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Not me, but I'm jointly culpable.
Ive been helping my neighbour rebuild his TVR Griffith. It's been a long job, but end is in sight. Body back on the chassis, engine running. Just needed to do up the stub axle bolts at the rear.
c.300Nm. Mate whips out the monster Sealey torque wrench. Asks me to do up the nuts (I'm younger, fitter *ahem* than he). I start at the Offside hub, RH thread, properly lean on the torque wrench 300Nm isnt fannying about. Get a click. All good.
Go and do the NS axle. Flick the reversible switch on the torque wrench, do up the LH threaded nut CCW, lean on it. No click yet, lean again, nut keeps on tightening, keeps on rotating, until it doesnt get tighter, it gets looser. That'd be stripped threads. We assumed that the old stub axle threads were ropey. He tracks down a replacement and without me around, does it all again. Stripped threads. We then test the wrench in the vice and sure enough, the torque measurement only works CW, not CCW.
So would you assume that a reversible ratchet torque wrench could measure torque in both directions or just CW? Obviously not many people come across LH threads, but at home bike assemblers like most of us will have in the context of pedals and BB cups at least.
We feel like a right pair of chumps, and poor matey is down a fair few quid buying up all the spare NS TVR stub axles in the country.
Yes - Presumably the 'reversible' switch is only to allow you to back a nut off a few turns.
I'm not a big fan of torque wrenches though.
So would you assume
Assuming stuff is the start of most stories like this!!
That's annoying and an easy mistake to make. I would have set a low torque 1st on the CCW direction as I know some torque wrenches only work CW. Not that that is of any help now though.
Nope.
It’s a bad workman blaming someone else’s tool.
I would not assume this, ever.
Although that's only because I've been told by the salesman that a torque wrench worked both CW and ACW only to discover that it was not the case. Fortunately on nothing anywhere near as expensive as a chunk of TVR.
Having been marginally involved in building cars in the past, none of which was as complex as even a TVR, I'd chalk it up to 'shit happens'.
At least you both made the same mistake ha ha.
should work in both directions imo
Although that’s only because I’ve been told by the salesman that a torque wrench worked both CW and ACW only to discover that it was not the case.
I think you have to have made the mistake at least once prior to be as confident as you are 😉
So would you assume
Never assume..... it makes a donkey of both of us.
Things is Im sure there are genuine LH/reversible torque wrenches. But cant find what to call them
Very very few flick a switch wrenches do both ways.
A push through head one will.
If it's a flick a switch id always check it in a vice first- I believe some pricy ones do it but I'd never assume.....
But guess how I know this.
Just like you have learned experiance comes just after you needed it most.
No, but only because having bought a 1/4" drive torque wrench to do a job on the car that involved a left-hand thread, it came with a big disclaimer on it that it didn't do torque measurement in "reverse".
Prior to that, though, it probably wouldn't have crossed my mind.
Just like you have learned experiance comes just after you needed it most.
Also, keep your fingers away from the chain.
Those that bend with a pointer against a dial work both ways, but I've never liked them.
You need a reversible head one - it only works / clicks in one direction, you have to put the drive bit on the other side to work CCW.
We poured over the sealy wrench box and printed destructions and no mention of no torquing in reverse.
One only needs a torque wrench to measure torque over 200Nm. Anything less than that is done by feel, shirley?
I found out exactly this in a similar way on some forks with a LH thread and a specific torque setting.
Like others, I'd assumed it would work the other way but soon realised it didn't.
300nm...
3 humphs and a grunt on a 1m bar when I do hub nuts 🙂
There's an awful lot of people in here who have learnt this fact on the wrong side of the event.
I think those wandering through this thread and yet to get this wrong owe us all a debt of gratitude.
It's obviously a subject that was left out of dad classes.
t_r - 200tdi crank pulley nut: 350Nm.
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with stud lock
🙄
bad design much?
Internet photos of some Sealey ones have a direction arrow and "Torques" written above the graduations.
Most of our work ones (Norbar) also have a more obvious direction arrow at the head.
Break in the middle ones are more obvious as single direction but tend to find they are only accurate if you set them on a wall mounted gauge and use the same hand position every time (hold the handle in a different position or have two people pull on it for say 800Nm and the result can be wildly different).
Some do some don't. I personally only use norbar torque wrenches and you have to turn the head around on them to get LH threads done
this is the model
https://www.sealey.co.uk/product/5637174915/micrometer-torque-wrench-34sq-drive
nothing about CCW operation/LH threads.
reverse switch almost certainly to back off a 1/4 1/2 etc turn per specs, not to deliver gauged reverse torque.
Also worth being wary about old torque wrenches as if the spring tension was left on at storage, its likely no longer accurate.
300nm.. thats 60kg at the end of a 50cm wrench. Always good to have a grasp on where you expect to get a click before hoofing in.
Also wonder if like others, the stub nuts are a use once design?
IIRC they're sometimes designed as friction fit rather than relying on nylocs or old fashined castled nuts, so once you install a second time, you'll be delivering higher torque as the friction element is gone.
Wait till you spot the arrow on the handle 😂
adds of list of lessons learned in life, thankfully by someone else
Always good to have a grasp on where you expect to get a click before hoofing in.
Is not stupid either. I've seen way too many poor reviews of cycling torque wrenches where people were aware of how low 4Nm is and so hadn't even felt the click. 300Nm is a different ball-park all together though.
I have a Park one that works CCW, It surprised me but I always assumed it did cos of LH pedals and BB cups, none of the previous Draper ones I've owned have worked CCW.
adds of list of lessons learned in life, thankfully by someone else
Same. Cheers to all the Guinea pigs out there.
Reminds me of the rear drive shaft nuts on my old Hillman Imp. Some big torque and 2" nuts. I popped up to the village garage to ask if they had anything I could borrow for the job. Old guy handed me a set of Stillsons and said "stand on those". Also mentioned my hands as "looking like worked in an office", which I did.
300Nm - that’s a ‘farmer’s nip’...!
Just keep a selection calibrated childerlings to stand on your breaker bar?