I'm new to using torque wrenches. By new, I mean I have never used one. And by used one, I mean never successfully.

My dad gifted me a 1/2" drive 10-200 ft/lbs Torque Wrench he bought but had never used. I just finished a total fluid change and had I wondered out loud what it would be like to have properly torqued drain nuts. So he dropped it off the nest time he was in town. It is a Craftsman from the early 1960's. The tool looks mint.

I was playing with it trying to hear the "click" at proper torque on the 10mm self threading bolt that holds the quarter panel to the frame under the hood when I broke the head off. The wrench was set for 10 ft/lbs and I used a single fluid pull. Is there a trick I'm missing? I don't own 1/2" sockets so was using an adapter for my 3/8" drive ones. I also was using a 3" extension. Is this bad? The physics of the wrench shouldn't change but like I said, I'm new to torque wrenches and I really do not know how to use the things. The instruction manual was not very useful in describing actually operation of the wrench. Looking for help.

 

the adapter is all the problem. Adapters allow for greater torque at the nuts, without showing as great a torque at the wrench.

 

How am I supposed to torque the spark plugs without an extension? You have to use one so how do you obtain proper torque? Also, the bolt I broke I would have guess was upwards of 50ft/lbs when originally secured, that's why I chose it because I figured I could safely play with it at a low torque setting. If I had a socket that fit a lug nut, I would have been playing with those.

 

50 FT lbs for a FENDER? no no no. 50 inch lbs maybe.

As for the spark plugs, just get em good and tight.

Anytime you use an extension, you get incorrect torque readings.

see this for a little more info: http://buy1.snapon.com/catalog/item....re&dir=catalog

 

It is likely if that small bolt were overtorqued on the prior installation, it was close to failure and broke when you re-torqued it, even at 10 ft-lb. Have had that happen before on the smaller 8mm bolts. I usually tighten all those by hand with a small combination wrench. I find torque wrenches are not very accurate down at the low end of their range. So while the dial may show 10-200 ft-lbs, that wrench is probably only good to use from say 40 or 50 ft-lb up to 200. For lower torques, get a smaller wrench.

 

I never thought of that. I suppose an extension would cause readings that are higher than the actual torque. And the longer the extension, the larger the gap between the read and reality. Agreed?

 

Only if the extension twists. If the extension is rigid, it wouldn't change the physics of the wrench. Now if the extension put the socket off of the center line, then it would certainly change the torque. In fact I have the calculations for that somewhere around here.

 

breaking bolts sux!

i have to agree that at 10' lbs your at the very low end of the range and accuracy.
its a craftsman, take it back and exchange for new

'antique' tools are only for displaying... or breaking things

 

Those are torque sticks that, when used with an air impact, flex enough to disable the hammer action in the air wrench. Their 'flexy-ness' is what defines the torque setting. They get close....Still, good tire places follow up with a torque wrench.

If a regular extension is used correctly with a torque wrench, it should have no difference on torque than if used without. Even if the wrench was 15 feet away from the fastener.

I have a few different kinds. Inch Pound and Foot Pounds, in a Lever-Type and Ratched Handle 'clicker' type. I like the Lever Type for lower torques. I was just given a torque 'screwdriver'. I can't wait to find a screw that needs to be torqued to something specific.

 

We change tires where I work and we torque all our nuts on the wheels. We use extensions and have no problem with that. I suspect that an extension over 12" might skew the tourqe but couldn't really tell you that. However if our wrench is not set right (lock out) it will not click but act like a breaker bar.

 

Bingo. Like I said, I'm new to torque wrenches and the original manual makes no mention on how to use the thing. Explain the lock out. Is the ratchet selector like a three way switch? Center to torque, left/right ratcheting breaker bar?

 

That doesn't make any sense unless you are putting so much torque on the extension that you are twisting it or the extension is really weak. As long as the axis of rotation stays in the same place and the extention or adapter doesnt give it shouldnt change anything.

 

My lock-out locks the torque setting. there is no ratchet selector on mine, but I have seen some like that.

 

I was recently removing some bolts on my front quarter panel and broke two heads, so it might not just be the wrench. You might want to compare the torque on your "new" wrench with another one.

 

Ratchet left, then torque reading right. Ratchet right then torque reading left. Dont ever abuse the torque wrench as a breaker bar. You should return the handle all the way down, lowest torque reading possible for storage. I bet I have the same wrench in my garage. Works great. If not stored properly the spring inside can loose tension over time. You could prolly get it calibrated by the snap on guy in your area. And yeah not real acurate down low. You prolly just over torqued that poor little rusty bolt. If you use an offset such as a crowsfoot wrench then yes the torque value must be calculated because of the offset from center of force, an extension doesnt change the geometry. All that and a dollar will get ya a cup of coffee.
Jim

 

The length of a socket/ext bar can alter torque, but no-one really knows why, think about when you want to drive a screw in or out with an old fashioned screwdriver, if you use a 3"long screwdriver, you can get the screw most of the way in, but if you use a 12" long screwdriver, you can screw it all the way home.

Try it for yourselves, get a pice of 2"x4" timber and a 2.5" x 12 guage screw and a long and short driver.

Maybe they should do it on "myth busters"

I would say if you want to torque evrything correctly, then you'll need a 1/4", 3/8", 1/2", and maybe a 3/4" torque wrench, and the socket sets to match, it could get expensive!

 

If your 200 ft/lb torque wrench was set to 10 ft/lbs,then you would not even realize it clicked!The higher the setting the louder the click.

 

HOW TO COMPUTE TORQUE WHEN USlNG ADAPTORS

If an adaptor or extension is attached to the square drive of a click-type torque wrench and this adds to its length, then the applied torque will be greater than the pre-set torque. A formula can be used to find what the preset-set torque should be in order to obtain the correct applied torque.

Here is the formula:

Pre-set_torque_formula.jpg (7562 bytes)

RS = Torque setting of the torque wrench.

wpe1E.jpg (3367 bytes)

A = Distance from the center of the square drive of the torque wrench to the center of the handle grip pull point.
B = Length of the adaptor from the center of the square drive to the center of the nut or bolt. Use only the length which is parallel to the handle. See figure 1
T = Torque desired. This is the actual torque applied to the fastener. Here is a typical problem: What should the setting be when ‘‘A’’ is 12’’, ‘‘B’’ is 6’’ and ‘‘T’’ is 30 Ib. ft.

wpe1F.jpg (4866 bytes)

Therefore 30 pound foot of Torque will be applied at the fastener when ‘‘RS’’ is 20 pound foot.

Note: If the torque wrench reads in pound foot, then ‘‘T’’ should also be in pound foot. ‘‘T’’ and ‘‘RS’’ should be in the same unit of measurement. ‘‘A’’ and ‘‘B’’ should also be the same unit of measurement.


This is calculated ONLY if the extension ADDS to the overall LENGTH!