Using a Torque Wrench on the rear brake calliper

supersaian

Hello;

I am started using a torque wrench recently, and I just found that the space between one of the disc brake calliper fixing bolt and the frame is not enough to use a torque wrench. Did you guys facing the same problem previously? If yes, what is your solution?

cooldad

An extension.

Chunkers1980

Be a man, don't.

ilovedirt

I've never used a torque wrench on my bike, and have never had any issues resulting from this fact.

rockmonkeysc

You don't need a torque wrench, thats why god invented different length allen keys.

abarth_1200

If they weren't so expensive I would use eon, the amount of bolts I've either stripped or haven't dared undo again because I felt the threads crack.

I don't understand how you can gauge the torque by the length of an Allen key, within a couple of increments stated on said fastener to not over do it, or just as bad under do it.

Back to the op, go ahead use your torque wrench knowing you are doing things the right way, get an extension out your local hardware shop or eBay.

BigAl

You really shouldn't need a torque wrench on a bike. Granted, disc calipers need to be 'tight' - so do them tight. But not so your knuckles bleed.

Anyone regularly stripping bolts needs to back off a bit.

russyh

If you have a torque wrench then use it, ignore the above. I just probably wouldn't buy one if you don't. Unless you have loads of carbon bits. I just don't understand why you can't access the caliper bolts ? Can you post a picture? Alternatively cooldad is right fit an extension

ilovedirt

abarth_1200 wrote:

If they weren't so expensive I would use eon, the amount of bolts I've either stripped or haven't dared undo again because I felt the threads crack.

I don't understand how you can gauge the torque by the length of an Allen key, within a couple of increments stated on said fastener to not over do it, or just as bad under do it.

Back to the op, go ahead use your torque wrench knowing you are doing things the right way, get an extension out your local hardware shop or eBay.

Well clearly you're cack-handed enough that you need one. The rest of us normal people find it fairly easy to tell what's too tight and what isn't.

Chunkers1980

and if you're that cack-handed then having a torque wrench opens up a whole new world of cack-handed opportunities.

taffygriffiths

i use my torque wrenches quite a bit...

mostly on pivot bolts, where too tight or loose can mean losing bolts, or clamping a pivot bearing/bush.

ironically.. a broken torque wrench was the recent cause of a sheared shock mount bolt on my nukeproof... the absolute crap titanium bolt didnt help mind!

not particularly necessary on things like caliper bolts mind.. though common sense does come into play.

the world does seem a bit thin on common sense mind!

ilovedirt

How did a broken torque wrench cause a sheared shock mount bolt on your bike? Please don't tell me you just kept tightening until it snapped. In which case, yes, common sense does seem a little thin on the ground these days...

t0pc4t

if you weren't aware it was broken though...

rockmonkeysc

t0pc4t wrote:

if you weren't aware it was broken though...

You must be a bit ham fisted to be shearing bolts.

taffygriffiths

RockmonkeySC wrote:

t0pc4t wrote:

if you weren't aware it was broken though...

You must be a bit ham fisted to be shearing bolts.

If thats your conclusion, dont ever fly again on any major airline

sheared shock mount bolt was from the hex drive being formed very deep into the cap head of said bolt making it very thin at the join between the shank and the head.

with a 15nm torque and a broken torque wrench, the bolt went up to perhaps 25/30 nm (doesnt take that much more of a turn to achieve an overtorque like that) and sheared right at the join of the threaded shank to the cap.

so.. thats the story! shit bolt... broken torque wrench!

rockmonkeysc

When you overtighten bolts you weaken them so if it hadn't broken as you tightened it then it would have failed in use at that far over the correct torque.
Nothing wrong with the bolt, the problem was you over tightening it.

Chunkers1980

How the hell do you actually know that?

The Rookie

It's partially true, if you overtorque a bolt it can stretch (plastically, that is it won't return to the original size after loosening) that stretch in one direction means a narrowing in another (volume stays the same) which may (or may not depending on the load condition) weaken it, not always the case though.

t0pc4t

so, in conclusion, it is worthwhile using a torque wrench then?

Chunkers1980

Training yourself with normal allen keys is much more useful.

They are good as proper workshop tools but on most people's bikes at home they can cause more problems than they solve.

t0pc4t

what problems would those be then? Other than the rare occurrence of a broken torque wrench causing a sheared bolt.

rockmonkeysc

Chunkers1980 wrote:

How the hell do you actually know that?

Over tightening bolts to double the recommended torque hugely increases the tensile load on the bolt, this will reduce the bolts capacity in shear loading by a very large percentage.

t0pc4t

I make the cases for torque wrenches because I did exactly that btw. Over torqued some saddle bolts on my commuter, they failed in shear about a week and a half later. So I looked up recommended torque settings (which were considerably less than I thought) and did it with my torque wrench.

Chunkers1980

t0pc4t wrote:

what problems would those be then? Other than the rare occurrence of a broken torque wrench causing a sheared bolt.

Like if you can't even gauge how tight is tight enough then working out how tight each bolt should be and not just the bolt itself, the thread part

Chunkers1980

RockmonkeySC wrote:

Chunkers1980 wrote:

How the hell do you actually know that?

Over tightening bolts to double the recommended torque hugely increases the tensile load on the bolt, this will reduce the bolts capacity in shear loading by a very large percentage.

Point was how do you know it wasn't just a duff bolt. You were very cut and dry, you're wrong

t0pc4t

Chunkers1980 wrote:

t0pc4t wrote:

what problems would those be then? Other than the rare occurrence of a broken torque wrench causing a sheared bolt.

Like if you can't even gauge how tight is tight enough then working out how tight each bolt should be and not just the bolt itself, the thread part

as a rule of thumb I tend to get the torque wrench out if there's a torque setting listed for the component. On my saddle obviously they were just M6 cap screws so I googled 'm6 cap screw torque setting'

So I'm still not really sure how using a torque wrench causes more problems than it solves.

rockmonkeysc

Chunkers1980 wrote:

RockmonkeySC wrote:

Chunkers1980 wrote:

How the hell do you actually know that?

Over tightening bolts to double the recommended torque hugely increases the tensile load on the bolt, this will reduce the bolts capacity in shear loading by a very large percentage.

Point was how do you know it wasn't just a duff bolt. You were very cut and dry, you're wrong

It failed at near double the recommended torque. Nothing duff about that.

stubs

A few years back there was a display at the Motorbike Show where you could try and do up a bolt to roughly the right torque. 1st with a 3/8" socket wrench then with a Torque wrench no one and I mean NO ONE got close to the correct torque figure with the plain socket wrench most people were overtightening by 50 to 100% and quite a lot of them were pro mechanics. Virtually all Alen keys sold these days are too long my 1st set of keys were about half the length of sets sold nowadays.

Things like stem bolts are 5 or 6nm if you can gauge that accurately with an Alen key then you are 1 in 7 billion because no one else in the world can. I am quite happy numpties keep on swinging on overlong Alen keys because it pays for my Beer and shiny bike parts, I am pretty good at removing broken bolts.