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Old 14-11-2018, 03:41 PM
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niknitrous niknitrous is offline
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Brake fade?

experienced some disturbing brake fade today. after about half hour of 'spirited' driving in Sydney the brake pedal felt very hard and very poor stopping power. I have wilwood discs on the front and drums out back which have all been going great for several years.
Engine was warm but not super hot, ambient temp was not that hot either.
It came good again straight away though... This is a new one for me. any thoughts as to cause
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  #2  
Old 14-11-2018, 05:46 PM
69JavelinMan 69JavelinMan is offline
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You can look at running better quality brake fluid with a higher boiling point and/or running a higher performance brake pad if this is something you plan to do on a regular basis. Adding some brake cooling ducts may also help.
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Old 14-11-2018, 06:03 PM
Geoff 4 Geoff 4 is offline
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Brake fluid absorbs moisture over time, which lowers the boiling point of the BF. I would flush the system & fill/bleed with new high temp brake fluid.
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Old 15-11-2018, 06:39 AM
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Thanks chaps, I have the high temp wilwood fluid in there. I'll check the pads as well but i would have thought if the pads were on the way out then performance would be consistently down rather than sporadic right?
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Old 15-11-2018, 09:03 AM
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More of a question than an answer. Is there a chance a piston hung up in the caliper for a time?
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Old 15-11-2018, 10:31 AM
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Quote:
Originally Posted by bonnevista View Post
More of a question than an answer. Is there a chance a piston hung up in the caliper for a time?
good question, how would you tell?
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Old 15-11-2018, 01:50 PM
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are you using a booster ? if so what type ?
Very hard pedal and low brake power - possible boost/booster issue

Tex
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Old 15-11-2018, 07:42 PM
Geoff 4 Geoff 4 is offline
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He says the hard pedal 'comes good', so unlikely to be a booster problem,
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Old 16-11-2018, 12:07 AM
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Still worth finding out if running a booster? Just to rule out any vacuum line issues (eg rubber hose getting hot when fanging and kinking on a curve? Dunno). Strange immediate 'come good' if fade/fluid related.
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Old 16-11-2018, 10:32 AM
69JavelinMan 69JavelinMan is offline
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I'm thinking that if it is a fluid related issue, then you will experience a soft rather than hard pedal.

Could be overheated pads, but not sure if that's going to make the pedal hard or soft but will likely reduce braking effort. Pads designed to work at higher temperatures, i.e. race pads generally don't work very well at low temperatures and are generally not suitable for street use and obviously street pads will not work very well in a race application because they get too hot.

Could be something really simple like the booster just running out of vacuum after repeated brake applications and not having time to recover, that would explain why the problem went away quickly, assuming in this case that the car is running a traditional vacuum brake booster.
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Old 16-11-2018, 11:03 AM
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Looks like running a booster, but the vacuum line appears to loop around behind the booster in a tight 180?
Name:  BoosterNik.PNG
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Not sure about others, but mine runs a direct line (albeit different inlet side as 'RHD' Holden).
Name:  BoosterRAW.PNG
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Although not been a issue in past, I still vote ran out of vacuum or line got kinked from heat. Fluid/pad issues would not be so instantaneous good-then-bad-then-good.

Sound like a one-off to me & not a big stress. I'd suggest just check the pads/caliper for debris/issues next time poking around in there to rule that out, try a direct boost line (unless this is looped length is commonplace?) and just monitor going forward. Good luck!
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Old 19-11-2018, 07:25 AM
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Thanks all for responses, especially Deano going the extra mile with the mark-up... nice one. I do have a separate vacuum boost canister. So a hose runs from the manifold to the canister and a separate hose from the brake booster to canister. Checked hoses and connections and looks to be ok.
wend for a little run around the block and problem persists unfortunately so will just book her in for a check up, pads and bleed.
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Old 07-12-2018, 08:25 AM
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Hey Nik - Did you sort this out? Am curious what it was...
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