on a mates 86.. used on the circut a bit.. has Hawk HP Plus pads on the front.. with ADM rotors and calipers.. the pads themselves don't fade.. but what is happening is the fluid (dot 3/4) goes to shit.. like the pedal goes to the floor after 3-4, 5 lap sprint sessions.. once the fluid is flushed and replaced the pedal is normal...
the brake fluid were using is toyota genuine dot 3, but have tried some dot 4 also.. only reason i use the toyota dot 3 is because i have a full box of 500ml bottles.. like a dozen of them..
would DOT 5 fluid be ok to use in this if it was flushed through and replaced?? it has new brake lines through out.. and master cyl and wheel cyls are not leaking etc.. all have been reced recently etc..
opinions... it's definitly the fluid going to crap the car can sit for days after a race meeting and the pdeal will still feel the same shitty half dow to the floor.. but once replaced it's perfect..
matty
i had a similar problem with my twinky where the clutch would go to shite after 30mins of driving, making it hard to change gears even when the pedal was being crushed on the firewall...
i ended up using some 500 to 600degree boiling point (or somecrap) brake fluid (dot5) and it seems to fix that problem quick smart
30kw club
Dot 5 is silicone based and not compatible with dot3/4 systems. I think it eats the rubber seals.
[taken from above link]
Boiling Point Ranges Dry Boiling Point Wet Boiling Point
DOT 3 205°C (401°F) 140°C (284°F)
DOT 4 230°C (446°F) 155°C (311°F)
DOT 5 260°C (500°F) 180°C (356°F)
DOT 5.1 270°C (518°F) 191°C (375°F)
Dot 5.1 apparently is safe on rubber systems, but I haven't seen them off shelf at your cheapo stores. There is high temp dot 4 (called super dot 4) rated up to 500-600 as Rthy says. Penrite is the cheaper one, then theres PBR and motul options.
Be careful with Dot 5, on previous research, if it boils over it blackens and can solidify like goo. I would just double check that.
RBF600 or similar (super dot 4)
my brakes glow at night its great stuff.
Ben.
yea i think it was 4.1 or superdot 4 or something, it was the Penrite one
30kw club
Try Motul RBF600, AP Racing AP600 or Martini GS610
All these are glycol based (ie. compatible with other dot 4, dot5.1 etc..)
If you are still boiling fluid then you need to get bigger brakes.
DOT 5 will apparently go off much worse than DOT 4, once it goes beyond its max operating temp then it changes and doesnt change back wheras DOT 4 is supposed to go back to normal... Most good DOT 4 should be ok (marked 'racing' or high temp or whatever, the brands mentioned are all good).
Your friend might want to get some temp paint (changes colour when gets to a certain temp) to see what his discs are doing (sounds like they are getting out of the pad operating range if they are doing that to the fluid). You could also try insulating the calipers from the pads with some sort of non conductive (and non flamable lol) material, try some ducting or as others have said upgrading.
ill try the hi temp dot 4 glycol based stuff...
yeh i know dot 5 was silicon based, and rubber doesn't like it very muchso i was just makin sure about the info..
the brakes seem very resistant to fade.. just the brake fluid seems to be shit for race applications.. hopefully this fixes some of the problem.. although a swap to rebuilt JDM calipers and JDM slotted rotors should help in the fade department.. i know it's not really an upgrade.. but it does make a difference keeping them cool!
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