What type of socket/ bit do I need for this?

[jgy6000]

On the back of a Mercedes calliper

Is it a 12 spline? I can only count 10!

[Collectingbrass]

Could be a T45 Torx bit, see here http://www.pelicanparts.com/techarticles/Mercedes-...

[E-bmw]

Torx are 6-point & without "sharp" corners, that is 10-point with sharp corners.



I have never seen a 10-point socket head fastening before, are you sure it needs to be undone?

[jgy6000]

I'm starting to doubt if it needs to be undone now!
I thought it did to allow me to change the pads but I can't find anything on the internet that matches these bolts

[E-bmw]

That sounds like your answer then.

Do you have any better pics showing the rest of the caliper so we may see another way.

[E-bmw]

Or, perhaps if you are unsure of what you are looking at the best way would be to take it somewhere more familiar with the car to do it for you.

After all, the car stopping when required is pretty important!

[melhookv12]

Looks like you need to undo the 13mm (?) Bolt there should be one top and bottom. But in all honesty if you can't see how they come apart take it to a garage. Brakes shouldn't be messed with, no offence intended. ☺

[normalbloke]

E-bmw said:

Torx are 6-point & without "sharp" corners, that is 10-point with sharp corners.



I have never seen a 10-point socket head fastening before, are you sure it needs to be undone?

That's not a Torx, that's half an oil pump......

[DrDeAtH]

jgy6000 said:

On the back of a Mercedes calliper

Is it a 12 spline? I can only count 10!

Those appear to be holding the caliper halves together.
You need the normal shaped hex head bolts to be undone..

[E-bmw]

normalbloke said:

E-bmw said:

Torx are 6-point & without "sharp" corners, that is 10-point with sharp corners.



I have never seen a 10-point socket head fastening before, are you sure it needs to be undone?

That's not a Torx, that's half an oil pump......

Look 1/3 way down the page.

http://www.ctatools.com/index.php?route=product/pr...

Oil pumps have flatter points to allow sealing on the shoulders of the splines.

[Mr2Mike]

DrDeAtH said:

Those appear to be holding the caliper halves together.
You need the normal shaped hex head bolts to be undone..

Which just goes to prove that the manufacturer was actually quite wise to use a special bolt head in this case.

[Krikkit]

I think that's an XZN socket cap as often used by VW/Audi etc in high-torque applications.

I've got a set of these which are tremendous: http://www.amazon.co.uk/Tx-Star-Spline-Mechanics-P...

[Jakg]

Krikkit said:

I think that's an XZN socket cap as often used by VW/Audi etc in high-torque applications.

I've got a set of these which are tremendous: http://www.amazon.co.uk/Tx-Star-Spline-Mechanics-P...

XZN = Triple Square = 12 points

OP's is 10 points.