Silly brake bleeding question.

Rick Lee · Rick Lee's Garage

If I mess up with my clutch bleed and introduce air into the system (from the master cyl. end), but was all done with the brakes, do I need to go back and bleed the brakes again?

Last night I was using my new black label Motive (love it) on the 993. I was all done with the brakes and went to do the clutch slave cyl. The Motive unit was kinda low on fluid, but I had enough to git'er done. But then it tipped over while I was under the car, the fluid level sloshed around and I got air into the line. My pedal stuck to the floor. I opened another can of fluid, put it in the Motive, pressurized it and, sure enough, got lots of air coming out of the clutch slave. Pedals feel very firm now, but I haven't put the wheels back on or started the car. Do I need to redo the brakes? Thanks.

Superman · 08-08-2008, 10:02 AM

I am not familiar with hydraulic clutch systems in a 911, but would be very surprised if the clutch and brake systems are connected. I would expect them to be 100% independent.

Rick Lee · Rick Lee's Garage

But they do share the same fluid reservior.

Fast Corners · 08-08-2008, 10:56 AM

Ok, I'll bite.

Rick is correct, they (brakes and clutch) share the reservoir. A thin baffle plate in the reservoir usually keeps the different circuits from compromising the other circuits. In other words, a leak in one system will not bleed the resevoir to completely dry on the other circuits.

If all of the pedals are operating properly and are firm in operation, I would say that you are ok. With that being said...an ounce of prevention is worth a pound of cure. How much would it hurt to re-pressurize the system and run some more fluid through for the piece of mind?

Just as a side note this is why I like the ATE fluid in blue and gold colors. You can easily tell when the system is flushed and you have completley replaced the fluid in that particular circuit.

Rick Lee · Rick Lee's Garage

Oh, I know all the old fluid is out. No question there. I went from gold to blue this time. But I don't really want to crack open another $15 can of ATE Blue and rebleed if I don't have to. Pedals feel find with the car off and in the air. It's a matter of whether wasting another can of brake fluid is worth not getting surprised by mushy pedals and then having to jack the car up and remove the wheels again.

Fast Corners · 08-08-2008, 11:10 AM

Rick,

With your motive bleeder do you pour the fluid in it and then pump away or do you fill the reservoir and then use the pump dry (just to supply pressure)? Just wondering.

If you are going to drive the car hard at a track I would re-bleed the brakes. If you are just driving around town you should be fine.

Rick Lee · Rick Lee's Garage

I use a syringe to take some old fluid out of the reservoir, fill the motive and pump away. I always do a full flush. I don't track anymore, so no bleeding/burping.

KFC911 · 08-08-2008, 02:09 PM

Rick, If I'm just doing a bleed, I use the Motive "dry", and it doesn't take much fluid at all for me to make a second pass around (930 calipers - 9 bleeders). Did you use up all your blue or do you still have a few ounces left?

Superman · 08-08-2008, 02:33 PM

Okay, they share a reservoir. Still, it would surprise me greatly if running that reservoir dry by draining the clutch system would affect the braking system. Plus......if there is any air in the brake system, the pedal would definitely tell you. A teensy bit of air means a spongy pedal. A firm pedal means all-fluid, no-gas. That's my two cents.