EdGasket

Can anyone explain in layman's terms why it is OK to only do a valve adjustment locknut up to only 13 ft-lb while the pulley nut is some stupidly high torque and many non-moving suspension nuts are also done up to a high torque value?

I'm genuinely surprised that with all the movement and vibration, the valve locknuts stay put with minimal torque whereas a non-moving part like suspension strut to hub, has to be torqued to 70 ft-lb or so. Even the sump plug on a Honda is torqued over twice the value of the valve adjusters and yet it is non-moving?? How do they work out what torque should be used?

GolNat

iTrader: (7)

Pulley nut is larger. Torque specs are related to size of the fastner which is related to shear and tension amounts. The grade also plays a role in determining that. If my memory from stress analysis class serves me well.

Suspension hardware is larger compared to other hardware used on the car.

Proper torque specs, lock nuts, lock washers and Loctite keep things from backing out

Helpful Chart:

ezone

Because they are tiny, and that's what the engineers decided is correct.

Got any idea what happens when you overtighten a fastener?


"Too loose is too loose, and too tight can be too loose too."

xRiCeBoYx

iTrader: (22)

Having had quality assurance training in the Navy (aircraft carrier nuclear power plant work), I can support these two guys in their statements. We dealt heavily with threaded fasteners, particularly torque and thread engagement. Threads on a fastener act as a pre-existing flaw in the metal surface, which gives the metal allowance to stretch and ultimately fail (shearing of the bolt). The cross section of a piece of metal the diameter of the valve adjustment screw requires less than that of the crank pulley to fail (shear). Now, throw in the aforementioned "pre-existing flaw" bit, and that piece of metal requires even less force.

If you try an apply 181 ft-lbs of torque on the valve adjustment bolts, I guarantee it'll shear off well before you get to your end goal.

EdGasket

Thanks for the replies. Just seems to me that a moving part like the valve pushrod ought to need more torque to prevent the nut rattling loose. A friend had one come loose once on an overhead valve car; made a dreadful racket but no damage. I dread to think what it would have done to an overhead cam engine though. Also with those valve adjuster nuts you are generally guessing the torque anyway because you have to hold the screw in position so can only use a ring spanner on the nut and have to guestimate the 13 ft-lb or so.

mikey1

13 ft-lb is basically finger tight and then a little snug with a wrench,

i would never need a torque wrench or use one on a bolt/nut requiring less the 30 ft-lbs, i know by feel,

however i don't know your experience or capabilities, anything over 30 ft-lbs is when i dust the cob webs off the torque wrench and use it,

moving part or not does not matter,

generally speaking the larger the bolt/nut is, the more torque that is required,

the material the bolt/nut is made of also comes into play,

when you are torquing a bolt you are actually stretching the bolt/head

xRiCeBoYx

iTrader: (22)

I do. Perhaps it's the incessant training that was beat into my head. I have 2 torque wrenches that I use, one rated at 150 ft-lbs, the other that reads to something like 250 in-lbs. It's a simple conversion for ft-lbs to in-lbs, and I'd rather be safe than sorry. I've sheared far too many bolts and have seen far too many bolts wiggle themselves loose due to improper torque specs.

mikey1

i have never had either of these issues, so it depends on experience i guess

xRiCeBoYx

iTrader: (22)

Shearing bolts hasn't been too much of an issue with smaller bolts, but stripping out the head has been. My original -a2 head probably has 2-3 stripped exhaust manifold mounting holes. Also, I thought I had torqued my TDC sensor on adequately since I couldn't fit my torque wrench down there, but I was wrong. Thing wiggled loose and ate my timing belt. That wasn't a fun experience.

mikey1

did you leave it too loose?

or did you strip it?

that bolt only needs to be finger tight, then a little snug with a wrench, that's all i do

xRiCeBoYx

iTrader: (22)

I took a wrench to it to make it nice and snug. Thing still managed to wiggle loose and frustrate the hell out of me.

EdGasket

RiceBoy - so do you torque the valve adjuster locknuts then? How can you do that with a screwdriver holding the adjuster? - or do you nip it up with spanner and use the torque wrench on the final tightening without holding the adjuster and check it all once torqued?

In answer to previous question, I do have good experience and can roughly gauge how tight to do a bolt depending on its size but am extremely wary of aluminium heads; plus the length of handle on the spanner/socket can make a huge difference to the 'feel' so if I can use a torque wrench, I will in preference to guessing by feel.

I wonder if the torque on the valve locknuts appears low because the threads will be drenched in oil? I understand oiled threads should be done up to a lower torque than dry threads for the same overall tightness if you get my meaning.

mikey1

yes i believe this is true

xRiCeBoYx

iTrader: (22)

I do torque the valve adjuster nuts. I use a crows foot on my torque wrench so I can still hold the adjusting screw with a screwdriver

EdGasket

With a crow's foot, do you have to multiply/divide the torque by some factor because you are now on the side and not directly on the nut?

mikey1

i wouldn't think a torque wrench would be accurate using a crows foot

EdGasket

That was my thinking; you can't just slap a torque wrench on a crows foot and expect it to apply the same torque as it would on a socket. An adjustment factor is required, see here:

https://www.engineersedge.com/manufa...e_wrench_1.htm

ezone

DNRTFA.

IF you set the crowsfoot perpendicular to the wrench so there is no added length, the effective torque value will remain the same at 100%. (Don't nit pick over decimals on this.)

IF you set the crowsfoot sticking straight out (or in) so the effective length of the wrench is longer (or shorter) then you must calculate to compensate for the new length of the lever (torque wrench).

OTOH a crowsfoot is really short so there won't be a whole lot of change.

GolNat

iTrader: (7)

Precisely.

Yes it will change slightly, but it is not going to make that big of a difference. So if you have a precision (decimal) torque wrench with a calibration certificate then calculate away.

sdaidoji

iTrader: (1)

remember, the camshaft for example spins. the valve adjustment does not.

among other things. Ask a mechanical engineer. (I am one :P)

feel free to over torque. not my problem Some will survive, some will do this:

xRiCeBoYx

iTrader: (22)

Alright, so the engineer in me nerded out something fierce and I did the maths. Had a whole response typed out, decided against posting it.

Cliff's notes of my maths: Assuming the crows foot adds 1" to the torque wrench (set straight out) and indicating 14 ft-lbs, you'd be applying just over 15 ft-lbs to the nut. Not dangerously overtorqued. If you set it to 13ft-lbs, you'd be applying just over 14ft-lbs.

Technically speaking, if you set the crows foot perpendicularly, you would be adding a bit of length, albeit almost negligible (assuming a 12" torque wrench and the crows foot is 1", the difference in length would be .04", and the increase in torque applied would be .6ft-lbs, but that's me being nit-picky at the moment).

TL;DR: crows foot causes negligible difference in torque applied, regardless of positioning on the wrench.

EdGasket

jeez I didn't realise those valve adjuster nuts could turn into bolts by overtorquing! (sorry couldn't resist)

mikey1

just like i said, its not accurate

xRiCeBoYx

iTrader: (22)

But with maths, it can be

sdaidoji

iTrader: (1)

Lol, good one

EdGasket

The sump plug torque specified for a steel sump is 32 ft-lb. However it does not specify if this is for dry or lubricated threads. As there are only about 4 or 5 threads in the typical pressed-steel Honda sump, I feel 32 ft-lb is too high for an oil change spec. I think the 32 ft-lb may come from the Honda spec for assembly in plant with dry threads and has just been copied to service manuals like Haynes.

After getting my daughter a Civic, I found the sump drain plug threads knackered but the sump threads took a new plug OK though I only tightened to 25 ft-lb with a bit of lock n' seal for good measure. 32ft-lb just seems too much for so few threads.

Any comments (apart from 'just snug it up' - I'm just not confident with that)?

mikey1

are you talking about the oil pan drain plug?

ezone

If one is using the correct spec aluminum drainplug sealing washer, it requires about 30 ft-lb to attain the "crush" necessary for it to seal as intended.
I can feel it crush as I pull on the wrench, but I know some people have absolutely no sense for these things.


Practical application:
I know both the pans and drainplug threads can last for lifetime of oil changes when done properly....but the engineers didn't leave hardly any room for error.
I know it all can be ruined either slowly or quickly by overtightening.

If you use a plug gasket that incorporates a rubber seal (or drainplug with an O ring seal), you don't need to get it very tight at all to make a good seal. Just gotta be tight enough to not fall out while driving.

I love this style of drainplug washers:





If I could find these in the right size for about 25 cents each I think we would keep some on hand at work:

mikey1

i normally use nylon washers/gasket on the drain plug,

i dont use a torque wrench, never have,

i just tighten it to crush the nylon a bit so it doesn't leak,

when i remove the plug it doesn't take much effort with a wrench,

if i had to estimate the torque that i use on my drain plug i would say 15 pounds 20 max,

i think you are over thinking this,

as ezone said, as long as it seals and doesn't fall out you are fine, anything done up slightly more then hand tight aint gonna fall out IMO

i think beginners (not saying you are) tend to over tighten drain plugs

ezone

Picture the JizzyLube kids who are constantly screamed at for leaving drain plugs loose and you should be able to picure how they get so badly and consistently overtightened.