brake fluid flush, procedures? Options

[TheCabinetmaker]

I'm going to my novice DE at Hallett raceway in two weeks, and need to replace my dot 3 with dot 4. I did a search but nothing came up. Everything else on the car is up to specs. Whats the best method to do this? Is it just bleeding the brakes till all the fluid is changed? Do I drain the entire system, then refill and bleed, bleed, bleed?

Thanks in advance, Curt

[seanery]

it's pretty easy if the new stuff is a different color than the old, just bleed, fill, bleed, fill, bleed til the color changes at each corner.

[brant]

yeah...

buy ATE blue (or gold) and then switch colors every year...

b

[TheCabinetmaker]

Cool. Should the the bleed sequence be backwards? I.E., front left, front right, rear left, rear right? or does it matter?

Thanks Guys.

[tat2dphreak]

I used my little vacuum bleeder... sucked out the resevoir, and then sucked out the lines.... add new fluid and bleed...

maybe that was the wrong way... but it worked

[brant]

I always follow the same bleed sequence and go furthest first... closest last...

if you take the reservoir down half way then you will use less fluid... flush half the fluid out through the caliper so as to get any grit or grime, rather than removing it by turkey baster....

then before the reservoir runs dry you can add the ATE.

I am so Jealous.. I hear AMAZING things from all my friends about hallet.. it is supposed to be a great teener track...

everytime an event comes up for me there, my car is not ready...

b

[TheCabinetmaker]

I've been a volunteer corner worker there for the last two pca club races. A very satisfied customer and friend paid for my DE as a tip for rebuilding his 1.7. I love 914 people.

Thanks for all the tips guys. I just remembered my vacuum guage doubles as a brake bleeder, so this should be easy.

[TimT]

flush half the fluid out through the caliper so as to get any grit or grime

Whoa nellie!!

I wouldnt want any grit or grime flushed through the caliper... I have drained the resevoir all the way down with a turkey baster.... then filled it with clean fluid for fluid flushes...

If the resevoir has some nasty goo in the bottom... you can completely remove the resevoir and clean it well, then replace it, then flush following the usuall procedures..

I bleed the fluid at least once per track event.... and change the fluid yearly... You wont have any grit or grime to contend with if you "maintain" your brake system

[tat2dphreak]

I didn't do the "turkey baster" through the calipers... I removed the BRAKE LINE... bigger hole to get crap out of!

I didn't want it through the caliper either...

[TheCabinetmaker]

Ok, We're getting there. I should empty and clean reservoir, remove lines at calipers, flush out lines, reinstall lines to calipers, flush calipers, bleed entire system. Still easy, but definitely longer.

[anthony]

I just did a brake job and installed speedbleeders. They seem to work pretty well but I still have a slightly spongey pedal.

I was thinking that driving it a bit and then rebleeding would cure it.

Any tips and tricks?

[lmcchesney]

A NEAT trick I found when bleeding brakes.
Get a 1pint plastic jar. Place the small plastic tubing, I believe about 3-4mm, about 1 ft long. Place one end of the tubing into the bottle and the other over the drain nipple. The 10mm open end wrench easily accesses the zert and you can drain huge quanities while keeping the floor and paint finish clean. Have fun. But, get the breaks done now so you can hit something at a reasonable speed prior to DE.
L. McChesney

[TheCabinetmaker]

Anthony, If the pedal will "pump up" it's still needs bleeding.

[Gint]

Anthony, sounds like air in the prop valve. That's why everybody hates 'em. Crack the lines on the valve and bleed. You can also tap on it while bleeding to help move the air bubbles to the top.

[anthony]

Yeah, it 'pumps up' a little. I've bled the system quit a bit.

[Curvie Roadlover]

I attended a 4 hour brake seminar a couple of weeks ago and learned a ton. Of particular interest were 2 things: 1. 17mm MC puts out more braking pressure than the 19 mm MC, and 2. Don't use a power bleeder, ie. one that pressurizes the resevoir.
1. Reason is the same reason a spike heel will sink deeper into the lawn than a flat heel. Less surface area with the same amount of pressure from your foot will deliver more PSI to the MC. This revelation came as kind of a surprize considering everyone always wants to "upgrade" to a 19 mm MC but what he says makes sense when you think about it. (By the way, he was the brake expert Grassroots Motorsports consulted for its' 914 racecar project. They had already installed a 19 mm MC on the car before consulting him. He made them put the 17 mm one back on)
2. Reason is that pressurized air in direct contact with the brake fluid forces air molecules into the fluid.

FWIW
The brake guru said vaccuum bleeders were fine to use in his opinion and he was indifferent about speed bleeders.

[tat2dphreak]

I attended a 4 hour brake seminar a couple of weeks ago and learned a ton. Of particular interest were 2 things: 1. 17mm MC puts out more braking pressure than the 19 mm MC, and 2. Don't use a power bleeder, ie. one that pressurizes the resevoir.
1. Reason is the same reason a spike heel will sink deeper into the lawn than a flat heel. Less surface area with the same amount of pressure from your foot will deliver more PSI to the MC. This revelation came as kind of a surprize considering everyone always wants to "upgrade" to a 19 mm MC but what he says makes sense when you think about it. (By the way, he was the brake expert Grassroots Motorsports consulted for its' 914 racecar project. They had already installed a 19 mm MC on the car before consulting him. He made them put the 17 mm one back on)
2. Reason is that pressurized air in direct contact with the brake fluid forces air molecules into the fluid.

FWIW
The brake guru said vaccuum bleeders were fine to use in his opinion and he was indifferent about speed bleeders.

I think they "outlawed" that type of bleeder... I haven't seen one in years...


the other point... I think that's only valid assumming stock or near stock brakes... the 19mm should still put out more MAXIMUM throughput for big brakes that need it...


true for the same force, you will get less pressure using the 19mm m/c... but that is only a good point until you reach the max output(not pressure... volume) from a 17mm, that is when you need the 19mm

correct me if I'm wrong... I'm not a physicist or a brake specialist, this is just what I've been told...

[Dave_Darling]

No, you're right. The 19mm will be able to generate a total of about 25% more pressure than the 17mm one will. But you will have to push much harder to get that pressure--to get the same pressure on each, you have to push 25% harder on the 19mm one than on the 17mm one.

I don't disconnect any of the brake lines when I flush the brake system. I do it just like bleeding the brakes, except that I use my Mity Vac to get almost all of the fluid out of the reservoir first and I re-fill it with fresh fluid. Then go to the right-rear, hook up the Mity Vac, and go until I get none of the old fluid coming out--all fresh. I will usually have to stop and re-fill the reservoir at least once during that process. (If you have upper and lower fittings, use the lower one. If not, no big deal.)

Then I go to the left-rear and repeat. Keep going until all of them have been gone through.

Then I go fetch an assistant and do the two-man push-the-pedal bleeding process, just to make sure that all the air is out.

--DD

[lmcchesney]

Some place there is that 17mm vs 19mm physics article. I think on PP.
L. McChesney

[Curvie Roadlover]

No, you're right. The 19mm will be able to generate a total of about 25% more pressure than the 17mm one will. But you will have to push much harder to get that pressure--to get the same pressure on each, you have to push 25% harder on the 19mm one than on the 17mm one.

25% harder for equal pressure. So to actually get 25% MORE pressure you'd have to push twice as hard, right?
100% more pushing for 25% more pressure (IMG:style_emoticons/default/huh.gif)