Torque wrench recommendation

[Boffin]

here comes the kicker, and the test question for the day:

when you torque to manufacturers specification, does it mean wet or dry bolt tread? can the bolt head or crush washer has oil on it? friction makes a difference!

 

You hit the nail on the head: yes, no, maybe, new or old gasket, depends on whether you have any idea what is recommended for THAT bolt, and even if you knew, do you have any idea how dry your bolt is????

(And all those issues are a good reason to be very afraid when you are supposed to use the BMW angle-torque method.)

If you use a beam/torsion torque wrench, you can feel what you are doing much better than with a clicker.

 

Ben

 

Those are the reasons why using the angle-torque method is stipulated, as it removes friction from the equation - the angle turned over a known spiral ramp (the threads) stretches the material by a known amount, giving a known clamping force due to the known elsticity of the material of the bolt or stud. Reasons to feel secure, not afraid.

 

[Joe Frickin' Friday]

(And all those issues are a good reason to be very afraid when you are supposed to use the BMW angle-torque method.)

 

Quite the contrary, as Andy has noted: when friction conditions are uncertain, and/or a very specific bolt preload force is required, the torque-turn method is far superior to a simple torque spec. And in fact it is not the "BMW" angle-torque method - the torque-turn spec is in widespread use across all sorts of machinery: motorcycles, cars boats, power plants and so on, lots of things not made by BMW.

[Peter Parts]

First, I have no quibble with the angle method in the controlled conditions of a quiet and clean factory (... kidding here a bit).

 

But the angle method esp with a clicker, in my opinion is MORE susceptible error. Have you forgotten that is always starts with a snug-up torque? Then it piles on, say 180 degrees.

 

Seems to me, when you are snugging up a very light torque, a bit of roughness on the thread or being dry on one thread turn and lubed on another makes one great big difference in where you come to stop (esp. if you are fooling with a large and heavy clicker and just waiting for it to click instead of eyeballing it real closely like you have to do with a torsion bar).

 

Sooo, if you are off say 90 or 120 degrees when feeling for that small torque resting place, you will be off a giant 90 or 120 degrees (light or heavy) on your final angle method resting place.

 

Much better for shade-tree fixers looking at partly lubed threads in an oiled cylinder head to simply stick with their torsion bar good-feel torque using the spec as their rough target.

 

Ben

[Joe Frickin' Friday]

First, I have no quibble with the angle method in the controlled conditions of a quiet and clean factory (... kidding here a bit).

 

But the angle method esp with a clicker, in my opinion is MORE susceptible error. Have you forgotten that is always starts with a snug-up torque? Then it piles on, say 180 degrees.

 

Seems to me, when you are snugging up a very light torque, a bit of roughness on the thread or being dry on one thread turn and lubed on another makes one great big difference in where you come to stop (esp. if you are fooling with a large and heavy clicker and just waiting for it to click instead of eyeballing it real closely like you have to do with a torsion bar).

 

It makes a difference, yes, but not a "great big" difference, because the snug-up torque being applied is relatively modest. This is in fact the entire point of the torque-turn method: to minimize the impact of bolt-to-bolt variations in the torque-versus-preload relationship.

 

Sooo, if you are off say 90 or 120 degrees when feeling for that small torque resting place, you will be off a giant 90 or 120 degrees (light or heavy) on your final angle method resting place.

 

if the bolt is so mangled that the snug-up torque does not actually snug up the parts, then yes, all bets are off, regardless of what method is used to tension the bolts. Service procedures and bolt tensioning specifications assume a fundamental level of competence on the part of the mechanic, part of which includes knowing that one should not use bolts that have been previously employed as doorstops, pry bars, drifts, or soil picks.

 

 

[Uncle Beemer]

Wow, 5 pages worth of torque wrench recommendations, cool.

Mine as well put in my 2 cents worth.

 

From a semi-pro's perspective. I am no longer a "life time and/or master tech" , but I have put in 10 years worth of professional wrenching early on..

 

Working for General Motors dealerships, I can assure... I have put in plenty torque-wrench time replacing Pontiac Grand Am and Chevy Cavalier 4 cyl. head gaskets; often and with good efficiency.

 

My recommendations:

for home use: a good craftsman clicker type torque wrench goes a long way. Craftsman

 

For home use/<-over achiever.. or for semipro wanna be.

go for the snap-on wrench with thumb screw adjustment

Snap -on

 

here comes the kicker, and the test question for the day:

when you torque to manufacturers specification, does it mean wet or dry bolt tread? can the bolt head or crush washer has oil on it? friction makes a difference!

 

Had 2 of the Craftsman clickers. Both went kaput after what I would consider "light" use. Junk in my opinion. As usual YMMV.

[Peter Parts]

"It makes a difference, yes, but not a "great big" difference, because the snug-up torque being applied is relatively modest. This is in fact the entire point of the torque-turn method: to minimize the impact of bolt-to-bolt variations in the torque-versus-preload relationship."

 

Mitch -

 

45-degrees is 45-degrees off.

 

My point is that light torquing is MORE susceptible to being off. Being off a mere 45-degrees at the light snugging (where bolt variation AND torque wrench variation are going to be larger) can lead to a major disaster when you crank in the angle (which by the way, you are required to do as a mindless robot would do it, no feel, no sense of tightness, no nothing).

 

A lot of people on this forum would bring up their breakfast if they thought they had tightened the angle to 185-degrees instead of 180.... but don't give a second thought to the gross errors possible in the pre-snug-up that sets the stage for big errors in final angle.

 

Let's say you are torquing a bolt to a force spec. You tighten to some figure on your torsion bar wrench. You say, ummm, bet it needs a bit more. Well, that "bit more" is likely to be just a few degrees. A whole lot less than the mindless angle method error that I described above.

 

Ben