Torque on disk callipers?

[maul]

Ok so i had to change my back brake discs (rotors) because they were really badly rusted and pitted in an uneven way. And being a bit pretentious i decided to go for drilled and grooved it wasnt any more money so i went for it. But couldn't just have the racing look on the back so I ordered the same for the front. I know  I'm a fashion victim   but it looks so good. So £215 later I've got new discs and pads for every corner. They arrived and I went out to fit them being  handy with a spanner. The thing is to change the discs you need to take the caliper right off.  So on goes the socket set and it wont budge 2 bolts hold the thing on the back ones are m14 3square spline drive the fronts 21mm normal bolts but all done  up to silly tight. I got my torque wrench on it  and it was right off the scale before i could shift any of them.

My question is  why so silly tight  and how do i if i need to get them that tight again will i be able to if its off the scale of my torque wrench. Ive just done them up really tight  for now, and they do look great

[BNT1985]

Were the bolts rusted?

[Petunet]

Front brake backplate screwed onto the wheel bearing housing, tightening torque is 200 Nm.

Rear brake backplate bolts are 90 Nm + 90°.

 

[maul]

1 hour ago, BNT1985 said:

Were the bolts rusted?

No its only a 2015 model i was surprised the discs were in such a bad condition the bolts were fine.

 

1 hour ago, Petunet said:

Front brake backplate screwed onto the wheel bearing housing, tightening torque is 200 Nm.

Rear brake backplate bolts are 90 Nm + 90°.

 

Thanks Petunet that explains it. Not sure how to get them back to that, my torque wrench doesn't go up that high may have to ask my mechanic friend to tweak them up for me the last bit

[hatchy]

Was going to say they probably have angular torque as well. Don't know if I would recommend using a torque wrench as a breaker bar.  

[hatchy]

I remember too when doing the discs on my mk2 vrs that the ones that needed angular torque were meant to be renewed as they were supposedly 'stretch bolts'.

[fabdavrav]

288mm & 312mm size disc calipers are as follows..& I think the 340mm are the same as the same base caliper casting:-

 

Big bolts 200Nm (148lbft), can be reused just clean thoroughly!

Calliper pin 35Nm (26lbft) (always renew or thoroughly clean & use blue threadloc if ok)

Splash shield 12Nm (9lbft)

ABS sensor & brake disc screw 8Nm (6lbft)

[hatchy]

What's it like doing the rear discs on a mk3? On the mk2 it was a bloody nightmare as there was hardly any access to get at the caliper bolts.

[fabdavrav]

17 minutes ago, hatchy said:

What's it like doing the rear discs on a mk3? On the mk2 it was a bloody nightmare as there was hardly any access to get at the caliper bolts.

 

No idea as I have the MK7 Golf which has the electric motor in the rears...no handbrake cables....but you need VCDS....

[maul]

It's a bloody nightmare and I needed a special spline drive m14. You dont have any room to get a long enough bar in. Its probably much easier in a garage up on a proper lift. then the ground wouldn't get in the way and you could use a longer bar.

[hatchy]

35 minutes ago, maul said:

It's a bloody nightmare and I needed a special spline drive m14. You dont have any room to get a long enough bar in. Its probably much easier in a garage up on a proper lift. then the ground wouldn't get in the way and you could use a longer bar.

 

Starting to bring back bad memories LOL. When I did the mk2 I was doing it on the drive (luckily gravel) and I ended up digging a hole so I could get a longer breaker bar to 'crack' the bolt off. 

[maul]

I did use the wheel brace handle as an extension to my little breaker bar handle to get a bit better leaverage right up against the inner wing liner. My arms feel like i have been  to the gym and showed off on the weights.  everything  is hurting now, silly old fool lol.

[flybynite]

The reason they are tight is they are stretch bolts. VW group use them on most of their suspension and brake components.

 

They are tightened by first a torque then a further angle to stretch them. (Like 70nm + 90degrees) it is what stops them undoing and they are single use. It says under each of these torque settings in the manual “replace after each removal”

 

There will be all the usual people that say they have re-used them with no issue etc etc but that is what it says quite clearly in the factory manual. Personally I will occasionally use some of the less critical bolts again, only if I know for certain they were stretched no more than once previously. Bigger ones or anything on my brakes I replace each time.

 

I see nowhere in the Skoda manuals for suspension, steering or brakes that the 200nm torque setting quoted above is not paired with a further 180degree angle. That is quite critical. If it is not done your bolt is not ‘locked’.

 

There is nothing wrong with people maintaining their cars, but these cars have modern materials, processes and sometimes need particular tools. 

 

If you are going to mess with important bits of your car there is really no excuse not to have the correct information from the official source as it is so easy and cheap to get.

[xman]

Never reuse a stretch bolt. Once stretched they cannot be reused.

 

http://vwts.ru/skoda/octavia3/skoda_octavia_3_brake_systems_eng.pdf

 

 

Edited 17 February, 2018 by xman

[flybynite]

10 hours ago, Petunet said:

Front brake backplate screwed onto the wheel bearing housing, tightening torque is 200 Nm.

Rear brake backplate bolts are 90 Nm + 90°.

 

 

^^^^ This is correct. One of the places that does not use stretch bolts is the front caliper carrier. These can be re-used if clean and undamaged.

 

Most other large bolts are 200Nm+180° And should be replaced, as should the 90Nm+90° bolts for the rear carrier. It is all in the manual ...RTFM 

 

All the manuals are available in this post in the sticky at the top of the forum which is better than nothing I guess. I still say for what it costs you should get the up to date version for your chassis number from ErWin if you are actually doing these kind of things yourself.

[Petunet]

10 hours ago, maul said:

It's a bloody nightmare and I needed a special spline drive m14. You dont have any room to get a long enough bar in. Its probably much easier in a garage up on a proper lift. then the ground wouldn't get in the way and you could use a longer bar.

 

It wasn't that bad. Having a good impact wrench helps though.