Brake fluid change.

[Easty]

Anyone performd a change yet? The track days I'm doing require for a flush and new fluid every six months. I've bought some castrol SRF and hopefully do it this weekend. And tips in advance? may be a great help.

Thanks loads, Brian

[Saaz]

I've always heard that a pressure bleeder should be used on ABS systems for a thorough flush. (Plus it's supposed to be much easier to use.)

But I don't have much first-hand experience flushing brakes, so that's about all I can tell you.

[dava]

You realy need a pressure bleeder to do what you want and some times it is necessary to use the star diag to completely bleed the ABS pump.

[CMiYC]

While I don't recommend not doing the flush, TWS doesn't really require it. (in other words, nobody is going to ask you to prove it otherwise.)

Most of the people don't. Keep in mind that the some of the cars there (the miatas especially) are older cars. I wasn't planning to flush mine until it is 12 months old, even though they want it done every 6.

[slk55er]

dava - 4/14/2006 10:37 AM

You realy need a pressure bleeder to do what you want and some times it is necessary to use the star diag to completely bleed the ABS pump.

I've not bled the brakes on my SLK55 yet, but I've done it many, many times on many BMWs. Yes, I believe pressure bleeding is necessary and I will plan to use my usual technique -- using my air compressor and my wife's assistance as follows:

I purchased a brake fluid reservoir cap for a VW Sirrocco. It does not have an electrical sensor or wire connector in it -- it is just a plain old screw-on cap. The cap on the SLK55 is similar. (Most BMW caps have a fluid level sensor in them.) I then drilled a 1/2 inch or so hole through it and installed an "L-shaped" air hose fitting to it with some gaskets to minimize air leaks.

First I remove the wheels and make sure I have the correct size wrench -- 7 or 8 mm on a BMW as I recall (flare wrench preferred) and clear hose to connect to the bleeder nipples. The hose should be looped once and inserted into a suitable container (old brake fluid bottle.)

I then use a turkey baster to remove as much old fluid as possible from the reservoir. Fill the reservoir with fresh fluid. (Alternating fluid color from one bleeing to the next makes it easy to see when you have flushed enough fluid through into each caliper.)

Then install the reservoir cap with the air fitting and connect it to a 15psi air hose. Start with the wheel farthest from the reservoir (right rear on US cars). Connect the bleed hose, open the bleed nipple and have your assistant press the pedal to the floor and hold it there while you close the nipple. Then have the assistant allow the pedal to return up to it's normal position. Repeat this as many times as necessary to see fresh fluid entering your hose and then a few more times for good measure. If you see any air bubbles, continue until there are none.

Make sure that the fluid level does not drop in the reservoir enough to draw air into the lines. Check the level a couple of times through the process.

Repeat the process for each wheel, doing the caliper closest to the reservoir last. When done, top up the reservoir with the proper level of fluid and re-fit the wheels.

Wear latex gloves when doing this ( the fluid is toxic) and don't drip or spill any on paint -- it will severely damage paint.

Any additional comments or corrections greatly appreciated.

[Easty]

Your a star mate, I used to do most of the stuff on my car.. but it's been a while. The reason I'm doing it within 6 months is that a tech form is required to partake in the track days and my friend can sign them off for free. He just asked that the brake fluid be changed within 6 months. Unless it's got some Castrol in it's vains. He used to do a lot of professional racing and this is his only reqest.

[Duo-Art]

What is the reason for them requiring you to change brake fluid every 6 months? Does it go bad from the heavy use of the brakes at the track?

[Easty]

Yes, general fluid boils under extreme use and gets saturaed with air. I was at my friends when he last did his elise and the fluid came out black. I used to change the bike fluid every three months if I was doing a lot of track days. It also deponds on the track, little pokey track with no straights are a lot worst than say TWS which has likea runway after every turn.