Probably OK, but I prefer old school.
Technical Rear wheel bearing
- Thread starter d4zzl3r
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Technical Rear wheel bearing
Yes, know what you mean mike. I do find some of the new technology difficult to get on with but this particular bit of kit I have really taken to. It uses remote type flat batteries (like in your key fob) and gives a warning when the batteries need replacing. You can set it to either display the torque in a rolling display - ie. increasing as you tighten the fixing, like a modern version of the old beam type torque wrench with a bendy beam and pointer - or you can set it to beep when the preset torque is reached, like my Britool/Norbar wrenches when they click. It's a great bit of kit which is well worth a look especially for someone who doesn't yet own a torque wrench so doesn't have previous with mechanical wrenches but also because it's range is so big.Probably OK, but I prefer old school.
I can see some benefits but I still trust my Britool torque wrench and others of that quality, I always keep it well oiled and unwound , then when ready to use set at approved torque and click it off a few times in the vice on my workbench so I know it "feels right" before use.
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d4zzl3r
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Thanks for that.
Aye, I completely understand what you're talking about. I grew up using wrenches of this type, like your's, pretty much all Britool brand. The reassuringly positive click these older type wrenches give is something you come to trust. I bought the Clarke torque adaptor mainly to take over from my big Britool which I was suspecting was no longer accurate and which would have cost more than the cost of the Clarke to have overhauled and recalibrated. Then it occurred to me I could use the Clarke not just for tightening stuff like hub nuts and crank bolts etc but to also do an approximate check on the accuracy of my smaller, more often used, ones. I have my original Britool (around 20 to 120 ft lbs I think? - sorry, I'm not at home just now so can't check) and a similar Norbar. Also a 3/8 Halfords branded (which I think is actually a rebranded Norbar?) and by removing the square drive from them I can "plug in" the Clarke and check the one against the other. By the way, yes the big Britool was reading way too low - It's now an "ornament" on my tool rack (too big to fit in my tool chest.) but, like all my older tools, it's a "friend" and I've had it for so long I just can't bear to think of disposing of it.I can see some benefits but I still trust my Britool torque wrench and others of that quality, I always keep it well oiled and unwound , then when ready to use set at approved torque and click it off a few times in the vice on my workbench so I know it "feels right" before use.
The Clarke does take a bit of getting used to when you've been used to the click type because it doesn't give any physical feed back through the wrench handle, you have to listen for the "beep" and stop as soon as you hear it. Also watching the display scrolling - if you decide to not choose the beep option - is difficult due to sometimes it being difficult to see the display but also it's not so easy to see a scrolling figure, bit like trying to watch a multimeter which is monitoring something with a varying output. You get used to it after a while though.
I have seen at Government auctions a Torque wrench test machine, as you will know you tend to trust your equipment until proven otherwise.
There are a lot of cheap torque wrenches available, I had to lend a neighbour one of mine as his new one resulted in snapping small bolts!
I have also seen s/h torque wrenches that are bent, so I don't know what animal has been using them!!!
Smaller range wrenches can be checked directly by applying a known weight at a known distance from the wrench square drive. For instance weld a length of stout tube, bar, angle iron or whatever to an old socket. If you're checking lbs force per foot (lb-ft) then slot a piece of tube through the square hole in the socket and rest it across the jaws of your vice or any other suitable support. Then use an accurate spring balance - or similar - to suspend the bar, tube, angle iron horizontally at exactly one foot from the pivot point which will tell you how much downward force the bar itself is exerting at this point (which is relevant to lb-ft). Now all you need is to plug the socket into the torque wrench you are testing and a range of weights which can be suspended at this one foot point from the pivot point. By adding the weight you measured of the bar with no weights and the chosen weight together - so, for example, maybe your weight is 10lbs and the balance registered 3lbs at one foot from the fulcrum then if you suspend the 10 lb weight on the bar at 1ft from the centre of the wrench square drive it will be applying a downward force of 13lbs at one foot from the wrench fulcrum which is 13lb/ftI have seen at Government auctions a Torque wrench test machine, as you will know you tend to trust your equipment until proven otherwise.
There are a lot of cheap torque wrenches available, I had to lend a neighbour one of mine as his new one resulted in snapping small bolts!
I have also seen s/h torque wrenches that are bent, so I don't know what animal has been using them!!!
You can mess about with lengths of tube, bar, angle iron and weights to get different measurements so, for instance, doubling the length of the arm doubles the original 10lbs/ft to 20 lbs/ft but remember there will be more weight in the longer arm so you have to weigh it at the 2ft mark to correct your applied force. This works well for smaller wrenches but gets very "silly" for big ones. 350lb-ft gets really unmanageable! You're not going to be as full proof checking your wrench this way as a "proper" check but you will get pretty close. If it's out by much and a recalibration is needed then life gets much more difficult as you often need shims etc and dismantling can be less than obvious too. Bear in mind also that the spring may not be linear anymore so other parts may be needed. Best sent off to a specialist.
I wouldn't buy a cheap one or a used one which I didn't know it's history comprehensively and, as has been said above, always back off the spring after use or it will quickly got out of calibration. Like you Mike, after setting up I always click them off a couple of times in my vice before applying to the work - I've got an old lambda sensor socket which I hold in my vice for this - so I can feel if it's feeling "sensible"
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Then you look at the various specs for high torque fasteners. From memory, the 1.3 JTD front crank bolt, Fiat use 240Nm but GM say 140Nm plus 90 degrees. Which is more accurate will cause yet more debate. Again from memory I think they are both +/- 10%.
Or "strip the threads and back half a turn" Yes, that is a Joke we were told as young apprentices when asking how tight to do something!
I believe in modern mechanics using windy guns, you now measure torque in number of "ugger duggers" before you stop pulling the trigger.Or "strip the threads and back half a turn" Yes, that is a Joke we were told as young apprentices when asking how tight to do something!
This is why most wheel bolts are tightened to 600ft/lb if you ever visit a high street tire fitters,
Having grown up with conventional torque wrenches, when angle tightening first became a "thing" I was highly sceptical. However as time has gone past I now would prefer if tightening is done by this method. Why? well for a number of reasons but mainly because it completely disposes of the problems introduced by friction when using a torque wrench to fully apply a tightening procedure.
If you're feeling puzzled by this then think about tightening with a torque wrench. what the wrench is actually measuring is the twisting force being applied to the fixing. Say this is a bolt, maybe a head bolt? let's consider If the bolt, it's threaded hole and the lands under the head are all clean dry and without any lubricant then the torque wrench will click when the friction between the bolt, threads and under the bolt head to casting reaches a certain degree of friction which stops the bolt turning. Lets say, just as an example, at the torque set on the wrench that it stops turning after half a turn. Now try lubricating the bolt and it's threads and all touching parts. Using the same setting on the torque wrench you might well find that the bolt turns three quarters of a turn, or more, before friction stops it.
So what does this mean for the two components the bolt is clamping together. In the first instance the bolt will advance into it's hole by half the pitch of the tread - it's gone half a turn hasn't it - this will achieve a certain clamping force between the head and block. However the lubricated bolt will advance by, let's say, three quarters of a turn so three quarters of the thread pitch. Thus exerting a far greater clamping force on any gasket or other part. Now think about this for a minute. What is of interest here is how much clamping force is being exerted, and that is simple to calculate if we consider how far a bolt is being advanced into it's hole and almost impossible to know if measuring this from the twisting force being applied to the bolt. So, in my opinion, initial tightening to a low torque figure will take the "slack" out of the job and the low figure will be reliably relevant because at low torque figures friction is very much less of a factor. Then by using degrees of turning as your measure you can very accurately exert a specific tightening force because you know that a certain degree of turning equates to a certain distance advanced by the bolt and thus the clamping force applied.
At the end of the day though, it is what it is. I the spec is for angle tightening then you get your degree wheel out and angle tighten it. If it's a torque figure in the book, you get your torque wrench out and torque it - Always remembering that torquing should be carried out in one continuous movement without stopping. If you stop and restart, the frictional forces increase and you won't get an accurate setting.
Some stretch bolts, car manufacturers say they can be reused, subject to them not exceeding the stretched length tolerance.
I always thoroughly clean the thread holes and where appropriate use bolt supplier lubrication etc. and it has been extra time well spent, as I didn't experience "CBJs" as we used to jokingly call come back jobs by dodgy mechanics.
I have seen "mechanics" tighten bolts where the threads are so dirty you can physically see the bolt spring back on release of the torque wrench etc. so it may have clicked off or met the degrees specified , there is no way it is pinching the head to the gasket etc. just dragging on the threads.
Much in the same way if you have a seized bolt when trying to undo without it snapping you can see it "springing" sometimes depending on where it is seized.
Some stretch bolts, car manufacturers say they can be reused, subject to them not exceeding the stretched length tolerance.
I always thoroughly clean the thread holes and where appropriate use bolt supplier lubrication etc. and it has been extra time well spent, as I didn't experience "CBJs" as we used to jokingly call come back jobs by dodgy mechanics.
I have seen "mechanics" tighten bolts where the threads are so dirty you can physically see the bolt spring back on release of the torque wrench etc. so it may have clicked off or met the degrees specified , there is no way it is pinching the head to the gasket etc. just dragging on the threads.
Much in the same way if you have a seized bolt when trying to undo without it snapping you can see it "springing" sometimes depending on where it is seized.
I take your point vexorg the whole point being that this process eliminates the friction factor which Mike so graphically describes above as causing problems. At the very least I'd be running a tap down the hole and blowing it out with an airline before running the bolt all the way in by hand to check it was free running. A lot of comebacks are due to ignorance or just plain simple "couldn't be bothered to take the time"!
I was deeply into Hillman Imps when younger and it was not at all unusual to find the holes in the block for the head bolts were stretched up proud of the block face. Then when you tightened the head down because the threads were pulled up above the block face you didn't get the clamping on the gasket. I think this was partly responsible for the bad reputation the imp engine got for blowing head gaskets? It was easy to check, just lay a file flat on the block face and rub it back and forwards a few strokes. If the hole had "pulled" you'd see a bright ring round it where the file had removed metal. Because I was doing it as a hobby I always drilled a chamfer on the hole to eliminate this pulled lip and then Helicoiled all the threads. Never had a problem with a road engine. The competition guys installed Wills Rings, but that cost too much and wasn't necessary for road use.
Some while ago I came across an interesting article on torquing up critical engine bolts. It's written for aircraft engines, but the engineering principles discussed are equally relevant to pretty much any internal combustion engine. It gets interesting towards the end of the second page, and reinforces most of what's being said in this thread.
The difference between torques for wet and dry bolts always surprised me. Or going further, ARP supply their own lube for the bolt/stud kits and have an even lower torque due to being super slippy.
Similarly, converting head bolts to studs give more control as the bolt is dragging more and more thread as it tightens, where as the stud conversion only has the nut as a constant.
Similarly, converting head bolts to studs give more control as the bolt is dragging more and more thread as it tightens, where as the stud conversion only has the nut as a constant.
I just read that right through jrk. Enjoyed it very much. Lots to think about when translated to vehicles. Thank you.
Cornish Ian
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Yes definitely very interesting.
Some years ago now I worked in the aero space industry doing defect investigation.
Most fastenings on our new or refurbished mechanical units were replaced for new, irrespective of cost, condition or age. An oil / molykote was often required to be applied to components and fasteners to reduce friction during assembly. Preload was so important that on most critical components an inspector was specified to be present to inspect the torquing of the fasteners.
It sounds from that article that aircraft engines do not always receive the same high standard that our design /production department used to work to though. Down to cost obviously but a bit of worry there on our next flight.
Agreed - the rear caliper carrier arrangement on 500s/Abarths is nuts! Plus internal hex studs routinely round off unlike normal setscrews. All a real ballache.
