Clutch Adapter Differences

[Colsbeeza]

Hi B'ON,
If memory serves me right, yours is a 1959 GF.
Correct Sleeve Bearing attached, with 8mm flange thickness.
I never did get to the bottom of my misalignment, but I reduced the flange by 2.9mm
Col

[chaterlea25]

Hi Ian,
I would try and find the correct sleeve if possible
Do not get too fussed over the spring compression , I am fitting an electric starter conversion to my SR at the moment and one of the modifications is to pack the cush drive spring with the provided shims/spacer from the kit
until the cams do not rise (separate) when the starter is turning the engine over, this is to prevnt the cush drive from trying to "kick back" through the starter gearing, the spacer is 5mm (from memory)

One of Your next checks should be to see how the scroll on the clutch adaptor is sitting into the sliding plate once the inner primary is bolted to the crankcase , add a spacer to the front screws to ensure the inner is fully against the case/ spacer ring and gaskets
Once the inner case position is established you can then make up the required spacer for the rear mounting

Col, You might have to review the machining of the sleeve when you go to fit the electric starter ??
The efforts to get the starter drive case parallel to the crankcase can involve loosening all the engine bolts and "prying" on the end of the crank to get things parallel. Although on my SR I could not get any movement

John

[BagONails]

Hi Fellas, Once again thank you all for your input.

Yes it is definitely the wrong part in there and I think I will be better off finding a correct replacement.
I could frig around making a spacer etc. but due to the critical nature of this joint I don't want to introduce yet another incorrect part in the mix. It would need to be a hard washer too which I could do but I'd still have the wrong sleeve and the support for the engine sprocket is not that great so out it goes! We could have swapped Col and resolved each others problems but now you've destroyed your one!  I will put mine in my coffee tin full of old rubbish removed from this bike, might have to get a bigger tin...

Mike's Classics list 5 secondhand ones in stock at $66 AUD's ea. plus postage of course  but can't see any stock elsewhere at the moment. I will try some local non-internet sources first.  Meanwhile back to inner primary fit up / scroll sealing and more spacers...so many spacers! 

[Colsbeeza]

You are right there Ian,
However, before I sent my 3 cush parts to UK for mods for the electric start (but not the spring), I hunted around for a spare sleeve, outer cam, and 21-tooth sprocket, as I did not want to lose it all in the post and have no replacements. Fortunately, everything came back from Steve McFarlane OK.
I bought a "second hand" sleeve bearing from Mike's Classic at that cost, and it appears to be brand new. It is a 42-0069 and has the 8mm flange. Pricy but obtainable. May be your best option?
My giant tin is now a huge tin.!!
If the BSA's were brand new today, I could have bought at least 2 new ones.
John, I suspect my new sleeve will be needed for the electric start. Fortunately, the starter gear is attached to the sprocket. I will have to make sure I have jerked the engine sprocket parallel to the clutch before measuring how much to machine off the sleeve bearing.
Col

[BagONails]

“Electric start “ Col?

From your youthful good looks I had you at not a day over 25 mate what’s all this assisted starting nonsense about then !?   

[Colsbeeza]

Hi Ian,
Unfortunately my avatar does not reflect my current condition. Add about 53 years to that and you will be closer.
Col

[BagONails]

The smokes will do that to you Col….

78 and still riding well that’s something I can aspire to anyway, good on ya as they say round these parts.  Actually I probably have been underestimating the average age of the guys on here but it matters not say I. It’s not the bikes in your life but the life in your bikes or something like that 

[RDfella]

I am fitting an electric starter conversion to my SR at the moment and one of the modifications is to pack the cush drive spring with the provided shims/spacer from the kit until the cams do not rise (separate) when the starter is turning the engine over, this is to prevnt the cush drive from trying to "kick back" through the starter gearing, the spacer is 5mm (from memory)

I would advise against doing that.
The starter is approx 2bhp turning the crank at around 300rpm. Same torque as 20bhp @ 3,000rpm or 40bhp @ 6,000rpm. Near as dammit the engine's max power, so shimming the cam until the starter doesn't move the cam means the shock absorber is virtually redundant at all times. Not good for the engine or transmission.
In contrast, the starter should turn backwards relatively easily (at least mine does). So, should the starter be disengaged whilst turning the engine over, the worst that will happen is that the cush drive cam will gently drive the starter backwards a little. Not violently as with a kick-back, but gently. That should present no problem to the starter at all. More important is to avoid kick-back by ensuring static advance is minimal (eg no more than 2*). That will most likely require modification to the advance / retard unit to 'stretch' its operating window to ensure sufficient advance at running speed.

[chaterlea25]

Hi RD,
That is what the instructions say 
I have a new cush drive spring and am going to try that for a start

Col,
could you PM me with your email address?
I have a few pointers that may save you some stress on fitting the ES

John

[RDfella]

Instructions are as maybe, but will the supplier replace your crank or any other damage potentially caused by a non-functioning cush drive?  Worrying about a possible gentle push-back from the cush drive - whilst ignoring the fact a similar push-back will occur when the engine stops and rocks back against compression - makes no sense. Indeed, the way this particular starter is designed, a functioning cush drive would actually soften the initial shock load as the starter is first applied.

[Colsbeeza]

Ian BON,
I have inadvertently misled you. My avatar looks 17 - then add another 53 years. Does that give me an extra 8 years riding?
Col

[BagONails]

Hi Team, I've resurrected this thread to keep all this together as it is all intertwined really so I've been waiting and waiting for parts to arrive from Blighty (the mail here is a bit sus due Covid etc) We've also been away in the NT for a week's holiday which was nice so yeah I've been a bit quiet lately but never fear work is afoot and the problems continue to manifest themselves.

After spending considerable time and effort to get the clutch adapter fitted correctly I found I had the wrong cush drive bearing. I have now procured a correct 42-69 part with the 8mm shoulder and 50.4 overall length only to then find with the original nut and cush sleeve done up tight against the end of the bearing there was only a 22mm gap for the spring.  When I squashed the spring it binds at 24mm - not ideal as we want to tighten against the bearing rather than the spring coils to stop the engine wrecking itself and in addition we need at least a few mm clearance for the cush sleeve to move or our cush will not be cushy or should that be cushty?

I then realised the original nut had been tampered with and had about 3mm ground off the end no doubt due to the incorrect original bearing so I then ordered a new nut and spring from Draganfly.  Now these parts have finally arrived I have checked and rechecked all my parts against those shown with measurements in John's primary fit up guide and after confirming all the dimensions are very close to those shown I am still only getting a spring gap of about 24.2mm and 3.34mm of axial "cush" movement on the sleeve. This doesn't seem to be sufficient to allow the system to function properly and it seems now the only option is to pinch a mm here and there to increase the spring clearance (reduce the preload and increase the sleeve axial travel to at least 5mm - 6mm.

As ever your thoughts, experience and combined pearls of wisdom are not only welcome but encouraged!

[berger]

has that sprocket got a mahoosive shoulder on it , if so i havn't come accross one with a shoulder as wide as that. as you know there are lots of different sleeves with thinner shoulders than 8mm. just looked again it must be the sleeve shoulder i see. how many coils has the spring got there are differences in spring coils and lenghts. i had a problem like this with mine in the 80's when doing the build. i went to a shop and the owner told me to look in a big box of cush drive parts and told me there were loads of miss matched parts put on these bikes over the years.

[BagONails]

No berger, the sprocket has a shoulder but its only 1.6mm The bearing has an 8mm shoulder but that is as it should be for the later S/A part 42-69. I do have some faith in this as its the only NOS part in the set up! The sprocket lines up nicely with the clutch now but I may be able to pinch 1mm off it which is a start. The sleeve is glass hard but I might be able to get a bit here too plus another mm off the nut shoulder and possibly a 3mm spacer between the nut and the end of the bearing but I'm a bit nervous about that due to the critical nature of the joint.

[Swarfcut]

 I'll try and offer some explanation and post under a new topic "Cush Drive Conundrum"

 Swarfy