head bolt retorque.

[Paul Sutton]

But........

.............Anti-seize on the threads means lubricated so if we go for 27ftlb we are effectively up at 36ftlb dry. Is the correct approach then to clean the threads and nuts of all lubricant and revert to 27ftlb?

 

[MaxPete]

Probably - and then see if it leaks (it likely will not).

P

 

[gggGary]

Yes per the SB in the first post (revised) Yamaha called for 27 with lube. Later Yamaha upped the torque spec without saying with or without lube, generally most around here lube or anti seize and go to about 30 lb. your 27 should be fine.

 

[5twins]

I'd say no. I thought we pretty much came to the conclusion here that the head bolt torque values Yamaha stated are for use on lubed fasteners. Just because every single manual doesn't mention it doesn't mean it wasn't still the norm. The factory shop manuals were written for the trained Yamaha mechanics. Every little detail wasn't always spelled out. They were expected to know a lot of that basic stuff and common Yamaha practices. It wouldn't surprise me if lubed head bolts were the norm on all Yamaha models. I'll bet it was just something the trained Yamaha mechanic was supposed to know.

Besides the M6 torque values I mentioned, head bolt values are another I've been reconsidering, especially since my head gasket has gone bad on me. I tried to cure it by upping the torque on the 8 big acorns to 32, then 35, but it did no good. And let me tell you, going all the way up to 35 wasn't easy. The studs didn't like that, lol. It felt like they were about ready to give out. 28 to 30 on lubed fasteners is probably all I'll use from now on. I still think the original 25 or 26 lb. spec was a little light.

 

[gggGary]

No need to apologize.This is the wild internet, and information flys around from many sources. Some of that information may be false.

The 10 mm head nuts had different specs at different years. Yamaha specd them as low as 22 to 25 ft-lbs. in early years. In later years such as 1978 and into the 1980's, the Yamaha Service Manual lists 27 ft-lbs.

The general concurrance is that 30 ft-lbs is more than enough to get the job done, and is a safe amount to not over stress the studs.

I used 30 ft-lbs on my top-end re-build about 7 years ago. One a year I check that they are still at 30 ft-lbs. My engine continues to run very well, and I have no oil leakage from the engine.

I thought this was about the settled numbers?

 

[kiwi]

I always but some oil on the threads, but that is me, others may differ. I was an engine rebuilder for a GM dealership back in the 70s, and it was normal practice to oil the threads, wouldn't have considered any other way. The guy that worked in the engine bay with me, an old Italian, used his trusty CP air impact gun on everything. Never saw him use a torque wrench, don't think he new how to use one, and he was still there when I left, knocking engines out. Crazy. And I reckon he never lubed his threads, took time, and time was money.

 

[Paul Sutton]

I am getting the impression from various other sites that lubricating head studs is the norm. Not being a mechanic I lack the experience of what is normal. This weekend I will retorque and stick to 27ftlb as I have not been experiencing any oil leakage.

Thank you for the voices of experience above.

 

[gggGary]

This might be relevant here. I have no relation to anything discussed in the video. I have two older beam style torque wrenches that I seldom use other than on the 4 outer cylinder head studs. Here's hoping the embed code works, From the EAA.
<iframe src='//players.brightcove.net/627008079/BJWJu665Qb_default/index.html?videoId=5724068600001' allowfullscreen frameborder=0></iframe>
if that didn't work try this. http://www.eaavideo.org/detail/vide...VNGhNRkUxY1hEMFVEdEdyXC9veHlFQnh3ZFVmZU9BaCJ9

 

[5twins]

The part about extenders was interesting, the fact that you don't need to recalculate torque value if the extender is at 90° to the wrench. I never knew that. Might be able to make one up to get at that rear M6 bolt now. A torque wrench won't fit in there once the top cover and breather housing are installed.

 

[Jim]

The part about extenders was interesting, the fact that you don't need to recalculate torque value if the extender is at 90° to the wrench. I never knew that. Might be able to make one up to get at that rear M6 bolt now. A torque wrench won't fit in there once the top cover and breather housing are installed.

90 deg. is a rule of thumb. The trick is to not change the distance from the center of the handle to the center of the fastener being torqued. The longer the extension, the bigger the angle...

 

[Jim]

I just happen to have a copy of AC43.13 right here on my bench
Here's the formula for extensions...

 

[Noidea]

View attachment 62867

Remember this little guy, it's a pain to get to, often isn't even hand tight, it is the only fastener for a long thin section of the head gasket. It's 6mm, use ONLY 7 foot pounds, that's just snug on a short 1/4" ratchet handle, go super man here and you'll break it or strip out the head!

Know this was a while back but just wondering what does this bolt do exactly considering the torque spec is so low. Does it just hold things together? Or does it apply some type of pressure to gaskets. I ask cause this bolt is broken on mine. itll tighten but not all the way cause part of the end bolt is broken.Would those 7 pounds create an oil leak?

 

[5twins]

It does apply some torque to the rear center edge of the head gasket. Yes, I suppose a leak is possible if yours is actually broken. Most are found quite loose because they're so difficult to access and re-tighten. Leaks there aren't too common, even with a loose bolt, but a loose bolt is still applying some pressure. You may have none with a broken bolt. If you can get yours to tighten up at least a little bit, you may be OK.

 

[gggGary]

An early head but the bolt in question is bottom center. it's the only thing clamping a kinda long thin section of head gasket. Try a slightly longer bolt? The threaded section that receives that bolt goes through to the cam chain tensioner opening.

 

[xjwmx]

I've never heard that length of the adapter matters if it's on at 90 degrees. In fact going by that formula E becomes 0, and the important thing L doesn't change no matter how long the adapter is.

 

[Jim]

I ask cause this bolt is broken on mine.

Define "broken." Bolt threads stripped? Hole threads stripped? Or bolt literally broke in two?

 

[5twins]

E won't remain zero if the extension is long. Look at Jim's drawing in the post above the one with the formula pic. The only way to keep it so would be to align the end of the extension with the arc he drew.

 

[xjwmx]

E becomes 0 the minute it goes on at 90 degrees. Also, there is no correction factor that I've heard of if it's 90, even though it will not be exactly in the arc. And they'd be made to approximate the arc, instead of 90. In fact I think I've read at garagejournal that you can add extensions to the adapter, no problemo. Some of them are lunatics there, but not all

 

[xjwmx]

Also if you put the adapter in the arc, it looks to me like E goes negative.

This is the kind of thing 2M likes to work on...

 

[Jim]

Applied force times distance equals resultant force. Change the distance and the resultant force changes. Stay on the arc and distance doesn't change.....
It's pretty basic math actually.