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Joining crankshaft assembly

Submitted by robert_tarr on Tue, 14/01/2020
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Heavy Twins

Hi,

I know to centre punch the small nuts but at the moment I am baffled as to how to handle the 2 large nuts at the top, the reason being is that they have an unthreaded bit that I wont be able to centre punch, so would some kind person please educate me how to proceed.

Many thanks jim

Submitted by Xanna_jeannett… on Wed, 15/01/2020

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Hello best I can tell you the crankshaft nuts and bolts are all the same size 3/8ths spanner combination undo top then bottom and across for a rebuilt you can ether replace all bolts and nuts and tab washers or just replace the nuts and tab washers torque settings are 30 to 35 pounds per square inch but go a round in stage's   , yours Anna j

 

Submitted by david_cooper on Wed, 15/01/2020

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Take care... crankshaft assembly torque in Haynes is given as 35 pounds.feet, but that is wrong...should be 25.

See Roadholder October 2011 pg 10

 

Submitted by robert_tarr on Thu, 16/01/2020

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Thank you David, 

I don't have that Roadholder issue I only go from November 2011 but I did read in Roy Bacons Norton twin restoration page 46 that they were to be torqued at 25-30 its a pity Haynes state 35 two major authorities giving conflicting sums.

Bacon also says that pessimists can also use Loctite and centre pop to make sure.                        This being my problem ! its an easy job to centre punch the small nuts but the larger ones on top have like a well where the nut is not threaded and the bolt only comes up to the threaded bit, I cant see how I can centre punch it, that's the bit I need help on. Maybe I should not be a pessimist as Bacon says and not bother to do anything but torque to required sum ?

Cheers jim

Thank you Anna,

I am grateful for your advice, but my problem is the 2 large nuts that are not threaded entirely through and the bolt only comes to the end of threaded bit , creating like a well, I cannot see how I centre punch (belt & braces) perhaps like Roy Bacon says for pessimists, and not do it ?

Cheers jim

hello there  should be four nuts four bolts and tab washers and two studs and nuts ether side with washers    if this is not the case on your crank then. Someone done a bodge job    yours anna j

Submitted by david_cooper on Thu, 16/01/2020

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Regarding the manual: that page is on the reprint copies under the 'Roadholder' tab on this web page (above).

As for the nuts - I also thought they were all the same.  I bought a new set when I did mine some years ago, after having broken one when trying to get it up to 35!  I knew I should have trusted the 'feel' of the spanner...and thrown away the torque wrench.

Can I throw in a closely related question?  I'm sure Bacon's Norton Twins Restoration says that two of the bolts are close tolerance and supplement the dowel to hold it all correctly.  Can anyone else confirm this?  The Haynes book does not mention it nor, I think, does the Neill Norton manual. Any ideas on this one, Anna?

And why did Norton only use tab washer plates on one pair of studs?  Is there any reason not to use them on all?

Submitted by richard_tool on Thu, 16/01/2020

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Hi Robert - If this is the condition you describe - the top two studs don’t extend to the outer face of the nuts and by “ center punching“ you mean deforming stud/nut interface to keep nuts from backing off   ( this was called “staking “ when I was schooled- not trying to be pedantic here - just making certain we are talking about the same thing) you have two options . Stake the interface between the base of the nut and the crank flange on the outside ( not recommended) or grind a punch to reach down the inside of the nut to get to the thread interface. By all means use threadlocker also if you are concerned.  David - I believe the tabs are only used at the bottom studs for two reasons- these nuts are more difficult to torque properly because the crank web interferes with the torque wrench and also the tabs span the ends of the dowel pins to keep them from coming adrift.

 Indeed two of the bolts are close tolerance to aid in locating in addition to the dowel pin.

Crank

 


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