k0bun

If I siphon (turkey baster) out the brake fluid from the master cylinder and then refill it with new fluid, do I still have to bleed the brakes? I'm curious what's done in between laps during HPDEs. Obviously this wont be a very thorough flush, but I figure it might help a little and save time, assuming you don't still have to bleed the brakes anyway.

School the ignorant please. :o

Wicked Weasel

Yes you need to bleed. The new brake fluid will not make it to the calipers without bleeding. New brake fluid should easily last a day for HPDE. At the end of the day you can bleed off at the calipers if you want but chances are for a single day event you will not have to.

k0bun

Thanks Bob. Do you think I'll be alright with the 30k mile, 3 1/2 year old, stock brake fluid? Trying to get everything ready for Monticello next week but not going crazy because I doubt I'll be doing anything the car can't handle. Just routine maintenance really. Oil, trans, dif, clutch, and PS fluids have all been changed/flushed. I was holding off on the brake fluid (no good reason other than probably just being lazy) and the coolant. Even though the brake fluid is probably the first thing I should do for a HPDE.

QSZOH6

Brake fluid flush should be pri 1. Flush with a new bottle of DOT4. You will see the fluid that comes out of the calipers and you will be glad you did.

k0bun

Yeah my Motive Power Bleeder just arrived so I'll change it this week.

Thanks guys

johninar

As was said above. If you are new to HPDE you will be hard on your brakes.
Make sure you bleed AFTER as well. That fluid will have been hot.
Stay safe, have fun, and keep your head screwed on straight!

TheKomoman

on the DOT4 recommendation. Tire Rack sells ATE fluid in both blue & amber. I know a lot of folks are fans of Motul and I'm sure it's great stuff, but the different colors are a VERY easy way to tell when you've gotten the old fluid out(maybe Motul comes in the colors too, I don't know). Just alternate from one color to the other on bleeds.

jaa1992

If you saw the nasty bottle of crap I flushed out of the wife's daily driver after 3 years you'd be saying to yourself "Hey - did you flush the brake fluid this year???"

Cereal - if your brake fluid is more than a year old - flush it before going to the track.

k0bun

Thanks everyone. I have a few extra bottles of Prestone DOT4 I just picked up for the clutch so I'll use that for the brakes too. And my MPB just arrived so I think I'll head to the garage and get messy.

davidfarmer

Prestone or Valvoline Dot 4 Synthetics are more than adequate..........

John Shiels

Would you go mountain climbing with an old rope? 3.5 years old is old rope!

punz

I thought synthetics for the brakes in our cars are not to be used?

lbs90ZR

Dot 4 Synthetic is ok. Dot 5 Silicone is not supposed to be used in ABS brake systems.

rfn026

Here's a lot of information about brake fluid. Also, I believe in changing it before every event. My last event at Homestead was rather amusing - if not dangerous. I lost my brakes loading the car on the trailer.

My crew had the ramps down and I thought it would be nice to just drive off the track and right up on the trailer. I forgot to drive around the pits for a little bit to let everything cool down. The brake fluid heat-soaked and boiled as I was carefully going up the ramps. A moment of panic. Nothing happened so no harm no foul.

Everything cooled off in about 2 minutes and all was fine.

Richard Newton
My Speed Blog

k0bun

I wouldn't go mountian climbing.

I agree that's why I put the little rolley eye guy there. I was just too lazy to do it today with all the other fluid swaps. Then my MPB came and I got my second wind. All changed.