Faulty torque wrench broke my engine!

atothej

Morning all - after quite a few years of happy purchasing, I have come up with a little problem. I used to use the excellent consumer direct service, but it looks as though this has now been cut...

Anyway, I am in the process of restoring a 1962 Lambretta scooter. The engine has been stripped, cleaned, all bearings and seals replaced and ready for rebuilding. To rebuild correctly, certain bolts need to be set to a certain torque to ensure that they can hold components in place. Many of these torques though are surprisingly low, which required me to purchase a special 'low range' torque wrench. I bought one from the Amazon website by an external company, but fulfilled by Amazon.

Now, the trick with torque wrenches is that after you have configured the settings, the wrench will give you an indication once you reach a required torque. This is usually a click which is both audible, but also kind of felt through the wrench.

Once received, I set about tightening some bolts. I was wary of using a new wrench so set the torque rating lower than required (I needed 5nm, so set it to 3nm). Unfortunately I have no idea what 3nm feels like, so with no indication of reaching the required torque (ie no click), I carried on slowly tightening. Needless to say I overtightened the nuts and have damaged the casing. One of the threads have been stripped and a section of the alluminium engine casing has come away.

I know that a bad workman always blames his tools (and I am quite a bad workman if honest) but the fact that I received no indication of the required torque being reached makes me think that the wrench is to blame, which moves me onto why I am posting here....

Am I in any position where I can approach the retailer and request that they cover the (probably quite costly) repair costs associated with the use of this faulty wrench? Should I get the wrench independently tested somewhere before approaching? I once had a faulty Xbox 360 that chewed up some of my discs, and I was allowed to have new replacements - does the same apply here?

If so, who should I be approaching? I suppose my contract is with the external company, but because it was fulfilled by Amazon have any bearing on this?

Any advice would be greatly received!

maninthestreet

Do you have link to the item on Amazon?

wealdroam

When did you buy this wrench?

molerat

These low torque click wrenches are difficult to judge as the click is very slight, best to test it on something to try and feel the click. 3-5 nm is not very tight at all and you must have given it some welly to strip the thread. IMHO any reasonable person who is competent to carry out that particular task would have known they were over-tightening it.

damsmi2002

To support molerat, I work on cycles and the crank bolts need to
Be 40nm, this is a very loud click which is also easily felt. Many other bolts need to be 5nm, this is barely audible, and certainly almost not able to be felt. If you had experience with doing this then you would realise that this was the case. To me this seems like user error, however, you could always ask a mechanic to test it and see if it differs to the one they use, obviously if yours is a much cheaper option then this would need to be taken into account

happybiker

3nm is very low, only just past 'finger tight' . I have a Britool low range wrench that is 1/4" drive and 6" long in total and can achieve 3nm with that by applying light pressure with 1 finger.

To strip almost any size thread on a Lambretta with a low range torque wrench would be almost impossible unless the operator was extremely inexperienced and heavy handed.

Personally, i don't think the torque wrench is at fault.

Ps. I also have a calibration rig, so I know my wrench is accurate.