Torque Wrench help needed

[GPZ592]

Sort of bike related, but I have a problem with settings on a new torque wrench. I've used torque wrenches before and my main one is a 3/8" Clarke which covers most normal applications and I have a Halfords 1/2" for larger jobs like clutch nuts. Both are calibrated in kg/m and I'm happy with their operation. I just bought a 1/4" Clarke torque wrench for smaller applications, which is calibrated in Nm, but it seems to take too much tightening for a given setting before it "clicks". Let me give you an example -

I used my 3/8" on the conrod nuts, which have a torque of 2.4 kg/m (23nm). Once set, I tried the 1/4" set at 23nm, but it started to move the nut and I had to step it down to 15nm before it clicked. Similarly, I tried the 1/4" wrench on the crankcase bolts, which are 1 kg/m (9nm). This time I used "feel" to set them, using a normal socket wrench, to a setting I was happy with and the 1/4" would only click at 5nm - anything higher it wanted to turn the bolt and I was not going to go any tighter for fear of stripping the bolts.

So my question is - am I doing anything wrong here ? I believe that 1 kg/m is 9.8 nm ? Can 2 different torque wrenches be so far apart in operation ? Have I got a faulty 1/4" wrench ?

Any help/advice will be greatly appreciated

Mark.

[ADRIAN H]

Would have thought the 1/4" needs calibrating, which should be done before it was sold. I would get it replaced.

[warren3200gt]

Any good make comes with a dated calibration certificate with a recalibration reqd date on it.

[GPZ592]

Thanks both. There wasn't any calibration certificate, just an inspection sticker.

I have found some info on the internet about testing a torque wrench yourself. Using a known weight and some calculations you can get a predicted value of torque, so I may try that just to compare the ones I have to see if there's any wild anomalies !

[Mr Bump]

Teng torque wrenches are good value and good enough quality, and come with calibration certificates.

Ive got 1/4, 3/8 and 1/2" ones. I tested them on a calibrated test rig about 6 months ago and all were +/- 2.5 % which is pretty much spot on for a spring torque wrench. The 3/8 is at least 15 years old and has been used quite a lot.

Olly