Torque wrenches

[Owl]

Someone like myself working on my own bike at home can take all the time in the world to do a job.

Pretty much how I feel about it.

Perhaps overkill, but I even torque my oil filter

[Brian d marge]

Ok, so if you think 50 lb-ft is ok on an axle nut that calls for 70 lb-ft - then is 40 lb-ft ok as well...??? Where is the line of it not being tight enough...???

On earlier GSX-Rs with the basically box section aluminium swingarms - you could damage them by over tightening the axle nut and you started to crush the aluminium. People using a torque wrench to factory spec would more lightly avoid that damage.

A GSX-R forum I hang out on is constantly getting people who have over tightened their sump plug and actually cracked the bottom of the sump pan. The thread didn't strip first - the pan cracked! People who use a torque wrench on the sump plug don't seem to have as many problems with them. Once someone that has tried to guess by hand and over tightened - has stretched and damage the thread from then on in.

I can understand mechanics at bike shops not bothering to use torque wrenches as much on routine maintenance jobs because of the large number of different bikes they see each day. It would be impractical to keep workshop manuals for every bike in existence and/or to take the time to look torque specs up all the time.

Someone like myself working on my own bike at home can take all the time in the world to do a job.

To answer your questions;

box section swing arm the box section shouldnt deform at all due to tightening of the nut on the shaft if it does , something else is wrong i.e and incorrect spacer or axil adjuster and if the axil digs into the aluminium . ( i think this is what you mean) then super mechanic needs to stop with the roids,,, or spread the load.

sump bolts answered later on ,,see ( insert required )

Technical info is readily available , a decent shop should have the infomation at hand ( in England it was a phone call to Chiswick in london ) and One should brng the tools ( and info ) to the Job ( IMHO and if you look at some race mechanics you will see them do the same tools in a tray brought to the bike )

so
Tis why you pay a professional , ( ie someone who has been trained properly , me Honda factory ,,bits of paper to prove it ,,,and 20 odd years of experience and still not as good as some I have seen )

As I said , the nut should be tightened to 90 % of its proof , or until the required stretch Has been produced ,

Opening bottle of wine ........

not being faseecious here , but a nut and bolt work like a big ole wedge that just happens to be wrapped around a cylinder , the wedge stretches the cylinder , the resulting residual stresses , must be more than the loads acting upon it , or the cylinder will stretch more than the wedge made it stretch , and the nut will loosen

In worst case conditions ( dry thread into dry thread ) nearly 50% of the force required to tighten the bolt can be used in overcoming friction , ( ie your torque wrench goes click , but the bolt is loose ) or ...

you require LESS torque as the thread is well lubricated and the thread will reach its limit sooner ..( sump bolts anyone ? ) ( from memory the difference is about 60 % Less force required on a oil lubed thread to reach the same stress level)
typically its the first couple of threads that take most of the load , and tend to be the first to go..
so ...as I said the Torque wrench is a good guide ( if you need one ) to bolt/thread stretch but not the be all and end all and for gawds sake dont trust it ....

Now on saying all of the above , snug , plus 180 Is More than enough for a 10mm dia stud into and alloy block ( Bmws Course thread?? cant remember ) and would be difficult on an inch dia steel shaft probably snug and a quarter if you are lucky ( someone else can help me here )
remembering all you are doing is compressing the top few female threads so that the compression is not removed during service ,,thats all ,,,, OR making the thread yield ,ie beyond its elastic limit ....( soft LM2 threads ,,, ie butter require a careful hand )
So for fine alloy sump bolts , Depends on the amount of leverage one applies , ie the spanner used
Car spanners can to be longer than bike ones and more robust, add a small amount of force and bingo, top thread goes ..

So choose right spanner for Job, and add 20 years of feel and bingo job done, ( con-rod in a vice , old of course , then tighten and measure stretch of nut and bolt ,,,,you get the idea, others may have differing methods )

now on saying all of that!!!! , i prefer the cheap , repco scale type , and then check the calibration , ( as per other posts ) marking as per

Then add a touch of feel , just because the manual say 12 lb , it may be a reused bolt that has stretched, ( Junked ) or super mechanic has wailed on the bolt , into soft alloy threads and they have yielded ( insert required ) or a whole host of reasons that you will never get 12lb.ft or it will strip Before you reach 12 ..

If you are really worried about a bolt coming loose , clean dry thread and a dab of low strength loctite , ( love the stuff I do )

So at the end of all that , it comes down to don't blindly follow the manual , think about what you are doing and whats happening , if in doubt , stop and think ,,, thinking is free and saves a ton of money and a torque wrench is a guide only , nothing more nothing less ( a handy guide , hence I like the scale ones )

A Engineer I like is a guy called Carrol Smith

he does a range of books one called . the nuts bolts and plumbing handbook

its a good read ,, non technical

got carried away ,,,again sorry Might edit this later ,,,,,,for clarity ..

Stephen

[dipshit]

box section swing arm the box section shouldnt deform at all due to tightening of the nut on the shaft if it does , something else is wrong i.e and incorrect spacer or axil adjuster and if the axil digs into the aluminium . ( i think this is what you mean) then super mechanic needs to stop with the roids,,, or spread the load.

Take a look at earlier Suzuki swingarms... http://raresportbikesforsale.com/wp-...alter-wolf.jpg

An over tightened axle nuts would slightly dent the soft alloy under the washer.

Technical info is readily available , a decent shop should have the infomation at hand ( in England it was a phone call to Chiswick in london ) and One should brng the tools ( and info ) to the Job ( IMHO and if you look at some race mechanics you will see them do the same tools in a tray brought to the bike )

I doubt your typical NZ bike shop mechanic will be assed to go find out though.

you require LESS torque as the thread is well lubricated and the thread will reach its limit sooner ..( sump bolts anyone ? )

Obviously factory spec takes that into account for recommended torque for sump bolts though. Very few people have trouble with sump bolts when they use torque wrenches.

If you are really worried about a bolt coming loose , clean dry thread and a dab of low strength loctite ,

It's not just about a bolt coming loose... it's also about the amount of force that is put through a system. Like the rear wheel for example. It is only the torque of the axle nut that is holding it in place. Loosen the axle nut and the rear wheel is free to move, yes.

Same for the pinch bolts on the fork tubes or front axle... or bolts holding the suspension linkages... or engine mount bolts. Proper torque is part of their design for those things to work properly.

[Brian d marge]

Take a look at earlier Suzuki swingarms... http://raresportbikesforsale.com/wp-...alter-wolf.jpg

An over tightened axle nuts would slightly dent the soft alloy under the washer.





I doubt your typical NZ bike shop mechanic will be assed to go find out though.




Obviously factory spec takes that into account for recommended torque for sump bolts though. Very few people have trouble with sump bolts when they use torque wrenches.





It's not just about a bolt coming loose... it's also about the amount of force that is put through a system. Like the rear wheel for example. It is only the torque of the axle nut that is holding it in place. Loosen the axle nut and the rear wheel is free to move, yes.

Same for the pinch bolts on the fork tubes or front axle... or bolts holding the suspension linkages... or engine mount bolts. Proper torque is part of their design for those things to work properly.

Stop typing , stand away from the keyboard

did you not read anything I wrote

Designing bike bits is what i do for a living ,,, the new house I am living in is being paid for by ,, bike bits

Torque wrenches have their place in the big scheme of things ,,, but they must be used by a semi literate human being , with a working brain

Stephen