Newbie Question Regarding Bleeding Brakes

[TD in DC]

Hello All:

I have two questions regarding Brakes and brake bleeding:

I have an '02 996 Targa that I use regularly for DEs. I use Castrol SRF Brake Fluid (and yes, it is pricy) and stock brake pads. I also have a Motive bleeder and have read the great bleeding DIY article on this forum. Thanks Loren

First Question: I have been told that you should be able to use the SRF Brake fluid for an entire DE season without any worries. I have also been told, however, that you can simply bleed the calipers to remove old fluid (rather than the entire system) to keep your brakes at an optimum level since the fluid in the calipers goes bad faster than the rest. Is this true?

Second Question: The last time I bled my brakes (I was receiving help from a very experienced Porsche tech guy who frequents Dorkiphus :wink: ), I put an air bubble in the system. What a PIA, and dangerous. We did nothing that was obviously wrong, and I still don't know how it happened. My question is about what common newbie errors you can make when bleeding the brakes? In other words, can someone make a top ten list of errors and how to avoid them. Assume I both (1) know nothing and (2) am an idiot. In other words, I will not be insulted by very basic explanations.

Thanks!

TD in DC

[Don Wohlfarth]

Tod, I would think the only reason the fluid would go bad in the caliper is if the fluid has been boiled.
The reason you bleed the brakes is you have overheated them (boiled the brake fluid). If your brakes have never become spongy or the car doesnot seem to stop as well as the last time you used the brakes, you may have boiled the fluid. Be careful as the next thing to happen is the brake pedal may go to the floor. :(
For de's the general rule is ATE blue/gold is good for 6 months, regular brake fluid is good for 3 months. Have not heard that SRF is good for 1 year.
The Motive bleeder is good for a 1 man brake flush but is overkill for bleeding calipers. Have someone pump the brakes and bleed 1 caliper at a time. After each caliper check the fluid level and replace as necessary. Of course you can use the Motive bleeder if your pit crew has wandered off. ;)
Only common error I can think of is having someone pump the brake and hold it while you open the bleeder port. You only allow a little fluid out and CLOSE the port. If you don't close the port and your helper releases the brake you will draw air back into the caliper.

[TD in DC]

Thanks Don. That is extremely helpful. My brake pedal feels very strong, but it seems like it is going down slightly more than usual (I can tell because I use the foot roll method of heel-toeing). I am going to Watkins Glen this weekend and thought it would be a bad idea to do some preventative maintenance, but I also don't want to make things worse by putting in another air bubble on the day before I have to drive 6 1/2+.

[Vicegrip]

The mystery is that a Motive Bleeder was used, it never ran low, the reservoir never ran low and the calipers were never opened with the system not under motive assisted 15 psi pressure. But it looks like a bubble still got into a caliper. This is a new one to me after many flushes and I don't know how it did. Ted drove home without my checking pedal feel. You can get a little complacent after a time or two :roll:

SRF as good as it is, is still subject to the 6 month rule for DE use. Not my call.


BTW If you open a bleeder while the pedal is at the upper stop rest fluid will come out not air go in. You can drip flush by tipping a can of fresh fluid upside down on the fluid tank like a water cooler and letting it drip out from each bleeder. No Motive, second person or pedal pushing needed. You can stir the fluid in the system up some by pumping the pedal some as any back sucking of air will burp out as the fluid drains.

[TD in DC]

Kurt and all:

My fluid is less than 6 months old so I am still good. What do you think about the following advice (which, if true, would be a little less messy) that I received on renntech:

You do not need to use 15-20 psi in the bleeder. 5-10 is plenty. You do not want to use more than that because theoretically you are compressing wet air on top of the fluid and forcing more moisture into the fluid.

You want to bleed starting from the valve furthest from the reservoir (right rear). Then move closer (left rear, right front, left front).

If you are just bleeding you do not need to put any fluid in the bleeder, just make sure that the reservoir is at least half full. You do not need to have fluid in the bleeder as the amount bled is small. (If you are paranoid about running out, then top off the reservoir first.)

I do not usually bleed after each event (I do 30-40 a year). I only bleed if I notice a problem.

[Don Wohlfarth]

"You do not need to use 15-20 psi in the bleeder. 5-10 is plenty."
I use 15+ but OK.
"You do not want to use more than that because theoretically you are compressing wet air on top of the fluid and forcing more moisture into the fluid."
This fellow has been spending entirely too much time thinking about compressing "wet" air on top of brake fluid. The Motive container is maybe 8" in diameter. Only the surface of the brake fluid is exposed to this "wet air" that is under 10-20psi. It should take even a slow person less than 30 minutes to bleed all 4 brakes. How much moisture could possibly be absorbed?
A little trick you may find helpful is to write the date that you opened your can of fresh fluid. Use the open can to top off the reservoir. If you are going to flush the system use a new can of fluid. Brake fluid is cheap, even SRF, compared to finding the brake pedal on the floor at 100mph. 8)

[matt de maria]

I use an old snap-on unit which is somewhat similar to a motive. But personally I keep the pressure to about 7. My first time I used about 20 psi and blew off the blue hoses off of the master cylinder. I lost a LOT of brake fluid. Then I began to have the fear of splitting the reservoirs open with a lot of pressure and puking b-fluid over the paint.
With pressure bleeding, the order of bleeding is irrelevant.
Brake fluid goes bad by absorbing moisture out of the air at the reservoir. Then is travels everwhere. 2% water drops the boiling point by 100F. Brake fluid also oxidizes and degrades. And lately I have read that it leaches the copper out of the european brake lines (they are brazed seamed pipe)

[Don Wohlfarth]

Thanks Matt, I'd forgotten about the extra hose. :oops: I've got twin m/c so it's never been a problem.

[Vicegrip]

I run it up to 15 and let it drop down to 4 or 5. Lower pressure = bigger bubbles= easer to get any bubbles out. I often gently push the brake pedal in about 1/2 way 3 or 4 times to cause some turbulence in the fluid as it is being pushed through the lines and calipers.

A flush only gets some of the old fluid out. If the fluid was real old I always recommend that the car be driven some over a day or so to dilute old with new and then be flushed again as needed until the fluid comes out clean and tests to new specs.
If you have an antilock system even less fluid is removed. You can jump two relay points in the wiring of the antilock system and run the pump to help flush that portion of the system.

I have two tests that use different methods to determine the condition of brake fluid. One is a chemical based multi point strip test that looks for contamination. The other is a electromechanical true boiling point test. The device heats the fluid until it boils and notes this point in deg. No ifs and or butts. True condition of the fluid. The fluid that came out of my car when I bought it had little droplets of rusty water in it. It was so bad I saved some and later tested it. It boiled at 214 deg.
I always have both tests at the track if anyone wants a fluid checkup. No glove or coughing required. ;)

BTW the ratings on the cans are very close to what I get from the tester and fluid that is 6 months old in my car has a mesurably lower in boiling pont.(I now flush/blead more often than required) Also, I have tested and noted a drop in the boiling point of open can contents over a one year time. I too write the open date on the can.

[APKhaos]

If you have an antilock system even less fluid is removed. You can jump two relay points in the wiring of the antilock system and run the pump to help flush that portion of the system.

Hey Kurt, where can I find out more about this? Its been bugging me ever since I got #11 that the fluid in the ABS system never gets flushed. I'm about to risk damaging my calipers to remove some frozen bleeder screws, so its a good time for me to get clued up on a full system flush.

[9NINE6]

Give me a Porsche shop manual and a rainy afternood and I get dangerous, but I have made every mistake possible changing brake fluid on my 996 until I followed the directions below.. so here's one more way, certainly not the only way.


"911 Carrera 996
Fill up the reservoir with new brake fluid up to its top edge. Connect a bleeding device to the brake fluid reservoir. Switch on the bleeding device. bleeding pressure approximately 1.5 bar

Continue with the brake fluid change at the brake calipers (no particular tyre sequence). Open every bleeder valve until clear, bubble free brake fluid emerges and until corresponding change quantity per brake caliper is reached (approximately 250 cc's). It must be noted that bleeding takes place at both bleeder valves on each caliper. Use a collecting bottle to accurately check the escaping brake fluid for cleanliness, lack of air bubbles and to determine the brake fluid used. Some brake fluid is also drained off at the bleeder valve of the clutch slave cylinder (approx 50 cc's)"

I had to look this up..
1 bar = 14.5 PSI
cc = .033 oz

[}{arlequin]

for the abs people, after bleeding, I'd intentionally activate the abs 3 or 4 times to circulate the fluid that sits there and then I'd bleed again. That way you can ensure that all the fluid is fresh.

How to activate the abs???.... if you have to ask..... :roll:

[TD in DC]

Thanks for the great information guys.

My #@$%^&* brake pad wear sensors came on AGAIN at Watkins Glen. This is after repair and replacement by dealer . . . I will tear into it myself this weekend.

TD in DC

[Chopper Dropper]

Most disconnect the wear sensor being carefull not to break the circuit or the light stays on and you have to bridge it. If you are doing DE, you should be checking the pads often enough to make the sensors superflous.
Dirk

[cmartin]

brake pad wear sensors

Come on man, those things weigh a ton! Drop the dead weight.

[TD in DC]

OK, OK. I give in. I plan to disconnect them. Next stupid question. What is the best way to do so?

[Vicegrip]

They are a closed loop system. That it the light comes on when the loop is broken or opened. The best or you might say, easiest way to remove them is to not remove them at all. :roll:

Remove each sensor from each pad socket, you can do this without removing the pads. Take care not to crack or break them. Now remove the wire from the spring clips on the pad spring. You should now have a wire with two sensors still conected to the plug in conector. Fold the wire with sensors up tight and using 2 or 3 good zip ties bundle them to the conector to keep it out of the way.
Another way is to remove as above but then cut each wire about 2 inches from the conector, strip the wires, wire nut the conductors together and tape tight. This will save at least a good 4oz unsprung weight.

If you have a cut through sensor now you will have to replace it or jump it out for the light to go off.

[sccaracer]

Here's a thought on brake fluid, but since it doesn't cost mega $ some people may not want to consider it. :evil: I use this stuff in my race car and have never had brake fade.

Motorcraft High Performance DOT 3 Motor Vehicle Brake Fluid, Part Number PM-1, minimum dry boiling point 550 degrees F., last price for 12 oz. was $3.24.

The wet boiling point only meets DOT 3 standard, thus the rating. Hopefully no one's leaving it in (or leaving your caps off) long enough for this to be a consideration.

Ford Super Dot 4 part # YS4Z-19542-AA fluid would have a higher wet boiling point, but I haven't used it or priced it.

Ford specified and starting using this fluid years ago as an antidote to brake dragging elderly drivers of its large-size sedans who were frying fluid.

[TD in DC]

Here's a thought on brake fluid, but since it doesn't cost mega $ some people may not want to consider it. :evil:

I did not buy Castrol SRF because I am out to spend as much money as possible on brake fluid. Rather, I am so new to this sport that I do not know very much about the different brands of brake fluids, and how they will/can deteriorate at the track. I also value my life and my car, so I did not want to save money at the expense of safety (kinda like buying a helmet that is so cheap it is not safe). Once I learn more about brake fluids, I will feel more comfortable in trying those with lower boiling points and cheaper prices.

For what its worth, I was sold the SRF Castrol by someone who said the higher boiling points were particularly important for daily driver cars which might be more susceptible to moisture. He also said that I would not have to bleed my brakes as much. The true reason was probably because newbies make easy marks, but don't hold it against us because it is not our fault :evil:

I am willing to try to cheaper brands now that I am learning more . . .

[sccaracer]

TD,
I didn’t make the statement about spending mega bucks to offend anyone. :oops: You are wise to use what are using. Until you know if you have any brake fade issues, it would be wise to ‘better safe than sorry’. I used (and wasted) a lot of Castrol. I even use it when I realize I need new fluid and the Ford dealer isn’t open.

I’ve seen a lot of people buy a $20 helmet for a $20 head. :roll: It’s my opinion that when it comes to going fast, spend your money first on safety equipment, then on go-fast goodies. It’s better to run at the back and be able to race another day, then run up front for a couple of laps and sit out the rest of the season.

Welcome to the sport.
Rich

[TD in DC]

TD,
I didn’t make the statement about spending mega bucks to offend anyone. :oops: You are wise to use what are using. Until you know if you have any brake fade issues, it would be wise to ‘better safe than sorry’. I used (and wasted) a lot of Castrol. I even use it when I realize I need new fluid and the Ford dealer isn’t open.

I’ve seen a lot of people buy a $20 helmet for a $20 head. :roll: It’s my opinion that when it comes to going fast, spend your money first on safety equipment, then on go-fast goodies. It’s better to run at the back and be able to race another day, then run up front for a couple of laps and sit out the rest of the season.

Welcome to the sport.
Rich

No offense taken. I have been a little spooked about brakes since I saw the video clip of the viper that went into the wall at full speed and flipped over upside down. I don't want that happening to me, and I am worried that I will pull some bonehead move that will compromise my brakes . . . With time, I am sure confidence (and hopefully competence) will come.

[Vicegrip]

What sets the SRF above other fluids is the excellent resistance to moisture absorption. Its wet boil point is as or higher than many fluids dry points and it does not absorb water as fast as most other fluids. If you have a street driven or $$$ track car that is having heat problems it is well worth the $. For a DE car it might not add any safety factor to a car that is not already having heat problems now. Also, until someone in PCA decides otherwise (I am not that someone) it too needs to be changed every 6 months.

If you switch over to SRF from super or regular you system will be at the old fluids boil points until ALL the old fluid is removed. A single flush is not enough to do this. Many flush and drive cycles will help but if the system still has any old fluid in it (ABS loop for example) the old fluid will be the weak point.