Braking issue. Master cylinder?

[Fred]

Hey guys i have an 04 Suzuki Aerio with abs, the brake pedal feels spongy and has been taking longer to stop. Also under hard stopping it feels as if the rear brakes are braking more than the front. Ive bled all 4 brakes, no air in lines and fresh brake fluid. The rear brakes are about 6 months old, front pads are at about 50% and no visible leaks. Do you guys think that the master cylinder is the culprit?

Thanks!

Also new to the forum but long time subscriber to etcg and happy to be a part of this community! 🙂

Topic

[Chris]

I’ve got a couple of questions.
1. When you bled the brakes, did you suck the old brake fluid out of the resivoir or did you run in through the system?
2. From personal experience, I’ve found out that certain vehicles need to be hooked up to an OBD device and setup to bleed the brakes like that while you work on the car. This may not be the case, but some hard online research and you might be able to find out if your car needs an OBD tool for the job. Your symptoms relate to mine when I bled my brakes without the OBD tool.
3. Did you see if your front calipers were in working order? ( not seized )

[Its me]

If there is no air in the system, check for a seized caliper pin. If the pedal feels spongy when you have vacuum boost, but normal and firm when the engine is off and the vacuum is depleted, check for a seized pin… A common misdiagnosis for this issue is a bad master cylinder…

Karl

[Brian]

I wonder if any grease has contaminated the front break pads? Sometimes it can be transferred if your working on something near by, or if a CV boot is leaking it. If any grease gets on the pads, even spray lube like wd40 liquid wrench etc, that can seriously diminish clamping force up front.
The previous advice given is good also. Perhaps changing the front pads with new ones would give you ample opportunity to check the caliper guide pins as well.

[Fred]

Hey thanks for the replies guys!

I sucked all the old fluid out with a turkey baster and added fresh fluid before bleeding. I haven’t yet checked the calipers to see if they’re seized i guess i should take a look and see. I was actually thinking of replacing both calipers with new pads and rotors, but i thought because of the spongy pedal that it was the master cylinder.

[Author]

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