Help getting firm brake pedal back

Well, the caliper rebuild/pad replacement/wheel bearing replacement is complete with new Super Blue Fluid, but my pedal is now quite spongy and has much more travel than before.

It used to be very firm and engage the brakes almost immediately. I bled the system at least three times over a 12-hour period, but with no driving in between.

I know about the trick to move the pistons further out, but I used the good caliper grease during the rebuild and the pads are right on the rotors.

I also know about the bed-in period for new pads and turned rotors.

Should I drive a few hundred miles and then re-bleed the system? braking seems adequate once the brakes engage even with the new pads (Ferodo), but I really want the old pedal feel back.

Thanks,

Olivier
82 SC

Hi Oliver, I posted this very same situation a few weeks back and got a number of replies, most of which suggested to do just as you say - drive it for a couple hundred miles. Check the archives (SC brakes) for the thread.

Sorry Oliver, I got my web boards mixed-up. I believe the most replies came from my thread on Rennlist.

Rebleed the system using an assitant to stomp on the pedal. All the other methods are good, but the force of the pedal being pushed helps to get trapped air out of the system:

http://www.pelicanparts.com/techarticles/mult_bleed_brakes/mult_bleed_brakes.htm

-Wayne

I had the same problem after my caliper rebuild. But just give it about 3-4 weeks and you will get your firm pedal back. You have to give time for the pistons to work there way out, so that the pads are closer to the discs.

I think you've probably seen my posts, Oliver. I could not wait for pedal travel to go away, so I pulled pads one at a time and blipped the brake pedal. Thsi moved the pistons out and removed the long pedal travel. Just driving it will also do this, but you must have more patience than I.

If, when brakes are applied, you get sponginess in addition to the increased travel, then there's air in the system. Besides Wayne's suggestion, you can beat on the calipers to loosen any bubbles that might be in there. loosen the two big mounting bolts and hit it with a soft hammer. Carefully but firmly.

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'83 SC

UHH, Guys, I think his name is Olivier, not Oliver. Probably not a big deal, since you are answering his questions, but....

Sounds well known:

http://www.pelicanparts.com/ultimate/Forum3/HTML/002591.html

Good luck, following the procedure should fix it it the brakes were bleeded correctly.

Jens

Thanks for all the replies, guys. I think I will drive a few hundred miles (put a gun to my head, I know) and then rebleed if necessary. After bleeding it som many times, I would be surprised if much air was left in the system. I am reluctant to use Super's shortcut because the pistons were a tight fit and I wouldn't want to overshoot and have to mess with clamping them back in.

The tech articale mentions the proportioning valve, is this taken care of simply by stomping the brake pedal during bleeding? The technique my wife and I used was to have her apply pressure with the bleeder closed, then open the bleeder and close it after the pedal hit the floor, and repeat. Does the stomping part apply during these steps? I have always had disappointing results after bleeding (except on motorcycles), so maybe my technique is poor.

I also used Speedbleeders from Wayne on the fronts, but I still asked my wife to help so I could monitor the air escaping (and the new SuperBlue fluid). I assume there are no draw backs to using bleeder valves with their own check valves (like maybe small amounts of air getting back in the system as the check valve closes?)

Thanks again, everyone. I will be happy to get the firm pedal back. The car has SS lines, and the brakes have always been confidence-inspiring like that, to say the least. The front end feels "lighter" and smoother after the caliper rebuild and bearing replacement. One stuck piston must have been causing a lot of drag.

Olivier
82 SC

Been there, done that. Are they spongy ? Or are they just not hard on the first pedal.
I too was not willing to be patient.
Trick that I picked up on a post on the board. I cut to pieces of plywood to replicate the pad. Then I pulled the pads out. Put in the plywood. Gave the brakes a slight tap. Which got the piston out further than it is currently going. Best explanation ( I think Warren ) that came up with is. The new wiper in piston is pulling the piston out to far after you step on it. There by creating a gap that must be retaken up when you use them again.

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Cary Kutter
77 Euro Carrera w/3.2
Rennlist Member
PCA Region - Big Sky

There definetly is a correct technique to bleeding. I have done the two person method and there is a pattern and techinique that is needed. Unfortunately, since I am the one pushing the pedal, I miss most of it. Here is what he has explained. Never drain your system completely dry and then refill, you will be creating many places of trapped air. Start with the caliper the farthest away and end with the rt front. Never press the pedal completely to the floor, you may disturb the seals in the master cylinder. After pumping the brakes about 15 times from pedal up to 3/4 down, he then applies pressure to the hose that is connecting to the bleeding nipple to force bleed any remaining bubbles. This is done by him squeezing the hose, me appling the brake pedal, and then him releasing the hose. You can feel this immediately in the pedal. Work all the calipers as described and then go back once more to check. Top off brake fluid. Some suggest using different color fluids, ATE blue and then gold, to tell when the new fluid is through. You can also tell by keeping tract of the amount bleed. My system uses about 8/10 of the ATE can. Close the remaining can and date it. It sould not be used after a month because of moisture contamination. We have done this every year with no problems and have not had to redue it after any track events.

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8 9 9 1 1, The last of the line.