Torqueing Lubricated Head Bolts with a dry spec.

[Stealthee]

Originally Posted by ducked

"Note here that tire pressures shown in your (car) owners manual are the minimum values, not the optimum. The manufacturers provide these values based on what is safe in all conditions and for the average driver, and biased toward quiet and comfort. Tires may be run at any pressure you like up to the maximum given by the manufacturer."

That is inherently false. The tire pressures in your owners manual are the RECOMMENDED OPTIMAL tire pressures based on engineers data. It is not minimum. If it were minimum it would say minimum. You will not find the word minimum ANYWHERE regarding the tire pressures recommended by the manufacturer.

[ducked]

Originally Posted by Stealthee

That is inherently false. The tire pressures in your owners manual are the RECOMMENDED OPTIMAL tire pressures based on engineers data. It is not minimum. If it were minimum it would say minimum. You will not find the word minimum ANYWHERE regarding the tire pressures recommended by the manufacturer.

I dare say they are optimal for something, and based on someones data, though it could be the marketing dept.

Its suggested in that thread they may be optimal for ride comfort, rather than handling or mileage. Clearly there is no ONE optimum number for all parameters, and the suggestion there is would be “inherently false”

You are correct that I wont find the word “minimum” in my handbook, though.

This is because
(a) not really interested in manufacturers recommended tyre pressures so am unlikely to look.
(B) handbook is in Mandarin (Taiwan only car) which I dont read
C) it got soaked a few monsoons ago and the pages are stuck together.

Which is all quite liberating

[ducked]

Originally Posted by CapriRacer

Ah ..... Mmmm ........ Oh boy! Lots to unpack here!

First is that the page referenced is a discussion page just like this one. Someone is giving their opinion on something. It's stated like it's a fact, but there is no reference to anything official from a tire manufacturer or a car manufacturer.

Second, the fact is that the tire pressures in the owners manual are specifications. They are not stated as minimums or recommendations.

Third is that car manufacturers test at those pressures. They know how the vehicle behaves at those pressures. Deviate from those pressures at your own risk.

Sure, you can run tire pressures at a different value, but the car will behave differently. The smart thing would be to test the vehicle at that different pressure to assure that the vehicle behaves benignly. People don't do that because you have to destroy a set of tires in the process - what would be the point?

So back to the original question: The specs for the bolt torque specify (there's that word, again!) dry, and there's no reason not to do that. Besides, you get different values depending on what lubricant you use. The specification is there because they know it works - reliably. Do otherwise and you run a risk of failure.

And just so you know, I am a retired tire engineer. Called on Ford for a while. I am familiar with how the tire pressure thing works.

I note that, as with the “torque translation” technique (though there with one honourable exception), there is no discussion AT ALL here of the technical validity of the method. You just don’t like its provenance. The fact that it doesn’t come as an official recommendation from a car or tyre company is enough to condem it out of hand.

The poster was a consultant engineer working on suspension systems, though mostly, IIRC, for Taiwanese motorcycle companies. This of course proves nothing, one way or the other.

But lets suppose, for the sake of argument, that the procedure is completely valid. There still would be slim to no chance of it being advocated by a tyre or car company.

The method is elaborate, with the possibility of error. It requires potentially hazardous on-road testing. It would perplex your average punter and likely put them off buying from any company that advocated it. [Insult removed by Moderator as it adds no value to the thread]

Companies are constrained by many limitations and potential liabilities, including those of the people they hope to sell to.

[ducked]

Originally Posted by Blue Bowtie

Another variable in this is whether the head bolts enter cooling jackets. I'm not familiar with the CB22 engine, but if the head bolts do not enter blind holes, a thread sealant would be recommended. While not a true lubricant, it probably does provide some lubrication when torquing the fasteners. How would you calculate that?

Of course, head studs (often used in higher performance engines) would completely eliminate that variable, but since studs are frequently a fine thread, fine nuts with hardened washers would have a completely different torque requirement from coarse threaded bolts.

I would assume that if sealant is required the torque spec would allow for its presence.

If it didn't, and gave a torque spec "dry", well tut, tut, but in principle one could use the "torque translation" technique to get the angle, which should be the same whether thread sealant is present or not.

[ducked]

Originally Posted by ducked

I dare say they are optimal for something, and based on someones data, though it could be the marketing dept.

Its suggested in that thread they may be optimal for ride comfort, rather than handling or mileage. Clearly there is no ONE optimum number for all parameters, and the suggestion there is would be “inherently false”

You are correct that I wont find the word “minimum” in my handbook, though.

This is because
(a) not really interested in manufacturers recommended tyre pressures so am unlikely to look.
(B) handbook is in Mandarin (Taiwan only car) which I dont read
C) it got soaked a few monsoons ago and the pages are stuck together.

Which is all quite liberating

Ok, I confess I got curious and unstuck some pages, 1.7 kg /sq cm. Which apparently is about 24 psi. I dunno if thAts officially a minimum, because I still dont read Mandarin, but its quite a lot less than i would use unless i was stuck in sand. .I run about 36 psi.

Maybe ill do some comparisons if the car ever runs again

[CapriRacer]

I am finding this thread very fascinating. I need to study it more to fully appreciate what is going on.

In the meantime:

To the OP - ducked:

Doesn't your car have a vehicle tire placard? In the US, since 2008, it's been required on the driver's doorframe. It's trimmed in yellow. Prior to that there wasn't a required color or shape and it could be anywhere - glove box, other doorframes, trunk lid, fuel filler door, etc.

Also, what do you think is the procedure car manufacturers use to determine the tire pressure?

And lastly, you've referred to the tire pressure in the owners manual using a number of different words and I wonder which of them you think is right: Minimum, recommendation, etc.

[ducked]

Originally Posted by CapriRacer

I am finding this thread very fascinating. I need to study it more to fully appreciate what is going on.

In the meantime:

To the OP - ducked:

Doesn't your car have a vehicle tire placard? In the US, since 2008, it's been required on the driver's doorframe. It's trimmed in yellow. Prior to that there wasn't a required color or shape and it could be anywhere - glove box, other doorframes, trunk lid, fuel filler door, etc.

Also, what do you think is the procedure car manufacturers use to determine the tire pressure?

And lastly, you've referred to the tire pressure in the owners manual using a number of different words and I wonder which of them you think is right: Minimum, recommendation, etc.

No tyre pressures posted that I’ve noticed, and I probably would have noticed them unless very well hidden.


Doesn’t seem to matter anyway, since now I have the handbook figure of 1.7 kg/sq cms, which is of some interest. Its the same as that given for the rather similar G10 Charade in one source I have, and probably the same as the very similar Charade G11, (of which the Skywing was essentially a local notchback variant.) though I don’t have any documentation for that.


As to the “specified” v. “recommended”, I think it doesn’t matter either, since, if there IS such an..er...specific term as “specified” in The Language of Smoke and Mirrors (which I don’t, as I’ve said, read), and they use it, in this case I’m going to take it simply as a recommendation anyway, at least for now.


As someone already pointed out. Its my ride, and I’m not much of a “The Handbook is Holy Writ” fundamentalist.


As to what testing the manufacturer did, at that pressure, I don’t know, though I imagine you’ll be in a position to tell me, assuming Taiwanese manufacturers follow industry testing norms, or, more likely, simply adopted the specification of the very similar Charade G11.


Extensive discussion of tyre pressures would take us rather far from the much simpler original topic of cylinder head torque translation, but there doesn’t seem to be any interest in that anyway.


Three pages in and we have a suggestion that estimating the angle with “My First Trig Set”will be less accurate than estimating the torque with “My First Torque Wrench”( OK, but unlikely in my hands, with my second, but still very basic, torque wrench. ) and the suggestion that lubrication will allow the bolts to rotate back out. These are legitimate and constructive criticisms, (and suggest the poster actually may “get” what I am trying to do), though I THINK I can discount them.
If “that’s all you got”, I suppose that might be reassuring, but the repeated statement that “lubrication affects torque”, backing up “JUST DO AS YOU ARE TOLD” from everyone else, rather suggests these respondents don’t “get it”, because they havn’t thought about it, which does tend to be an effect of “JUST DO AS YOU ARE TOLD”.
Not much I can do about that.
You can flog a dead horse underwater, but you can’t make it drink.







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[CapriRacer]

ducked,

Thanks for replying and particularly for replying to all 3 of the questions I asked. Many folks wouldn't do that. Plus it is appreciated that you had expanded responses.

The problem the way I see it is a balance between what is known to work and what might work but is somewhat unexplored territory. People tend not to go in underexplored directions if a solution is available that is known to work. That's the case here.

Looking for alternatives to established procedures is fun to do. But not everyone wants to go on that journey.

[ducked]

Originally Posted by CapriRacer

ducked,

Thanks for replying and particularly for replying to all 3 of the questions I asked. Many folks wouldn't do that. Plus it is appreciated that you had expanded responses.

The problem the way I see it is a balance between what is known to work and what might work but is somewhat unexplored territory. People tend not to go in underexplored directions if a solution is available that is known to work. That's the case here.

Looking for alternatives to established procedures is fun to do. But not everyone wants to go on that journey.

Thanks, and fair enough.

Re “Established procedures that are known to work” there ARE obvious downsides to dry torquing, and these seem likely to get worse with repetition and age, though this will be of limited concern to manufacturers.

If its taken as a general spec (as it often is) and applied to things like lug nuts, where corrosion is likely, badness happens. Ive never used a torque wrench on a lug nut or put one on dry, but I have had to deal with it on used cars I bought, and it was no kind of fun.

Anyway, aluslip is on the head bolt threads so the dice are rolled and that dilemma is done

My current one is the crankshaft pulley bolt. As well as being less confident of the wisdom of lubricating that, I dont have a spec for it.

CB20 engine is 37-43 ft lbs
CB23 engine is 65-72 ft lbs, so there was a sizable change between the two

This is a CB22 in an-almost-but-not-quite Charade G11. “Splitting the difference” doesnt seem very defensible, but may be the best I can do.

[ducked]

Since the average tightening angle corresponding to 40 ft-lbs dry was 220 degrees (see graph up above…er…somewhere) I tightened the head bolts (with the threads lubricated with Permatex Aluminium antiseize) in 4 X 55 degree increments, recording the torque reached.


The first 2 torques, at 55 and 110 degrees, are “nominal”, since the wrench is almost unreadable at these low values. Not very precise at the higher values either, but I think some of that scatter is real.


Unsurprisingly, torque values reached lubricated are less than the dry specification.


forumosauploads-12829.kxcdn.com/original/3X/3/4/34...g

[RidingOnRailz]

Originally Posted by ducked

Since the average tightening angle corresponding to 40 ft-lbs dry was 220 degrees (see graph up above…er…somewhere) I tightened the head bolts (with the threads lubricated with Permatex Aluminium antiseize) in 4 X 55 degree increments, recording the torque reached.


The first 2 torques, at 55 and 110 degrees, are “nominal”, since the wrench is almost unreadable at these low values. Not very precise at the higher values either, but I think some of that scatter is real.


Unsurprisingly, torque values reached lubricated are less than the dry specification.


forumosauploads-12829.kxcdn.com/original/3X/3/4/34...g

You had to do all that experimentation after three... four?.. others on here told you it wasn't necessary?

[ducked]

Originally Posted by RidingOnRailz

You had to do all that experimentation after three... four?.. others on here told you it wasn't necessary?

Evidently. Looking at the graph again, there seems to be a systematic increase in torque across the tightening sequence, IOW from the centre of the head to the outside. I suppose this may reflext a “bowing” of the head, and may not be a good sign.

If the head gasket pops it wont necessarily invalidate this method, but it wont give me much confidence in it.

And vice versa, of course

[ducked]

If with a constant bolt tension across the head, you get more torque at the ends, as it seerms above, this seems to imply that a constant torque across the head wont give you a constant bolt tension, (and this may not be what you need, as I ve been assuming)

If ive got this the right way round, you”ll get, and may need, more tension in the middle.

Tricky

[ducked]

Actually, when I plot the final torques (at 220 degrees with aluslip) there is a suggestion that the first central diagonal pair of bolts tightened (front left to back right) may take the tension off for the next pair (front right to back left) and so reduce its torque, but beyond that there isn’t a clear pattern, so I’m not going to worry about it for now.


forumosauploads-12829.kxcdn.com/original/3X/c/4/c4...g


I just lost the timing belt tensioner spring, so I'll worry about that instead.

[buick8791]

An questions(maybe an wrong issue on this thread, sorry) regarding WD-40 used to the rubber parts in the car, for instance the brake caliber rubber o-rings related to the caliber sliding parts:

Is that stuff swelling the rubber parts some how?

BR,

buick8791