The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: taroha10 on 20.02. 2011 09:14

Title: Another clutch question
Post by: taroha10 on 20.02. 2011 09:14
Hi all,
I know this one has been covered before but I would just like some reassurance.
I have a 4 spring Triumph clutch which I have just dismantled for inspection.It had a friction plate at the back and the front which seems to contradict what the parts diagram says.As there are slightly proud rivets at the back of the chainwheel it just dosn't go right in my head that it would have a plain plate running against it, but then they would I suppose also eat into the friction plates aswell.Also having metal to metal on the last outer plate against the pressure plate seems wrong too.
Has anyone done a good few miles with 6 plain and 5 corked plates just to put my mind at ease!
Just incase someone asks if it worked ok before I took it apart, the answer is not exactly.I've had various problems but mainly with drag and getting out of gear .
Cheers to you all for a fab forum!
Mark.
Title: Re: Another clutch question
Post by: bsa-bill on 20.02. 2011 09:49
Had the same thoughts when I changed mine Mark

six metal and five friction, really says it all if you think about it
Metal first and metal last the book is wrong (see it's not only Haynes)
the last metal plate up against the pressure plate is not a problem as once the clutch is disengaged the metal plates are not driven.
Don't be tempted to put an extra friction plate in first, it won't do anything as it will not get right up to the inner face of the clutch

I also have some of the thinner friction plates that are around, this allowed me six friction and seven metal, seems all right at the moment
Title: Re: Another clutch question
Post by: chaterlea25 on 20.02. 2011 12:01
Hi Mark and Bill,
The number of plates depends on whether the inner clutch drum has a lip to hold the innermost plain plate or not
Later Triumph/ BSA clutches do not have this lip and have a thrust washer on the shaft adaptor, behind the chainwheel.
Then the innermost plate is a friction one
this is fixed by the tongues in the slots and doesn't rotate against the rivited drum
The next plain plate sits against this as there is no lip to hold it

On the earlier ones where the plain plate sits against the lip on the inner drum theres a tendancy for this plate to bow
from the spring pressure, other makers sometimes fit a thick plate in this position!!
The pressure plate turns with the last plain plate  and so there is no relative movement between them

HTH
John O R
Title: Re: Another clutch question
Post by: taroha10 on 20.02. 2011 13:35
Thankyou Bill and John for your speedy replies.I have been backwards and forwards from the shed and have decided to go for the plain plate first.The inner drum does have a lip to stop the plate touching the rivets ( can't believe I didn't work that one out )I can see how the back plate could warp but i'll try it and see.
When I took it apart it had a friction plate first.I have some new friction plates and have dressed  the drum a little to remove burring.
It was hard to get the old friction plates out but the new ones slide in a treat so that has got to be  an improvement  for a start.
Now I have 6 plain & 5 friction and will report back.
Thanks again guys.
Mark.
Title: Re: Another clutch question
Post by: bsa-bill on 20.02. 2011 19:20
Wayhay John - I didn't twig the difference as I have obviously the earlier one on the RGF, the other A10 (Flash) is 61 so will have the later one but I have not taken that apart as it's performing ok

Nice one - you never stop learning here
Title: Re: Another clutch question
Post by: chaterlea25 on 20.02. 2011 22:38
Hi Bill
The inner drum without the lip is I believe a 60's/70/s item
SRM used to do a kit with the "modded" inner drum and shaft adaptor with thrust washer for the pre unit models
I think it might be standard setup on the late(r) A65's and later Triumphs

HTH
John O R
Title: Re: Another clutch question
Post by: taroha10 on 22.02. 2011 12:15
Well it's  good and bad news. The orininal problem of drag has not changed to slip.
I can now sit with the engine running and take the bike in and out of gear, but even with the adjusters nearly wound right home,the kickstart slips sometimes and under power there is slip. I havn't changed the springs yet but they seemed alright before.
As I said before, when I dismantled the clutch it had an extra friction plate at the back. I wonder if it is worth trying a second plain at the back .I just can't get my head around the consequences of this! Help!!!
Cheers .Mark
Title: Re: Another clutch question
Post by: taroha10 on 22.02. 2011 12:27
Almost seconds after my last posting it occured to me that now with a plate less the clutch springs are relaxing after years of extra tension .Would one plate difference have this effect?
Title: Re: Another clutch question
Post by: chaterlea25 on 22.02. 2011 12:45
Hi Mark,
As you say the clutch springs can get tired, Another possibility is that the clutch plates are contaminated with oil
did you oil them before assembly?? DONT!!
If "car" type multigrade was used in the primary a lot of these oils have slippery additives which cause problems.
ATF or 10/30 motorcycle oil is what I find works
I can recommend fitting these clutch springs from SRM, stock code 57.1560 (T120) These give a nice light clutch and no slip *smile*

HTH
John O R
Title: Re: Another clutch question
Post by: taroha10 on 22.02. 2011 17:12
Thanks again John for your speedy reply.Have just gone and got some new springs ( I think they are T140 ) to try.
I didn't oil the clutch but must confess that I  was short on ATF which I normally use and topped up with multigrade (bad Boy).
Have drained this out and will try new springs tonight with fresh ATF.
If it still slips I will try adding the extra plain plate at back of clutch.
Right, I'm off to the shed.
Cheers. Mark.
Title: Re: Another clutch question
Post by: LJ. on 22.02. 2011 19:09
ATF might be good but it don't half leak out if your case joints are poor. I use Halford 20/50 in all my bikes primary chaincases with good results.
Title: Re: Another clutch question
Post by: trevinoz on 22.02. 2011 20:17
Mark,
             I think you will find T140 springs too heavy. They are for a three spring clutch and are a lot stiffer than four spring types.
                      Trev.
Title: Re: Another clutch question
Post by: taroha10 on 23.02. 2011 10:44
Well thanks again for all your replies.
Took clutch apart yesterday,tried an extra plain at back but there was no room.Have cleaned it all up, added new springs and refilled with ATF ( a test for the chaincase seal).I have had to screw the adjusters fully home but went for a test this morning (in the rain)and it now all seemes ok.
The springs don't seem too heavy ,I can select neutral at a standstill, and so far I don't think there is any slip.
It will be good to see how it is after a long run.
Cheers again for all the input.
Mark
Title: Re: Another clutch question
Post by: Guy Wilson on 06.05. 2011 15:58
Its reassuring to read the book is wrong! I'm fitting a 4 spring clutch with 6 plain plates and 5 corked that I took off an early 60's  A10. I'd assumed, wrongly, that it was later clutch and original to the later bike. It seems from what I'm reading its an earlier clutch and probably what was originally fitted to the 1955 Gold Flash I have.
It would have confused Sherlock Holmes...
Title: Re: Another clutch question
Post by: chaterlea25 on 06.05. 2011 22:58
Hi All
Guy,
Yes late A7/10's were fitted with the 4 spring clutch from the factory

HTH
John
Title: Re: Another clutch question
Post by: trevinoz on 07.05. 2011 01:22
Guy,
           '55 Flash originally had a 6 spring clutch.

     Trev.

               
Title: Another clutch question
Post by: Guy Wilson on 07.05. 2011 06:10
The one that came in the box of bits with the bike was a six spring clutch. Its not all there, hence fitting the 4 spring clutch from the later bike.

Can any one tell me about the 'Spacer' bolt or bolts at the back of the chain case? I seem to have two slim headed bolts that held the roughly oval washer/plate that secures the felt washer in place behind the clutch. Both are long, about three cm in length and had a spacer tube before being secured by a nut. Do they serve a purpose? Again the Haynes manual is unclear....

Many thanks
Guy
Title: Re: Another clutch question
Post by: bsa-bill on 07.05. 2011 09:19
Hi there - I've not seen those bolts but have heard on here they are for holding the front bit of chaincase on, the spacers going through the chaincase bit.
Sounds like a job for very articulate fingers
Title: Re: Another clutch question
Post by: Guy Wilson on 07.05. 2011 10:17
yes, thanks. It makes sense for the enclosed chain guard. My scrap bike must have had one....
 
Title: Re: Another clutch question
Post by: trevinoz on 08.05. 2011 00:28
Guy,
            They all used the front section regardless of whether the fully enclosed guard was fitted or not from 1956.
Usual bodge is to fit spacers on the bolts when the section is discarded.
I gather that your bike is a '55. It would have had short bolts originally as there was no front section fitted.
It seems that your inner case came from a later model.

  Trev.
Title: Re: Another clutch question
Post by: Guy Wilson on 08.05. 2011 07:27
Thanks Trev,
My bike is 1955 and looks to be identical to yours in your photo, same colour etc. The donor bike I've been using is, I think around 1960. It had had the frame chopped sometime in the 70's (not something I did). I rode it a couple of times with the chopped frame, but with our roads in Kenya, it wasn't easy and I spent more time picking it up of the road than riding it. I bought the second bike as a frame donor, but soon found it be better than the one I had and its now the one getting all the attention. It was in bits when I got and It took me about two years to find all the parts. Its originally a South African ceremonial Police bike. I swapped it for a BMW diff and frame and was assured the missing bits would be available in a week or so. It took two years to find the rest the parts in various sheds around rural Kenya. Apart from being dismantled at some point in its history, it seems to have had an easy life and is pretty standard all through. The biggest problem I have is finding enough time to work on this and few other bikes I have. I enjoy riding and I'd like to get the Gold Flash moving so I can do a bit of bush riding and photograph it in from of an elephant or two...
There still seem to be a number of old bikes to found in Africa.  I have a couple of feelers out in Uganda at the moment. A couple of years ago I bough a completely rust coloured Triumph Model H. I was hesitating about buying it and the seller got nervous and turned it over on the spot and it started. I've not run it since as the oil lube stuff is missing and I don;t want to risk damaging it before I'v e had a good look at it. Time again is the enemy...
Thanks for the info on the chain guard. Its all helping and the bikes (slowly) coming togther
All the best
Guy