first A7 was '47, so now I just don't know  *dunno*

Just shots in the dark, but both the XB31 and ZC11 had tank top speedo's.
Title: Re: slipping clutch
Post by: bsa-bill on 21.08. 2015 08:32
I use a modern multigrade in the primary without issues at all

as for modern oil having friction modifiers, isn't that what oil is and has been since Adam was a lad, and if the suggestion is modern oil will make your clutch slip then get some in as more of us will have a problem with clutch drag than slip  I reckon ( just though I'd mention like  >:D )
Title: Re: slipping clutch
Post by: Topdad on 21.08. 2015 09:56
I just use mono 40 grade which come to think of it is probably why I have to back the cable right off on first start but apart from that I've had no other issues.
Title: Re: slipping clutch
Post by: Sam C on 21.08. 2015 12:45
Wow.

Thanks all - plenty of food for thought there.

This has left me suitably respectful of the workings of an old motorbike clutch, and aware that oil types are rather more important than I'd expected, and (weirdly to me) it would appear that oil, to some extent, is meant to be on the clutch plates provided its the 'right type of oil'. Is that right?

For the time being I am going to leave well alone until I'm sure I know what I'm doing. Seems much more complex than a car clutch to me.

I really appreciate all the comments - this is proving to be an extremely helpful forum with really knowledgeable people using it (wish I could say the same for the various car forums I've used in the past for older cars!). A10s clearly attract a better breed of spannerers!

One final thing: My bike was stood for a few months while I did my lessons and passed my test. Consequently when I first fired it up it dumped a fair amount of oil straight away out the bottom of the bike: I think this is normal and to do with the oil working its way back through some sort of vale, into the wrong place. Running the bike is meant to move the oil that's not been dumped back to the 'right place'. I therefore simply topped it back up using the same type of oil as had been used before, and using a torch I checked that the oil seemed to be circulating by looking in the tank: and it was spurting away as I think it should.

But could that action of oil 'ending up in the wrong place' have caused oil to get onto the clutch plates though? Similarly could the oil be wrong (it's what the previous owner used - my stepfather in law - who generally knows what he's doing).

The oil I used is Classic Motor Oil SAE40 and I simply topped up what seemed to be the oil tank right next to the batter (on the right hand side looking from the back of the bike).

Thanks all - the questions and long posts will ease off in a bit I hope!

Cheers

Sam
Title: Re: slipping clutch
Post by: a101960 on 21.08. 2015 14:25
Sam, you are correct in your assumption that the oil was dumped because the bike had stood for a while with out being started. The oil drains under gravity from the oil tank into the bottom of the crank case (the sump). How quickly this happens depends on a number of factors. To prevent this happening again, before you start the engine remove the oil tank cap and check out the oil level in the tank. If the level has dropped substantially then it is quite likely that when you start the engine the oil in the sump will be forced out via the engine breather. That is what happened to you on this occasion. The simplest way to deal with this problem is to buy and fit a sump plate/cover fitted with a drain plug. If the bike has a tendency to drain the oil down then it is a simple matter to undo the plug and drain off the excess oil. You can then pour the oil back into the tank. I think you will find that is what most A7/A10 owners do. Obviously you do this before attempting to start the engine. Some people blame wear in the pump for this problem, and some say the cause is the anti drain valve not seating properly. Having said that I know of people that have fitted new pumps and still had the problem. To rectify the valve a complete engine strip is required. Most people just learn to live with it until a complete engine rebuild becomes necessary. Just get your self a sump plate with a drain plug. Oil could get onto the clutch if the crank case has filled up with oil, it depends on how much oil has passed from the engine into the chain case. By the way, a word of warning. Do not top up the oil tank if the oil has drained down to the sump. Once the oil is circulating there will be to much oil in the system and it will find its way out again making a mess all over the floor, or all over your leg if you ride off.
John
Title: Re: slipping clutch
Post by: Sam C on 21.08. 2015 15:15
Thanks A101960 - very clear and helpful explanation.

No idea if I have a drain plug, but I'll take a look. And thanks for the tip on not filling up - I did guess at an amount broadly equivalent to the puddle on the garage floor and fortunately I didn't seem to get any more spurts of oil anywhere. So hopefully it's alright.

HOWEVER: I am intrigued by the possibility that this has resulted in oil ending up on the clutch.

Reading everything that's been written this is what I think I've learnt:

he chain chase is meant to have a little bit of oil in the bottom of it. The chain moves through this oil, ensuring it always remains lubricated (so no need to 'oil the chain' as I've heard people talking about: the oil in the chain case will do that for you).

Given that the clutch is in the same place (i.e. inside that chain case), some oil inevitably gets onto / into it, but that's normal. The key is for there to be little oil on /in it rather than none at all. It's not like a car clutch which must be spotlessly clean and oil free.

If oil does get into the clutch (I.e onto the clutch plates) then depending on the amount that can cause slippage - since it's a lubricant! - but it can take a bit of oil. However, if oil does get in, centrifugal force ought to force it out again in time but I guess that depends on the type of oil - thin oil will spin out quickly, thick oil slowly or not at all.

You use different oil in the chain case to the oil that you put in your main oil tank in part because you're lubricating different things (an engine in the case of the latter, a chain in the case of the former) and because thicker 'engine oil' is more likely to end up with a slippy clutch if it gets onto that.

Sound right?

Sorry: steep learning curve to begin with!
Title: Re: slipping clutch
Post by: morris on 21.08. 2015 16:06
thicker 'engine oil' is more likely to end up with a slippy clutch if it gets onto that.

Or a sticky one...! DAMHIK
But since going to hydraulic ISO 32 grade (equivalent of a 10W monograde) the clutches on the plunger as well as on the SA behave flawlessly.

Regarding your question about engine oil in the chain case, there's no connection between crank case and chain case. If the crankshaft's oil seal and the two bolts that hold the inner case to the crank case are ok, no engine oil can find it's way to the chain case.
Title: Re: slipping clutch
Post by: RichardL on 21.08. 2015 17:37
Nevertheless, check the level of your chaincase oil/ATF by whichever method is used on your bike, either an overflow screw one back from the bottom large screw near the front of the cover, or an overflow screw screwed into a bottom drain plug in the case cover.

Richard L.
Title: Re: slipping clutch
Post by: Greybeard on 21.08. 2015 18:33
...You can then pour the oil back into the tank...
My take on this is that oil is not so expensive that I would risk using possibly contaminated oil.

Quote
By the way, a word of warning. Do not top up the oil tank if the oil has drained down to the sump. Once the oil is circulating there will be to much oil in the system and it will find its way out again making a mess all over the floor, or all over your leg if you ride off.
Oh yes, I recently made that mistake!
Title: Re: slipping clutch
Post by: worntorn on 21.08. 2015 18:38
Sam, I will add that ATF is grippier than any motor oil I have encountered and that TYPE F ATF is the grippiest (not sure that's a word) of the ATF types.
Type F ATF fixed my slipping /dragging Norton Commando clutch years ago and now this BSA A 10 clutch. I didn't even disassemble, just drained off the old oil and replaced with clean ATF, rode 50 miles, drain off the ATF and refill with new ATF.
This really cleans things up in there.

Glen
Title: Re: slipping clutch
Post by: RichardL on 21.08. 2015 23:29
This really cleans things up in there.

Hmmm? I guess that's because oil is all over the place in there.  >:D *smile*

Richard L.
Title: Re: slipping clutch
Post by: oldbeezageezer on 24.08. 2015 17:40
Sam
Re your oil dump. When the bike stands for a while the oil does drain t the bottom and is generally called 'wet sumping'. They are all prone to this. Mine has a had an on/off valve which looks suspiciously like a plumbing 'ball-a-fix valve fitted in the supply line by the previous owner. The down side is that it is under the gearbox and out of sight. I turn it off when I put the bike in the garage if I am not riding it for a while and turn it on, obviously essential, if I am going out on it. One of our BSAOC members has fitted an old gas valve to his and run it on top of the gearbox so it is easy to see whether it is on or off before you go out. I will scan a photo of it and re post that later.

Good that you are taking the time to 'gen' up on the workings of the old bike and making use of the wealth of knowledge here. I did, and probable still will whenever the need arises.

Alan
Title: Re: slipping clutch
Post by: oldbeezageezer on 24.08. 2015 18:35
Sam
 One of our BSAOC members has fitted an old gas valve to his and run it on top of the gearbox so it is easy to see whether it is on or off before you go out. I will scan a photo of it and re post that later.
Title: Re: Slipping clutch
Post by: oldbeezageezer on 31.08. 2015 09:06

Managed to get bike back together and out on the road. New 4 spring clutch from SRM works well although it wants a bit of tweaking. Disengages fully on half pull of lever but practically have to have the lever fully released before it bites. One success,,, I can select neutral at standstill!

Also electric ignition seems spot on and 12 volt lights all working and charging just above tick over.

Indicators next I think.

One problem with road test. After about a mile suddenly heard a loud, brief scary metallic sound from the left hand side then a swishing noise. After the initial noise it it did not have any effect on the running and got home ok but just with the swishing noise.

I am almost sure the that the noise is caused by the cush drive nut that has come undone. PO had omitted a tab washer and put a cut down nut on the shaft. The inside of my chaincase already had a groove in it but I, doing things as the book. added the tab washer, tightened the cush drive nut with a C spanner and then a few hefty clouts with a hammer and punch and inserted a split pin.

Now got to remove the chaincase again, new gasket, oil etc and probably put the PO nut back on or get SRM's cush drive nut. Bugger.