Calliper bolts, 12 point socket?

**Bohica** · 25th February 2025, 07:11 AM

Is there a special socket for these? I use what I think of as a 12 sided socket.

**p38arover** · 25th February 2025, 08:02 AM

I can’t remember if it’s a standard 12 point socket or a reverse Torx.

**AK83** · 25th February 2025, 08:33 AM

IIRC std 12 point socket 19mm???

it will be normal for a socket to be hard to get onto the bolt unless you've been absolutely thorough in cleaning the underside after some off roading.
A small amount of crud on the bolt head makes it difficult for a 12point to slide on easily. give them a wire brush and I think they will go on more easily, if this is the current issue.

**Bohica** · 25th February 2025, 09:39 AM

A standard 12 point is just a regular 'normal' socket? What I think of as 12 sided?

**Tins** · 25th February 2025, 09:51 AM

Originally Posted by Bohica

A standard 12 point is just a regular 'normal' socket? What I think of as 12 sided?

Yep. Just a standard, double hex, socket in this case, and generally. But, it wants to be a good quality one, as the bloody things will be tight, and/or loctited and a cheap socket will break.

**Bohica** · 25th February 2025, 12:17 PM

Originally Posted by Tins

Yep. Just a standard, double hex, socket in this case, and generally. But, it wants to be a good quality one, as the bloody things will be tight, and/or loctited and a cheap socket will break.

Thanks, it's the terminology that gets me, double hex sound right. As for tight, the fronts are 180Nm!

**Blknight.aus** · 25th February 2025, 12:18 PM

they are a special 12 point bolt, the angles on the faces are made by 3 squares offset 30 degrees and not from 2 hexs off set. that said, a normal bi hex socket works fine but as mentioned, get a good set off the top of my head the torqing and retaining are 110nm, with spring washers, with loctite 263. break out torque is usually in the 400+nm range

**p38arover** · 25th February 2025, 03:55 PM

After seeing Dave’s post above, I did a little research and found it’s called a triple-square bolt. I’d never heard of it before.

See File:Screw Head - Triple Square.svg - Wikipedia

Thank you Dave.

EDIT:

triple-square.JPG

**Bohica** · 25th February 2025, 08:04 PM

Well, now I know, thanks guys for the info. The next question is, why use this type of bolt? They had spares left over from something?

**Blknight.aus** · 25th February 2025, 08:35 PM

Originally Posted by Bohica

Well, now I know, thanks guys for the info. The next question is, why use this type of bolt? They had spares left over from something?

its a grading thing.

automotive bolts are usually grade 3,5,7 for imperial or 6.6 8.8 10.9 and 12.8 for metric certain fasteners that must be of a certain standard can have a different bolt head for 2 reasons

1. to identify it. I know when I look at a caliper if it doenst have the 12 point or the allen key socket head then I might have the incorrect bolt in the hole
2. drive torque, Some of the torque specs for the bolt are high enough that a 6 point head wont give a good engagment and can cam out of the socket as you're leaning on it. They also accept a higher torque loading in general due to a higher number of points of contact and a lower distance from the engagement point to the root. (same concept as 10 spline vs 24 spline axles given the same metal)

a third reason can be to do with the initial machine aseembly, the 12 point bolts stay in the socket much better than the 6.

Thread: Calliper bolts, 12 point socket?

Thread Tools

Calliper bolts, 12 point socket?

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions