How important is it to Torque Bolts?

[Son of a beesting]

This may sound like a silly question but I am having a chat with a mate at work.

I want to rebuild my front calipers in the coming weeks and I was looking at buying a torque wrench to make sure I torque them up correctly when putting it back together. The only thing is I dont have a torque wrench and they start at about £50 (halfords Pro).

He said not to worry and just tighten them up using a ratchet.

What do you guys think? Do you torque your brake bolts?

[Owenski]

I dont have a tw, but then again things have a habbit of falling off my bike...

I'd have one if I could be bothered to get one but I think it comes down to common sense. If something feels loose, tighten it more.

£50 is steep though, get to a market you'll pick one up for £20

[Son of a beesting]

Thanks for the response.

Not sure I wold trust a £20 one though?? And it probably wouldnt be accurate after a few use as well.

I am tempted to do it up so its 'tight'

[Scoobs]

I think I have a good feel for when a bolt is done up tightly enough and I would (and have done) be happy enough to tighten caliper bolts without the aid of a torque wrench. I wouldn't, however, trust myself to tighten the bolts holding the cylinder heads on - not because I couldn't do them up tight enough, but I couldn't guarantee they would all be torqued to the same degree.

[Owenski]

dont forget certain things get really really hot and so expand. Oil Filter, Sump Plug etc. Dont over tighten those just grip tight should do. Same with spark plugs, apparently its quite important to tighten the front sprocket nut, and use the locking washer if you change the sprockets over.
What kind of idiot would rush that job?:-dd

[Scoobs]

Sump plugs and spark plugs have compression washers so grip tight ain't tight enough in my opinion. The front sprocket nut has to be tightened to precisely "fookarn tight" as well. You can really lean on this bastid with a breaker bar.

[Son of a beesting]

Really? I was going to do an Oil change as well and I have always just tightened them to tight on cars and never had an issue!

[Scoobs]

Grip tight plus a bit more. Don't go trying to get another 2 turns on it. 1/4 should do it. Each to their own though. I take no responsibility for fooked sumps.

[Son of a beesting]

Yeah that is what I normally do on my car.

Never done it on a bike before! (oh-err!)

[keith_d]

Many years ago I tightened the cam belt pulley bolt on my car by hand. It didn't feel right but I ignored my instinct and ran the engine. No problems, and everything worked fine for a few weeks until the pulley dropped off and all the valves got bent.

Turned out I'd stripped the threads inside the camshaft. I suspect that if I'd use a torque wrench I would have noticed that the pulley wasn't seated properly instead of just tightening it until it looked right.

So, these days I regard a torque wrench as a good investment. It's a whole lot cheaper than a replacement camshaft and five valves. :smt013

Keith.

[Owenski]

Grip tight plus a bit more. Don't go trying to get another 2 turns on it. 1/4 should do it. Each to their own though. I take no responsibility for fooked sumps.

lol to be fair, isnt that how all people tighten things anyway lol.
"there thats tight enough now, and just a bit more for good measure"

lol. Maybe just me then but still made me laugh thinking about it.

[the_lone_wolf]

New bike : £5,000

150pc Socket set : £100

Haynes Manual : £19.99

That feeling when the bolt you're tightening suddenly goes loose : Priceless

Mechanical experience; For everyone else there's Torque Wrenches...

;)

[Son of a beesting]

the_lone_wolf: I am sure you have posted something good I just cant take my eyes of your avatar

[the_lone_wolf]

the_lone_wolf: I am sure you have posted something good I just cant take my eyes of your avatar

You know you love me, s'just more cushion for the pushin'

:smt008

[Scoobs]

the_lone_wolf: I am sure you have posted something good I just cant take my eyes of your avatar

Looks like he's been working out since the last time I saw him. ;)

Anyway - just to clarify. I do possess a torque wrench but I don't use it for everything. My choice and nothing has dropped off yet. ;)

[sunshine]

people use a torque wrench, i agree with leedsmatt tighten it up till its about right then just abit more for good measure. :)

[kwak zzr]

I have 3 TW's varing in nm (Halfrauds pro make) trouble is i never trust them? sometimes they click out early other times they seem way to tight! as scoobs said early'r i think i too have a feel for a thread and how much pressure you can put on it, ive never had a thread strip or break or had a bolt come loose.
If i was doing something serious like tightening a head down or summit then id use one.
My thinking is "if your ham fisted with a socket set then use a TW"

[Sid Squid]

It really comes down to how much you trust yourself to know when it feels right.
If you have relevant experience and have been spannering for some time you can probably be relied upon to make a useful enough estimation, if you don't then I'd say a torque wrench was a good move.

Also I echo the comments above about getting the same torque setting on something that has a number of fixings, often the specific torque isn't that critical - ensuring they're all similarly tightened is.

Don't overtighten the sump plug of an SV, the sump isn't separate form the cases, fixing it ain't as easy as with many other engines.

[boot]

I have two, a heavy duty Teng and a light duty Draper. I always find it satisfying to know I've done things as they should be.

I figure, they don't list all those settings for nothing.

[ophic]

I have a large cheap one from the market - only really use it on the rear axle nut, and even then it doesn't feel tight enough, so I usually tighten a bit more.

Anyone got a good method of testing torque wrenches?

[Steve_God]

I've been doing the odd bits and bobs of servicing my bike since I've had it (over 3 years) including a chain and sprocket change, and never felt the need for a Torque Wrench.
I too am tight with my money :p lol

Personally... if I started looking at taking apart parts of the engine, or other related internal type stuff, I'd buy one. But for now, I don't see the need :)

[timwilky]

If I have to use my big torque wrench anywhere near a bike there is something wrong. It is a 4ft 3/4" drive britool jobby I used to use for truck wheels.

I do have 1/2" and 1/4" drive ones as well for small stuff.

why use a torque wrench. Well the idea is to maintain a fastener within the elastic region of a stress/strain relationship. Once you have overtightened 2 possible effects are :-

you strip the threads or you have passed the fastener yield point (Not fracture point) and and stretching of the fastener which gives it its clamping effect is permanent and the more strain you apply there after will not result a proportional clamping force.

It is impossible without specialist fasteners to know the stress you are exerting on a fixing. Therefore fastener manufacturers have invested time and money in investigating torque needed under specific conditions (Ie dry, with thread lock, etc) that will produce a clamping force yet leave the fastener "elastic" and therefore exerting its clamping force.

[Dicky Ticker]

All this palavar and techno speak---learners code--tighten it till it strips and then go half a turn back:D NO NO NO

[yorkie_chris]

Most of torques in the haynes etc. are dry torques, so when you use copperslip, alloy antisieze etc etc you actually exert more tension force than the manual reckons.

So even with a calibrated torque wrench there is still some uncertainty.

[lee67]

i use a tw' for every bolt on every bike..im fastidious wi things like that..great tool:D

[yorkie_chris]

Inside engine nearly every bolt, outside I don't bother.

[embee]

Just an additional note to what the others have said.

Many modern engines have major/critical fasteners, i.e. cyl.hd., main bearings, con-rods, designed as "torque to yield". This means that the fastener is designed to be tightened until it is into yield, at which the clamping load is well controlled by the design of the fastener itself. This tightening is done with a torque/angle sensing system so it recognises when the torque does not increase proportionally with the angle turned and the material is yielding.

These fasteners are not intended to be repeatedly re-used, often a limit of one or 2 re-uses are specified (bearing in mind they are often already used once during manufacturing/boring etc.), then they must be replaced.

Since in the average workkshop the yield sensing wrenches are not that common, an alternative method of "torque plus angle" is specified for servicing, this applies a known torque which takes the fastener near to yield, then an angle of typically 90deg which is known to take it into yield but not so far that the material will fail.

AFAIK no commonly serviced fasteners, like brake calipers etc, are ever designed like this.

A word of caution is to be extra careful when dealing with fine pitch threads because the "feel" is much reduced compared to standard coarse pitch ones. Caliper bolts are often a fine pitch. When dealing with these I like to set the torque wrench at maybe only half the spec and see what it feels like, then work up towards the spec value in two or 3 steps, bearing in mind what the others have said about lubrication reducing the necessary/desirable torque compared to the spec, so if it says 28Nm in the book I might only use 25Nm (i.e. 10% reduction).

Often people over-estimate the necessary torque, a common one is with car wheel nuts. 100Nm is not all that much, a 1/2" torque wrench will be about 1/2 metre long, so needs 200N force at the end, i.e. 20kgf or only about 1/4 a typical person's weight.

I certainly don't use a torque wrench on everything, but like some of the others here I've been doing it for an awful long time. :-({|=

[G]

I am quite anal when torqueing up bolt. To many bad experiences in my early days of over tightening the like of pinch bolts....snap :oops::(:reaper:

[Taipan]

Inside engine nearly every bolt, outside I don't bother.

Same here. I dont like retorqueing bolts that have previously been done up with a TW. If I do I'd back off the setting a bit. In the main I have a "feel" for how tight to do things and its served me well so far....