Re-torquing Cylinder Head Bolts

What is your preferred method for re-torquing cylinder head bolts? There are two schools of thought here and I can't seem to settle on which is the best. Perhaps it makes no difference.

Ok, so here goes: Method 1) Simply install the socket and torque wrench on the bolt or nut that needs attention and turn clockwise until the proper torque is reached. Method 2) Same as method 1 except turn the fastener counter clockwise for an 1/8 or so turn first, then turn back clockwise until the proper torque is reached. (Remember in both methods we are re-torquing ).

Any opinions on which method would produce the most accurate bolt pre-load?

Jason

I would go for #2. I think it's more accurate.

Method 2.

Method 1 not accurate.

Debby

Boy, I didn't intend to create a dud of a thread. I thought for sure there would be some lively discussion on this one.

So, it looks like everyone is sold on the concept that break-out torque is always greater than make-up torque. Is anyone concerned about unwinding the stud/bolt in method 2?

What do you mean by unwinding the bolt, Jason?

Debby

When a bolt is torqued it tends to windup, like a torsion spring. For instance, a 3/8” diameter X 4” long bolt will windup 3-degrees with 24 ft-lbs of torque (assuming one end is fixed and 24 ft-lbs torque is applied to the other end). So, a bolt may unwind when loosening it and then try to wind back up when retightening.

Now if the friction between the bolt head and its mating surface increases when retightening, the bolt may not wind back up fully and preload may be lost.

Having said that, Norton studs are probably too short for any significant windup and their preload requirement is very forgiving. Notably +/- 25% is the advertised error for preloading fasteners using the torque method. So no harm done loosening first, and it certainly reduces errors associated high breakout torque.

Bolt preload is an interesting and often controversial subject; I was just fishing for comments.

I use flame ring head gaskets and with those, I know that the fasteners will turn before the torque figure is reached when re-tightening. In those circumstances I don't see any benefit in backing off first.

I think it's a bit different with substantial steel parts bolted together where the correct torque figure may still apply.

Commando heads don't need check-tightening after 100 miles they need pulling down

I'm more or less with 79x100, as I would attempt to tighten to the required torque figure first, if the fastener started to turn before the intended torque figure was reached, then I can't see any reason to slacken that fastener off.

Well here's my method now---retorque the first time at about 5lbs under the max on all bolts and nuts. Then adjust the wrench to the torque value you are checking and proceed again---this way you will not over torque the fasteners but still "runup" the bolts/nuts to the torque setting you have set.
The first time I torque is after the first startup on a fresh rebuild. let the engine run to op temp and shut off. Go have a few beers or go to bed and recheck the next day. Then go for a ride for a few miles--15--20 or so. Bring it home and let it cool down overnight and recheck again. Then go for another ride about 100 miles or so and yes, go through this same procedure again--this will make the 3rd pass. You will be surprised to find that the bolts/nuts will have been a wee bit loose after each session.
After this maybe recheck every few hundred miles or so. If the threads were in good condition there will be very little if zip loosening from here on untill the next time you have to take the head off. It will be good practice to recheck every once in awhile when time allows just to make sure all is well.

NOTE: USE A GOOD TORQUE WRENCH--INCH LB RATING OR 0-TO 50 LB.
FORGET THE TOOL SHACK/WALMART VARIETY
LUBE THE BOLTS BEFORE INSTALLING--DRY METAL TO METAL CONTACT WILL PRODUCE DIFFERENT TORQUE VALUES.
I like copperkote.

Joda

Joda said:

LUBE THE BOLTS BEFORE INSTALLING--DRY METAL TO METAL CONTACT WILL PRODUCE DIFFERENT TORQUE VALUES.

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The only problem there as I understand it, is that the torque values generally given for British bikes at least (*certainly for Triumphs) are the DRY VALUES.

Lubricating the threads or even using lube under the bolt heads can considerably affect torque.

* Information given in Triumph factory workshop manuals torque figure sections "TORQUE WRENCH SETTINGS (DRY)"

Indeed, lubrication has a huge effect on bolt pre-load.

It has been my experience that torque values for many motorcycles are based on dry threads/heads, unless otherwise specified.

Are we disscussing Nortons here or Triumphs?
For refences:
Norton sevice manual--no reference to lubing/not lubing that I have seen.
Haynes service manual 1982---ISBN 0 85696 125 6 ---ditto nothing I have read in it.
Clymer--1974 -- ISBN 0 89287 158-X --Nothing here as well.

By lubing I mean a small dab of copperkote paste to the first few threads of the bolt----not dipping them into a bucket of oil and installing them dripping wet. Sometimes common sence is needed when working on things mechanical in nature.

I have been lubing my head bolts for quite a long time without any problems occuring---threads pulling out etc. I have "never" had a blown headgasket. ?????? This is "MY" experience.
For the record---Those out there who are INOA members---if you have kept all your NORTON NEWS DIGESTS-- look at NN# 43 page 11.
Also, if you have a TECH DIGEST Version 3.2 September 1999, refer to page 1-5 paragraph 4. under the heading: HEAD BOLT TIPS.
I'm not sure of when I began doing this on my Nortons , perhaps around 1986, but I can remember back in 1959---60--63 --65 or there abouts when we would rebuild our Chevys, Olds, Pontiacs or what have you, we would always lube the head bolts--the practice just stuck with me in all my rebuilding since then--unless specifically instructed not to lube. Sometimes this was done. It would depend upon the situation and the objects being assembled.

If this reference is in error---then I am completely wrong, and I apologise for any agony that this may have caused anyone, and, that I have been doing something contrary to popular belief & engineering specifications.
But, if I am correct---well, let's just say some of us may have just learned how to maybe properly torque head bolts; on Nortons, not Triumphs.
Perhaps this will eliminate a lot of lost time and help reduce our dependance on foreign oil.

Joda

Joda said:

By lubing I mean a small dab of copperkote paste to the first few threads of the bolt----not dipping them into a bucket of oil and installing them dripping wet.

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I'm not sure I agree that "a small dab" would not be enough to alter the bolt torque?

Joda said:

Sometimes common sence is needed when working on things mechanical in nature.

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I couldn't agree more, and I'm sure a significant proportion of our members are also blessed with some, along with your good self.

Perhaps the next logical step in this discussion is for someone with the engineering background and capabilities to conduct an experiment. I have neither. I'm just a bike nut.--But also I like to do things right the first time and and I like to be as careful and exact as I can be---no half-way hurry-up GET-R-DONE type with things mechanical where my life is concerned.
Using two methods under supervision by an unbiased observer, lubing one bolt and not the other---torque to a specified amount-say 25 foot lbs.
Then check with accuracy the absolute torque on each. And, pray tell--what is the difference--2--3 ft lbs; 10---15 ft lbs ???
I don't concern myself nor do I loose sleep over the fact that maybe--just maybe I overtorqed the head bolts by a few lbs.
This was just my method of doing this and take it for what it's worth--correct or not correct procedure.

Joda said:

Perhaps the next logical step in this discussion is for someone with the engineering background and capabilities to conduct an experiment.

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There are quite a few torque spec. charts on the Internet already:
Example: http://www.thelenchannel.com/1torque.php

Any non-standard plating on fasteners or use of a different bolt grade then adds extra variables to the equation, if fasteners are used that may not have been manufactured to exactly the same specification as the originals then the stated torque figures would no longer be accurate.

Joda said:

Norton sevice manual--no reference to lubing/not lubing that I have seen.
Haynes service manual 1982---ISBN 0 85696 125 6 ---ditto nothing I have read in it.
Clymer--1974 -- ISBN 0 89287 158-X --Nothing here as well.

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Nevertheless, using common sense ought to dictate that we all work from a known base line? So torque figures are normally given dry, unless it says otherwise?
'Wet' (lubricated) could be interpreted in rather too many ways (unless the particular lubricant is specified), adjustment can then be made to the dry torque figures, according to the type of lubricant used if lubricant should be considered necessary for a particular application?

Incidentally, in the NOC Norton Commando engine rebuild video Mick Hemmings does mention using "a little bit of Copaslip" (like CopperKote) on the head bolts, however as he tightens down the cylinder head, he goes on to describe the tightening of the head bolts, saying "...you don't need a torque wrench, just use good spanners, and tighten them sensibly..."

Hooray for Mick. I am certainly not going to argue what he has to say about Nortons. At least we agree on the lube bit---but since my fingers may not be as experienced as his are---I will keep on using my torque wrench.
Is this country great or what. Where else can there be so many different opinions on such a topic and everyone in some way or another is correct. So many different points of view but yet--nothing has been chisled into stone tablets stating the "Thall Shalt' do it this way and this way only. I love it. This is what makes Norton Owners so interesting to talk to. There is never an end to what I learn about the care and feeding of this Motorcycle.

Joda

Joda said:

Is this country great or what.

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This website is great! But we have members here from all around the world, who all appear to share a common interest in Nortons and willingly contribute their knowledge to the forum.

This forum is great!... remember the shabby little newsletters etc that we'd anxiously wait for to get a dab of information on our various pursuits 'back in the day'?

Now, we can have international debate on the tinyest topic related to our beloved bikes. Just awesome:

I ran and rebuilt boilers in the Navy (225 years ago) and I can't remember any of the technical mandates regarding torquing of any machinery, but that work DID give me a rather educated arm. So I tend to follow the Mick Hemmings school.

Personally, I think that if you have used a particular method and have had no difficulties , such as blown head gaskets or ultra loose engine bolts, then you should continue doing what you are doing . If you are new to this type of issue, it seems that general consensus seems to lean on technique #2..... To lube or not doesn't seem to affect outcome, so long as you are consistent in your approach.

Happy Sunday

Karl

Wow--225 year ago--lets see--"1783'---I wasn't aware that Washington crossed the Delaware in a steam vessel.
Just kidding.

Dito--as long as the procedure you use works fo you---whats the difference---this is perhaps one of the reasons some bikes run great most of the time and others do not---just the way some race bikes run faster than others and some DNF. If everyone did the same thing the same way all the time there would no progress. Sounds familier to what happened to these bikes back in the 60's---70's.

And I stand corrected---"Is this Forum great or what".

Joda