Head Stretch Bolts

[roger]

Can anyone tell me torque settings for new stretch bolts for RV8 without using angles ?
Thanks
roger

[russell_ram]

Nope, thats why they're stretch bolts. You 'stretch' them a known ammount (just enough to take the bolt into yield) by using angle (given the pitch etc of the thread) ensuring that they are all equally tensioned. This eliminates all the things that mess up a conventional torque measurement eg varying friction in the threads and under the head, thread damage etc etc.

Correct procedure is 20Nm (snug seating torque) + 90 deg + 90 deg. What's the problem with doing that?

If you really don't want to do that, then you could just use the torques for the 'old normal' type bolts but you'll get inferior clamp pressure distribution and much lower ultimate clamp load.

Do not under any circumstances use torque + angle with tin gaskets.

Russ

[roger]

Hi Russ
When tightening bolts after torqeuing do you just turn wrench through 90 deg followed by another 90 deg, doing each bolt one stage at a time in the correct order ?
roger

[russell_ram]

Yes, that's correct. It's easier also if, after initial torque down to 20Nm, you put a paint mark line on the head of each bolt all lined up along (or across) the engine. Then when you start to go round and do the first round of +90s you can see which you've done and which not. Second time round you'll then have all the lines lined up along the engine again. Easy peasy.

Russ

[roger]

Thanks (again) Russ
roger