Torque Wrench Check
Drifting
Joined: Jun 2005
Posts: 1,950
Likes: 498
From: Chino Hills CA
If you live near a Costco, stop by the Tire center. Each Shop is equipped with a torque analyzer for checkingthe accuracy of their torque wrench. If you ask the manager nicely he may let you check the accuracy of your wrench ( I would...)
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Originally Posted by Kim72
I'm not sure my torque wrench is working correctly. Anyway to check them.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
you know an easy way to check is to find the torque specs for a bolt and then tighten it until it breaks.....the breaking point is approximately twice the torque spec
Melting Slicks
Joined: Dec 2005
Posts: 2,441
Likes: 0
Here's a fundumental method for checking a torque wrench...
http://home.jtan.com/~joe/KIAT/kiat_3.htm
http://home.jtan.com/~joe/KIAT/kiat_3.htm
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Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
Originally Posted by bobs77vet
you know an easy way to check is to find the torque specs for a bolt and then tighten it until it breaks.....the breaking point is approximately twice the torque spec
You can calibrate a torque wrench using a vise and a known weight.
Clamp the drive of the torque wrench in your vise so the handle is horizontal +5 degrees, - 0 degrees.
ACCURATELY weigh some thing you can hang from the center of the handle that is about 25% to 50% of the full range of your wrench.
Measure the distance to the center of the handle and hang the weight at that point.
The torque reading should match the weight in pounds times the length in feet from the drive to the point the weight is hung.
For example if your wrench measures 18" to the center of the handle, has a full scale reading of 100 ft-lbs, you would find a 30 pound weight, hang it, and read 45 ft-lbs (18"/12" = 1.5'; 1.5' times 30 lbs = 45 ft-lbs) on the dial or beam. If it a click type, you'd set it at 45 and see if it just clicks when the weight is applied. If not you'd go up or down in 1 ft-lb steps until it clicks when the weight is applied to the wrench.
If you want to be seriously precise make sure the handle is horizontal when the weight is on the wrench.
Last edited by StickShiftCorvette; Mar 3, 2006 at 07:08 AM.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by StickShiftCorvette
.....
For example if your wrench measures 18" to the center of the handle.....
For example if your wrench measures 18" to the center of the handle.....
thats pretty neat....why is it the center of the handle as opposed to the end or the length of the wrench???
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
We never used or calibrated beam type wrenches. The snap over or click type wrenches can be calibrated by ddjusting the spring inside. It became part of our calibration procedures for ISO certification, was kind of a PIA but it really made a difference in failure rates.
Melting Slicks
Joined: Aug 2004
Posts: 2,165
Likes: 950
From: Keizer Oregon
Originally Posted by bobs77vet
thats pretty neat....why is it the center of the handle as opposed to the end or the length of the wrench???
As far as actually changing the calibration of the wrench......???
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
This is to answer the question:
"Why use the center of the torque wrench handle?"
Because the actual torque generated is the force times the lever arm. Most wrenches are designed to be used from the middle of the handle. To illustrate, if the handle were 2' long, 18" to its center, putting a 30 lb weight in the middle of the handle would yeild a torque of 45 ft-lb, towards the front (nearer the drive end) the torque would be 15 ft-lb, and finally at the extreme end the torque would be 75 ft-lb.
That is why you need to use the middle of the handle. This is really an issue when you use offset extensions (the kind you need to torque the center intake manifold bolts around the choke heat stove), since you use the equation:
Output Torque = ((A+B) * Wrench Setting)/B
or
((Output Torque)*B)/(A+B)=Wrench Setting
Where A = offset length of adaptor in feet
Where B = torque wrench length to center of handle from square drive
"Output Torque" is the torque applied to the nut or bolt and "Wrench Setting" is the reading or setting of the torque wrench.
"Why use the center of the torque wrench handle?"
Because the actual torque generated is the force times the lever arm. Most wrenches are designed to be used from the middle of the handle. To illustrate, if the handle were 2' long, 18" to its center, putting a 30 lb weight in the middle of the handle would yeild a torque of 45 ft-lb, towards the front (nearer the drive end) the torque would be 15 ft-lb, and finally at the extreme end the torque would be 75 ft-lb.
That is why you need to use the middle of the handle. This is really an issue when you use offset extensions (the kind you need to torque the center intake manifold bolts around the choke heat stove), since you use the equation:
Output Torque = ((A+B) * Wrench Setting)/B
or
((Output Torque)*B)/(A+B)=Wrench Setting
Where A = offset length of adaptor in feet
Where B = torque wrench length to center of handle from square drive
"Output Torque" is the torque applied to the nut or bolt and "Wrench Setting" is the reading or setting of the torque wrench.
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Originally Posted by GDaina
you need another one, preferably a beam time and check one against the other...course you need a 1/2" adapter
