Author Topic: Crankshaft side play/shims etc  (Read 3949 times)

Offline ellis

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Re: Crankshaft side play/shims etc
« Reply #105 on: 17.08. 2018 19:59 »
SRM recommend the cush drive nut should be torqued to 60-65ft lbs. I do think they know what they are doing. Add some Loctite for added security if you wish.

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Re: Crankshaft side play/shims etc
« Reply #106 on: 17.08. 2018 20:19 »
Well, as an engineer I care to disagree with them. 65lbs is the sort of figure you expect 10mm bolts to be torqued to these days. The BSA mainshaft thread is 3/4" dia, if I recall correctly. See my earlier post about figures for that size nut / bolt.
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Re: Crankshaft side play/shims etc
« Reply #107 on: 17.08. 2018 20:58 »
 G'day RD, maaaate (spoken in Aussie accent).
In the old days torque wrenches were few and far between. Most mechanics used the 1, 2 or 3 GRUNT method or heavier hammers. Now days most hobby/home fiddlers have a torque wrench. Any literature I have/can find states 65ft/lb for that nut. If SRM agree I take it as gospel.
There's another old saying. "You can lead a horse to water but you can't make him drink".

For the last 20 years that I can remember all tyre shops down here use a torque wrench to tighten wheel nuts. Would be due to wheels falling off and litigation. The general rule is 80ft/lb, some manufacturers require more or less. Out on the road I use two grunts.

Just had to check my memory so looked up VW flywheel nut. Flywheel gland nut M28x1.5, 217ft/lb for 1500cc and less, 253ft/lb for 1600cc. One of my first jobs as a 1st year apprentice was rebuilding VW motors.

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Re: Crankshaft side play/shims etc
« Reply #108 on: 19.08. 2018 12:02 »
Seems to me the spanner v hammer and punch debate falls into two camps. So I’d like to conclude my input with the following observations.
Firstly, the brevity of my comment about disagreeing with SRM may have seemed a little pompous. Those who know me will vouch that of my many vices, arrogance or pomposity do not feature. Maybe I was a bit short because I get irritated when people take the view that because a company is well-known or big, it is automatically right.
I have known the Ford motor company to be wrong when it advised a certain piston / liner pairing that were actually a mismatch. I could give many similar examples - no-one has a monopoly on wisdom. It happens I am an engineer, and I do disagree with a 65ftlb torqueing of the mainshaft nut but, having said that, I also appreciate there are people on this forum who know more than I. Here’s why I disagree with using a spanner:
1.   Accepted wisdom from those who built them originally is that a hammer and punch is superior to a spanner. Why go against that advice?
2.   When using a punch there is no need to lock the engine. With a spanner there is, but how? Remember, if restraining the shaft with the sprocket, the cush-drive cam will be forcing against the nut you are trying to tighten.
3.    If using a spanner, what torque do you apply? We know that nut has to be TIGHT, so why choose a figure that is only around half that of the industry-recommended torque for a nut of that size?
Would be interesting to know whether those who are experiencing failures are using a spanner or a punch. I will continue using the latter, as in over fifty years of fettling BSA’s I’ve never had a mainshaft nut come loose.

'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

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Re: Crankshaft side play/shims etc
« Reply #109 on: 19.08. 2018 12:36 »
 Well I've found the method that works for me and I'll keep using it, which I needed to again today, and just to throw a spanner in the mix, the torque wrench I used (new acquisition clicky-ratchet one) is in Newton-metres/Kg/cm....everything except Lb-Ft/Ft-Lb...maybe even gallons *conf2*...I got it to ~110 N-M whatever with very little effort

 each to their own.....


 Hey Admins, brief (further) off topic (but will be wherever it goes), I noticed the other day the little thing over there --->> in the bottom right corner that seems turned out to be a kind of 'edit' button...is that new?
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Re: Crankshaft side play/shims etc
« Reply #110 on: 19.08. 2018 14:00 »
torque wrench I used (new acquisition clicky-ratchet one) is in Newton-metres/Kg/cm....everything except Lb-Ft/Ft-Lb...maybe even gallons *conf2*...I got it to ~110 N-M whatever with very little effort


65 lbft = 88.12 Nm. 110 Nm = 81.13 lbft.
Downloaded a converter app thingy to my phone. Comes in quite handy sometimes  *smile*
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Re: Crankshaft side play/shims etc
« Reply #111 on: 19.08. 2018 22:54 »
 
Quote
Quote from: duTch on August 19, 2018, 22:36:01

    torque wrench I used (new acquisition clicky-ratchet one) is in Newton-metres/Kg/cm....everything except Lb-Ft/Ft-Lb...maybe even gallons *conf2*...I got it to ~110 N-M whatever with very little effort


65 lbft = 88.12 Nm. 110 Nm = 81.13 lbft.
Downloaded a converter app thingy to my phone. Comes in quite handy sometimes  *smile*


 Yo thanks, Haynes graciously put one in my Hilux manual, and I used the conversion factor last time to 80-something (the setting on the handle is a bit vague), but just did it to a bit more to test the wench... *whistle*


  Probably should split this off into a talk wench torque ... *bright idea*....?   
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline Colsbeeza

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Re: Crankshaft side play/shims etc
« Reply #112 on: 20.08. 2018 03:29 »
Can't remember where this came from. I think it was in the box my torque wrench came in.
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Offline Colsbeeza

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Re: Crankshaft side play/shims etc
« Reply #113 on: 20.08. 2018 03:35 »
Spose I should explain. There are 9 columns. Each three columns are a conversion from one to another, starting with a round number. The first 3 columns convert from ft-lbs, the next 3 from Newton-metres, the last 3 from Kilogram-metres.
Clear as mud.??
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Offline RichardL

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Re: Crankshaft side play/shims etc
« Reply #114 on: 20.08. 2018 06:02 »
Well, If you've bought an SRM cush nut, I would definitely recommend against using a hammer and drift. Then, if you've bought an SRM timing disk, you might have some trouble using it with a standard cush nut, If you are following BSA Service Sheet #208, you will be using a C-spanner to tighten your cush nut "as securely as possible" (maybe 65 ft-lb?). If that C-spanner is, say, 9" long, tell our arm to press with about 87 lb. force.  (I don't think they considered Archimedes and cheater leverage bars when saying "as securely as possible.")

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Re: Crankshaft side play/shims etc
« Reply #115 on: 20.08. 2018 11:16 »
Hey Admins, brief (further) off topic (but will be wherever it goes), I noticed the other day the little thing over there --->> in the bottom right corner that seems turned out to be a kind of 'edit' button...is that new?
Where? Can you take a screen grab?

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Re: Crankshaft side play/shims etc
« Reply #116 on: 20.08. 2018 13:34 »

 
Quote
Quote from: duTch on August 19, 2018, 22:36:01

    Hey Admins, brief (further) off topic (but will be wherever it goes), I noticed the other day the little thing over there --->> in the bottom right corner that seems turned out to be a kind of 'edit' button...is that new?

Where? Can you take a screen grab?
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

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Re: Crankshaft side play/shims etc
« Reply #117 on: 20.08. 2018 17:21 »
Oh yes, I just tried it one of my posts. It went into Modify mode, just like clicking on the word 'Modify' ;)

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Re: Crankshaft side play/shims etc
« Reply #118 on: 20.08. 2018 18:34 »
 
Quote
  Oh yes, I just tried it one of my posts. It went into Modify mode, just like clicking on the word 'Modify' ;)

 ...except it didn't support adding pics.... *dunno2*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

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Re: Crankshaft side play/shims etc
« Reply #119 on: 20.08. 2018 22:53 »
Quote
  Oh yes, I just tried it one of my posts. It went into Modify mode, just like clicking on the word 'Modify' ;)

 ...except it didn't support adding pics.... *dunno2*
Oh yes, I didn't notice that!