The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: a101960 on 09.06. 2018 18:42

Title: 4 spring Cluch adjustment
Post by: a101960 on 09.06. 2018 18:42
New clutch springs, adjusters, and cups arrived from C&D Autos this morning so I have spent a great deal of time today setting up the clutch. Most of that the time was spent adjusting the springs to ensure that it lifted evenly. It was a very long winded procedure, but eventually (according the dial gauge) I managed to get it lifting absolutely square. How anyone does this job with just a wire pointer I will never know. My clutch is fitted with an SRM ally pressure plate with an SRM Radial bearing fitted to the push rod. I have posted here a sketch showing how the adjusters ended up. Seems odd to me but the position of the spring adjusters as shown in the sketch is what eliminated the run out on the pressure plate. I did check the springs before fitting and they were identical in length. They are 42-3273 springs by the way. I ended up with one clutch adjuster positioned as in A two positioned as in B and one as positioned in C I am a little bit worried about C but that is what it took to get a dead even lift. It all works just fine but I have to ask is this unusual and has anyone else had similar experiences?
John
(http://)
Title: Re: 4 spring Cluch adjustment
Post by: chaterlea25 on 09.06. 2018 20:27
Hi John,
It can happen like that, what ever works, works

Earlier SRM pressure plates have a cast finish on the outside so this cannot be used to adjust correctly

John
Title: Re: 4 spring Cluch adjustment
Post by: duTch on 09.06. 2018 22:12

 What's even more confusing is the adjusters appear to have left-hand threads (yeah I know) *smile* , but as John says " what ever works, works"....

 I bought a dial gauge, but gave up and now just eyeball it downwards past a reference point - works for me and still have a variety of thread showing (Plunger 6 Sp.)
Title: Re: 4 spring Cluch adjustment
Post by: Greybeard on 09.06. 2018 23:18
I do pretty much what duTch does. Maybe the six springer is easier to balance the pressure.
Title: Re: 4 spring Cluch adjustment
Post by: a101960 on 10.06. 2018 11:14
Quote
What's even more confusing is the adjusters appear to have left-hand threads (yeah I know) *smile*
Ah that's why it took so long to get right then *smile* It really was a long and protracted affair.  Anyway here is a couple of pictures of the clutch pressure plate so you can see more clearly what I was talking about.  Thank you everybody for your reassurances. I just could not believe how much variance there could be despite every thing being new. What the original problem was that started all this fiddling about, was that the clutch tended to drag a bit after I had done a few miles and it had warmed up. Hopefully now this work will eliminate the problem. We shall see!
John


(http://)
Title: Re: 4 spring Cluch adjustment
Post by: chaterlea25 on 10.06. 2018 15:05
Hi All,
To bastardise the saying  *eek*

"springs ain't what they used to be"   *smile* *smile*

John
Title: Re: 4 spring Cluch adjustment
Post by: A10 JWO on 10.06. 2018 17:21
I just fitted a new four spring clutch and springs from Kidderminster M/C's. Got it running quite square luckily but it's very heavy to pull in the lever still. My cable has no sharp bends and is new and greased. I just tried my mates 750 Rickman Mietise Triumph, I could pull the clutch in with one finger. How do we get the tension of the springs right. Sorry to hi-jack, but there are obviously clutch experts viewing this thread. Thanks.
Title: Re: 4 spring Cluch adjustment
Post by: ellis on 10.06. 2018 18:33
Hi A10 JWO,

Adjust the springs  for an even lift. Start the bike with the front wheel against a wall at tick over and let the clutch out until the engine stalls. Keep slackening the springs until the engine doesn't stall then tighten the springs a little bit at a time until it does. Then that should give you your light clutch.

ELLIS
Title: Re: 4 spring Cluch adjustment
Post by: RogerSB on 10.06. 2018 20:05
Here's photos of mine showing engaged and disengaged. It's a complete kit from SRM, so there was no mix of parts and I fitted it last Feb.

Maybe I was lucky but I just adjusted it so that one spring coil was just showing above the top of the spring cups as per the SRM instructions. No messing around with dial guages or bits of wire. Operating arm is adjusted to be parallel to gearbox cover joint when lever is pulled in.

Works perfectly, light clutch lever, no slip or drag and more than often my wife is pillion - and there are lots of steep hills in this part of the country that'll test a slightly slipping clutch.

Title: Re: 4 spring Cluch adjustment
Post by: JulianS on 10.06. 2018 21:01
Fitted SRM clutch 2 months ago, same experience as RogerSB. Grips, disengages and light action.

No difficulty or need for pointer or dial gauge in balancing springs with the radial lift bearing.

Woth every penny.
Title: Re: 4 spring Cluch adjustment
Post by: A10 JWO on 10.06. 2018 22:19
Ellis that sounds good, will give that a go. Many thanks. Colin
Title: Re: 4 spring Cluch adjustment
Post by: morris on 11.06. 2018 21:36
Installed an SRM clutch kit over the weekend.
To those with a four spring clutch and who are still doubting, go ahead and do it.
Get rid of that silly tin pancake that wants to sit all over the place except in the middle.
The only regret I have is that I didn't do it sooner instead of hoping that the bloody thing would work one day.
Title: Re: 4 spring Cluch adjustment
Post by: duTch on 11.06. 2018 22:33

 
Quote
...... How do we get the tension of the springs right.........

 What Ellis suggests is fine, but I with the hand lever held in with a hi-tech tool, I adjust the springs so that I see a gap in the plates, and in top gear the wheel can *just* turn easily by hand, Then you can do The Ellis plan to confirm ( I'm lazy, and saves a lot of potential start/stop).

 After a few goes you'll work  out your own best plan *smile*
Title: Re: 4 spring Cluch adjustment
Post by: wortluck on 29.07. 2018 22:25
I have the original set up.  I get it about right the way duTch suggests - eyeballing it.  Then I go to the lever adjuster and get it just touching the rod before releasing it a tad.  Works really well, just a slight clunk when getting first - neutral is easy if you select it just before you pull up.  When the motor's hot, I have to adjust on the handlebar lever.  I like original as far as I can!
Title: Re: 4 spring Cluch adjustment
Post by: bsa-bill on 30.07. 2018 09:44
had my clutch apart last couple of days, my SRM plate is not machined as pictures here also has Devimead cast in it, on re-assemble I consulted SRM site (just don't trust my memory these days, guess some of you are similar) and lo and behold I had a plate to many, I had a steel plate first, SRM say friction plate first, so put it together that way, seems fine , one spring turn showing, one finger operation.
Had to take off some adjustment at the handle bar, we shall go for a run if it stays dry and I get other stuff sorted ( got no charge on ammeter)
Title: Re: 4 spring Cluch adjustment
Post by: chaterlea25 on 30.07. 2018 20:38
Hi Bill,
Which plate goes in first depends on which inner drum is fitted,
If the inner drum has a lip at the inner edge then a plain plate goes in first
The "later" clutch with the thrust washer and no lip on the inner drum, then a friction goes in first sitting against the back of the clutch basket
I put a bit about it in this topic https://www.a7a10.net/forum/index.php?topic=9646.msg70166#msg70166

John
Title: Re: 4 spring Cluch adjustment
Post by: bsa-bill on 30.07. 2018 21:59
Thanks John, wish I'd mentioned it before I put the cover on  *roll*
I'll have another look at your bit before I take it out, the thrust washer?? are you referring to the large thick washer that goes on after the tab washer and before the clutch nut?
Title: Re: 4 spring Cluch adjustment
Post by: chaterlea25 on 30.07. 2018 22:24
Hi Bill,
Quote
are you referring to the large thick washer that goes on after the tab washer and before the clutch nut?
No,
Attached is the photo of the shaft adaptor fitted into the chainwheel, the thrust washer can be seen between them
When the unlipped inner drum is fitted the spring pressure pushes the plate pack against the basket
so a thrust bearing washer is needed to let the chainwheel rotate freely on the rollers

John
Title: Re: 4 spring Cluch adjustment
Post by: bsa-bill on 31.07. 2018 09:34
Thanks John, I don't recall the washer, the bike is 61 but as you know that does not mean the clutch is 61,
The extra plate makes it really difficult to get the spring nuts started, was thinking of making something to allow a couple of nuts diametrically opposed to get on without springs to compress it a bit before fitting them all.
MMM a bit of a dilemma then - strip it down again or ride and see, first I need to look at your piece
Title: Re: 4 spring Cluch adjustment
Post by: JulianS on 31.07. 2018 10:00
The thust washer is not a standard A10 4 spring fitment, it needs a special adaptor to take it. The adaptor comes with a complete SRM clutch and at one time was listed in the Unity Equipe catalogue.

The SRM clutch takes the standard number of plates for the 4 spring clutch- 5 bonded 6 plain, plain in first.


As an aside if you want extra plates in your 4 spring clutch it will, provided your hub is standard width and not one of the narrow ones, take 6 bonded plates plus one extra plain from the BSA/Triumph unit twin multiplate clutch kit. The bonded plates are both thinner and narrower than the standard ones and appear to have lining made from different material.
Title: Re: 4 spring Cluch adjustment
Post by: bsa-bill on 31.07. 2018 12:34
Quote
provided your hub is standard width and not one of the narrow ones, take 6 bonded plates plus one extra plain from the BSA/Triumph unit twin multiplate clutch kit.
.

OK John that's what was in, I've put it back with the first plain plate out.
It did work well, only thing was as I said getting the springs pressed in and turning the spring nut at the same time to get it on the thread.
when adjusted nicely there was one coil of spring showing.
yea I think safest thing to do is dismantle and put back as was or with one of each plate out, think my plates are original type certainly smaller pads of friction material than in your pic.
Many thanks for your input once again