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  • FIRST POST
    • kfw
    • By kfw 20th Mar 17, 9:39 PM
    • 54Posts
    • 29Thanks
    kfw
    Front brake pad change
    • #1
    • 20th Mar 17, 9:39 PM
    Front brake pad change 20th Mar 17 at 9:39 PM
    Hello


    I will be changing my front brake pads soon and just wondering whether I need to take off the master cylinder reservoir cap?


    My pads are about 80% worn and the metal indicator flap is almost touching the disc.


    Fluid was changed by the main dealer last April so it won't need changing/flushing.


    Should I check the reservoir level first and if the fluid is at the min level then it's ok to leave the cap on, as when winding the caliper piston back it will naturally raise the level back.


    If the fluid level is any higher than min, would winding both calipers cause fluid to overflow. I have read horror stories of damaging the seals if I do not open the fluid cap or open the bleed nipples.


    Thanks in advance for your opinions.
Page 1
    • docmatt
    • By docmatt 20th Mar 17, 9:54 PM
    • 699 Posts
    • 331 Thanks
    docmatt
    • #2
    • 20th Mar 17, 9:54 PM
    • #2
    • 20th Mar 17, 9:54 PM
    Yes take the cap off
    • RickRastardly
    • By RickRastardly 20th Mar 17, 10:33 PM
    • 25 Posts
    • 9 Thanks
    RickRastardly
    • #3
    • 20th Mar 17, 10:33 PM
    • #3
    • 20th Mar 17, 10:33 PM
    Always take the cap off, if it overflows it overflows, you could always syphon it out and then replenish with new stuff after the job or catch the overflow with absorbent pads.
    • debtdebt
    • By debtdebt 20th Mar 17, 11:30 PM
    • 132 Posts
    • 80 Thanks
    debtdebt
    • #4
    • 20th Mar 17, 11:30 PM
    • #4
    • 20th Mar 17, 11:30 PM
    Take the cap off, stick a clean rag in the neck and it'll soak up any overspill.

    Sheessh if you took the cap off and didn't need to, you just need to screw it back on.
    • atrixblue.-MFR-.
    • By atrixblue.-MFR-. 21st Mar 17, 12:27 AM
    • 6,413 Posts
    • 4,450 Thanks
    atrixblue.-MFR-.
    • #5
    • 21st Mar 17, 12:27 AM
    • #5
    • 21st Mar 17, 12:27 AM
    Take the cap off but if you don't feel confident enough to mess with your brakes, get a local good decent garage to change them out for you.


    If you have screw out self adjusting - wind back calipers, Theres always a risk of damaging the seals when you wind the piston back even with a rewind tool and an open filler cap it depends on how perished (if at all) the seals are.


    The method your going with is called "gravity bleeding" theres tutorials all over Utube for this method.
    I make spelling mistakes, its not intentional, its a condition I have please afford people who have these conditions some respect and not single out their posts for correcting mistakes.
    • angrycrow
    • By angrycrow 21st Mar 17, 6:14 AM
    • 274 Posts
    • 185 Thanks
    angrycrow
    • #6
    • 21st Mar 17, 6:14 AM
    • #6
    • 21st Mar 17, 6:14 AM
    There is a view that it is poor practice to push fluid backwards on an abs breaking system as it can push dirt back into the abs unit. I was taught to gently clamp the flexy pipe. Open the bleeder with a pipe on it into a jar and then wind the piston back in.this expels the old fluid in the piston out of the system. Once finished top the reservoir up to max with fresh fluid.
    • Tarambor
    • By Tarambor 21st Mar 17, 8:06 PM
    • 669 Posts
    • 418 Thanks
    Tarambor
    • #7
    • 21st Mar 17, 8:06 PM
    • #7
    • 21st Mar 17, 8:06 PM
    Caliper pistons hold about a couple of teaspoons full of brake fluid when not under pressure. Use that as a guide to see how much the fluid level will rise.
    • debtdebt
    • By debtdebt 21st Mar 17, 8:37 PM
    • 132 Posts
    • 80 Thanks
    debtdebt
    • #8
    • 21st Mar 17, 8:37 PM
    • #8
    • 21st Mar 17, 8:37 PM
    There is a view that it is poor practice to push fluid backwards on an abs breaking system as it can push dirt back into the abs unit. I was taught to gently clamp the flexy pipe. Open the bleeder with a pipe on it into a jar and then wind the piston back in.this expels the old fluid in the piston out of the system. Once finished top the reservoir up to max with fresh fluid.
    Originally posted by angrycrow
    Yep that's best practice but to be sure you've not introduced air bubbles, you'd have to bleed the brakes through. I'd hazard a guess that less than 10% of garages would use that method.
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