downimpact Posted May 21, 2011 Share Posted May 21, 2011 This has been going on for some time and was hoping for an answer. On any track day after a session, once the car has cooled ready to go out again, the first time I go to use the brakes the pedal travels excessively without significant stopping power. If I pump the brakes they then go hard again and back to normal. This happens after every session on track. I've recently changed from jap spec to UK brakes and both do the same thing, is this normal and what's causing it? Fluid was changed within the last month. Quote Link to comment Share on other sites More sharing options...
Tyson Posted May 22, 2011 Share Posted May 22, 2011 possibly air in the brake fluid? What about excessive heat in the fluid i.e boiling it Quote Link to comment Share on other sites More sharing options...
skippyboyo1 Posted May 22, 2011 Share Posted May 22, 2011 id go with air in the lines 100%,im running a standard brake set up and no matter how hard i drive on the track the brakes have never faded or done anything like this,the tyres go off before anything.boiling the power steering fluid yes but brakes no.defo bleed em up and if your not already run dot 5 fluid Quote Link to comment Share on other sites More sharing options...
Tyson Posted May 22, 2011 Share Posted May 22, 2011 braided lines are always a worthwhile upgrade as they don't expand like the standard lines do. Quote Link to comment Share on other sites More sharing options...
downimpact Posted May 22, 2011 Author Share Posted May 22, 2011 yeah have braided lines and highest temp racing fluid I could find (better than Motul's 5.1). I wondered about boiling it though don't have any issue while on track with fade. This has happened for a number of years after a number of brake fluid changes, which I suspect mean it's something else? Quote Link to comment Share on other sites More sharing options...
Dnk Posted May 22, 2011 Share Posted May 22, 2011 Have you looked at the master cylinder ? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 22, 2011 Share Posted May 22, 2011 Dirty fluid in the MC may have blocked the fluid return bleed hole. A new MC would be nice, a full strip and clean, with a new OEM seal kit, next best. Quote Link to comment Share on other sites More sharing options...
downimpact Posted May 23, 2011 Author Share Posted May 23, 2011 Thanks fella's I did wonder if it could be this, though don't have the technical knowledge to back up my hunch. New master cylinder it is then. Quote Link to comment Share on other sites More sharing options...
nevins Posted May 23, 2011 Share Posted May 23, 2011 When you on track next Jon? Quote Link to comment Share on other sites More sharing options...
downimpact Posted May 24, 2011 Author Share Posted May 24, 2011 When you on track next Jon? Probably July, to try out BPU before sprint series. Quote Link to comment Share on other sites More sharing options...
dr_jekyll Posted May 24, 2011 Share Posted May 24, 2011 bad news jon , llandow has been cancelld, round 4 is now 190 miles away:( . Quote Link to comment Share on other sites More sharing options...
downimpact Posted May 24, 2011 Author Share Posted May 24, 2011 bad news jon , llandow has been cancelld, round 4 is now 190 miles away:( . oh yeah Cottesmore will have to think through plans now....grrr Quote Link to comment Share on other sites More sharing options...
CanisLupus Posted May 25, 2011 Share Posted May 25, 2011 Dirty fluid in the MC may have blocked the fluid return bleed hole. A new MC would be nice, a full strip and clean, with a new OEM seal kit, next best. Do you probably have a Part Number for the Seal kit? Mine does the same to a certain point after this weekend at the Nüburgring. Quote Link to comment Share on other sites More sharing options...
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