grdunn123 Posted April 8, 2007 Report Share Posted April 8, 2007 Probably been done to death in other threads but what's the concensus on discs and pads for 2002 A8 4,2QS? I reckon mine will need replaced soon, probably worth doing a fluid change too? Quote Link to comment Share on other sites More sharing options...
NickGUK Posted April 9, 2007 Report Share Posted April 9, 2007 Imo stick with "original" parts, unless you like to drive that little bit faster and maybe run on track days when you would probably want fast road pads and maybe grooved discs All depends on how deep your pocket is really Fluid change should be done every 2 years as brake fluid is hydroscopic, If you have no record of it, then get it done and then you know where you are. Quote Link to comment Share on other sites More sharing options...
Lusso Posted April 9, 2007 Report Share Posted April 9, 2007 Excuse my ignorance but what does hydroscopic mean, and if you dont change after 2 years whats likely to happen ? Quote Link to comment Share on other sites More sharing options...
mlillywh Posted April 9, 2007 Report Share Posted April 9, 2007 I'll have a stab at this... correct me if I'm wrong Hydroscopic means attracts water - the brake fluid slowly absorbs water which eventually makes it more 'elastic' Net effect is spongy brakes - as you push the brake, you first compress the water in the brake fluid, before the brake fluid then starts to move the brake pistons Brake fluid should be changed every two years as part of the service, to avoid this, but unless you have proof........ Quote Link to comment Share on other sites More sharing options...
NickGUK Posted April 9, 2007 Report Share Posted April 9, 2007 [ QUOTE ] I'll have a stab at this... correct me if I'm wrong Hydroscopic means attracts water - the brake fluid slowly absorbs water which eventually makes it more 'elastic' Net effect is spongy brakes - as you push the brake, you first compress the water in the brake fluid, before the brake fluid then starts to move the brake pistons Brake fluid should be changed every two years as part of the service, to avoid this, but unless you have proof........ [/ QUOTE ] Quote Link to comment Share on other sites More sharing options...
grdunn123 Posted April 9, 2007 Author Report Share Posted April 9, 2007 Very nearly right Nick! It's hygroscopic though, attracts moisture from the atmosphere......I know,I know,I'm a smart a**e! Quote Link to comment Share on other sites More sharing options...
NickGUK Posted April 9, 2007 Report Share Posted April 9, 2007 [ QUOTE ] Very nearly right Nick! It's hygroscopic though, attracts moisture from the atmosphere......I know,I know,I'm a smart a**e! [/ QUOTE ] i did just finish a night shift, i knew what i meant Quote Link to comment Share on other sites More sharing options...
grdunn123 Posted April 9, 2007 Author Report Share Posted April 9, 2007 Funny the things you remember! Somebody corrected me with on the same thing about 15 years ago!! I'm thinking of getting the alloys refurbed in a week or 2 so I'll check out discs and pads properly when the wheels are off! Quote Link to comment Share on other sites More sharing options...
NickGUK Posted April 9, 2007 Report Share Posted April 9, 2007 Just read a very interesting article... Brake Pads And discs BTW if your thinking of getting the wheels refurbed i can HIGHLY recommend this place, they did mine for me, super job, quick turn around and VERY reasonable cost. I would have no probs in using them again. Alloy Wheel refurb Quote Link to comment Share on other sites More sharing options...
grdunn123 Posted April 9, 2007 Author Report Share Posted April 9, 2007 Think I'll stick with 'stock' discs and pads when I replace them....does seem to be a lot of confusion surrounding braking systems. I' a bit too far away to use these guys for the wheel refurb, pity. Quote Link to comment Share on other sites More sharing options...
fudge Posted April 9, 2007 Report Share Posted April 9, 2007 Still not quite right! Water is not compressible (neither is brake fluid). However, water boils at 100* C and steam is compressible. Hence if you have brake fluid with water in it the water can boil under heavy braking giving spongy pedal and brake fade. Usually only apparent if you are braking heavily with little time between applications for brakes to cool down. Quote Link to comment Share on other sites More sharing options...
grdunn123 Posted April 9, 2007 Author Report Share Posted April 9, 2007 Brake fluid can even absorb water through the plastic container which most brands are now sold in! The better stuff comes in a metal container. Fluid has a Dry Boiling Point and also a Wet Boiling Point...the higher the stated values the better! Here endeth the lesson..... Quote Link to comment Share on other sites More sharing options...
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