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-   -   Power Brake bleeding procedure difference. . (http://forums.pelicanparts.com/porsche-911-technical-forum/969515-power-brake-bleeding-procedure-difference.html)

Lmarche 09-22-2017 07:14 PM

Finally I did the brake bleeding, My first time with motive bleeder. Flushed two bottles of the racing stuff, didn't touch the brakes, I'm pretty comfortable with the braking action.
When I bought the car, brakes where stiffer, but during hard braking the car wanted to turn a little. A local shop performed the four caliper overhaul, they found a couple of frozen caliper pistons. Since then pedal stiffnes hasn't been the same.
Should a blame dose two frozen caliper pistons for the less pedal displacement it used to have?

911pcars 09-23-2017 08:33 AM

The brake system only needs 1 liter for a complete fill. Wasting new brake fluid is well.... wasteful. Spitting out a liter of new ATE Blue is about $10, Motul RBF about $17, Castrol SRF about $65, but that's the result when pressure bleeding to drain, flush and refill.

Sherwood

adias 11-22-2017 09:39 PM

There is a hose (venting?) on the side of the MC reservoir. Does that have to be plugged/sealed when using the Motive?

Rawknees'Turbo 11-22-2017 09:42 PM

Quote:

Originally Posted by adias (Post 9824462)
There is a hose (venting?) on the side of the MC reservoir. Does that have to be plugged/sealed when using the Motive?

The Motive supplies air to the cap area, correct? If so, then yes, the vent has to be plugged or air and fluid will flow out of it.

PS - when pressure bleeding with a compressor, you can attach the air supply to the vent nip and leave the original cap on.

adias 11-22-2017 10:12 PM

Quote:

Originally Posted by Rawknees'Turbo (Post 9824464)
The Motive supplies air to the cap area, correct? If so, then yes, the vent has to be plugged or air and fluid will flow out of it.

PS - when pressure bleeding with a compressor, you can attach the air supply to the vent nip and leave the original cap on.

Makes sense. Where does that vent lead to? I suppose one just removes that tube and attaches a clamped one.

bkreigsr 11-23-2017 06:30 AM

Quote:

Originally Posted by Lmarche (Post 9732087)
... 2 cans of the blue stuff and lots of towels. ...


How old is that stuff?
If it's older than a year I wouldn't be using it.
Bill K

911 Rod 11-23-2017 08:18 AM

The vent is for boil over and should come out just in front of the driver's a-arm. I use a set of surgical forceps that clamp down.

I thought an unopened can of brake fluid should be good for a couple of years. I didn't think you could get blue anymore.

adias 11-23-2017 08:36 AM

Quote:

Originally Posted by 911 Rod (Post 9824848)
The vent is for boil over and should come out just in front of the driver's a-arm. I use a set of surgical forceps that clamp down.

I thought an unopened can of brake fluid should be good for a couple of years. I didn't think you could get blue anymore.

The vent tube is now 30+ yo. Is it wise to clamp it?

You say surgical forceps... the typical ones do not self clamp. How do you keep them clamped down?

911 Rod 11-23-2017 09:33 AM

Quote:

Originally Posted by adias (Post 9824865)
The vent tube is now 30+ yo. Is it wise to clamp it?

You say surgical forceps... the typical ones do not self clamp. How do you keep them clamped down?

If you did damage the hose you could cut the damaged part off and re-attach.

The forceps you show do self clamp.

chrismorse 11-24-2017 07:29 AM

Having spent 10 years as a service writer/manager at GM/fiat/ssubaru dealership, I often got called on to push the pedal for the mechanics. Most of the cars were fairly new but some of them were 10-30 years old.
I noticed a significant number of the older cars experienced a failed maaster cylinder right after the bleed. I put this down to the "full" travel of the MC piston(& cup seal) during the bleed. My sense was that during normal use the brake pedal would only travel part way down the bore. The seal would push any debris only part way down the bore. If you pushed the seal past/over this pile of crud you risk nicking the seal.
If the fluid is flushed, every one or two years, (not just bled), you are ok to use foot power.
IF you don't know the service history on the car, foot bleeding is a risk.
BTW, the shop went to power bleeding and master cylinders enjoyed much longer life.
I have had good results with mighty vac. When I install the lift (& do more brakes), I will go to the motive bleeder.
Chris

911 Rod 11-24-2017 07:43 AM

^^ What you say is true and that is why you put a block of wood under the brake pedal so it does not go all the way down.


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