Torque settings for BSC threads

gsneyd · Post by **gsneyd** » Sun May 19, 2002 8:52 pm

Has anyone got a reference sheet for the torque settings to be used for British Standard Cycle threads, say 1/4 to 1/2in, or possibly greater using EN3/4 mild steel, or indeed any other commonly used material.
I am about to re assemble my G12 and it would come in useful
Graham

Biscuit · Post by **Biscuit** » Sun May 26, 2002 9:24 pm

I'm pretty sure you will not find a reference sheet for general torque settings. The manufacturer would have specified the grade of material for the bolt or stud, together with the material into which the stud was inserted, and from this the torque settings would have been calculated. Bearing in mind the vast range of steel grades, it would seem that any such reference sheet would be a mighty tome indeed!.

Jackson · Post by **Jackson** » Thu Jun 06, 2002 9:03 pm

I have also been trying to find torques!

gsneyd · Post by **gsneyd** » Mon Jun 10, 2002 11:13 pm

Alan and Graham. Many thanks for your responses. What I was really after was what torque settings do I use in re assembling my 1963 G12. As Graham (2) has the same problem the infornmation seems to be thin on the ground. Perhaps a general letter to the Jampot my provide the necessary infomation.

Jackson · Post by **Jackson** » Wed Jun 12, 2002 9:59 pm

I wrote to Jampot in May.
Torques (lb/ft) I use on my 1955 G80S 500 are:-
Fork caps 1/4W 7:front Axle 3/8W 21: Front brake torque arm to cover 5/16W 18: Mudguard to front fork 1/4W 9: Rear brake stay to swing arm 3/16W 8: R/C r/c 3/16W 10: top fork nuts 5/8W 26: rear axle 1/2W 40.
All for lightly oiled parts - they work for me! Any thoughts?

Biscuit · Post by **Biscuit** » Mon Jun 17, 2002 3:15 pm

Graham Jackson's reply on torque values needs a little further explanation. For example, fork cap studs are 5/16"CEI,Mudguard to fork also 5/16"CEI, both being BSF into the slider.Top fork nut is 15/16"X20. He has suffixed all the thread dimensions with'W', generally accepted to refer to British Standard Whitworth, whereas all the threads referred to, fork top nut excluded are CEI threads. The only Whit. threads I am aware of on a fifties single are the bolts securing the magneto to the platform and the Kickstarter cover screws, and possibly the dynomo field coil. At least Lucas and Burman new the correct threads for aluminium, a fact not shared by AMC. If Graham thinks his fork cap studs are 1/4", and has tightened them accordingly, I hope I never ride behind him.

Jackson · Post by **Jackson** » Tue Jun 18, 2002 9:04 pm

Thanks to Alan, at least someone can educate us on the thread types used.
To avoid confusion I quoted Whitworth socket sizes in my original message, which I believe are 1/16 less than stud diameter?

gsneyd · Post by **gsneyd** » Wed Jun 19, 2002 12:10 am

Oh dear, what a can of worms - but still no nearer the answer for BSC 26 tpi screw torque settings.
I suggest that I simplify the question.
Torque settings for 26 tpi screws sizes 1/4, 5/16, 3/8, 7/16 and 1/2 inch using EN3B. This would be the lowest setting. If using EN8 then a slightly higher setting could be used.

A second question, what should the 5/16 cylinder head bolts be torqued down to?

If you can please advise alternate direction / source of information

Graham Sneyd

Biscuit · Post by **Biscuit** » Wed Jun 19, 2002 9:07 pm

Graham S. have a look under 'Technical-Twins dismantling' on the website, some torque figures are given, including the head studs. 5/16" and 3/8". But what if they are HT specials?. Graham J. - checked my fork cap nuts ('56 G11) and they are torqued to 20 FT/llBs. Question, carburettor studs/nuts, same thread, same diameter would you torque these to the same value?

gsneyd · Post by **gsneyd** » Tue Jun 25, 2002 10:41 pm

Alan. I have printed off the information you identified.
On a separate note. I hope that the Technical Tips book promised in a recent Jampot will provide a lot of information re these ad hock questions.

Many thanks for your help.

Graham