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Old 04-07-2018, 02:04 PM   #1
snowrx
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Default 2012 Impreza soft brakes return after bleeding

My wife's 2012 Impreza Sport Premium has a soft brake pedal, almost to the floor. We bled the brakes and the pedal firmed up nicely, but the next time she drove the car after it sat a bit, the pedal was soft again. Fluid level in the reservoir is/was good, no sign of leaks. Clear brake fluid. No ABS codes. All OEM brake equipment. Car stops straight and fairly quick, just a lot of pedal travel.

Before I start swapping out parts, can someone point me to a way to pinpoint the suspect failure? The pedal seemed to come back promptly as I started bleeding the rear calipers, so my first inclination is to replace those with new or rebuilt units, but with safety on the line I don't really want to waste time with random ordering and swapping if there's a quicker/better way to go about the diagnoses.
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Old 04-07-2018, 02:14 PM   #2
Charlie-III
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So, roughly 6 year old car.
How many miles?
Why did you bleed the brakes? To cure the soft pedal or just in general?
Is this 4 wheel disc or disc/drum?......nevermind, reread your post......
Any new brake parts recently?
How many miles on the car?


Have you checked the E-brake adjustment?
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Old 04-07-2018, 02:34 PM   #3
snowrx
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57K miles, Bled the brake to cure soft pedal. No recent repairs to car, replaced discs and pads maybe a year ago mostly due to uneven pad wear with sticky slider brackets.

Hate to replace the calipers and find it was the master cylinder or some such.

E-brake on this car is a separate mechanical shoe brake inside the rear hats

Last edited by snowrx; 04-07-2018 at 02:45 PM.
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Old 04-07-2018, 03:25 PM   #4
Charlie-III
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If the soft pedal started about the time of the rotors, maybe you have crud between the hub and the back of the rotor.
This would impart a "wobble" in the rotor pushing the pads out.
First pedal push would take up this slack, second should be firm/firmer, sorta like air in the system.

Maybe jack the car up, remove wheels, spin 2 lugnuts down on each rotor, spin the rotor by hand.
You "may" see the wobble if my guess is correct. A dial indicator would be more exact.
If so, pull that rotor and clean the rotor/hub mating surface, assemble and drive it.
If in doubt, pull and clean all 4 rotors.

BTW, it is "possible" a big curb hit could bend a hub face, but not likely.
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Old 04-07-2018, 04:04 PM   #5
snowrx
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Nope, rotors were long ago and the softness is new. I don't think the pedal pumps back up, I'll check it again next drive. No pulsing from the pedal.

Can't find much to go by in the Subaru Service manual, just bleeding and vacuum booster check procedures.
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Old 04-08-2018, 09:12 AM   #6
Charlie-III
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When the pedal travel increases, does it also feel hard as well?

Any recent brake work done?
What about dealer service work where maybe the did a brake/ABS recall or TSB?

When you bleed and get to good fluid, do you leave the bleeder open and compress the piston? If fluid comes out fine, then close bleeder and move on. If it comes out looking like dark maple syrup, close bleeder, pump the brakes back up and bleed the caliper again.

Otherwise, last thing I would lean to is an issue with the master cylinder.
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Old 04-10-2018, 11:04 AM   #7
snowrx
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Engine off, the pedal seems hard and won't descend with constant pressure. But when you start the engine and get some vacuum to the booster, the pedal goes almost to the floor and feels a little softer with the assist. I'd probably ignore the feel, but the extra travel is a concern.

No recent brake work, car does not go to a dealer.

Fluid coming out was clear throughout, I did not pull the caliper to compress the piston.

I guess I'll try and run a bunch of fluid through the system with another thorough bleeding. Unless a hose is swelling and about to burst, it sure feels like air in the system.
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Old 04-10-2018, 02:09 PM   #8
Charlie-III
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You don't need to pull the caliper to bleed the piston, just get good fluid coming out, close bleeder, pump up brakes, open bleeder and compress piston.
Everything clean and moving, likely can just grab the caliper and pull it towards you until the piston bottoms. Having pistons on each side of the caliper means, do the far piston, close bleeder, pump up brakes, open outer bleeder, push caliper in.
Or, use a large C-clamp and compress pistons if you can't slide the caliper easily.
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Old 04-10-2018, 03:57 PM   #9
snowrx
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Good idea, I put fixed 4-pots on a couple cars and forgot how the rest of them work
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Old 01-22-2021, 01:01 PM   #10
snowrx
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Any one know if the early 4-pot calipers can be made to work on this car?
I have a rebuildable set on hand, and am sick of salty caliper and pad sliders
wearing out one pad at a time.

And yes the soft pedal remains, does not get harder with use/pumping.
So air in system, line or caliper flex, or some ABS mystery component.
I'll get a set of braided lines to rule that out and do an exhaustive bleeding when I put them on.
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Old 01-24-2021, 06:53 PM   #11
UptownSport
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Default What's your Pedal Travel? 2014 CT Excessive Pedal Travel

What is your pedal travel?

My GF's 2014 Crosstrek (4w disc) has excessive pedal travel.
100% OE
Gravity bled,
then
Powerbled.
No joy.

And no, I'm not about to do TIR on the rotors.

I read "This is just the way they are. MC bore is excessively small."

I thought I'd ask "What's your pedal Travel" before R&R the MC for no reason.

I already have @snowrx answer.

Thanks in advance!!!
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Old 01-25-2021, 11:29 AM   #12
UptownSport
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Anyone?
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Old 01-25-2021, 12:06 PM   #13
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based on another thread on this, try bleeding while vehicle is running...the ABS can sometimes be tricky to bleed...to test MC I find that resting my foot on it while running and see if it settles to the floor...normally means time to operate on it...
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Old 01-25-2021, 05:19 PM   #14
UptownSport
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Quote:
Originally Posted by Jedi03 View Post
based on another thread on this, try bleeding while vehicle is running...the ABS can sometimes be tricky to bleed...to test MC I find that resting my foot on it while running and see if it settles to the floor...normally means time to operate on it...
Thanks Jedi!

I understand- There's no pedal drop once it reaches actuation point. Just massive travel.
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Old 01-26-2021, 01:15 PM   #15
UptownSport
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My other question is How- How would air get in the lines???

I've owned $500 cars going back to the mid sixties- and worked at a shop for a couple years- I've seen, or done all kinds of 'unorthodox' things.

I've never seen a car just 'Get' a ton of air in the system- Letalone one that is (relative to my vehicles) so new and untouched.
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Old 03-01-2021, 01:32 PM   #16
snowrx
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In the end I put 294mm front rotors and 2006 WRX 4-pot calipers with Stoptech street pads on the front and we have good brakes now. Everything bolted up nicely on the 2012. Time will tell if the softness returns.
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