There is a thread going on in the roadracing forum regarding how often to flush and or bleed the braking system. The general consensus was that it should be done before every HPDE.

I had a complete flush 2 HPDE's ago. From my understanding a complete flush require a gm tool to be done on the C6. I know I paid about $100 to have the flush done last time.

Is it reccomended to do a full flush before every hpde and do I need that special tool? Or can I just bleed all the old fluid out and replace with new fluid?

What are your thoughts



Thanks

 

I pressure bleed mine after every HPDE, and have never used a tech2 to flush the abs. Ive had no problems. When i burnish pads i hammer on the pedal, and this does my abs flushing LOL. Motive bleeder works great.

 

Ok so excuse my ignorance but bleeding the fluid until it comes out clear is the same as flushing right?

 

any one

 

Yes you can either do it the old fashion way with 2 people or
gravity bleed(I have done this and it works great only takes a couple
hours to complete tho)best bet is to get a motive bleeder and be done in half hour(my new prefered method)I do it before EVERY track day

 

thanks

 

Best and fastest way to bleed the brakes is the 2 person pump method. Just have one person in the car pump the pedal until it is hard and then hold it down while the other person opens the bleeder screw. Start with the caliper farthest from the master and work your way closer. As far as a time frame to change the fluid, you can never change it too often. The moment that you open the new bottle of fluid, it starts to absorb moisture, lowering the boiling point. Just because the fluid is clean does not mean that it couldn't be full of moisture.

 

You don't need to do the ABS bleed unless air has gotten into the brake system above the brake pressure modulator valve. If you keep fluid in the master cylinder while bleeding you will not get air into the BPMV.

You can be **** about things but I believe you should do what you can get by with. You only have so much time to do things and it is always better spent doing things that need to be done Vs doing things that don't need to be done.

Yes, moisture gets into brake fluid and there have been lots of people say it drops from the dry boiling point to the wet boiling point within a few days. In 17 seasons of HPDEs I haven't experienced it dropping that fast. I flush/bleed the brakes several days before an event and then spend a couple of days at the event and I never bleed while at the event. Have never had an issue with boiling the brake fluid and I use race compound brake pads that run at 1300 degrees and turn the rotors red hot. If there are several weeks between events I bleed the calipers several days before that next event. I do not bleed after an event and I drive the car on the road as much as possible between events and the brakes work fine without doing that bleed.

I have bled brakes by using the pumping method, a vacuum unit that is driven by my compressor and with a Motive Pressure bleeder. The pump method is actually slow and requires a second person. The vacuum method works well but the unit I have can suck brake fluid out of the lines so fast I have to be careful not to empty the master cylinder. I prefer using the Motive unit. I use the vacuum unit to suck almost all of the fluid out of the reservoir and then refill with fresh fluid. Then I use the Motive to pressurize the system to 20 psi. By the time I have done one rear and one front caliper I need to remove the Motive and top off the reservoir. Then I pressurize again and do the remaining calipers. Two 12 oz bottles of Wilwood 570 are required to do this.

Bill

 

This is just plain wrong...you never "pump the pedal until it is hard" when bleeding brakes and the FSM specifically says not to do this.

 

Over here mechanics are advised no to use this method anymore, it's old school and can damage you piston seals in the master brake cylinder. Over time there will be small edges in the cylinder wall where the piston stops when you brake, when you use the old method you push the piston beyond these edges and this can damage the piston seals. It's much better to use a pressurized brake bleeder.

 

To be honest, I do not understand how it is "just plain wrong." After making sure that you have no air coming out of the calipers, how do you double check that there is no air in the system?

 

I do understand that this is an older method but it is the method that we use and it works well for us and we have had no failures of master cylinders due to this bleeding method.

 

Same deal. That bleeder really does the job!

 

I use a Motive Power Bleeder myself. The unit is designed to put fluid into the bottle, however I just use the bottle simply as a pressure source. I don't put any fluid into the Motive bottle - I just hook the cap up to my m/c and pump the Power Bleeder up to about 12-15 psi and it pushes fluid through the brake system real well. You just have to check often to make sure the m/c doesn't get empty.

But many people do not like the way it pushes the fluid through your brake system with pressurized air. Whether you put fluid in the bottle or just use it as a pressure source, you're applying pressurized air to the surface of your brake fluid.

You want to try to keep moisture out of your brake fluid. As has been mentioned, as soon as you open a bottle of brake fluid moisture from water vapor in the atmosphere can start to get into the fluid.

If you apply pressurized air to the brake fluid, it may push that moisture into brand new brake fluid as you flush it into your system. David Farmer has reported that he has rigged up a tube and cap for the master cylinder that he hooks up to a nitrogen bottle. Pressurized nitrogen is virtually completely dry (no moisture in it at all) and is inert so it won't add anything unwanted into your brake fluid.

Very high end power bleeders have a diaphragm that pushes on the fluid, so you can pump up the unit with air but the moist air never touches the fluid.

Also, pressurizing by pushing the brake pedal will not introduce moisture into the system. It may be "old school" and fred_S is concerned about it damaging the piston seals, but if that's the case then you better never push on that brake pedal while driving!!!! When you stop, especially a hard stop in traffic or at the track, you're pushing a helluva lot harder and creating a lot more pressure in the system than when you're bleeding/flushing your brake system.

So.....many ways to apply pressure (or vacuum) to the fluid when bleeding/flushing, and unless you're really worried about adding moisture to the system with pressurized air, the Motive Power Bleeder works very well.

Bob

 

In your first post you weren't checking for no air in the system, you were clearly saying to pump the brake pedal until hard after which the bleed screw is opened which is a bleeding technique although an incorrect one. Even at that, you don't "pump the brake pedal" to check for air for the same reason you don't pump the brake pedal to bleed the brakes.

It's obvious you don't understand how it is plain wrong...if you had read the FSM before performing repairs, you would know. From the FSM:

"Rapid pumping of the brake fluid pushes the master cylinder secondary piston down the bore in a way that makes it difficult to bleed the system."

You're also suppose to release the brake pedal slowly and wait 15 seconds before continuing the bleed sequence. If you don't know the reasons the FSM specifies this distinct procedure, you're customers would really be better off going to the corner garage. Get a set of FSMs and educate yourself for the benefit of your customers... you clearly don't understand how a dual master cylinder operates.

Even in the "old days" of single master cylinders, the rapid pumping method was incorrect...the only thing you would possibly accomplish is aerating the fluid which is exactly the opposite of what bleeding brakes is suppose to accomplish. It's just another "old wives tale" that won't go away because people supposedly in the know perpetuate it.