Changing Brake Discs

[RickH]

OK ... finally weather allowed me to do this job ....

Had a loan of a code reader so retracted the EPB fine.
Armed with M7 allen socket, calliper pins came out OK, calliper removed and old pads out ....
Then the failure .... the M12 'Triple square XZN' bolts ..

I bought a set of 'Triple square XZN' sockets: https://www.amazon.co.uk/gp/product/B086WKD65Z/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
but the M12 is simply far too loose .... fully inserted you can give almost a 1/4 turn, only tips seem to be engagging, it will round out the bolts.
The set comes with M12 standard and a M12 long reach - and both the same ... far too loose.


This video shows how loose ... and as posters have said these are fitted with high torque they would round out

That is a brand new bolt - all 4 are the same.


This is even on the replacement 'new' bolts ...... so it looks like they are not M12 sockets... even though the thread measures as M12.
Reassembled for today .... may take bolts to a tools shop tomorrow to see if they have something that fits it ...... but the 2 x new M12 sockets I have are certainly too loose a fit.

Does anybody know if this is a 'VAG' specific tool ?

 

[Burnerman]

Pretty sure these are 14mm spline and you must use the 1/2" drive extension.
Laser tools do them, as do Halfords but please pay more for a quality bit....it'll end in tears if they round out!
John

 

[RickH]

They don’t measure as 14mm …. on new bolt ... its 13.5 Maybe that is tolerance for a 14mm

 

[Burnerman]

Either way, I'd head to Halfords or whatever and get a hold of the correct spline bit....sorry I'm not at home just now so I can't report on what's written on mine.
John

 

[RickH]

Reassembled and postponed job for today.

I can find ... https://www.ebay.co.uk/itm/273459348469?hash=item3fab7283f5:g:HZoAAOSwaf1bmjNi
or BGS on amazon https://tinyurl.com/kn39svxc

or also this BGS one https://tinyurl.com/yk8u2bj9

Not familair with BGS brand

..... either of those makes any good ?

 

[Mottie]

 

[Burnerman]

Those bits you list should be fine.....I don't use an impact wrench on these though but I do heat them up first.
You can sometimes wriggle the disc out if you slacken the centre hub nut if you get stuck......but not the SEAT type with the splined bolt.
John

 

[RickH]

As in heat to red heat ... or just a bit of localised heat to cause expansion.

 

[Burnerman]

The heat softens the locking compound that's on the screw threads and may help with the rust that's kicking around. I use my Mapp gas torch and get the threaded area nicely hot.
Believe me, the affect is significant!
Keep heat away from any rubber, cables and ABS sensors of course.
John

 

[RickH]

Smoking the seals not a good idea

The M14 Triple Square XZN socket bit ordered - so when I have that I will also apply some heat.

 

[Old Salt]

Dont think he’s started yet, at least another 4 pages to go

Told ya

 

[RickH]

Told ya

thank you ... helpful

 

[Mottie]

Well, I did tell you what bit to get in post #66. Even gave you a link..........

 

[RickH]

I had placed an order for the set just before I saw your post .. my fault set only goes to M14 I had incorrectly based it on the bolts being M12 thread diameter.
Now ordered an M14 XZN spline socket ..... have to do job next weekend (weather permitting)

 

[Old Salt]

thank you ... helpful

I offered help in post 33