brakes

[thumper]

Strange thing happened.After my feature,when the race was over.my brakes went to the floor.I thought I blew a line.I have the factory dual master cyl so I should have had at least 2 wheels working.I could pump them up.When I unloaded the next day the brakes were fine again.

 

Question; is a thick pad more heat resistance or a thin pad.I have run the same pads since 2002.They are the Autozone metallacs.There almost wore out now.Would new pads last longer in a race before it overheated??? Is there a better fluid to use???Why did they quit AFTER the race was over??? First time for me for this problem. The rear are drum.The fenderwells are sealed because this car runs on dirt too.More air??? Master cyl weak??

[jwmbishop]

Sounds like fluid and pads need changed. Moisture accumulates in the fluid and becomes steam, which rises to the top of the system - the air in the steam will cause you to loose the "bleed" on the master cyl and the make the pedal drop. After cooling the moisture will be in the top of the resevoir (the sludge that accumulates below the feeder holes and under the cap) - so the fluid can get "firm" again (plus the MC can "self" bleed sitting).

 

Typically good dot 3 or better fluid will "spread out"enough moisture that you would have no problems - until there is enough to cause a problem - and its usually not a gradual thing. Yes thin pads transfer more heat to the fluid - and even if you boil one wheel the steam will go up to the MC (steam seeks the highest point in the system). For the cost - new pads and fluid should always be on your preseason checklist - its a wee bit less expensive than fixing damage from sudden failure. As a pad wears it is also filling up the pores of the material with rotor dust. Even though they look good - they are less effective (for racing) once they are 75% worn away (as the glazing reduces applied friction - they still run hot just do not hold the heat to the rotor where you want it). Street machines I like to replace at 50%. Rarely have to turn a rotor if you do this.

[thumper]

That sounds exactly like what happened.I will put new pads and flush the fluid.Whats the opinion on ceramic pads.Are they any better for racing or are the metallic better?/

 

Thank you

[jwmbishop]

If the metallics work stay with em - ceramics are longer lasting (and you can "tune" the brakes with compound selection) but they are harder on the rotor (and budget).

 

If them metallic pads lasted you 8.5 seasons I would say they are adequate! Retire them sooner though. (I know I will hear flack from this as used pads are hardly recomended by the NHTSA - but I used to rotate my old racing pads - among other parts such as used spark plugs, wires etc) out to my street "fleet" - another reason to stay away from exotics unless you really need them).

[neon14]

G.B. are you sure you were pressing the brake and not the clutch or the gas. Just checking you know. lol!

 

On a serious note auto zone sells a vacuum pump for 29 bucks that makes bleeding brakes a breeze.

[jwmbishop]

I use a vacc pump to do a first bleed (and to pull out the old fluid on a change) - however air can still get back in from around the threads of the bleeders (not saying it DOES - jus saying it CAN - and I don't like CAN). I know some guys even gravity bleed - just leave the bleeders very slightly open and let mother nature (gravity) do its work. Last bleed is still (for me anyway) a pressure bleed. And on race cars I pressure bleed em a second time after a good heat and cool cycle - like the Sunday following (street cars usually don't see the extreme heat and related steaming issues).

[poorboy]

GB replace the brake fluid at least 2 times a year. I use Mercedes Benz brake fluid which is Dot 4 plus. It's made by ATE. I'm sure it's the same as VW , Audi , Porsche, and BMW. Also replace the brake pads every year no matter what they look like.