Can't get a 12mm bolt off a brake caliper?

missing_link_2

boingsaidzebedee wrote: »

Anyone recommended the mobile phone handy for when the car sways off the jack onto your legs ?
Make it secure with blocks and never trust a jack---just a suggestion.

good advice...I do hope rix195 is ok,he hasn't replied.
Anywhere near Manchester rix195?

vaio

is this a 12mm head (so M8 thread)? or a m12 thread (so 19mm head)?

If it's the former then forget breaker bars etc as anything more energetic than putting a spanner on it and bouncing your hand on the end is likely to shear the head off.

M8 is likely the fixing used on the sliders, M12 could be fixing the calliper to the hub

forgotmyname

I assume they meant a 12mm spanner, Which did seem a bit small to me.

Usually 14mm - 17mm, Thats why i queried the correct bolts in a previous post.

mgdavid

forgotmyname wrote: »

I assume they meant a 12mm spanner, Which did seem a bit small to me.

Usually 14mm - 17mm, Thats why i queried the correct bolts in a previous post.

never good to assume but setting that aside, I've worked on many cars with 12mm heads on the sliding pad holders...

vaio

Everything I can remember with a 12/13mm head is M8 for sliders and "bouncing" a hand on a spanner on them will undo them (or snap it)

Fixings for callipers to hub are M10 or 12 (normally fine thread and 10.9 or higher tensile strength) which will have a 17/18/19mm head and might well need a breaker/impact wrench/hammer to loosen them

Maybe the OP will return & clarify

TrickyWicky

vaio wrote: »

Everything I can remember with a 12/13mm head is M8 for sliders and "bouncing" a hand on a spanner on them will undo them (or snap it)

I find the best way is to pull the spanner / ratchet as hard as you can and then just keep the pressure on without trying harder. Eventually the nut or bolt will give way and crack loose under the constant pressure thats applied to it. It doesn't always work but it does most of the time.

Wig

It's a 12mm head on an M8 bolt. they do get tough, and you should never IMHO use thread lock, there is simply no need on these. If you want to check for re-tightening, after a few hundred miles you can do that..

They will come off with an 18inch bar on a 12mm impact socket, with not too much force. If it is an 8in - 10in ratchet you will struggle a lot.

westwood68

Wig wrote: »

There would, however, be no point using WD40 or Plus Gas because the bolt threads are deep inside the caliper and nowhere near the bolt head which the OP can see.

Ever wondered what the term "penetrating oil" means?

OP. Just ignore this advice. Plus Gas *will* get down the thread to where you need it. I speak from experience

Wig

westwood68 wrote: »

Ever wondered what the term "penetrating oil" means?

OP. Just ignore this advice. Plus Gas *will* get down the thread to where you need it. I speak from experience

Rubbish and totally unecessary.

There won't be any rust for a start, which is why it's unecessary, that and the fact that this *will* easily undo with a 18 inch bar and a small amount of effort turning the bolt in the correct direction.. The bolt is about 2.5 inches long half of it has no thread, the bolt is in a horizontal position. You could spray a whole can on the head of this bolt and none of it would reach the thread but you will have a nice puddle on your driveway.