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Join Date: Dec 1999
Location: Folsom CA USA
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Well, After following the Bentley procedure, I can not "pump up" the pedal to get a higher pedal. This took four more quarts of brake fluid. It is still a little mushy just after the 1" free-play. This is with the engine off.

I am still disappointed.

I just don't recall the pedal being so mushy before when I first got the car.

I will go for a test drive in a little bit...

Thanks for everyone's replies, I anticipate with the higher pedal, HOPEFULLY, bedding-the-pads-in the next couple of hundred miles will help with the braking power.

Time for a test drive, I will post back.

Thanks again to Everyone! This board rocks!

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Nick
'85 Carrera
Old 06-18-2003, 02:14 PM
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The "too much freeplay" problem is common after changing pads, and especially common after rebuilding calipers. Using a flashlight, see if you can see any light between the pad and the rotor. There should not be. If there is, then remove the pad, push the puck out slightly, and gently hammer the pad back in as a tight fit.

Sponginess on the other hand, always means air in the system.
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Old 06-18-2003, 02:57 PM
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After a caliper rebuild (or a pad replacement, if you push the pistons in too far) it will take a while for the pistons to work out to their proper "at rest" position, (with the pads just off the rotors). The seal on the piston grabs the cylinder walls a little bit so that when you let off the brakes they release. If this is the problem you will need to push harder or even pump the pedal, as the pistons have farther to travel before they contact the rotor.

It should be easy to check if this is your problem. Pull the wheel off and have a look, if there is any space at all visable between the pad and the rotor, you need to get the pistons to extend more. Some people say to use a block of wood in place of the new pad, or an old pad. If this is what is happening, it will fix itself over time, as you brake and the pistons work their way out normally. In other words, "It fixes itself"

The proceedure from the Bentley manual doesn't look right. I was taught that you shouldn't pump the pedal with the valve open, as releasing the pedal will draw air in the bleeder valve.

The way I learned it is:

Helper pumps until firm pedal and hold, says "OK"

Open bleeder valve, helper feels the pedal soften, but doesn't push all the way to the floor as overextending can damage the M/C

Close bleeder valve when fluid stops, moving. Say "OK"

Repeat as necessary.

Tom
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Old 06-18-2003, 02:59 PM
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Thanks for the replies Super and Emcon.

Emcon, that's what I thought - and that's how Bentley specifies if your are NOT using a Pressure bleeder.

With the pressure bleeder, and described above, I have a tube on the nipple and the tube goes into a waste container and is full of fluid. So, if it did make a vaccum (but with pressure on the M/C I presume it couldn't) on the bleeder it would take back in the "old" fluid. In my case it was all good fuid....


I can brake and lock-up the front and REAR - right side of the car.

My rear tires are kinda' bald though. I got new ones so no worries.

I presume my right side is locking up because of the way I set my ride/height and weighted my car. I set as +/- 20 lbs in each corner. Hence, with me in the car... I get right side lock-up

I do need to check the air pressures in tires still though.


It still seems like I need more pedal pressure than I should....
Maybe I am too used to a small import car (driving the wife's import while I was working on mine).

I think I will still get new bleeder nipples though. It looks like I get just teeny-tiny bit of fluid on the nipples after pumping the brakes hard. I put a hose on them and routed the hose upward. I am not 100% sure if it was fluid left in the hose, or fluid coming out the bleeder.

Finally, I hope my driving will help finish-off and BED-IN the pads.

Free-play seems normal, as there is no feedback in that first 1" of free-play before contact with the master cylinder.
I would double-check and see what free-play should be with the Bentley manual after a few hundred miles.

THANKS TO EVERYONE ON THIS BOARD FOR THE HELP!!!
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'85 Carrera

Last edited by nhromyak; 06-18-2003 at 04:01 PM..
Old 06-18-2003, 03:56 PM
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Nick,

Did you ever solve your brake issues? I am experiencing the EXACT same thing. The pedal is great after about halfway down.

I have a new M/C, new pads, rotors, calipers...As I am tracking my car I have been constantlly changing these parts. Have had gallons of fluid through the system. I have also had a Porsche master mechanic work on it and he has had no luck. Nothing so far has made an improvement.

There is something I am missing, I am sure. I might just replace the M/C again as the pedal seems firmer when you press it HARD. But this would be the 3rd M/C on the car in 3 years.


I was thinking of two possibilities: either replacing the stainless braded lines (2 yrs old) or replacing the proportioning valve.

You definately aren't nuts...
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Casey
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Old 10-26-2003, 04:01 PM
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As I recall, I went through 8 quarts of fluid.



The best sign of hope I had was swapping bleeder nipples on my rear calipers. That seemed to make the most difference.

Almost everyone I talked to said, I have air in the system. Some thought the air is either still in the M/C or in the little pressure regulator to the rear brakes.

I still lean towards leaking bleeder nipples on mine.

But yah, it is solved.... for now....

PM me if you and see if I can help.

LMK what all you have done so far.

Good luck.

P.S. "Bedding-in" has done nothing for me since I swapped my rear bleeder screws around. The pedal is high and hard.
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'85 Carrera
Old 10-26-2003, 05:40 PM
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Ok,

THis is a slightly old thread, but it is always nice if you are running a search on this BBS to get answers to the problems originally posted. Sooooooo....


I replaced my rear bleeder valves and got a near immediate improvement in my pedal. At that point I was trying one thing at a time. I realize it seems like an obscure thing to do, but I just wanted to go on record as saying it made a significant improvement. My mechanic thought I was nuts when I said I was going to try it, yet he has mentioned he ran into the same problem recently with a customer, replaced the rear bleeder screws... it solved the problem.

I guess I am thinking that as corrosion builds to the bleeder screw threads you can't get the same snug fit as when new. )My bleeder screws were most likely the original ones from 1978). As a result you can suck a little bit of air back into your system when you let off the brake pedal.


Hopefully this will help someone else out one of these days.
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Casey
Road-rally, Targa Newfoundland junkie!!!
1969 RSR 3.4L PCA class GT-3 (in progress)...1800 lbs and dropping
Thinking of driving in TARGA NEWFOUNDLAND? Contact me and I can help answer your questions. The event is awesome!
Old 01-01-2004, 12:19 PM
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Thanks Casey. I always try to update any old post like this too if I find the soloution to the problem.
Old 01-01-2004, 12:43 PM
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I hope your mechanic's Ego isn't too big... With some mechanics, after you solved a problem they sweared would never work, and it works for you, they give you the brush-off from then on.

Glad to hear it worked for you!
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'85 Carrera
Old 01-01-2004, 04:01 PM
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If you have any brake fluid on the pads, cleaning will not help. The friction material on the pad is porous and will soak up the brake fluid. Only solution is to replace the pads after thorough cleaning of the surounding parts and rotor.

My car had a passenger rear caliper leak recently, with lots of brake fluid on the pads with similar mushy pedal and a clicking action about 2" in before real braking took place. I had both rear calipers rebuilt and new pads fitted by my workshop tech. Braking action was fully restored, and I did notice that they bled the system in the correct order (longest line fisrt).

I suggest you change the pads for new ones, and get a professional to bleed the system if you are unsuccessful doing it on your own. In my case, I noticed 3 techs working on the car simultanously when they did the bleeding, one to push the pedal, another working at the bleed screw and a third at the m/c.

good luck

LeRoux

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Old 01-01-2004, 10:17 PM
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