Clutch etc.

[Zander]

today I installed the clutch assembly and was relieved to find that having fully tightened and locked the centre nut, the chainwheel ran freely with just a trace of lateral play, so I'm happy with that. Fitted the plates, tightening the four springs as per the manual and found that the clutch activation required much more effort than previously so I backed the spring screws off until it was as light as it was when  I got the bike.  This setting shows about two coils of the springs, and I found that on starting the bike, selecting first and holding the clutch in, it's dragging. I  then counted the turns of each screw until it was released and found that he screws are engaged by only four threads, which seems marginal to me, especially as I need to back them off a bit more. Question, please?: obviously, I'm adjusting the clutch prior to fitting the outer casing so when it's fitted, would the addition of oil eliminate the drag, albeit that it's only there to lube the chain?

[morris]

How many plates have you got in and which one have you got in first?

[Zander]

Four spring, five plate.  First one in was a plain plate.

[Triton Thrasher]

No, oil won't help.

[Zander]

Re plates, removed them this morning and there are 5 friction and six plain, which, according to the manual I have, is correct for the plunger model.
My bike has a '58 engine in a '59 frame and is fitted with a 4 spring clutch chain wheel  with "Triumph" stamped on it.
Again, according to my manual, the sw. arm model has 6 friction and 4 plain, but one of the friction plates is incorporated in the chain wheel.  My chain wheel  isn't like that.
The centre hub on my clutch needs a plain plate on first.  Looks like I have too many plates! Further investigation / experimentation required!!

[duTch]

 

.....and there are 5 friction and six plain, which, according to the manual I have, is correct for the plunger model.

 yep, it's all a bit baffling; I bought five new Surflex friction plates for my Plunger GFR, and it was much like you described, way too fat to the point the pressure plate was only just on the centers splines, so I dumped a friction plate (but can't remember if I left the plain plate against the pressure plate for no particular reason- just experimenting), and it works much better but there's not much allowable movement before the springs bind. It's a bit of a fine balance at times, but can find neutral and first gear at standstill with no argument and doesn't drag but slips a bit if I give it (far) too much up steep hills (I think), which maybe can be attributed to the extra plain plate...

[Zander]

I've decided to leave the clutch as it is, but for peace of mind have made four new brass shoulder screws about 1/4" longer than standard, thus increasing the number of threads engaging on the spring bolts.  I'll give that a try tomorrow.👍

[JulianS]

The 4 spring clutch takes 5 bonded plates and 6 plain plates. Shown in photo.

This was originally fitted to the A twins from mid 1960 but frequently fitted to earlier swinging arm bikes as an improvement.

Only the 6 spring swinging arm clutch had inserts in the chainwheel.

The 4 spring is usually a nice light action so you could have the wrong springs or poor cable run. The control lever centres can also have an effect. They came originally with either 7/8 inch lever pivot to centre of cable nipple or 1 1/16  inch. The former gives a lighter more progressive action but can allow clutch to drag and the later can cause a heavy less progressive action but more lift so less chance of drag. 

[edboy]

there are long and short sizes of spring cups. the drawings dont show them but i think the pre units use the deeper ones so the nuts can be turned in further.

[chaterlea25]

Hi Zander,
There were different depth "Triumph" clutch baskets and centres
So the number of plates varies,

John

[Zander]

Thanks for all the comments and help, which is much appreciated.  It's always the same when you get a different bike - always something to sort, which I suppose is part of the fun!  I've previously mentioned that the PO had done a lot of work on this bike, and going by the pristine condition of the top of the pistons, it hasn't done much, if any mileage since rebuild.  The unfortunate part of this is that there's no paperwork or invoices to offer a guide as to what's been fitted, so a bit of digging is required.
Unfortunately, once I find a problem, I look to not only sorting it, but also to see if I can improve whatever it is I'm dealing with. For example, I'm not too keen on the "top hat" in the thrust plate whereby the flat end of the push rod bears against a flat surface in the top hat.  I  can do something about that, but I have to try to stop inventing the wheel! It's a disease, I'm afraid - a bit like thinking you only need one Moto Guzzi!! (cue Cyclobutch) The basket itself is nicely filled by the plates, which is what I would expect, so the problem, if there is one, would appear to relate to springs and cups.  I'll see what today brings!  Thanks again, gentlemen

[Billybream]

Hi.
A good improvement is the SRM alloy clutch pressure plate with top hat pusher and needle bearing.
This arrangement is similar to Japanese clutches.
SRM also sell just the top hat and needle bearing which you could adapt to work with the std A10 plate.
Another worthwhile mod is to cut the clutch push rod and insert a ball bearing.

[Zander]

Hi.
A good improvement is the SRM alloy clutch pressure plate with top hat pusher and needle bearing.
This arrangement is similar to Japanese clutches.
SRM also sell just the top hat and needle bearing which you could adapt to work with the std A10 plate.
Another worthwhile mod is to cut the clutch push rod and insert a ball bearing.

+1 to all that. Thank you

[morris]

Four spring, five plate.  First one in was a plain plate.

The combination of 5 friction and 6 plain plates should work ok.
I have the same configuration in the SA's four spring clutch which is a feather light two finger pull.
In the beginning it did drag a little though, but that was entirely my fault for using a to thick (gearbox) oil in the primary.
Changing the oil and cleaning the plates a couple of times cured that.

[Zander]

I've put the clutch back in it's original state, apart from reducing the lateral play. Operation is nice and light, and there's just a slight hint of drag, which may increase when it gets hot.
It's a shame they omitted the screw cap in the outer case housing to enable spring adjustment so just in case I've got to reset spring pressure, I've lubed the chain with spray so I can have a short test ride to see how it goes, and I won't have the usual mess if I have to remove the chaincase outer.
Primary chain alignment was corrected by fitting a spacer on the crankshaft shock absorber assembly.  When I entered the garage this morning, there was a small covering of oil from the drive end of the gearbox on the floor so I've cleaned everything I can get at to see if I can locate the exact source of the leak tomorrow.
  On to next problem, posted in the carb section!