99 C5 Brake is spongy after Pad replacement
08-22-2015, 02:20 PM
#1
99 C5 Brake is spongy after Pad replacement
Brakes were perfect before pad replacement.
Pulled the cap off the master cylinder
Removed the calipers, and pulled the pads.
Front pads first. Inserted an old pad over both pistons and slowly pressed with a C clamp to retract the pistons.
Removed each rotor and had it shaved smooth (didn't need it, but cut them anyway)
Did the same for the back. Very little fluid came out of the master cylinder.
I replenished the master cylinder and reinstalled everything
Started the car and pumped the brakes.
Spongy pedal.
Pumped them more.
Took the car for a test drive and the brakes barely stop the car as they feel spongy and wont lock up. If I don't pump the brakes before I try to stop, I will have a tough time stopping.
Added speed bleeders and re-bled them with the car off.
Pumped the brakes with the car off and they felt good. Started the car and the spongy pedal feel was back and I am no better.
I noticed that there is a small amount of air at the top of the master cylinder. The brakes will not lock up.
They used to lock up prior to the pad replacement anytime I went over a hard bump and the ABS would turn on.
Now I can barely stop the car without pumping the brakes.
This car is going to kill me.
Any input would be awesome.
Pulled the cap off the master cylinder
Removed the calipers, and pulled the pads.
Front pads first. Inserted an old pad over both pistons and slowly pressed with a C clamp to retract the pistons.
Removed each rotor and had it shaved smooth (didn't need it, but cut them anyway)
Did the same for the back. Very little fluid came out of the master cylinder.
I replenished the master cylinder and reinstalled everything
Started the car and pumped the brakes.
Spongy pedal.
Pumped them more.
Took the car for a test drive and the brakes barely stop the car as they feel spongy and wont lock up. If I don't pump the brakes before I try to stop, I will have a tough time stopping.
Added speed bleeders and re-bled them with the car off.
Pumped the brakes with the car off and they felt good. Started the car and the spongy pedal feel was back and I am no better.
I noticed that there is a small amount of air at the top of the master cylinder. The brakes will not lock up.
They used to lock up prior to the pad replacement anytime I went over a hard bump and the ABS would turn on.
Now I can barely stop the car without pumping the brakes.
This car is going to kill me.
Any input would be awesome.
08-22-2015, 04:28 PM
#2
Le Mans Master
Member Since: Aug 2005
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St. Jude Donor '13-'14-'15
You need to BLEED the brakes !!!!!!!!!!
Start with the passenger side rear 1st
then driver side rear
Pass side front
Driver side front
As you are bleeding them make sure the master cylinder does not go dry or you'll have to start all over again--
It's a 2 man job--One to press and hold the brake pedal and one to open the bleeder and purge out all the air bubbles---Keep purging/bleeding until you see no bubbles---
Start with the passenger side rear 1st
then driver side rear
Pass side front
Driver side front
As you are bleeding them make sure the master cylinder does not go dry or you'll have to start all over again--
It's a 2 man job--One to press and hold the brake pedal and one to open the bleeder and purge out all the air bubbles---Keep purging/bleeding until you see no bubbles---
08-22-2015, 04:49 PM
#3
You need to BLEED the brakes !!!!!!!!!!
Start with the passenger side rear 1st
then driver side rear
Pass side front
Driver side front
As you are bleeding them make sure the master cylinder does not go dry or you'll have to start all over again--
It's a 2 man job--One to press and hold the brake pedal and one to open the bleeder and purge out all the air bubbles---Keep purging/bleeding until you see no bubbles---
Start with the passenger side rear 1st
then driver side rear
Pass side front
Driver side front
As you are bleeding them make sure the master cylinder does not go dry or you'll have to start all over again--
It's a 2 man job--One to press and hold the brake pedal and one to open the bleeder and purge out all the air bubbles---Keep purging/bleeding until you see no bubbles---
I guess I forgot to write that i bled them numerous times. Had my son pump them up with the running, then had him pump them up without the car running. Didn't notice any air and the master cylinder only lost a little fluid when i originally pressed the pistons back in. I installed speed bleeders and bled them 2 more times with the engine off. They felt great until i started the engine. Then they went to mush again. I'm really concerned because they wont lock up, and a simple pad replacement wouldn't damage the ABS. I feel that the ABS is loaded with air.
08-22-2015, 05:20 PM
#5
I'm sure the air has to be coming from ABS as i filled the master cylinder to the top and notice air at the very top of the master cylinder. You can see it below the filler neck (which is loaded all the way up) as the color at the very top below the filler neck is a lighter color than the entire remainder of the master cylinder resevoir. It looks like one or 2 mm of air on top of an entire master cylinder of brake fluid and then clean brake fluid above the air pocket/bubble.
I have not removed the master cylinder or bled the master cylinder mainly because i have no clue as to how to do it.
One person stated that i should jack the rear wheels off the ground and drive 11mph to fool the ABS system, then bleed them with the car running. Don't know if the car should be in drive or park when i do this since the wheels will be off the ground.
Not sure this will work.
I've replaced brake pads on this car 2 times as I have owned it for 10 years and it only has 58k on it.. This is a mystery, but it is VERY dangerous
Last edited by aerovette99; 08-22-2015 at 05:24 PM.
08-22-2015, 07:47 PM
#6
Use a pressure bleeder
You need to bleed the system, this can and should be done with the car not running. I use a Motive pressure bleeder, if you can get you hand on one of those that would be best. Make sure you are using the correct Dot-3 quality Brake fluid.
08-22-2015, 08:45 PM
#7
Race Director
Member Since: Apr 2007
Location: South Western Ontario
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You might need a TechII to bleed the ABS pump because if you get air into certain pockets of it you just can't get it out with bleeding.
You also might have damaged the master pushing fluid back into it. I always open a bleeder and let that fluid out at the caliper.
You could try the jack and bleed. Basically, jack it up and support it well on blocks or stands. Take the rear wheels off and then use a couple of nuts to hold the rotors in place. You have speed bleeders so open them now and hook up a hose and container to catch the fluid. Then, start it and let it run in gear so the traction control comes on and brakes the rear wheels which will pump fluid out of the calipers and hopefully clear the air from the ABS. Obviously, be very careful since you're working around moving parts. You'd also likely have to pump bleed it more after you let the ABS pump some fluid.
You also might have damaged the master pushing fluid back into it. I always open a bleeder and let that fluid out at the caliper.
You could try the jack and bleed. Basically, jack it up and support it well on blocks or stands. Take the rear wheels off and then use a couple of nuts to hold the rotors in place. You have speed bleeders so open them now and hook up a hose and container to catch the fluid. Then, start it and let it run in gear so the traction control comes on and brakes the rear wheels which will pump fluid out of the calipers and hopefully clear the air from the ABS. Obviously, be very careful since you're working around moving parts. You'd also likely have to pump bleed it more after you let the ABS pump some fluid.