Torque Wrench Notes

[VT]

intkmnfldfld03cv6.jpg (311.18 KiB) Viewed 839 times

I snapped the ratchet in my (cheap) and trusty (but short life) Craftsman 20-70 ft. lbs torque wrench. They repair them for $45.00, but it takes 4 to 6 weeks, so I bought a new one on sale for $60. They still might be, it's the #44594
http://www.sears.com/shc/s/p_10153_1260" onclick="window.open(this.href);return false; ... e+Wrenches
I read over the Important Suggestions section of the directions and they say:

1. Threads on nuts and bolts should be clean and smooth. A lubricant applied to the threads and under the heads of the bolts will produce more accurate and consistent results.

2. Never torque a fastener that is already tightened. Loosen it first with a breaker bar, then re-torque to desired specs.

3. Torque cylinder heads in a criss-cross pattern, first to 60-70% of desired torque. If your torquing heads to 65 ft. lbs., then that's 40 ft. lbs. for the first pull, then a final torque of 65 ft. lbs..

[Cotten]

Life is much easier with a dime-store torsion wrench.

But the chrome ain't as good.

...Cotten

[Panacea]

VT, is that the angle you tourqed at? I always stick to 90 degrees but I'm sure there are formulas for other angles, I actually try to keep the distance from the bolt head to the center of the handle the same with an addapter as without....Mike

[VT]

Life is much easier with a dime-store torsion wrench.

Yes. The craftsman tools are the way to go if you don't use one everyday. I thought I didn't get much wear out of my 20-70 ft. lb. one, certainly not the 5,000 pulls they require for the first re-calibration maintenance schedule, but I put extra abuse on it pulling head bolts to 40, 50 and 65 lbs. Probably it's better to pull to 40 lbs, then 65 lbs. I used a thin film of Tri-flow on the threads, then dusted with graphite powder.

Stett pulls his head bolts to 70 ft. lbs. He said 65 is okay too. For Pan heads with those webbed inserts, I'm sticking with 65 ft. lbs.

is that the angle you torqued at? I always stick to 90 degrees but I'm sure there are formulas for other angles,

You mean what's the torque formula when using an extension "foot"? Actually there isn't one for the position you see above.
"This is because the foot is at 90 degrees to the head of the torque wrench".
A government engineer called us in 2000, to say he used the book and the torque extension (no-formula necessary) description in Vol. 1 to a class he was lecturing. I had made a mistake in one photo caption in the book (Page 268), where I incorrectly stated ".....90 degrees to the head of the bolt".
You know, thankfully, there's somebody out there that's going take the time to let you right away when you print a mistake. You can always print a correction. But, other than the one wrong word, the fact that you don't need to calculate for the foot in this situation still stands.
••••••••••••••••••••••••••••••••••••••••••••••••••••••••
The Craftsman Microtork® book reads:
"Regular socket extensions (foot in this case), which extend directly under the drive head along the axis of rotation of the ratchet do not affect the calibration of the torque wrench".
I think we say the same thing in our explanation.

[Cotten]

Let me make myself clearer:
Toss that silly clicker in your metric drawer and get a common cheapo torsion wrench.
Life will be simpler.

....Cotten

[VT]

I dunno...that's a big swing scale of foot lbs. You need to have a non-parallax view (looking directly down at the needle, not off to the side) of the scale when your working. Longer handle to deal with too. I have one but, it's not as easy to use, with the foot, on the inside V bolts.
Some people like them, some people like to wait for the click. It's good to have all options revealed though.

[cory]

Here's my 2 cents I picked up from my Dad. Clickers are easier and more fool proof then a torsion style for the simple fact that you sometimes can't get yourself right over the dial to maintain accuracy. (he's a retired heavy duty diesel mechanic)
And that a clicker type may be out a little, but at the very least all fasteners will be torqued the same amount which is more important.
Happy Fathers day to all the Dad's out there![/i]

[Cotten]

Please consider:

A "clicker" uses a spring that lets a cam snap when a pre-set force is reached.
A torsion wrench constantly applies the force indicated.

My background includes R&D, where readings actually had to not only be laboratory precise, they had to be reproduceable.
For a fastener design to produce exactly the same stress and preload every time, specified force must finally be applied constantly while the fastener creeps to a stop. The slower the creep, the more precisely the force is applied.

So yes, torsion wrenches aren't foolproof; They require patience.
Clickers were invented for mindless production work, rapid maintenance, and Christmas gifts.

But in fairness,.. for our motors, accuracy is secondary to even-ness among the fasteners. That depends entirely upon being able to get an extention on the damn things, especially for that re-torque in the chassis. A dual drive, both up and down, makes a $10 torsion worth more than a $150 clicker, or much more if you consider the flat-rate for avoided chassis R&R.

And it doesn't take acrobatics to read a torsion scale. Good ones are graduated on two faces. Mark it on the back with a felt tip pen if you must!


...Cotten

[VT]

For knuckle and pans you almost for sure need an extension foot. The two bolts (one one each head) that are in the middle of the "V" on both cylinders are "caved" (shown in the pic at the top). That's where you might have a problem with a torsion torque wrench. You have limited swing clearance in those V-areas. You can make one short pull in there, then the foot barely fits in there to be re-positioned. (I said on one post that you had to move to the right side of the machine, but that's not true. You can just barely re-position the foot from the left side of the bike.) Anyway, without the ratchet head on a torsion wench, you have that fixed square lug. If the fixed square lug won't meet with the fixed square hole in the foot. You're not going to be able to use a torsion wrench on the "V" area bolts.
The click-wrenches I use are 3/8 drive. Smaller bulk than a 1/2" drive torsion torque wrench. The handle on a 20-70 ft. lbs. click-wrench is shorter. If I were to use a larger, longer and 1/2" drive click wrench that goes up to 250 ft. lbs. the handle is too long to feel any control.

[Cotten]

What you 'need' is a little ingenuity.

....Cotten

[VT]

Wow! Any extension formulas needed with those guys?
I can appreciate the work and ingenuity in making the adapters, but the click-wrenches are only 60 bucks, if you buy them before the Father's day bru-ha is over.
http://www.sears.com/shc/s/p_10153_1260 ... e+Wrenches
Give pop a click-wrench instead of a (noose) neck tie.

[Cotten]

Formula is the same:
An angle drawn from your hand to the drive head to the fastener should be as close to a right angle as possible.
The extention can snake any way it wants in between.

An acute angle divides the force, and an obtuse angle multiplies it.

Long extentions and sloppy adapters introduce some torsion error, but it is insignificant compared to not being able to control the fastener stress at all.

....Cotten

[Pantony]

VT, I don't know where you learned that the click type is the better option. for one you can't "see" bolt stretch with one where you can watch that happen with a torson wrench. When I go into the gauge lab at work there are no click types anywhere. How do you know they repeat? You don't, just as Cotten said they are made for "mindless production work, rapid maintenance, and Christmas gifts" And I might add for those who don't know a lot about fasteners and what happens at there limits. When on the Indy Car team I never once saw a click type wrench. And as far as (VT Wrote)"I dunno...that's a big swing scale of foot lbs. You need to have a non-parallax view (looking directly down at the needle, not off to the side) of the scale when your working. Longer handle to deal with too. And you write books with advice in them? I never had ANYTHING I was working on, autos, motorcycles, World War 2 and vintage aircraft or any raciing car; Funny cars, Indy Cars, long distance Lemans Prototypes, that I couldn't read the scale!
Cotten I scribe a second scale on the bottom and braze a second needle for the bottom scale.

[Cotten]

Here's one of my favorite torsion wrenches, although its a little big for carburetors: 1/2" drive on backside; pool-cue "cheater" inserts into handle.

Found in dumpster (FID).

....Cotten

[Pantony]

Ya I like those the best Cotten; noticed "Caterpilliar Calibrated 1976" I spent a lot of time in East Peoria, (East Pee-onia we used to call it) installing machines.