Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Have you checked your torque wrench calibration?

I sucessfully changed my 4/4 cambelt, a feeling of smug satisfaction.

A few days later I came across a YouTube video, 'How to calibrate your torque wrench'.
https://www.youtube.com/watch?v=XaqBA-xSGbc

Out of curiosity I checked my large torque wrench, 60 - 220ftlbs, which was spot on. However, when I checked my small torque wrench, 10 - 80ftlbs, which I have had for about 10 years, I found it was 'clicking' at a value approximatly 25% below the set value. There are videos on YouTube which show how to reset a torque wrench, so now, it is spot on.

Then I realised I had a problem! My small torque wrench is very useful for the low values required when working on an aluminimum engine and I had used it for the majority of the cambelt change. 10 -15% error I could live with but not 25% when a cambelt is involved. So yes, I took it all apart and put it back together again, with the correct torque values.

The learning point, 'It pays to calibrate your torque wrench now and again'

Interesting. "Every day is a school day".

Yes, once a year and always just before I rebuild an engine. It helps that my neighbour can get them recalibrate and certified.

How many people know there is a correct way to store a torque wrench?

Arwyn

Although I have a torque wrench (which I do store correctly, fully slackened) I find often I just use an electronic fish scale (like that used in the video) to apply a measured amount of torque. Hook it into the end of a ring spanner, measure the distance, and it's easy to calculate the correct weight to pull at. Very handy when a full size torque wrench can't be brought to bear.

Torque wrench...? I was taught that the size of bolt, the material used and the thread type, alongside the likely spanner weight and length averaged out one`s expectations on how much pressure to apply when tightening things....?

But in more advanced engineering terms, I ever park my torque wrench with it wound right back taking pressure off the spring...

Certainly an entertaining video! He needs to do a follow up on how to recalibrate your luggage scale, perhaps by weighing a litre of water at 4 degrees C? Then another one on how to recalibrate your thermometer ...

I read somewhere of a study that demonstrated that for fasteners tightened without a torque wrench, the vast majority of small sizes were over-tightened, and the vast majority of larger sizes were under-torqued.

I was amazed when I did the cambelt on my Ecotec engine. Because it has variable cam timing I decided to replace the cam wheels at the same time as they have internal oil ways and gubbins to do the phase change. There are no keyways or detents on the cam shafts, the wheels are just dialled into position and locked on to the taper with torque, about 95 ft-lb if memory serves. You certainly wouldn't want to get that wrong by under-tightening and having them come loose! :-)

V good tip .Going to check.

Stefan

The first time I used a torque wrench on small bolts, in this case for split brake caliper, I was surprised how much torque was physically needed - way more than I would have naturally used for the size of bolt.

ETA: On the other hand, an old school Rolls Royce trained engineer once told me they were only issued with short open end/ring spanners to avoid over-tightening.

Ian... you omitted to suggest checking at what temperature one`s steel rule would be accurate.... unless it was made of invar.. (-:

No argument from me as to the value of a torque wrench..... provided it has an in date calibration certificate...(-: