Author Topic: Torque values  (Read 720 times)

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Offline tacc13

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Torque values
« on: September 23, 2019, 02:45:39 AM »
I've just assembled my CB550 cases using ARP 12 point bolts (which are little works of art).  I torqued them to the Honda specs but have noticed ARP suggest a slightly higher value for the M6 and M8 bolts.  Is this because of the stainless they use? Should I stick to the Honda specs? Thanks. 

Offline PeWe

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Re: Torque values
« Reply #1 on: September 23, 2019, 03:19:21 AM »
If you tighten the cases, beware of overtighten the bolts!
It is the aluminium that will not withstand the bolts max torque. Threads will  be stripped!  M6, never over 10Nm in the old alu even if thread lengt is 15mm.

A std 8.8 M6 has a max torque of 12Nm which is more than an alu thread can take. Steel with thread lenght over 10mm  another thing.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline tacc13

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Re: Torque values
« Reply #2 on: September 23, 2019, 03:25:06 AM »
Thanks,  will be leaving them at the factory spec.

Offline rotortiller

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Re: Torque values
« Reply #3 on: September 23, 2019, 03:47:39 AM »
A bit more will not hurt. Since the threads are so long in the casing they will take more than say threads the depth of a nut in aluminum. So if someone gave you a general torque value for threads of a specific size  it could vary by application to a  degree up or down. So a specific torque for a specific application would be more critical. There is a CDF factor and a 10% error in a torque wrench generally will not destroy serviceable threads. Adding oil to threads will stress the stud more so ask yourself how many guys have done that. LOL  The book is a guide so if you  are reasonably close in torque values I'd not worry. I would be cautious with camshaft towers with known stripping issues. The book tells us lots of things that we often deviate from slightly The question is what value is 'slightly'? If a part made of aluminum is repaired with a steel helicoil that thread will now take more stress before it is strained. (Some stud threads have a tighter fit than say the common nut and bolt, how easy did they thread in. These are considered permanent installations)
« Last Edit: September 23, 2019, 04:05:24 AM by rotortiller »