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Does it really need new caliper bolts?

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by AndymacA4, Dec 30, 2008.

  1. AndymacA4
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    AndymacA4 Member

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    [Dec 30, 2008]
    I have set aside tomorrow to change the front discs and pads from 288mm to 312mm. I had a quick look in the old haynes manual to check I had all the right tools to hand. The haynes manual says that if you remove the caliper carrier bracket, you must use new bolts to put it back on. Now I have never changed a set of bolts when I have changed discs before. Is this just a best practice thing?

    I intend to put a line of blue threadlock on when they go back on to help keep them in place!

    Anyone got any views on the new bolts thing? I'd usually go and get some from Audi, but I really don't want to go across town at the moment, traffic is murderous!
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  3. docurley
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    docurley Moderator Staff Member Moderator

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    [Dec 30, 2008]
    That will work and I have never changed the bolts on any of the cars I have worked on.
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  4. AndymacA4
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    AndymacA4 Member

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    [Dec 30, 2008]
    Okay, I decided to attack my discs this afternoon. I got the caliper off, stripped out the pads, cleaned and hung the caliper, then I came to the caliper carrier. The bolt needs a 21mm socket I assume and I don't have one!

    The 20 was too small and the 22 didn't locate properly so it came off when I applied force.


    Is it a 21mm bolt, or am I just a weakling?
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  5. Macduff
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    Macduff Member

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    [Dec 30, 2008]
    My Honda VFR has the same thing in it's Haynes manual. You have to be careful re-torquing the bolts as you might find that the old ones stretch. However I've had the calipers off and on a few times before changing the bolts.

    One of the other reasons for changing bolts is that Audi might supply the new ones pre-prepared with threadlock. As long as you use a die to clean the old bolt and apply new threadlock (not too much) and torque to the correct setting you should be OK.

    I'll be interested to know how you find the brakes afterwards as I am considering this conversion and if you have the time, a step by step guide would be good :)
    #4
  6. AndymacA4
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    AndymacA4 Member

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    [Dec 30, 2008]
    I'll take photos as I go and I'll attempt a simple walk through. It's just a dirty tedious job! I always promise myself I'm not going to diy it again, then I forget!:jump:
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  7. Marko
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    Marko Member

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    [Jan 1, 2009]
    From memory I think it is 21mm I had the same prob! 22 seemed ok but 21 fit like a glove. I had to buy one. You'll be fine with the same bolts.
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  8. spartacus 68
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    spartacus 68 Active Member

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    [Jan 1, 2009]
    Yes it's 21mm. In my experience a closed-end spanner is more beneficial than a socket drive for removing the carrier. If it's stuck, a couple of sharp blows with a lump hammer does the trick.:whistle2:
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  9. AndymacA4
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    AndymacA4 Member

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    [Jan 1, 2009]
    Nice one, I have got hold of a 21mm socket, and if the temperature goes a bit above zero, I'll give it a go tomorrow! too cold to be sitting on cold concrete today!
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  10. Les 51
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    Les 51 A pint of Diesel please!

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    [Jan 1, 2009]
    Be careful with a socket, they were so tight when I did mine I split the socket and had to go and buy a ring spanner!
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  11. AndymacA4
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    AndymacA4 Member

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    [Jan 2, 2009]
    Right I have been defeated. I got the car nice and high in the air on stands, pulled of the calipers, tied them up and then got to the caliper carrier bolts. No movement, I WD40ed them, I GT85ed them, I left them to soak, I assaulted them with both a 21mm socket and a 21mm ring spanner. My full weight (which is a fair old bit) and nothing, I even assaulted them by whacking the end of the spanner with a big hammer. Nothing!

    I have never encountered a bolt that tight. I tried all 4, both sides, nothing. The only thing I haven't tried is a breaker bar as I don't own one yet.

    I used a torque wrench just for fun, it goes right off the scale!

    It is mental!

    I'm going to have to ask a garage to do it. Air tools might be able to do it!

    Any thoughts?
    #10
  12. evilscotsman
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    evilscotsman Space Cowboy

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    [Jan 2, 2009]
    the golf was the same mate, I used a long pipe on the spanner and broke the lock eventually, thats why they say new bolts should be used because the force to remove them is fecking massive.

    I got a breaker bar from an auto parts shop for £9, although they are £25 from halfords, and they are the dogs ******. The only thing is they will easily split a normal socket like chocolate, and are meant to be used with hardened "impact" sockets which are black.

    Heres a poit to remember, if you weigh 15 stone, thats 210lbs, so hanging from a 12" spanner with your full weight is still only 210 f/lbs of torque, a lot, but not enough. If you get a 24" breaker bar, your force is doubled to 420 f/lbs max, so you will do it a lot easier using half the energy.

    You can also heat the bolt surroundings with a gas burner but carefully so you dont boil the fluids or burn anything, that will help but a BB & impact socket should get them off.

    Also if your left handed, make sure you were trying in the right direction???
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  13. AndymacA4
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    AndymacA4 Member

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    [Jan 2, 2009]
    Nice one, I'm going to leave them as is for the time being, I'm going to be on the look out for a breaker bar in the jan sales if they ever start. I picked up a guaranteed for life Halfords 21mm Socket so if it does break it can go right back!

    Impact Wrench might be a nice after Christmas pressie to myself!
    #12

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