Caliper Pistons Pitting

Discussion in 'Technical Help' started by DanielB, Dec 1, 2019.

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  1. DanielB

    DanielB Noble Member

    Jan 13, 2019
    881
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    Abingdon, Oxfordshire
    darn and blast....i got brake fluid all over a brake pad (the important side)...

    Do i need to scrap it, or will it be ok with a clean with brake cleaner...?
     
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  2. joe mc donald

    Subscriber

    Dec 26, 2014
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    slough / burnham
    DanielB.
    Depends how much. If they were saturated then replace. If just a splash clean them of with some petrol and give them a light sand of the medium emery. And dry out well. Should do the trick. Next time make sure you clean the disc's with brake cleaner to make sure they are clean and don't contaminate new pads. Hope this helps.
    Regards
    Joe.
     
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  3. DanielB

    DanielB Noble Member

    Jan 13, 2019
    881
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    Abingdon, Oxfordshire
    Thanks Joe. Saturated...I didn't realise when I had them off that as I was cleaning everything else the old fluid had pooled....guess where...right where my pads were sitting.

    Ah well.... what's another 25 quid when I'm this far in:confounded::confounded:

    These calipers are turning in to "Triggers broom"!!
     
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  4. joe mc donald

    Subscriber

    Dec 26, 2014
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    DanielB
    You are not on your own mate I certainly have doe similar as I am sure a lot of patrons on here would say. New pads will be a whole new lease of life to add to the work already carried out. Let us all know how you get on.
    Regards
    Joe.
     
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  5. Tricky-Dicky

    Tricky-Dicky Crème de la Crème

    Dec 12, 2016
    2,441
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    Norfolk UK
    I reuse pistons like this with no problem as that pitting is where the crud gets into the rubber boots...if you have them apart then measure the actual depth that the pistons can retract to ...most will still be slightly proud of the caliper and nowhere near the seal which normally sits further down the bore...but if it does then by all means replace them.
     
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  6. DanielB

    DanielB Noble Member

    Jan 13, 2019
    881
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    Abingdon, Oxfordshire
    thanks... I have however decided to replace the pistons. I have got a whole new set of pistons and seals (for two calipers) all for £100....so I am feeling like I am quids in - sort of... Whilst I hear what some of you are saying, I feel I won't rest easy unless I replace the pistons... Plus, it's always nice to have a package turn up in the post!

    (plus, plus, I put the address in my wife's name, so she will think she has a gift...) :laughing::joy::laughing:
     
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  7. DanielB

    DanielB Noble Member

    Jan 13, 2019
    881
    393
    Abingdon, Oxfordshire
    Afternoon all, progress is going good...but can't find a torque setting for the 4 (silver in photo) bolts that clamp the two halves of the caliper together.

    Any thoughts?

    IMG_20191208_132157.jpg
     
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  8. Tricky-Dicky

    Tricky-Dicky Crème de la Crème

    Dec 12, 2016
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    Did you undoo them? tighten them to aproximatly the same.
     
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  9. DanielB

    DanielB Noble Member

    Jan 13, 2019
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    Abingdon, Oxfordshire
    Thanks...I'll try that. They weren't too tight if I remember correctly....
     
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  10. DanielB

    DanielB Noble Member

    Jan 13, 2019
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  11. freck

    freck Elite Member

    May 4, 2017
    1,718
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    Preston, Lancs, UK
    I’d say about 20Nm will be about the right torque. I’m guessing they’re M8 bolts.
     
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  12. DanielB

    DanielB Noble Member

    Jan 13, 2019
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    Abingdon, Oxfordshire
    Thanks, my thoughts too...yes, m8.
     
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  13. capt

    capt Elite Member

    May 8, 2016
    3,050
    750
    western Australia
    Just use an air gun ! Low pressure !
     
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  14. DanielB

    DanielB Noble Member

    Jan 13, 2019
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    Abingdon, Oxfordshire
    I had thought that was indeed the only way Capt, however the foibles of my 955 calipers is that the air gun won't work. And, if it does, it'll only do so on one pair of pistons from each caliper....

    I could have bought an airgun...but I already had some sockets! :D
     
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  15. capt

    capt Elite Member

    May 8, 2016
    3,050
    750
    western Australia
    Put a block of wood in between the opposing pistons , all will move , lube and compress back in , reapply air , repeat until you can remove pistons. They will work loose. I used a lanolin based spray lube internally and rubber Grease externally. I pulled the the calipers apart on my last 2000 sprint this way.
     
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