Author Topic: Crankshaft side play/shims etc  (Read 3956 times)

Online ellis

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Re: Crankshaft side play/shims etc
« Reply #90 on: 15.08. 2018 19:15 »
Doh, didn't have my maths head on *doh*  65+65=130ft lbs that's better.

ELLIS

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Re: Crankshaft side play/shims etc
« Reply #91 on: 15.08. 2018 21:07 »
Years ago, before everything including the light switch self tapper had a torque reading,  fitters had a feel for how tight a nut or bolt should be. Things were either loose, hand-tight, tight or 'very tight' and the crankshaft nut falls into the latter category. The trouble with torqueing the nut, is how do you lock the engine without causing damage? I note one person a while back suggested jamming a piston. I wouldn't recommend that, as the torque required could well crack or at least distort a piston, and possibly the conrod too. As for amount, I see Muskrat suggests 65ftlbs. If I were using a torque wrench, I'd double that.

I believe the BSA manual says something like 'Do the cush drive nut up very tight'. No torque values quoted. Most home mechanics in the 1950's & 60's would have bunged a lump of wood against the sprocket to jamb the primary chain and used either a large Stilson wrench or a hammer and a drift.

Online muskrat

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Re: Crankshaft side play/shims etc
« Reply #92 on: 15.08. 2018 21:14 »
G'day all.
65ft/lb isn't that tight. The flywheel nut on a VW is 240ft/lb!
Mostly I put the bike in gear and lock the rear brake. I have jammed the sprocket with timber if the wheel isn't on.
Cheers
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Offline chaterlea25

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Re: Crankshaft side play/shims etc
« Reply #93 on: 15.08. 2018 21:31 »
Hi All,
The easiest and safest way  (I find) to lock the crank and clutch/ gearbox shaft is with a clutch locking tool
two old plates bolted together and to a two foot handle
I have several sets of plates that suit different clutches that fit the same handle,
Today I added a further pair to suit a Pearson (Suzuki based) clutch on a 350 Goldie

I would think 130ft/lbs torque would break or bend something *warn* *warn* *pull hair out*
65ft/lbs and a drop of threadlock  and I have never had a problem

John
1961 Super Rocket
1963 RGS (ongoing)

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Re: Crankshaft side play/shims etc
« Reply #94 on: 16.08. 2018 09:20 »

   In addition to my earlier reply;
 
Quote
Reply #89 on: Today at 04:59:30

 I remembered that I think the S/A inner case bolts may be 5/16" whereas the Plunger Primary tensioner studs are 3/8" (casing end), and also there was mention in a different thread of one of the three front S/A outer case (5/16"?) screws may be able to serve the same function (locking the web if too long).

 By my reckoning, this could be easily and safely researched by anyone with the barrels and outer Primary case off to have a visual on the progress .
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Online cyclobutch

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Re: Crankshaft side play/shims etc
« Reply #95 on: 16.08. 2018 10:04 »
On my Sportster they have a reputation for the engine sprocket coming loose, and this is retained by a large hex nut. First time had to pull that I found it so extraordinarily tight I had to make up a plate with pegs to lock the clutch, then with a socket and bar I had to slip a length of about 5 foot of scaffolding tube over it and apply myself to that. I’ve had the misfortune to have to go in there a few times over the years and always use, by feel, whatever that torque setting must produce – and I imagine it must be quite a big number. I also Loctite it each time.

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Re: Crankshaft side play/shims etc
« Reply #96 on: 16.08. 2018 14:02 »
RD fella what you say takes me back to when as a 13year old I put a cylinder head on a 2 stroke field bike and PING a long stud came flying up at me which had snapped off at the crank mouth. dad said I was too ham fisted or words to that effect{long time ago} anyway he got the remainder out and turned me another stud. over the years  he taught me to -FEEL FOR IT, and  I,ve very rarely used a torque wrench . only on straight 6 car engines, my mate was amazed how close I could get them pulled down to near the torque.

Offline chaterlea25

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Re: Crankshaft side play/shims etc
« Reply #97 on: 16.08. 2018 17:10 »
Hi All,
One of the best tool investments I have made in recent times is a (second hand) Snap On 18v battery impact wrench
It is fkn great at opening things like Cyclo's HD engine shaft nut (and retightening them too *smile*)
It works great on the clutch and the likes of flywheel extractors, the rattling of the impact just pops them off
It does not need full throttle on the switch to do this,
great care is needed when using it to do up small diameter nuts and so on

I learned the "feel" factor as a skinny kid, and only occasionally resort to the torque wrenches

John
1961 Super Rocket
1963 RGS (ongoing)

Offline RDfella

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Re: Crankshaft side play/shims etc
« Reply #98 on: 17.08. 2018 14:26 »
In an effort to allay fears about applying excessive torque, I tried to find my list of bolt torques for given diameters / steels. Couldn't find it, but did come across the following:
If I recall correctly, the diameter of the thread concerned is 3/4" and the torque for a nut of that diameter (fine thread) varies (depending on the quality of the steel) between 101 ftlbs for grade 1 to 480 ftlbs for grade 8.
I seem to racall those mainshafts were EN32 case-hardened, which has a tensile strength of 71,000 lbs / sq.in. That would put the torque required in midrange, well over 130.
In conclusion, the words of Bruce Main-Smith (from his Gold Star book) may be relevant, as the singles have a similar mainshaft.
"The precaution is to keep the nut really tight. And the penalty for neglect can be disentregation of the mainshaft. It is more effective to jar the nut tight with a hammer and brass punch than to heave on a spanner".
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

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Re: Crankshaft side play/shims etc
« Reply #99 on: 17.08. 2018 14:35 »
In conclusion, the words of Bruce Main-Smith (from his Gold Star book) may be relevant, as the singles have a similar mainshaft.
"The precaution is to keep the nut really tight. And the penalty for neglect can be disentregation of the mainshaft. It is more effective to jar the nut tight with a hammer and brass punch than to heave on a spanner".
Or an impact wrench?

Offline RDfella

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Re: Crankshaft side play/shims etc
« Reply #100 on: 17.08. 2018 14:59 »
Not keen on impact wrenches unless the torque can be dialled in, otherwise the tightness achieved is anyone's guess. Mt pet hate is garages doing up wheel nuts with them. Seen wheel studs stripped this way and others sheared off. I gave up on 1/2" IW's. Current one is 1" drive and runs to 1,800 ftlbs. Better not use that on the A10!
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online bsa-bill

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Re: Crankshaft side play/shims etc
« Reply #101 on: 17.08. 2018 17:33 »
Quote
pet hate is garages doing up wheel nuts with them

Can understand that but around here they do them up so far with he rattle gun then pull them up with a torque wrench, send you up and down the road a bit and torque them again.
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: Crankshaft side play/shims etc
« Reply #102 on: 17.08. 2018 18:29 »
Quote
pet hate is garages doing up wheel nuts with them
Can understand that but around here they do them up so far with he rattle gun then pull them up with a torque wrench, send you up and down the road a bit and torque them again.
If you watch the tyre jockeys they pull the torque wrench until it clicks...then give an extra yank. Great!

Online bsa-bill

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Re: Crankshaft side play/shims etc
« Reply #103 on: 17.08. 2018 19:22 »
Quote
If you watch the tyre jockeys they pull the torque wrench until it clicks...then give an extra yank. Great!

Ha yes I have seen that but not on a wheel, well thing is - vote with your feet
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

Offline RDfella

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Re: Crankshaft side play/shims etc
« Reply #104 on: 17.08. 2018 19:46 »
Bill - they actually use a torque wrench?? Must be a Bentley franchise. When I spent five years in the garage trade I preferred a spider. All down to that 'feel' again.
But back to the crankshaft nut question - it needs to be TIGHT. With an impact wrench I'm never sure whether the nut / bolt I'm on is tight enough or too tight. So I only ever use them for undoing things - like the crank bolt on a car to get to a timing belt.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.