Red5

Last weekend I was racing in an autocross and I literally lost my brakes in the middle of a run. One of my fellow racers said that it was because my brake fluid had not been changed in 10 years of hard core auto crossing. Guessing it is time for a change.

So ids there a simple procedural on changing out all of the fluid? I want it ALL changed and I'm guessing that means I have to actual the ABS system. (Am I right or wrong on this?)

What do I need to do to change this fluid and what fluid do you recommend?

Bill Dearborn

If you want the fluid out of the ABS unit you may have to have the dealer do a Tech2 automated bleed. Any DOT3 fluid will work for autocrossing. Ford's fluid has a 550 degree dry boiling point and is very low cost. It is known as the best kept secret in racing. All the Tech2 does is operate the ABS valves so fluid trapped in non direct flow areas is pushed out of the unit.

If you don't mind leaving some of the old fluid trapped in the ABS unit then a conventional bleeding will work just fine. When you engage the ABS the fluids will probably mix and the old fluid will be diluted into the new fluid. You can try and use normal ABS action to try and flush the unit by flushing the fluid, taking the car for a drive and getting into the ABS on all 4 wheels a few times and then going home and flushing again. Repeat this a few times and you may be able to clear the old fluid (and any air if there is any) out of the ABS unit. I have tried this a couple of times and it seems to firm up the pedal but getting the Tech2 bleed done is easier. Just make sure to take your choice of brake fluid with you.

Bill

parsonsj

I seem to remember someone saying that pressure bleeding at > 12 psi will get all the fluid to flow, even the ABS. Anybody else ever hear that?

blackbeast99

I never used the Tech II, but as Bill mentioned, would drive and get the ABS to activate and bleed again. Then again...after track sessions.

0Anthony @ LGMotorsports

If you stay on top of it, most of the fluid in the system is going to be "fresh" anyway.

What you are trying to do at the end of your weekend (or end of each day) is get the fluid that saw the most heat (at the caliper) flushed out, along with any air and flesh at the caliper.

If you do one or two track days a year and the fluid sets or you are flushing and starting over with a new fluid that might not be compatible then you need to do the Tech II flush.

froggy47

Not that I know of.

froggy47

If you drive hard enough you should be in the abs quite a lot, hence it gets new fluid from your last brake fluid service. That's what I figure.

chetly

I flushed my brakes with a presure bleeder and put 2 cans of ate 200 brake fluid through and had zero air coming out after I was done yet still my pedal is soft and I'm constantly getting abs active on the display screen.

This is on a c6z with -3° camber in the front -1.5 rear braking in a straight line.

Is the abs active normal? Or is a tech 2 bleed in order or is there something else going on here.

Rx7Rob

I hate it when flesh get stuck at the caliper!

Scooter70

Yes, you will get lots of "ABS ACTIVE" notifications on track. Completely normal. No need to do a Tech 2 bleed unless you think that there's air in the ABS controller. You can just go find a dirt road and romp on the brakes a few times to activate the ABS then bleed some more. It's the same thing that the Tech 2 bleed does.

chetly

Ok thanks. Wonder why my pedal is so soft. Guess I'll have to bleed some more and see if I get any air.

0Anthony @ LGMotorsports

flesh
fresh
fresh flesh..


Its a zombie thing.......

icntdrv55

Mea culpa to the OP if this sounds like a thread jack, but this seemed like a good place to post this question without starting a new thread that would become duplicative….

So, for us 'slow guys' who use this magnificent machine for pleasure driving without seeking it's limits on a regular basis, is there any benefit or sound mechanical reason to do some threshold braking, maybe in the wet or, as suggested in an earlier post, on a dirt road (shudder… ) to activate the ABS valve(s) and flush the static brake fluid in the ABS module every so often?

hklvette

No. Just do a standard bleed procedure. Your brakes won't get nearly hot enough to warranty anything more involved than that.

strano@stranoparts.com

You lost the brakes, as in to the floor? Well that's not fluid, it's not good to have 10 year old fluid mind you, but you are losing a master cylinder. Not uncommon with the GM cars. I lost one in my 2001 Z28, and two in my 2007 Z06. My girlfriend also lost one in her Z06 (some of these had as little as 4k miles on them when they went).

Do you need a tech2? No but it can be helpful if you have trouble getting the system bled properly at the end.

larryfs

Brake fluid doesn't move that much. So what exactly does the tech2 do when it activates the ABS unit ? Just how far can the fluid travel ??

I have a soft pedal in my truck, and I'm thinking of taking it to a Chevy dealer for a full flush. I already gravity bled it, wifey bled it, and it still isn't what it should be.

froggy47

Rained yesterday in SD, took my Suburban out & engaged the abs a couple of times = flushed the abs, no Tech 2 or 2 hr wait at the dealer required.



Plus it was a good lesson that even with good brakes / tires 6000 lbs does not stop very fast on a wet road.

Note to self, leave a couple more car lengths ahead of the next guy in line.

larryfs

I still don't see how activating the ABS flushes it out. All it is, is a piston that moves in/out very quickly. The brake fluid doesn't move very far.

To flush the ABS, you need to activate it, while having a bleeder valve open.

Bill Dearborn

Larry, activating the ABS opens the valves in the BPMV and once a valve is opened it might be possible for an air bubble to move upward into the brake line. However, you may have noticed the term "possible" that doesn't mean it will always happen or that it is probable. It is worth it if you can get into the ABS a few times and clear the air out of the unit and avoid paying a dealer to bleed your brakes. If it doesn't work then you can always go to the dealer to get an ABS Automated Bleed done. Even the Service Manual describes bleeding with and without doing the ABS bleed.

By the way to you still have the same Yukon XL? Those suckers and the Tahoes like my 03 Tahoe just seem to have a soft brake pedal all of the time. I rarely got into the ABS on the Tahoe since I couldn't generate enough brake pressure to lock up the wheels on dry pavement. I had to be on gravel, snow or ice to get into the ABS. This last April after 11 seasons of driving and sitting in the upstate NY salt/sand mix they apply to the roads I got nervous about the brake lines rusting out from the outside so had them and all 4 brake hoses replaced. The brake pedal feels more firm than it did when I bought the thing 12 years ago but it still doesn't feel as good as the pedals on my 08 Bu or the Vette.

Bill

larryfs

My son had the Yukon out west, and a brake line rusted through above the gas tank. He was 1000 miles from home. Had it towed to a dealer. They dropped the gas tank, and replaced both metal lines. They do not come pre-bent. The dealer had to bend them, and flare them. Flush the entire system. Etc, etc, etc. Cost me $1000. They claimed it needed a double flush, and new bleeders. Which it probably did.

The trucks are known for rusting brake lines from road salt. It was in the news, but GM said they will not issue a recall, because the trucks are 10 years ++ old. Some say the zinc coating was never applied correctly to the metal lines.

170,000 miles on that truck, and still going. Original spark plugs !!! The transmission slip shifts between 1st & 2nd. I'll get another year out of it.....

I don't like the 2015's, so who knows what I'll get.

As far as the ABS, it seems prudent to have the dealer do it. Otherwise you have a 50/50 chance of bleeding it, it seems.