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Need a new diaphragm for Clarks Evo hydraulic brakes

Hi, I'm servicing my dad's brakes because he says they don't seem to be working. On investigation, the diaphragm in the rear brake lever's reservoir is actually the wrong size! There's no way he would have been fiddling with this, so either it was supplied wrong from the off (from Halfords) or somehow got into this state when it had its only service (also from Halfords). It was bought / serviced several years ago.

So I'm assuming the wrong diaphragm has been in there for several years and gradually letting DOT 4 out.

Photo shows the rear brake cover & (the oversize) diaphragm at the top. And front brake cover and (the correct) diaphragm at the bottom.

I'm not having any luck sourcing a replacement diaphragm though for the back brake. Any suggestions?


  • whyamiherewhyamihere Posts: 7,678
    Have you tried Clarks directly? You can order spare parts for the current brakes from their website, you could try contacting them to see if they have parts for older brakes too.
  • alex_ukalex_uk Posts: 56
    Good suggestion, but already tried looking at Clarks and they don't have the Exo listed. I will try contacting them though
  • reaperactualreaperactual Posts: 1,183
    edited October 2022
    I suspect that diaphragm wasn't oversized to begin with. It looks like it's swollen and damaged.

    It's not impossible to believe at the service the wrong oil/fluid was used instead of DOT 4?

    I see the brake on there but not the diaphragm you need listed on the Clarks U.K. Stock Catalogue pdf at the bottom:-
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