Brake disc fixing hole size?

[PistonAFC]

Hi,

I previously had a lot of issues getting a brake disc off a hub. I noticed the discs have fixing screws to help get them off but I don't know what size they are. My car does NOT need/use screws to hold the disc on the hub so I thought I could use these screw holes to get the disc off the hib which has been on for 100k miles so will be rust welded on!! Does anyone know what size the screws usually are or other ways for a home DIYer get them off? I had to use many hard hammer strikes last time but looking for a gentler way that won't risk damage the hub.

The disc is the one below:

https://partsfinder.bilsteingroup.com/en/article/f...

Edited by PistonAFC on Saturday 3rd August 21:00

Edited by PistonAFC on Saturday 3rd August 21:00

[Fore Left]

The holes in the discs are not threaded so I don't see how they will be any help in getting the disc off.

Fair play on getting 100k out of a set of discs though

[Sheepshanks]

Think they're 8mm thread. Believe it's a bit of a Japanese thing.

[finlo]

Fore Left said:

The holes in the discs are not threaded so I don't see how they will be any help in getting the disc off.

Fair play on getting 100k out of a set of discs though

They are on lots, 17mm headed bolt {whatever thread size that is} just wind it in to push the disk off.

[Super Sonic]

Fore Left said:

The holes in the discs are not threaded so I don't see how they will be any help in getting the disc off.

Fair play on getting 100k out of a set of discs though

You should see how long he makes tyres last!

[Bainbridge]

The last time I had stuck discs, my ball pein hammer wouldn't budge them.

A couple of firm blows with a lump hammer and they popped straight off.

No apparent hub damage, but I appreciate it's not a very gentle way of removing them.

[hidetheelephants]

finlo said:

Fore Left said:

The holes in the discs are not threaded so I don't see how they will be any help in getting the disc off.

Fair play on getting 100k out of a set of discs though

They are on lots, 17mm headed bolt {whatever thread size that is} just wind it in to push the disk off.

That would be M10.

[stevieturbo]

Never had any issues just hammering them off.

the only way to know what thread might be on your discs...is to look/measure your discs. Nobody here can see them

[Sheepshanks]

hidetheelephants said:

finlo said:

Fore Left said:

The holes in the discs are not threaded so I don't see how they will be any help in getting the disc off.

Fair play on getting 100k out of a set of discs though

They are on lots, 17mm headed bolt {whatever thread size that is} just wind it in to push the disk off.

That would be M10.

Yeah, 17mm head seems too big. I’m sure they were 8mm thread on a Jazz we had and a quick Google suggests that’s the common size. M8 is normally 13mm bolt head.

[E-bmw]

PistonAFC said:

Hi,

I previously had a lot of issues getting a brake disc off a hub. I noticed the discs have fixing screws to help get them off but I don't know what size they are. My car does NOT need/use screws to hold the disc on the hub so I thought I could use these screw holes to get the disc off the hib which has been on for 100k miles so will be rust welded on!! Does anyone know what size the screws usually are or other ways for a home DIYer get them off? I had to use many hard hammer strikes last time but looking for a gentler way that won't risk damage the hub.

If they were lightly greased with an anti-seize grease when fitted they should come off just fine.

"Jacking screw" holes (what you are referring to) are typically 8mm, however if the discs are badly rusted & the holes weren't also greased for protection from rust then a screw/bolt may well not go in enough to be of help to you.

Normally a couple of swift hammer blows will do the trick and is quite normal.

One thing I was told all those years ago when I was an apprentice was "always assume YOU will be the next one to do the job again" which basically means treat to protect from rust & seizure with the appropriate grease, then you don't have the same trouble again.

[ARHarh]

They are a japanese thing as suggested. They are m8, a bolt that accepts a 13mm spanner. Just wind it in and the discs will pop off. Every japanese car I have had has these hole. sure I have seen it on other cars as well.

[PistonAFC]

For posterity they are M8 x 1.25mm and bolts available from from Toolstation for cheaps,

[gt40steve]

ARHarh said:

They are a japanese thing as suggested. They are m8, a bolt that accepts a 13mm spanner. Just wind it in and the discs will pop off. Every japanese car I have had has these hole. sure I have seen it on other cars as well.

Our Cayman has these, so perhaps other Porsche & VAG group cars do ? I've also seen them on Volvos. Much nicer than having to use a hammer.

[richhead]

ARHarh said:

They are a japanese thing as suggested. They are m8, a bolt that accepts a 13mm spanner. Just wind it in and the discs will pop off. Every japanese car I have had has these hole. sure I have seen it on other cars as well.

and if using a jap bolt it will be a 12mm head

[ARHarh]

richhead said:

ARHarh said:

They are a japanese thing as suggested. They are m8, a bolt that accepts a 13mm spanner. Just wind it in and the discs will pop off. Every japanese car I have had has these hole. sure I have seen it on other cars as well.

and if using a jap bolt it will be a 12mm head

Luckily it fits French bolts as well.

[spikeyhead]

I usually just loosen off the wheelnuts a little, drive to about 5mph and stamp on the brakes. Only once did that fail, and I had to take an angle grinder to the disc to get the thing off it was so corroded on