Sheared a bolt.

[Liroka]

I've sheared one of the bolts while trying to remove the old rear brake disc, is there any way I can remove it without resorting to a drill?


Also, has anyone got any tips on removing the rest of the bolts as they all seem to be well and truly stuck?


Many thanks

[darrsi]

Easier said than done i'm afraid, i did exactly the same, all were stuck then one snapped, i ended up buying a 2nd hand wheel to get the bike back on the road as quick as possible.
Took the old wheel into my machine shop at work and they couldn't budge them either so i binned it.
The heat transfer from the disc through the bolts welds them to hub, it's a proper pain.

[unfazed]

Heat is your friend here, since the hub is aluminium and the bolts are steel the wheel will expand faster than the bolts and allow you to undo the bolts. Be aware they are also loctited in place which makes it even more difficult but the heat will soften the loctite, good luck.
If necessary they can be drilled out. In the past I have drilled holes down throught the bolts prior to attempting to undo them as it is easier to centre the drill in the hex hole than trying to centre it on a sheared bolt.

[Liroka]

Cheers for the replies. Seeing as I'm a ham fisted numpty at the best of times I've gone with the option of picking up another wheel. This way, I can get the bike back on the road and also allow me time to get the existing wheel sorted properly.

[darrsi]

I'll be changing my disc again in the next few months, i hope i don't have to go through all that again.
I had a friend giving me a hand who's very mechanically competent and we tried soaking the bolts as much as possible, heat treatment, brute force and a lot of swearing, then when the only bolt we could budge snapped in half i knew it was game over and time for Plan B.
It was a bit more comforting to know that they couldn't budge them at work either!
And there was me thinking i'd quickly change the rear disc and pads.
"How hard can that be?" 

[keithfzs1000]

for future reference
gentle heat, lots  penetrating fluid then an impact driver with a star drive 
ruins the bolts  but never snapped a disc bolt yet 

[Mutleyx]

In the past I have drilled holes down throught the bolts prior to attempting to undo them as it is easier to centre the drill in the hex hole than trying to centre it on a sheared bolt.

Very good idea that!

[darrsi]

Is there not a trick to prevent them seizing in the first place?
I torqued mine up properly, but i've absolutely no doubt the previous owner would have jumped up and down on an extension bar to tighten the bolts, judging by the state of the bike when i bought it, and the things i found wrong with it.
Finding 4 litres of oil in the engine for example got me off to a bad start..... 

[AdieR]

One method worth trying is welding a nut on the sheared bolt.
Getting steel (or stainless) screws out of ally is always a ball-ache anyhow, plus they they're Loctited in.
It's a galvanic reaction between two dissimilar materials that cause the seizure.

One common error when tightening bolts is to use ratchets etc that are far bigger than need be for the job in hand (compare an Allen key with a socket ratchet / bar for length and you'll see what I mean) - even a long Allen key can apply far more force than is often realised.

[darrsi]

One method worth trying is welding a nut on the sheared bolt.
Getting steel (or stainless) screws out of ally is always a ball-ache anyhow, plus they they're Loctited in.
It's a galvanic reaction between two dissimilar materials that cause the seizure.

One common error when tightening bolts is to use ratchets etc that are far bigger than need be for the job in hand (compare an Allen key with a socket ratchet / bar for length and you'll see what I mean) - even a long Allen key can apply far more force than is often realised.

I'd imagine anyone who doesn't use a torque wrench will over tighten the majority of bolts on a bike.
The torque setting on disc bolts feels very light when it hits the clicking point, and you almost feel like giving it that little bit extra.
Add the fact that the heads of the bolts seem to be made from marshmallows and you can quite easily turn a very simple job into nightmare. 

[richfzs]

Beat me to it darrsi, the "common error" is not using a torque wrench. None of us can guess, and consistently get right, when they've tightened a bolt to (say) 10Nm, particularly when the lengths of the tools being used is constantly changing.

A torque wrench is not massively expensive these days, but can save you from a very expensive or dangerous mistake.

Sent from my HTC Desire S using Tapatalk 2

[darrsi]

Disc bolts in particular should always be torqued, for evenness and to discourage a world of pain when trying to remove them, 'cos they're not meant to be tightened up too much, only 23Nm which feels like nothing, especially if you're heavy handed.

[AdieR]

Just as a point of interest, the torque figures quoted by factories are for clean, dry (new) threads (it's reliant on a given friction level). If a thread is rusted / dirty, or indeed oiled (as some people do), the friction level alters (therefore, even with a wrench, the final torque figures can still be "wrong", if you see what I mean).

I recall a gut-wrenching error by a lad working on his mates bike years ago: said lad was a bit of a know-all (his brother was a mechanic), and took a spark plug out. On re-fitting it, rather than heed the advice of other, clued up mates (ie, finger-tight-and-a-fraction-more), he uttered those infamous last words "I know what I'm doing" and promptly stripped the threads from the cylinder head...

I also remember working for a marine engineering firm about 10 years back and had a bloke ask to borrow my Allen keys (not an inexperienced apprentice either, but a bloke 6 month from retiring) to strip a pulley from a trawler. Seized with rust from years of salt water spray it were obvious (to me anyhow) it were obvious it wouldn't move easily. Allen keys came back chewed up (they weren't cheapo things either), and the screws totally unmoved.