bob_dallas

Anybody have an easy way to completely replace the brake fluid? I want to change to SRF. The problem is getting it out of the ABS system. I know the mechanics have a tool and I had them do it in my last car but I'd rather not pay them to change my fluid if I can avoid it. I had heard that you can flush the ABS system by pumping the brake with the ignition on (engine not running)?

Thoughts?

mds

Bob, are you saying that a power bleeder like this one won't fully flush the system?

Karl S

Bob,

There is nothing special about flushing brake fluid with the ABS system. You might be thinking about bleeding the clutch, as this shares fluid with the brakes. If you want to do this, there is a good DIY from Loren at

Loren's brake fluid DIY

Karl

bob_dallas

Power bleeder gets everything but what's kept in the ABS own internal reservoir. I just found an article that references it so I guess I'm not crazy. The ABS reservoir is not part of the brake circuit until ABS is activated so a normal flush doesn't get this out. Typically not a huge deal with most fluids and I'd bet most dealers probably don't think about it when they flush it for you. I ran across this a few years back due to an incompatibility between my new brake fluid (AP600) and the old which was causing my pedal to go soft when they mixed.

Here's the article that explains it better than I can: http://www.stoptech.com/whitepapers/...abs_122701.htm

Greg Fishman

Bob,
The tool is called a "Hammer" and most dealers and independent shops should have them. As you are bleeding the brakes you activate it and it cycles the fluid through the ABS system with the new fluid.

SundayDriver

Bob,

You are correct. AP600 is not compatible with other fluids and I seem to recall reading the same for SRF. I would not take the chance - get someone to do this with the Hammer to get all the old fluid out of there.

BTW - If you have an application where AP550 is suitable, that has the same specs as Ford Heavy Duty fluid, but the Ford stuff is a fraction of the price and easy to find. Great dry performance, but I would not use it in a street car due to wet specs. I use that in my race cars as that fluid gets changed constantly.

bob_dallas

Thanks Greg and Mark - I remember "hammer" now. Mark - I'm curious about your point that you wouldn't use 550 in a street car due to wet specs. I've heard this before but never heard the explanation - is it that it's more susceptible to absorbing water and needs to be changed more frequently?

I ran AP600 for several years in my prior 996 with no problems (once I sorted out the fluid incompatibility). I was thinking of running it again but thought I might try the SRF since I'm starting from scratch again.

TIA /Bob

JohnM

Castrol say SRF is miscible with all conventional brake fluids that meet DOT 3 and DOT 4 standards, but the mix will not have the full performance (boiling points) of SRF alone.

I've run at the track after a conventional flush through to replace standard Porsche fluid with SRF (without bothering with the ABS reservoir flush), and subsequently done bleeds and top-ups with standard fluid, with no adverse effects.

SundayDriver

Bob,

The Ford fluid is DOT 3, so the performance falls way off when it picks up some water. I would only use that in a car where I was doing a lot of bleeding/flushing to make sure it is fresh. That is the only reason I would not use it in one of my street cars unless it was a track car with lots of maintenance. Otherwise, if you can live with 550, it works well.

bob_dallas

thanks - found the stats, I see wet boiling point is 150 degree Celsius - that is quite a drop.

bob_dallas

Thanks John - that's good info, I think SRF is the way to go. It's expensive but I figure that's an area that I can afford to spend some $$...