recommendations for torque wrench pls

[Geoff101]

Halfords Professional torque wrenches used to be made by Norbar so were very good (I have one). Don't know if that's still the case for that model.
I've also had parts replaced by Halfords on one of their sockets sets with a lifetime guarantee with no issues. I didn't even have a receipt as it was a gift.

[JonE]

The tide is starting to turn in favour of another trip to the secondhand tool shop...!
Yes, I'll be winging it over calibration buying secondhand, but it still had its barcode sticker on the handle... and I can always go and check it with someone owning a posh one that has a full service history and has only been used on Sundays...

[Charles P]

The tide is starting to turn in favour of another trip to the secondhand tool shop...!
Yes, I'll be winging it over calibration buying secondhand, but it still had its barcode sticker on the handle... and I can always go and check it with someone owning a posh one that has a full service history and has only been used on Sundays...

No need to wing it. 

Fasten the square end in a vice.
A 5 litre water can weighs 5 KG (11lb). Two of them, tied together with string weight 22lb.
Set the torque wrench to 22ft lb and attach the two water containers at a point 12" from the fulcrum. 
The wrench should just click (with a light push either way). If the weight needs to be moved further out  to make it click it over reads (i.e. 22 ft lb on the scale is actually less in reality).

Any second hand tool shop that won't allow you to test it or return it if it's more than an agreed amount out isn't worth buying a torque wrench from

Charles

[jansens]

I suspect a lot of the benefit of using a torque wrench on 7s is consistency rather than absolute values. A simple test like Charles mentions will tell you if it's more or less accurate.

On assembling my engine I suspect the only place I will use mine is with the Phoenix big end bolts (since there is a recommended value for them I think?) and the head studs, just to get them all the same.

Calibration and accuracy of measuring equipment is always an interesting problem. I have a bunch of different temperature measuring devices, electronic and physical, they all read differently so you're never sure which one is 'right'.

There's even is a name for it, Segal's law (not Steven).


"A man with a watch knows what time it is. A man with two watches is never sure".

Simon

[Bob Culver]

Torque wrenches are useful when working in awkward positions. Whilst an appropraite pressure can often be judged at a bench lying under a car can be different. The simple pointer type also then sometimes awkward although otherwise fine. 

Machinerys Handbook gives the accuracy of applied tension as + or - 25%!!. By hand (presumbaly an experienced operator) + - 35%. it is generally reckoned even very experienced workers tend to overtighten small threads and under tighten large. 
The thread is not reckoned to make much difference except as it affects the core size.

Only a fraction of the torque contributes directly to tension; most is friction. For the same total tension producing same  joint compression, torque increases more or less in proportion to dia.

Decades ago when tools were expensive, for use on family moderns my father and self made wrenches out of 1/2 inch HT rod and filed Seven axle bits.

[Chris KC]

I suspect a lot of the benefit of using a torque wrench on 7s is consistency rather than absolute values. A simple test like Charles mentions will tell you if it's more or less accurate.

On assembling my engine I suspect the only place I will use mine is with the Phoenix big end bolts (since there is a recommended value for them I think?) and the head studs, just to get them all the same.

Calibration and accuracy of measuring equipment is always an interesting problem. I have a bunch of different temperature measuring devices, electronic and physical, they all read differently so you're never sure which one is 'right'.

There's even is a name for it, Segal's law (not Steven).


"A man with a watch knows what time it is. A man with two watches is never sure".

Simon

Quite so Simon. As observed above it's highly doubtful what the 'correct' torque is in most cases anyway, especially when dealing with 'used' joints. If you also plan to use it on your modern car I would take a different view.

While I think to mention it a Halfords trade card is well worth having. If can plausibly argue that you work in the motor trade (business card?) don't be shy about asking.

[Phil Kingdom]

Another consideration when taking accuracy into account is temperature, hence the need to re-tighten cylinder heads after every thing has expanded, a recommended torque setting in the automotive sense is really only a guideline to provide consistency and to insure a fixing is tightened to its recommended setting give or take a bit. Going back to my rigging days, part of a radio towers maintenance schedule is a 10% bolt tightness check, on one tower in Essex of an unusual construction the preferred method of tightness for the 1 inch thread diameter bolts was by means of a dimpled washer, the dimples on the washer were compressed by the nut until a 10 thou feeler gauge was just nipped, now working in thous on a inch bolt might sound a bit over the top and you may think the altermate torque setting has been achieved which may be true , but in really hot weather it was not unknown for the tower legs to expand enough to shear of the head of the bolt.

[JonE]

I was dismayed to read quite when I first posted this thread, as it just shows how long getting anything done on my car takes without getting diverted onto some other horror fault! Suffice to say I went back to s/h tool shop to buy the Halfords Norbar, and the darn thing had of course gone. But have picked up a new unused with 2018 certificate Norbar (annoyingly 1/2") 0-50Nm for £35 on ebay, so nearly ready to put my head back again now...

[dickie65]

Hi Jon,
The Norbar should be fine for the Austin engine small stuff.
Yours will be too light for the flywheel nut.


Big ends about 18 ft Lb
Head Nuts about 18 ft Lb
Block can not be done with a torque wrench so you have to make sure all the nuts are evenly tight.
assuming good threads in the crankcase I suspect 11 ft Lb.

Maryland metrics have a very good Torque Chart.
The idea is to slightly stretch the bolt / stud but stay within its elastic limit.

Sorry for my earlier error as I use 35 ft Lbs for my big ends on an 1 1/2 crank ( 3/8 UNF Bolts )

Top Quality 5/16 Bsf X grade will take 32 ft Lbs

[Steve kay]

Reading earlier contributions to this thread, I came upon a person claiming to cheque the accuracy of his torque using a couple of gallons of water, a ruler and a piece of string. Might we see a diagram, or even better some youtube footage to indicate that this is serious, and not a very splashy moment in the pantomime in the village hall. Does sound technical though, piece of string and not baler twine!