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thankyou all - didn't think that was going to be simple!
But that narrows down things considerably so I can start talking to people. I'l ask the nice second hand toolshop locally... I suppose it would be good to adopt the 'reasonable spanner' route and then test out what I have achieved by hand in relation to what is deemed as correct.
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Location: Darkest Bedfordshire
John is spot on in saying you need to know whether the torque is for a 'wet' or 'dry' joint (and this is often unclear). Of course it's equally true that you need to take this into account when tightening with an ordinary spanner, oiled threads use less of the torque in friction and more in generating axial clamp force. Using a torque wrench you know that you've set the right tightness and that it's consistent across the joint. A skilled operator can do this by feel, but that's the point of the torque wrench, anyone can do it reliably.
+1 for Phil's advice too - a breakback wrench needs to be applied slowly or you will not get the right torque.
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
In the day many persons were experienced from work on bicycles, motorcycles etc and tended to use standard spanners of appropriate length so many got along perfectly without torque wrenches. Now persons lack experience and tend to use ratchet sets etc with one handle for all sizes and do not adjust the hold..
It is common to find be bolts stretched.
Some published figures for Sevens are plain wrong and others excessive; OK for the racers using exotic bolts.
The be bolts on Sevens are not heavily loaded; many much larger engines use the same size.High head tensions distort valve seats, bores, and prompt cracks.
Before using any figures it is prudent to compare with published figures for ordinary carbon steel HT bolts; it is unlikely the original materials were hugely superior. Important to distinguish the degree of lubrication or not intended.
It is a good idea to compare hand tension to calibrate yourself. You may not need a wrench.
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Location: Ripon
I use a click type but my good pal who is a serious engineer swears by the pointer/scale type as being gentler and progressive.
A good point regarding lubricated threads, I have a printed out table on the tool box lid showing values for diameter, pitch and dry/lubed values.
I sometimes actually refer to it as well!
(My favourite setting is "wind it up till it strips , then back off a quarter turn")
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28-06-2018, 04:41 PM
(This post was last modified: 28-06-2018, 04:42 PM by Steve Jones.)
Whilst I have no, specific, experience of the torque wrench, Halfords 'Professional' are a very good brand and they sell quality tools at sensible money. When bought new they have a lifetime guarantee and you have to be confident in your product to offer such a thing. Looking at the photo, it has both imperial and metric scales and that's important. Some torque wrenches are metric only and I vividly remember Malcolm and I changing a head gasket to a side valve Anzani engine at Prescott. We'd borrowed a torque wrench but it was metric only. We also knew the torque we wanted but only in imperial. Took some while before we found a clever chap who could convert one to the other!!
Steve
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Location: Sheffield South Yorks
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Perhaps I ought to use mine. It’s still in its wrapping after 6 years. It’s probably not very good. (From Lidl) It was a gift from a friend.
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Location: Nottinghamshire. Robin Hood County
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Steve just a word of warning about lifetime guarantee. I don't know what Halfords policy is on this but a lot of companies state it is the lifetime of the tool and that can be a short time when it is in their favour.
John Mason
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.