Clutch and shock absorber problems

[muskrat]

That looks like a '64-'65 clutch hub adapter and thrust washer.
A7/10 ones should look like pic below.
Cheers

[chaterlea25]

HI Bob, Muskrat,
The pic shows the modified adaptor as supplied by SRM
It allows a friction plate to be placed against the clutch chainwheel as on the later A65's and Trumpets
therefore the spring pressure is not against the innermost plain plate which only has a small lip for support
With the mod the lip can be removed or the innermost friction plate centre hole enlarged to fit over the lip

read back through the thread where I gave a link to it

HTH
John

[sprint]

Just looked at your parts and have got to ask what type of washer that is also where does it go I can't remember having one on mine , Oh s*** I feel a job coming on, if it's important that is ,BobH

Hi Bob

The washer I think you are referring too, copper faced, is because I have decided to fit a SRM clutch adapter. If you look at it you will see that it has a larger back face to a normal adapter so that the large washer fits between the adapter and the back face of the chainwheel. It is supposed to provide more support to the chainwheel and stop 'wobble'?

As I was having to fit a new chainwheel I thought it was a good idea to 'upgrade' the adapter at the same time? So it not something that is missing on your bike, unless you have the SRM adapter fitted, so no need to panic.

It also does away with the scroll to the rear face and uses a felt washer between the adapter and the sliding plate. Not sure if its actually any better than he std scroll in keeping the oil in the chaincase but time will tell.

[Topdad]

Thanks for that and the numerous pictures ,thought for the past 40 yrs I've been missing a part , can now hopefully ride the bike before this glorious weather departs ,best wishes BobH.

[bsa-bill]

Ah now I see - thanks sprint, looks like a useful mod to consider for the future

A picture paints a thousand words

[sprint]

Well, tried to install the new SRM clutch adapter and new chainwheel. On tightening up the clutch center nut the hub and chainwheel locked together.

Took it apart and checked everything and re-fitted, same problem!

Tried the old adapter and no problem, the hub and chainwheel spin independently.  Ring SRM and they more or less say that it can only be guaranteed to work if you buy the whole kit from them as they very often have to machine the parts to fit. It seems that you only have a few thou to play with and sometimes the bearing of the chainwheels need to be machined to fit! Well the old adapter fits, so should the SRM one?

Guess I will live with the original one and the SRM one can go back, pity as having the thrust washer supporting the chainwheel the the right way to go, but if you have to machine parts to fit it's not much use to average guy who just wants to buy and fit.

With the new chainwheel fitted and the correct cush drive sleeve (8 mm deep lip?) I now find that with no shims between the sleeve and the oil seal spacer that the engine sprocket is about a mm or so forward of the chainwheel?

It's difficult with the collar on the chainwheel to get a straight edge between the two sprockets so I have used the clutch rod, see photos.

Can't seem to win with engine! Not possible to space the chainwheel out and I don't want to start machining the cush drive sleeve so is this amount of misalignment to much?

[bsa-bill]

now then just a suggestion but does this not remind me of a too long roller issue someone encountered some time ago

[muskrat]

I was thinking the same thing Bill. But if they work in the old set up they should be right.
Cheers

[trevinoz]

Yeah,
             1/4" x 1/4" rollers are too long and cause lock up.
Original are 1/4" x 15/64".

Trev.

[chaterlea25]

Hi All,
Andy, Dont despair just yet 
Yes agreed about the rollers,
Andy's bike has the cush type centre fitted
I have come across the same problem when the spider in the cush drive is worn or wear in the plates either side of the spider. The spider can become damaged where it sits against the roller race and then will sit in further closing up the clearance required
It can also happen if the cush drive spider is not located against the rear plate of the cush drive
as there is some (large??) clearance between the spider and side plates
There seems to be very wide (sloppy) tolerances even with new components 


The last one I did on a T120 nearly drove me nuts
I had to make up a jig which would hold the spider against the rear plate while I fitted the shock rubbers 

HTH
John

[sprint]

Thanks for all the replies.

I should have thought of checking the rollers, but since it works with the old adapter (which should be interchangeable) it points to other factors, possibly those raised by John?

Having taken it apart several times now I am a bit concerned about taking it apart again as torquing to 65 ft/lb's and pulling it off the taper so many times is not doing any favors to the parts?

I think at the moment as it works with the old adapter I should try to get a few miles on the bike and re-visit this at a later time?

What is the opinion on the sprocket alignment? I currently have the engine sprocket too far forward by about 1 mm or so with no shims fitted?  

UPDATE

Well, as they say curiosity ................

Not wanting to be defeated by possible oversize rollers I removed the chainwheel. All bearings measure between 5.93 and 5.98 mm, all well below the 6.35 mm which is 1/4", so they are not the problem.

Across the faces' of the central bearing of the chainwheel it measures 6.14 mm, the same as the old chainwheel.

Fitted the new chainwheel to the SRM adapter, first with the thrust washer fitted and slid a ruler down the side of the adapter until it rested on the lip where the hub sits and find that there is no clearance between the lip and the face of the chainwheel. Fitting the hub and applying hand pressure bind the two together.

Removed the thrust washer and there is now clearance between the lip and the chainwheel. Clearly there is not enough clearance and the lip needs to be slightly higher to allow clearance when the thrust washer is fitted?

Back face of the hub/spider is fine.

[chaterlea25]

HI Andy,
Have you compared the old and new chainwheel thickness at the bearing race?
I think I remember that you were buying one from a Triumph supplier????
If they are the same I would send the pics to the guys at SRM and ask them to measure a chain wheel thickness

As already said sloppy tolerances from somewhere or other
= 

John

[sprint]

Checked both baskets and they are both the same at approx 6.13/14 mm. The chainwheel came from Wilemans, but it is sold by L F Harris for both Triumph and BSA:

This listing is for one New and unused clutch basket/ chainwheel .

As fitted to Triumph pre unit models and BSA A7 A10 late models fitted with the four spring type clutch.

Part number : 57-1549,42-3266

SRM sent the following details:

Clutch basket thickness = 0.241" to 0.242" = 6.12mm to 6.146mm
Thrust washer thickness = 0.053" = 1.346mm
 
Distance centre drum location face to back face where thrust washer sits = 0.296"- 0.2968" = 7.52mm -7.54mm
 
Deduct thrust washer from the above if u use lower limit which leaves less room 7.52mm minus 1.346mm = 6.17mm so should be clearance for drum to rotate after centre nut is tightened.
 
Ensure the hardened ring pressed into the chainwheel basket is flush both sides, sometimes i have seen these pressed in too far or little which in effect increases the chainwheel width and will make the basket lock up.

So the basket bearing dimension is OK, so it has to be down to SRM adapter as they recon I should be OK up to 6.17 mm and I have 6.14 mm? Thrust washer measures 1.35 mm.

[chaterlea25]

Hi Andy
Could you post a pic of the back of the clutch centre where it buts up against the adaptor bearing shoulder?
I will take a pic or two of a couple tomorrow ( I think I may still have one with slight damage which caused lockup)

JOhn

[sprint]

Hi Andy
Could you post a pic of the back of the clutch centre where it buts up against the adaptor bearing shoulder?
I will take a pic or two of a couple tomorrow ( I think I may still have one with slight damage which caused lockup)

JOhn

Hi John

Couple of photos as requested.

Mine looks to be OK?

Regards

Andy