Author Topic: cush drive nut and sleeve  (Read 1951 times)

Offline coater87

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cush drive nut and sleeve
« on: 26.07. 2017 20:32 »
 OK guys,

 My converted clutch is installed, and I moved on to the cush drive.

 I know you are supposed to have 70 pounds of torque on this.

 The problem (maybe) I am having is that the cush drive nut is bottoming out on the cush drive sleeve long before I have anything near 70 lbs. of torque. I have all the correct parts installed as far as I can tell against an old parts manual.

 All I can think is that either this is how its supposed to be, and I am just giving 70 pounds of tightening to keep it tight, or my spring has lost its tension.

 I have broken the camera on my new Samsung phone (supposed to be military spec, either I am one tough old man or the military is much softer than it used to be *conf*) so I am going to try and take some pictures with my old phone and transfer them to the computer if you need pictures to help me with this.

 Lee
Central Wisconsin in the U.S.

Offline JulianS

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Re: cush drive nut and sleeve
« Reply #1 on: 26.07. 2017 20:55 »
The nut must bottom on the sleeve before you torque it.

Personally dont use a torque wrench on my SRM nut just do it up very tight with a bit of loctite

Online Greybeard

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Re: cush drive nut and sleeve
« Reply #2 on: 26.07. 2017 20:55 »
I'll jump in quick with my opinion that may be improperly understood: The spring has to have room to compress so the cam device can work. The nut bears on the inner sleeve that bears on the crankshaft bearing and holds the crank firmly in place; hence the heavy torque required.

Offline coater87

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Re: cush drive nut and sleeve
« Reply #3 on: 26.07. 2017 21:00 »
 Thank you guys!

 I was worried my spring had taken a bad set and lost its tension. *sad2*

 Lee

 
Central Wisconsin in the U.S.

Offline Gavin

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Re: cush drive nut and sleeve
« Reply #4 on: 27.07. 2017 14:56 »
Hi Lee, I may be right off the page, but there are several different shaped Cush nuts. But the issue that has made a massive difference to my 2 plunger A10's is making sure that the cush dog can slip over the smaller portion of the cush nut. Orabanda shaved about 20 thou off the offending cush nuts and the dog now works as it should giving me amazing gear changes and no longer sending pillion riders either over my head or back 3 spaces.

so take it apart, ensure the cush dog has the required travel and then tension the nut up  (I use 65 ft/lb) n loctite or split pin or whatever...

Can send photo's of different cush nuts if you like. I Suspect plunger and swinging arm use different nuts.

Online RichardL

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Re: cush drive nut and sleeve
« Reply #5 on: 31.12. 2017 00:53 »
New thread in old topic.

Is washer #3 really needed? If so, why?

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online ellis

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Re: cush drive nut and sleeve
« Reply #6 on: 31.12. 2017 01:46 »
Hi RichardL,
 Yes the washer is needed as it is a locking washer for the original Cush drive nut. Even if you use a thread lock I would still use the washer. We call it belt and braces.   ;)


ELLIS

Online RichardL

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Re: cush drive nut and sleeve
« Reply #7 on: 31.12. 2017 05:28 »
My edit saying I have the SRM nut didn't take. 
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Greybeard

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Re: cush drive nut and sleeve
« Reply #8 on: 31.12. 2017 09:38 »
The split-pin/cotter seems to just be there to stop the nut coming into contact with the case if the nut works loose.

Offline RogerSB

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Re: cush drive nut and sleeve
« Reply #9 on: 31.12. 2017 11:42 »
If it's any help:-


Took this photo a few weeks ago when I fitted an SRM 4 spring clutch and at the same time I replaced the original cush drive sleeve nut with SRMs version. According to SRMs instructions you torque to 60 - 65 ft lbs. I tightened mine to 65 with Locktite on the threads. I must admit I didn't fit the washer because with this nut there's nothing for it to lock into and I couldn't see it would do anything useful (I hope I'm not wrong!).

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Online bsa-bill

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Re: cush drive nut and sleeve
« Reply #10 on: 31.12. 2017 11:48 »
Quote
According to SRMs instructions you torque to 60 - 65 ft lbs.

Yes that was my first thought when I read the first post from Lee
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

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Re: cush drive nut and sleeve
« Reply #11 on: 31.12. 2017 12:16 »
...making sure that the cush dog can slip over the smaller portion of the cush nut...

Maybe this is not what you are describing but I'm pretty sure I've read here that the cush drive lobes should not actually pass over each other; the idea is that they take some of the shock out of heavy acceleration and/or dropping the clutch too quick.

Online Greybeard

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Re: cush drive nut and sleeve
« Reply #12 on: 31.12. 2017 12:18 »
...I replaced the original cush drive sleeve nut with SRMs version...

That SRM nut is pretty but is it's only advantage that you can put a socket on it?

Online bsa-bill

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Re: cush drive nut and sleeve
« Reply #13 on: 31.12. 2017 12:35 »
Quote
it's only advantage that you can put a socket on it?

just about, probably a good reason the nut bit is so shallow
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online chaterlea25

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Re: cush drive nut and sleeve
« Reply #14 on: 31.12. 2017 13:29 »
Hi Richard,
My opinion is that the washer is best left out
My reasoning is that the washers is soft, so over time it compresses as its placed between hardened parts
Thread locking fluid has always worked for me (and others)
I'm sure if it was available back when the bikes were built it would have been used by BSA

John
1961 Super Rocket
1963 RGS (ongoing)