Replacing Brake/ CLutch fluids

[Shaun12]

I am about ready to drain the stock DOT brake fluid and add the Castrol stuff. I have heard that the Stock fluid is used in both the brake and clutch systems. If I drain my brake system and replace it, will I have to do the same with the clutch reservoir or will they mix if I don't? I'm a little confused on this and don't want to waste my time by having Castrol mix with the stock fluid if I don't do it correctly.

 

[DEye]

If your planning on draining the fluid to replace it, take it to a shop...

 

[F.D. Sako]

Since our cars share the a reservoir for the clutch and brakes, there will be some minor mixing, but it shouldn't be an issue. You'll also get some mixing from the ABS module, since it has fluid in it that only circulates once the ABS is activated.

I'd just syphon and refill the reservoir, then bleed the brakes until you start seeing the new fluid coming through. Then a couple of months and track events later, repeat the same steps and you should have most of the old fluid out the system. I wouldn't pay a shop to do this, not worth it... You could buy a second bottle of SRF for the price of labor and bleed it twice, as mentioned.

 

[WinterSucks]

What I did was buy a cheap DOT4 and flush the system of the OEM DOT3 with it. Then I flushed that with the ATE Blue. That kept the nice ATE fluid from being diluted with DOT3 at least. But I forgot to pump the clutch with the cheap fluid to flush the clutch lines of the DOT3...oops. Then I hosed down the driveway and stood on the brakes to get the ABS to activate. ;D

If I could go back in time I would: flush with new cheap $5 DOT4, pumped clutch 30 times, and activated ABS. THEN flush with the nice stuff.

 

[Grant 302]

I flushed first with a cheap DOT4 first. Used a new turkey baster to get as much fluid as possible out of the reservoir before filling with new fluid. Bleed brakes to get new fluid in lines. Pump clutch or drive until old fluid or 'dark floaties' show up in the reservoir. Drive and get the ABS to activate. Repeat everything with the desired fluid.

 

[JScheier]

Then I hosed down the driveway and stood on the brakes to get the ABS to activate. ;D

Not sure if it works on the S197, but on my E36 M3, I would put the car up on jack stands (all four in the air) or a lift. Start the car, put it in gear and 'drive'. step on the brakes and ABS would activate because the front wheel sensors would detect no movement vs. the rear. Worked very well and was relatively quick (assuming you already had the car on the stands or lift).

Worked on my 86GT with SN95 ABS as well.

 

[WinterSucks]

I will give that a try when I swap wheels again later this week, thanks.

 

[TGR96]

I flushed first with a cheap DOT4 first. Used a new turkey baster to get as much fluid as possible out of the reservoir before filling with new fluid. Bleed brakes to get new fluid in lines. Pump clutch or drive until old fluid or 'dark floaties' show up in the reservoir. Drive and get the ABS to activate. Repeat everything with the desired fluid.

Forgive my ignorance, but what is "dark floaties?"

 

[F.D. Sako]

Forgive my ignorance, but what is "dark floaties?"

Black material collects in the reservoir. My guess is it's breakdown residue from all the rubber hoses. Not sure if people who don't track the car experience the same thing as well.

 

[Grant 302]

Black material collects in the reservoir. My guess is it's breakdown residue from all the rubber hoses. Not sure if people who don't track the car experience the same thing as well.

Not sure what it is, but pretty sure it's coming from the clutch side of the fluid circuit. Street driven cars eventually get it as well. I figure whatever it is, it can't be good for the fluid or its boiling temp.

Also forgot to mention the vacuum bleed procedure on the reservoir side. Not sure if it helps, but it can't hurt...and I haven't had any issues with either Boss or GT.

 

[WinterSucks]

I never had black floaties in the brake reservoir. There was a lot in the coolant reservoir.

 

[Hermes]

Forgive my ignorance, but what is "dark floaties?"

I too get the dark floaties. My understanding is that clutch material gets past the seal on the clutch slave cylinder / throw out bearing and works its way up to the reservoir. I too am planning to start using SRF but I plan to add a separate clutch reservoir before I do so. There's a good thread on that in this forum.

 

[dmichaels]

Not sure if it works on the S197, but on my E36 M3, I would put the car up on jack stands (all four in the air) or a lift. Start the car, put it in gear and 'drive'. step on the brakes and ABS would activate because the front wheel sensors would detect no movement vs. the rear. Worked very well and was relatively quick (assuming you already had the car on the stands or lift).

Worked on my 86GT with SN95 ABS as well.

Anyone try this? I am also going to be switching to SRF right before my Watkins Glen outing and I'd like to activate the ABS while bleeding.

Related question - activate ABS after refilling the reservoir or after fully bleeding the system? I hate to fully bleed the system, then have to fully bleed again after getting ABS to activate a couple times? SRF is a bit pricey....

 

[WinterSucks]

Definitely don't use the brakes with an empty reservoir. I would just bite the bullet and do a complete flush with cheap fluid then good stuff. Seems like I am not alone in that practice. If time is the issue a power bleeder will speed it up incredibly versus having someone pumping the brakes.

 

[dmichaels]

Not sure if it works on the S197, but on my E36 M3, I would put the car up on jack stands (all four in the air) or a lift. Start the car, put it in gear and 'drive'. step on the brakes and ABS would activate because the front wheel sensors would detect no movement vs. the rear. Worked very well and was relatively quick (assuming you already had the car on the stands or lift).

Worked on my 86GT with SN95 ABS as well.

For anyone interested I tried this yesterday. Did not activate ABS