SXIPro
JM781 Big Bore
- Location
- Here on the 'X' mostly
Anybody?
The purpose of torquing isn't only to prevent them from backing off, it also is to prevent bolt and thread damage. 23Ft/Lbs is a little much for a 8mm bolt/thread. If you often R & R the head or bolts, thread damage can occur if over torqued. Its a matter of time. However, if you Helicoil a thread, it is actually stronger and can tolerate 23ft/lbs on an 8mm. If you find yourself needing to over torque to prevent it getting loose, then your threads or bolts may be compromised (provided it has a proper lock-washer or chemical).34ftlbs girdle nuts, 23 ftlbs headbolts.
Those aren't the official specs, but if you don't want them backing off, use those.
The purpose of torquing isn't only to prevent them from backing off, it also is to prevent bolt and thread damage. 23Ft/Lbs is a little much for a 8mm bolt/thread. If you often R & R the head or bolts, thread damage can occur if over torqued. Its a matter of time. However, if you Helicoil a thread, it is actually stronger and can tolerate 23ft/lbs on an 8mm. If you find yourself needing to over torque to prevent it getting loose, then your threads or bolts may be compromised (provided it has a proper lock-washer or chemical).
I like 18Ft/Lbs for most 8mm bolts and 28Ft/Lbs for 10mm bolts.
T.M.I: Something most never talk or think about when re-using bolts, bolt stretch. On critical assembly and when it allows, this is the proper method used for "torquing" down. Over time a bolt (and nuts) actually fatigues (softens, twists, lenghtens). Nothing can be done to prevent this and its natural. However, bolts should not be reused as often as we reuse them. Lucky for us these aren't mission critical jobs. Technically, studs are so much better it isn't funny. I'm going to also stud my 8mm head.
The purpose of torquing isn't only to prevent them from backing off, it also is to prevent bolt and thread damage. 23Ft/Lbs is a little much for a 8mm bolt/thread.
The OE Yamaha manual calls for 26Ft/lbs for second round of torque on head bolts. 11 on first round.
Charles
Well, if we are going to quote manuals then the ADA billet head instructions says..."all head bolts to 18ft/lbs and the girdle nuts to 23ft/lbs."The OE Yamaha manual calls for 26Ft/lbs for second round of torque on head bolts. 11 on first round.
So how is a guy to know what to do then...... I have the ADA girled hardware, and soket cap mcmaster head bolts (18-8 I believe... possibly 306)..... I followed the ada instructions.......
That depends on the material of the bolt.