Klayfish
Klayfish PowerDork
7/16/18 6:04 a.m.

EDIT:  OK, forgive the type in the title, should say "squishy"

This is my wife's DD, a 2010 Kia Sedona w/85k miles.  As the title says, we're getting a brake pedal with an inconsistent brake feel.  It's a bit hard to describe.  Sometimes it's fine...well, as fine as minivan brakes get.  But sometimes the brakes will bite properly for the first inch of pedal travel, then get a long squishy spot before they bite more.  Other times even the first inch is squishy.  Can't find a pattern as to when it'll do any of the three above...I don't drive the van all that much, but have been playing around with it recently trying to get a better handle on it.  Had the fluid flushed at the local NTB, as it was past due.  That helped a bit, but issue is still there.  Ideas?

Knurled.
Knurled. GRM+ Memberand MegaDork
7/16/18 6:23 a.m.

Check the wheel bearings for play, then yank the wheels and check all the slide pins to see if any are seized, and make sure the pads can move freely.

 

 

44Dwarf
44Dwarf UberDork
7/16/18 6:46 a.m.

Sounds like classic signs of bad master cylinder.

z31maniac
z31maniac MegaDork
7/16/18 7:47 a.m.
44Dwarf said:

Sounds like classic signs of bad master cylinder.

This was my first thought. 

Or the booster/check valve/plumbing from IM to booster.

Ranger50
Ranger50 UltimaDork
7/16/18 8:06 a.m.

I had something similar going on with my Avalanche. I knew I had to fix the rear brakes due to pad wear down.  When I got around to fixing it, one of the slide pins was completely frozen in place. I had to impact to get the pin free enough to turn. Overall, mine is consistent and crappy as good as a 6000# SUV brakes can be.

Klayfish
Klayfish PowerDork
7/16/18 8:33 a.m.

Thanks guys.  I'll check bearing play to be sure, but I don't think that's it.  I know that's a problem we see come up in one of our LeMons cars where a bad bearing causes pad walk back.  I don't think that's it because the problem is much more inconsistent, and even after I step on the brakes a few times, I still may get a squishy pedal.  Plus pretty often the first inch of travel of the brake pedal actually gives braking, then there's a big soft spot before getting more.

AngryCorvair
AngryCorvair GRM+ Memberand MegaDork
7/16/18 12:52 p.m.

44Dwarf is on the money

dclafleur
dclafleur None
7/16/18 1:04 p.m.

My experience usually points to a bad/failing master cylinder.  When you're already stopped does the pedal continue to sink towards the floor when you continue to apply pressure to it?

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