Replacing disc brake pads (GT85 contaminated)

TomM546
TomM546 Posts: 5
edited November 2010 in Workshop
I recently got a Candondale Bad Boy which has hydrolic disc brakes.
The brakes have been contaminated with GT85 and are now totally slack.

I have been quoted by evans cycles, that each set of brakes pads will cost £12 + £30 to fit, so will cost £84 in total
This seems a little excessive to me, however I am certainly not skilled enough to do this sort of thing myself.
Anyone have any experience of this, or can advice that this is what I should expect to pay?

Comments

  • Monty Dog
    Monty Dog Posts: 20,614
    DIY - it's pretty straight foward. Check out www.parktool.com for detailed instructions. Basically remove the wheels, open the master piston, push the pistons back into the body, release the retainer clip and remove the pads. Clean caliper, fit new pads / retainer clips and follow makers instructions for reseating.
    Make mine an Italian, with Campagnolo on the side..
  • rich164h
    rich164h Posts: 433
    Should be really easy to remove and refit the pads. On my juicy 3's all I need is a flat headed screwdriver. When you do it though, look at how the springs hold the pad as it will make refitting them back much easier.

    Before you buy new ones though try roughing the old ones up with some sandpaper. The contamination might just be on the surface and rubbing the top layer away might be enough to allow you to refit them rather than replacing them.

    Make sure you clean the disks as well with some sort of detergent (washing up liquid perhaps) to fully remove any GT85 that's still present.
  • christurbo
    christurbo Posts: 432
    Buys some surface cleaner used for car brakes. That will get rid of your contamination.
  • Andy!
    Andy! Posts: 433
    £30 to change brake pads! Did they show you the bottom lube when they quoted you?

    What brakes are on the bike? should be pretty straight forward to change the pads. £5 per brake should do it if you are buying the pads from them.

    apparently you are not supposed to use car brake cleaner on bike brakes but you need so little the extra cost of bike specific disc brake cleaner is not a problem and it's handy to have some for those little GT-85 incidents. when doing car brakes you can easily go through half a can but at £1.80 a tin it is nothing. Bike disc brake cleaner is normally about £6 for a large tin - I get the yellow finish line one and it is very good.
    Merlin Malt 2
  • fleshtuxedo
    fleshtuxedo Posts: 1,860
    They want £60 to change your brake pads? :lol:

    Go to another bike shop and they'll do it for much less than that.
  • ugo.santalucia
    ugo.santalucia Posts: 28,337
    Look...

    I've learned to change the pads without any instructions or videos... it's very straightforward... it takes a bit of fiddling with the allen key to get them well aligned, but we are talking minutes, really...

    DIY, you really can't do it wrong... the difficult thing would be to change the fluid, that requires some knowhow, but you don't need to do that

    The price you were quoted is simply ridiculous
    left the forum March 2023
  • ugo.santalucia
    ugo.santalucia Posts: 28,337
    In addition,

    I understand the porous structure of the pad might have absorbed the oil, but surely the process is reversible, just by dipping them in saying petrol or other organic solvent, the oil should be washed off.

    Worth a try, before giving up on them
    left the forum March 2023
  • crankycrank
    crankycrank Posts: 1,830
    Sand the pad surfaces down with some sandpaper (not sure if that is the proper UK term for abrasive paper?) on a flat surface until the pad surface appears new again. Replace pads in calipers and enjoy.
  • keef66
    keef66 Posts: 13,123
    Sandpaper is the correct colloquial term this side of the pond too. Lots of others; emery, carbide, wet'n dry etc etc.

    I know the manufacturers always say you should bin any contaminated friction pad, but I have successfully decontaminated them on several cars using hot soapy water, thorough rinse, and recondition when dry with something clean and abrasive on a very flat surface.
  • jairaj
    jairaj Posts: 3,009
    Get some bike specific brake cleaner or some IPA and try giving the pads a clean first. (Car brake cleaners can be too aggressive and damage bike pads)

    If that doesn't work then get your self some new pads from http://superstar.tibolts.co.uk/index.php?cPath=21

    And use the Park tool guide and fit them your self. Depends on the brake manufacturer some are easier than others, eg Shimano is dead easy. But even the trickiest of brakes are still not worth going to an LBS to fit them and most definitely not worth paying that crazy price!
  • TomM546
    TomM546 Posts: 5
    OK so today I took the bike to a local cycle shop.
    They took the pads out for me, sanded them down and cleaned the discs. The brakes are better, but still not that good.

    The brakes are:
    Tektro Aigura Sub

    Apparently the pads are a new design, and so I the mechanic couldn't find any replacements, so I've had to order some from manufacturer.
    Although he quoted £8 to replace each pair. A lot better then Evans.

    Still, what a costly error.
  • ugo.santalucia
    ugo.santalucia Posts: 28,337
    TomM546 wrote:
    OK so today I took the bike to a local cycle shop.
    They took the pads out for me, sanded them down and cleaned the discs. The brakes are better, but still not that good.

    The brakes are:
    Tektro Aigura Sub

    Apparently the pads are a new design, and so I the mechanic couldn't find any replacements, so I've had to order some from manufacturer.
    Although he quoted £8 to replace each pair. A lot better then Evans.

    Still, what a costly error.

    You've probably noticed how easy the job is... anyway, if you refuse to tackle it yourself, then I'd say 16 pounds for the pair is reasonable...
    left the forum March 2023

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