One brake disc bolt wont undo

[IamGroot]

I'm about to replace the hub ball bearings in my 29er mountain bike rim and there always has to be one bolt that wont undo.
The other 5 bolts has some kind of loctite on the threads and were unbelievably tight and the head in the picture the T20 socket just slips in the head. I've tried all my T, PH and PZ sockets trying to get one to grips but because its either over tight or the wrong kind of loctite used it won't budge, oh and now the head insert id rounded.
What would my best option be, an eziout or would there be a pliers type tool that might grip and undo.
The rotor is 6 months old and was mounted by a bike shop mechanic.

[Duck!]

It should be a T25 Torx head, not a T20. There is often for some inexplicable reason one really tight one. Give the Torx key a tap with a hammer to seat it right down in the bottom of the bolt head and find some remaining corners to bite into.

[hedgehog]

and if you are out of torx key grip,cut a trench with a cutting angle grinder and use a flat screw driver.
and yes tap twist with hammer.

[IamGroot]

and if you are out of torx key grip,cut a trench with a cutting angle grinder and use a flat screw driver.
and yes tap twist with hammer.

Did this one and still no go, bloody tight. Went and purchased a 3mm eze out and 2 new drills to give the eze out method a go.

[Nate]

apply heat to the brake rotor & see if that helps.

[Thoglette]

to give the eze out method a go.

EZE outs rarely are.

Having b****d many bolts in many places, this is the LAST resort (before taking it to someone with an electric arc eroder to remove the remains of your drilled out bolt threads and the broken eze-out)

Heat*, penetrating oil, slotting the head and, finally, drilling the head off come long before reaching for the EZE out. If you've cut, ground or drilled the bolt head off, you should be able to grind flats on the remains to get enough grip in the vice to use the wheel as your lever.

If that doesn't work grind off the bolt at the hub (which is usually where the bolt will fail anyway) ; drill out the guts (with the correct undersize drillbit) and then remove the old threads. If they're not corroded in they'll come out with a little encouragement from a pointy object (big sewing needle with a bent tip) your eze-out or the correct metric tap, once you can seat it in the first few threads. Otherwise it's more corrosion; arc erosion or helicoils.

*I'm guessing the hub in which the bolt is seized is aluminium. That's where you want the heat as Al expands faster than the steel of the bolt. If you're removing the bearings and any plastic/rubber bits you can get quite carried away with the heat. But I find a few minutes in front of a standard "foot warmer" heater (get the Al almost too hot hot to handle =~ 50C) is usually enough to do the job.

[IamGroot]

to give the eze out method a go.

Thanks Dave, I'll this a go first. The only reason I want to remove the disc to is replace it, a big creek bed stone flicked up and bent the rotor.

[Tim]

Thanks Dave, I'll this a go first.

You've just ignored Thogllette's good advise;

EZE outs rarely are.

Having b****d many bolts in many places, this is the LAST resort..

I've tried using EZE outs on numerous occasions on boats and cars.
They have never worked.
All they do is screw into the broken stud or bolt, expand the diameter of the broken part and jam it in place even more firmly.
Try all the other methods first.
If that doesn't work I very much doubt that an EZE out will do the job.

[koshari]

If the t25 slips try peaning the head of the bolt in to make the hole slight ly smaller. If you have a screw gun use the rattle/hammer function. The shocking action often gets stuff away.

[human909]

There is often for some inexplicable reason one really tight one.

If it is often just one bolt, then there is likely a very logical reason for it.

Probably because of the bolt group receiving shaft loading from the braking disc. During initial loading one bolt will end up taking the full braking torque. Likely result might be might deformation of the disc until other bolts are subsequently loaded. This deformation would cause very slight disc expansion thus significantly increasing the tightness of the bolt.

It might seem perverse but tightening the bolts tighter initially may stop this from occurring. With appropriately tight tension the bolt group will resist the torque via friction rather than bearing so the the load will be more evenly spread across the disc.

[twowheels]

rattle gun ... anticlockwise.

[LG]

Had one recently that wouldn't budge until I gave the bolt head a tap with a cold chisel which freed it up. Generally IME heat as mentioned earlier and some kind of shock force (hammer or rattle gun if you have one) will work 90% of the time if a stuck bolt is going to come out at all, after that good luck.

[IamGroot]

All fixed and fitted the new disc and screws, ended up drilling off the head and then when I went to drill the stud with a 3mm drill she unscrewed.