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Tightening torque big end

Submitted by vito_capponi on Thu, 31/03/2016
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Hello everyone! Does anyone know the big end nuts tightening torque for a '48 ES2?

Submitted by ian_richtsteig on Fri, 01/04/2016

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I tighten my single big end nuts to 60 foot-pounds of torque. I use a modified socket to ensure maximum grip by machining off the bottom of the socket so that the nut is held tightly. If you can find one, a 6 point socket is better than the normal 12 point sockets.

regards,

Submitted by ian_richtsteig on Fri, 01/04/2016

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I tighten my single big end nuts to 60 foot-pounds of torque. I use a modified socket to ensure maximum grip by machining off the bottom of the socket so that the nut is held tightly. If you can find one, a 6 point socket is better than the normal 12 point sockets.

regards,

Submitted by ian_richtsteig on Fri, 01/04/2016

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I tighten my single big end nuts to 60 foot-pounds of torque. I use a modified socket to ensure maximum grip by machining off the bottom of the socket so that the nut is held tightly. If you can find one, a 6 point socket is better than the normal 12 point sockets.

regards,

Submitted by paul_knapp on Fri, 01/04/2016

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Hi Vito, on my ES2, I tightened the two big end pin nuts to 150 ft. lbs. I had to borrow a large torque wrench from my mate as my home workshop (duel signal) one only reads maximum 120 ft. lbs. I held one socket vertical in the bench vice and sat the crank assembly horizontal on it, holding one nut,then tightened the other nut so that both nuts were being pulled together against one anotherwhile being tightened.I have read that 200 ft. lbs. is the correct tension, but I decided at the time that 150 would be ample. I'll bet they never used a tension wrench in the factory.

Thanks for the research.  Ian R. reported an oversight and that his intention was 160 ft lbs.  I would only comment that the BSA big end bearings have tapered bosses as compared with the Norton straight bosses.  Harley uses tapered bosses and I am told they required a lot of fettling to get them aligned.

I'm going to use somewhere between 155 and 160 ft lbs if my torque wrench will cooperate.

Thanks to all!

After posting this I did some web research on standard thread torque recommendations.  A Grade 5 (105K to 220K lbs/sq inch ultmate tensile) 3/4 inch X 16 tpi UNF bolt can be torqued to 297 ft lbs!  For plated or lubricated screws about 15% is to be deducted.  Obviously on a precision ground thread formed or chased on a high tensile steel something on the order of 200 ft lbs is not unreasonable.
Pardon my use of "Imperial" units, we still operate with colonial measure!  Of course, Bracebridge Street would have used metric with the exception of the ball and roller bearings they often chose.

Submitted by paul_knapp on Fri, 01/04/2016

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...further more, at those rather high torques, it matters if the thread is oiled or dry. Mine was oiled, so I called it quits at around the 150 mark.

Submitted by vito_capponi on Fri, 01/04/2016

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My torque wrench reads 155 ft. lbs maximum, it should be enough. I don't know if they used a torque wrench in the Norton factory, but I have some experience with H.D. engines and I bet they use impact wrenches because all Harley flywheels I've seen were badly out of alignment.

Submitted by ian_richtsteig on Sat, 02/04/2016

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Hello. Yes my post should have read 160ft-lb. Tried to edit it twice but still posted the original figure.

Submitted by vito_capponi on Sat, 02/04/2016

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Tightened at 155 and "some more" (my wrench reads 155 max), clearance in the cases adjusted and... back in the box where it will sit for some other months (I'm very busy at the moment).

Thanks for all replies!

 



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