Author Topic: cush drive nut and sleeve  (Read 1954 times)

Offline JulianS

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Re: cush drive nut and sleeve
« Reply #30 on: 02.01. 2018 13:02 »
No torque figure given in the period BSA literature. Back then not many owners had a torque wrench. And the original castellated nut lending itself to a socket and torque wrench.

There is a nice photo in The Gold Star Book by BMS showing the cush nut on a Goldie being finally tightened using a hammer and brass drift. That method being the cause of many mangled cush nuts, but it certainly tightens them.

Before going the SRM way I used loctite, the lock washer and the hammer/drift.

After going SRM I use loctite and a long wrench and do it up as tight as I can.

Offline RoyC

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Re: cush drive nut and sleeve
« Reply #31 on: 02.01. 2018 13:56 »
No torque figure given in the period BSA literature. Back then not many owners had a torque wrench. And the original castellated nut lending itself to a socket and torque wrench.

There is a nice photo in The Gold Star Book by BMS showing the cush nut on a Goldie being finally tightened using a hammer and brass drift. That method being the cause of many mangled cush nuts, but it certainly tightens them.

Before going the SRM way I used loctite, the lock washer and the hammer/drift.

After going SRM I use loctite and a long wrench and do it up as tight as I can.

The SRM Clutch mainshaft nut, SRM state 60/65 ft lbs, so it should be tight enough for the cush nut.  *dunno*
As you say "Back then not many owners had a torque wrench." but we all had a big hammer in the coal shed. *bash*
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Offline muskrat

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Re: cush drive nut and sleeve
« Reply #32 on: 02.01. 2018 14:20 »
I can't remember (that's normal) the last time I used a torque wrench on that nut. I use a rattle gun set on 4 (f'ing tight) even on the SRM nut, you'd be doing well to get it undone with anything but a rattle gun. That thread will take a lot more than 65ft/lb.
Going back to my earlier post.  *red* "The washer is a barrier between the spring and nut." *bash* Sorry, too much NYE cheer anesthetized my few remaining brain cells.
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Offline RogerSB

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Re: cush drive nut and sleeve
« Reply #33 on: 02.01. 2018 15:05 »
I echo Julian's comments exactly.


In most of the 'period' literature I've read it usually says something like 'tighten the sleeve nut fully' and some elaborate by suggesting a C spanner or a drift and hammer. I'd be surprised if you could actually tighten the original BSA sleeve nut to 60 - 65 ft lbs with an ordinary C spanner and even if the spanner didn't bend (like mine did) you'd need to be Desperate Dan or Popeye!


Is it feasible that the 60 - 65 ft lbs that we all hear about is the results of the likes of SRM coming up with something a bit more refined and after their (hopefully) R & D expertise making that recommendation?  If that is the case then tightening the original nut to 60 - 65 ft lbs and with some thread locking compound maybe, as Richard was quick to point out, that would make the lock washer unnecessary.


Of course if you are using the original BSA sleeve nut and lock washer to lock shaft and nut together you'd be silly not to do it, even if using thread locking compound and tightening it to 65 ft lbs.


But if using the more modern replacement nuts as intended it's not possible to use the lock washer or use a split pin. In my opinion, here we have to trust in the expertise of knowledgeable developers such as SRM and make sure we follow their instructions explicitly.

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Offline RogerSB

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Re: cush drive nut and sleeve
« Reply #34 on: 02.01. 2018 16:25 »
Further to my previous post:-

As I bought one of SRMs cush drive nuts last month I thought I may be entitled to some tec support so I phoned their technical assistance number to ask if a lock washer is required with their nut. The answer was a definite 'No' followed by 'It was designed not to be used with a lock washer'. He then confirmed that thread locking compound is a good idea and that it should be tightened to 60 - 65 ft lbs.

So that's good enough for me guys.

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Offline RogerSB

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Re: cush drive nut and sleeve
« Reply #35 on: 12.01. 2018 18:09 »
Are you supposed to jam a punch betaeen the spring coils and somehow smash the edge of the washer into the notches in the nut? That's dumb, or I am.


Hey! This explains it, BSA had a special tool :! .

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Offline duTch

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Re: cush drive nut and sleeve
« Reply #36 on: 12.01. 2018 22:33 »
Are you supposed to jam a punch betaeen the spring coils and somehow smash the edge of the washer into the notches in the nut? That's dumb, or I am.


Hey! This explains it, BSA had a special tool :! .

 Not to me  *conf2*

  i deferred from reply earlier as this has been covered in several other threads, but FWIW, as far as I can tell there are two different standard item Swing Arm model cush nuts (which may or not be interchangeable, but Plunger model ones are different as the sliding sleeve is longer and nuts have a stepped section for the sleeve to slide over as Gav noted,....

 I had a whinge in another thread a while ago about a replacement spring being the wrong measurements from my original Plunger one (replacement shorter and fatter), a few thousand miles later it still clunks and bangs  *pull hair out*, but that was here;https://www.a7a10.net/forum/index.php?topic=9968.msg73326#msg73326, so won't get involved in it here


 I made my own tool which is much like the ones pictured in replies 26 & 27....but with an over-sleeve to hold it in place;

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