How to collapse a drilled out bolt?

[Falco]

Having exhausted every other avenue, I find myself having to drill one of the pad pins out of my caliper. Apart from breaking one of the centre drills it has been OK.

But now I am at the point where most people say "collapse the bolt" and I am unsure how you do this? The major diameter is 9.9mm and the minor is 8.5mm. How far out can I drill before I damage the threads (I would guess 8.5mm?)

Will the head collapse on its own, or will I need to help it out with a gently applied punch pin on the outer edge or similar?

[davebike]

Brake calliper pin ?? if so it a 10X1.00 thread super fine

Not economic to do get a calliper

If you must you need a SET M10X1 taps

Drill 9mm if it central you on re cut thread starting with taper then middle and using bottoming tap to Finnish

PIG of a job to get right Without locking the calliper in a mill I bet you will not even get the drilling central !
I with years of experience and a workshop would not do it but a used calliper off ebay that what I would do
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Dave
NC750Xdct + others at work !
[email protected]

[Ichy]

Is the bolt only threaded at one end and can you drill that end?
With this kind of work I find left hand drills to be a very useful option. Don't drill the head off the bolt unless you really have to, it'll come in useful.
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[Ichy]

[c_dug]

Somebody is confused here.

If it's an 8.5mm 'minor' then it's a 1.5 pitch thread.

I don't know much about brake pins, but if davebike is right and it's a 10 x 1 then your minor drill size (in other words the drill required to remove the bottom of the thread troughs (for lack of a better term)) is going to be 9mm.

In any case, the idea is to drill out until the remaining bolt wall, including the threaded section is dead thin, allowing you to essentially pick the 'bolt' out of the 'nut'. I wouldn't go all the way to the minor limit unless I had it clocked up on a mill, as you'll likely damage the threads in the calliper trying to go so close by hand.

Work out what thread size the pin is first as you'll either be verging on damaging the threads, or still have a good quarter mm of bolt wall holding the thread in.

I agree by the way, I wouldn't feel comfortable doing this without at least a decent vice.
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[Ichy]

Question needs pics.
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[stinkwheel]

As above.

OR

Drill it all the way out and put a thread insert in. (if you can find someone with ai time-sert kit of the correct size, this would be a pretty good option)

OR

Make a plain pin from a bit of steel bar that goes snugly through your current hole and hold it in place with an r-clip on the inside of the calliper. Drilling a hole for the r-clip would be a challenge.
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I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Ichy]

Good answers stinky but doesn't a 10 mm calliper pin seems a bit large for a bike? I'm confused.
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[Falco]

[Falco]

[davebike]

[P.addy]

[Islander]

[stinkwheel]

Agreed. It just needs to not fall out. The thread isn't seeing any load, Even the pin is just preventing the pad falling out, it doesn't carry any of the braking force.

The pad pins on many bikes are pushed into place and held in place with a 1mm R-clip or a piece of lockwire.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Ichy]

[Ichy]

[Islander]

[Pete.]

[Ichy]

[Major Doss]

[WD Forte]

I've removed siezed bleed nipples and exhaust studs
using this method and probably fooked up as many as Ive fixed
so its desperate measures.
Good luck with it!

If you're near Bristol I'll have a go at tacking a hex key in for you
If you're not and you tell us your area
there mey be someone near you with the kit to try it
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bikers smell of wee

[MCN]

This thread is a pun.

The drill size for tapping may be metric or imperial and one or two sizes here or there. It is called a 'Tapping Size Drill' and can very easily be found by googling tapping size drill on Google.
If I was doing the job: Drill pilot and step-ups until easy out size.
I'd drill much smaller than tapping size first and hope the action of drilling loosened the remnants of pin and it could be removed with an easy out.
If no joy then go with the tapping size and dig out the bits using a pick.
Tap out.

The pads are only prevented from falling out by the pins. The sides of the backing rest on the insides of the caliper a when braking so there's effectively no loading on the caliper pins. Except possibly some squeeze out from braking.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Ichy]

[MCN]

[Falco]

Got it!

https://i65.tinypic.com/21jdlbq.jpg

(Honourable mention goes to the new 8.5mm drill bit)

Not got time to type a full reply as I have to go to work, I'll do a proper one when I get back.

Thanks for all the advice guys!