Engine: Torque and torque wrenches

[BShaw]

In reading a recent thread about what can heppen if the crank bolt isn't properly torqued i decided to double check the torque on mine, as well as the crank fan drive pully.

I also became a little concerned because the crank fan drive pullys wobble ever so slightly when the car is running. I don't know what the actual runout is but it is visible although I have experienced no vibration associated with that. Thoughts?

Anyway, back to torque... Book says the crank fan drive pully is to be torqued 15-17 f.p. (180-204 i.p.). i used my inch pound wrench at what I believe is 192 and was careful to alternate nuts as I would putting on a wheel. It seems to me that that is not much torque as it is still pretty easy to tighten/loosen the nuts. Should I locktite these?

I have ordered a new crank nut lock plate as mine has been "massaged" so many times I am also worrying whether it is ineffective. Then, I don't know if I can trust my big f.p. torque wrench's accuracy.

Of course, maybe my Harbor Freight torque wrenches are crap. Well, I expect them to be less than professional quality but should a feller not skimp when it comes to a torque wrench? What brand and style are you using that you have confidence in? Digital? Twist to set? Original pointer style?

[jclary]

Here again, I find myself commenting on something I am under-qualified. Also hypocritical...'cause I used to sell some awfully expensive torque tools. Back then, I preached to my customers the value of precise accuracy and repeatability. I sold major brands of hand tools and even computer controlled torque systems (costing thousands) capable of providing printable documentation.

However, what I use at home is an old craftsman deflection bar torque wrench calibrated in ft. Lbs. I have a couple of adjustable micrometer type "clicker" torque wrenches...but just feel more comfortable with the old dumb technology. Old habits die hard.

[Mike Van Veghten]

As John says...

While I do use my Sears, 1/2" click wrench, every so often, I double check it with my well cared for beam wrench (though it COULD be off too!).
I only have a beam type 3/8" drive.

Since I work in the Space part of the AeroSpace industry, we have to be very cautious of over OR under thightening things.
Add to that, when you use any type of lock nut...you need to know the torque to overcome the locking torque value.
We use a "torque checker" tool before all flight torque applications. While the wrench is calibrated at +/- 4%, the checkers are calibrated at +/-1%.
A place I used to work...the checker was calibrated at 1/10 of 1%

THEN....there's the lubricant...dry, engine oil, moly base lube, anti-seize compound, etc., etc. They all change the "pounds of "load" per a given "torque" value.

Veritable bag of snakes when you get right down to it.

Mike

[jclary]

Exactly, Mike, and what a slippery slope it becomes. We sold torque calibrators that were "certified." Then, ...ever so often...the torque testers have to be shipped back tor "testing" and re-certifying.

Thank goodness our little Studes are a bit more forgiving. If they weren't... none would have survived the "bubba" torque (one more jerk on the wrench!) that most have been subjected to over the years.

[studegary]

I still use my old Snap On with a dial on it.

[tbirdtbird]

there is nothing wrong with a beam type torque wrench. The click type depends on a spring inside and that spring can age. And the click type should be stored with the setting backed way off to take the pressure off the spring

[doug]

In aviation all our torque wrenches and ohm meters have to be checked for calibration once a year to be legal to use. Don't know if they were ever off or needed adjustment, but needed a sticker.

[Dan Timberlake]

While torque is the best tightening measurement most of us are going to be able to make, like Mike VV said, the resulting clamping force (which is what really holds the joint together and protects the fastener from atigue loading) can vary a lot. On some engineering forums discussions about fasteners and tightening generally start off with some folks saying torque is useless because the achieved clamping can vary 25% or more. I think most designers understand this, and choose fasteners and specifiy torque that will achieve more clamping than is needed, rather than try to hit a bullseye painted on a chimera.

ARP the premium automotive fastener maker publishes some stuff about nut/bolt/screw tightening.

http://arp-bolts.com/images/techimages/PreloadGraph.gif

http://arp-bolts.com/pages/technical_installation.shtml

I think it's interesting that putting an oiled non-torque-to-yield fastener thru a half dozen torque cycles can smooth the sliding surfaces (that must be hard enough and big enough to prevent embedment) so much that it will clamp harder than a fastener lubed with moly lubed fastener assembled once.
And, that by the 10th torque cycle they all clamp about the same, and 30 or 40% harder than a new oiled fastener's first time.

[jclary]

How 'bout this, Bob Shaw

and all you want to do is tighten your fan

Do you think that way back in 1959...young teen-age Billy Bob Somebody, working at the local corner service station, would have been so detailed in replacing a failed water pump on your car? Unless I'm mistaken, those bolts have lock washers to help keep them in place as well as the clamping force of torque. Use some common sense, get them tight, and either the pointer on a beam type wrench or a click, should confirm they are tight enough. If you get that accomplished and the hood closed with no skinned knuckles...go for a ride with pride.

[hausdok]

I think the HFT wrenches are fine. If HFT had existed 40 years ago, I doubt the quality would be where it is now but there have been huge improvements made in machine tool tech over the past 40 years and the Chinese seem to be keeping pace - definitely not like the Chinese-made tools you'd buy in the 60's where they'd bend or break if you looked at them the wrong way.

I picked up one each of the 1/2-inch 3/8-inch and 1/4-inch HFT click-type wrenches for less than $10 each on sale and am very happy with them. They are machined to about the same quality as the wrenches I used to buy off the Snap On or Mack trucks 40 years ago and are probably as good or better than the torque wrenches used in the common shop back in Stude days. I dinked around unscientifically testing the 1/2-inch model using my old beam-type Craftsman t.w.. I set the HFT to 80 psi and clamped it in a vice. Then I put a square socket on the Craftsman and applied force to the HFT wrench. At 80 psi I had to concentrate to keep my hand balanced and the beam steady but there was a resounding "click" at right about 79 psi on my old beam wrench. Close enough for gov'mint work.

[52 Ragtop]

If you have a "click" type, be sure to reset the setting back to zero before putting it away. In other words, don't leave it set to 45 ft lbs that you last used.

Jim

[jimmijim8]

While on the subject. I have and don't need any longer a SNAP- On torque wrench. "Torqometer" 175 ft. lbs 1/2 inch drive that has the gauge/meter. It is able to torque in both directions. It is in as new condition with case and owners manual with certification papers. It is not an obsolete piece but a current offering by Snap On. I00.00 with free shipping. This would suffice for the type of person that has to have high end tools. cheers jimmijim

[gordr]

For most of us, the crucial feature of a torque wrench is not so much absolute accuracy as it is repeatability. Your 289 probably won't care if its head bolts are torqued at 69 ft-lbs, rather than 72 ft-lbs, but it would like to see all its head bolts set at the torque chosen.

I'd have to think the click type is inherently more repeatable than a dial type, because the click occurs as the fastener is still turning, and the torque passes the set point point. If you are watching a dial, it would be easy to slack up a bit on the force as you approach the target value, have the fastener stop moving, and then not move again as you apply a little more force to get the desired dial reading, because of the fact that static friction between two parts usually exceeds moving friction.

[sweetolbob]

While on the subject. I have and don't need any longer a SNAP- On torque wrench. "Torqometer" 175 ft. lbs 1/2 inch drive that has the gauge/meter. It is able to torque in both directions. It is in as new condition with case and owners manual with certification papers. It is not an obsolete piece but a current offering by Snap On. I00.00 with free shipping. This would suffice for the type of person that has to have high end tools. cheers jimmijim

JJ Pm sent, Bob

[BShaw]

I also became a little concerned because the crank fan drive pullys wobble ever so slightly when the car is running. I don't know what the actual runout is but it is visible although I have experienced no vibration associated with that. Thoughts?

Thanks for the comments and suggestions. Any further thoughts on the above?

BTW, this thread is very first time I have heard that one must return a click-type torque wrench to zero after use. Mine have set at various settings for the years I've owned them. So, I am definitely going to buy new ones (and recheck all my intake and head bolts!)