Spongy Brakes - 89 535i

[angusbn]

New Brembo rotors and pads all around 4k ago. I do not know the history of the calibers, master cylinder or servo since I bought the car in 2006.

Brake fuild flushed last Fall.

No brake warning light.

Pedal travel is about 4 inches and distance from the firewall is 3 inches approximately. Just feels weird.

Searched around in the archives but didn't find anything similar.

Thoughts?

[BigKriss]

flush the brake fluid

[Russell]

is it soft and seems to require a lot of pressure? Mine is similar after Ate rotors and Raybestos Qs ceramics. Been so for about 25,000 miles for the front. Rear rotors/pads this year did not change anything.

[angusbn]

Not actually a lot foot pressure per se, it just the pedal travel distance seems excessive. The braking distance seems a tad longer. Feels like I'm almost clutching :>

[winfred]

make sure that all of the calipers have their spring clips inplace, they can be seen though the holes in the wheel, if they are missing the caliper can flex away from the carrier, this is on all cars with single piston calipers, on cars with multi piston calipers (pistons on both sides of the rotors) one piston or one side can stick and the other side still works, this will eventually start flexing the rotor more and more as it wears the pads on the dead side

[Russell]

mine has a lot of travel as well. Pretty sure, I have all the springs as winfred states. Even so, I will check for caliper travel.

[winfred]

i have come across a e34 with a partially stuck brake booster that made for long travel now that i think about it

[bmwrp8]

New Brembo rotors and pads all around 4k ago. I do not know the history of the calibers, master cylinder or servo since I bought the car in 2006.

Brake fuild flushed last Fall.

No brake warning light.

Pedal travel is about 4 inches and distance from the firewall is 3 inches approximately. Just feels weird.

Searched around in the archives but didn't find anything similar.

Thoughts?

try bleeding the system might be air

[Alexlind123]

try bleeding the system might be air

ditto. If that works but it happens again, its probably time for a new master cylinder.

[bmwrp8]

ditto. If that works but it happens again, its probably time for a new master cylinder.

Ahh ok probably the master cylinder...not sure though

[angusbn]

New symptom - brakes are taught in the morning but get progressively worst driving in the intense heat and humidity today. After a hour of driving they're very spongy again. Any ideas?

[Rick L]

I have Raybestos QS ceramics and they don't bite! In turn more paddle pressure to stop... I guess it's a trade off from clean rims or dirty rims... :( On my M3, I'm sticking with aggressive pads and away from ceramics (don't want to loose performance and I'll can deal with cleaning)...

Try bleeding air out first and if that doesn't resolve the problem, you might need to look at your master cylinder...


is it soft and seems to require a lot of pressure? Mine is similar after Ate rotors and Raybestos Qs ceramics. Been so for about 25,000 miles for the front. Rear rotors/pads this year did not change anything.

[Ferret]

New symptom - brakes are taught in the morning but get progressively worst driving in the intense heat and humidity today. After a hour of driving they're very spongy again. Any ideas?

Rubber brake hoses starting to swell?

When the pedal eventually stops moving, is the pedal firm underfoot or does it feel like it could travel more?

[Russell]

May switch my front pads to Akebono. Heard they bite better. However, not proven.

[angusbn]

ferret - when the pedal stops moving, it stops moving. I'll check the rubber hoses and will try to bleed the brakes. Weird problem.

[Martin in Bellevue]

May switch my front pads to Akebono. Heard they bite better. However, not proven.
Akebono ceramic pads on my m3 don't bite too well either. They aren't scary, but I miss the bite from the Hawk ceramic pads. The Akebono ceramic pads are very nice on the wheels. The Hawk ceramics were better than stockish pads, maybe slightly less dusty than metal masters, but still left niticeable residue each week.
I'm going back to the ceramic hawks, or the hawk hps street pads with the great initial bite.

[angusbn]

Question - if there's air in the brake line OR the master cylinder is acting up, wouldn't the brakes feel spongy ALL the time, not just once in a while?

[bsell]

Question - if there's air in the brake line OR the master cylinder is acting up, wouldn't the brakes feel spongy ALL the time, not just once in a while?

Ding, Ding, Ding!

I think you are on to something here.

I had a '73 Capri with a sticking caliper that caused similar symptoms. Think about this, as the sticky caliper drags the pads thereby causing mad heat build-up, the brake fluid heats past the boiling point creating your bubbles and spongey pedal.

So after you drive for a while and get the different pedal feel, stop the car and feel NEAR the wheel centers on all four corners. I did not say touch anything, but to FEEL NEAR the wheels/brakes. If you have a sticky caliper and the boiling fluid, the wheel and brake assembly that is sour will be mad hot! You should easily feel a temperature difference from one or more wheels if you have a sticking caliper after putting some miles on the car so go easy on the feely.

Brian