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Discussion Starter · #1 ·
OK, I've read the forums on brake threads and am still searching for an answer. Here's my question.

The brakes in my 2000 9-5 wagon won't engage powerfully enough to engage the ABS on dry roads. They just seem weak and unable to give me enough force to get the car to stop dramatically in an emergency. The pedal isn't truly spongy, and it doesnt' sink to the floor at all. However, hard you press though (pumping doesn't make a difference) you can't get these things to lock.

Here's the condition of things. The car is farily new to me so I can't speak too much to history.

Rotors are reasonably thick and unscored. Pads have lots of material on them. However I suspect the pads were repalced on old rotors by the PO.

ABS system works. On slippery roads it works fine.

Booster seems to work. I've done the test when you start the car and feel the pedal depress. That seems to work fine.

Pedal action. As above, it's not spongy, but also not nearly as firm as in many other newer cars I've driven.

Here's my theory. I think it's bad/old fluid. I don't know when it was last repalced. I've never encountered this as a problem before, so don't know what it might feel like.

Any advice or input would be appreciated.
 

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echrisconnor said:
OK, I



Here's my theory. I think it's bad/old fluid. I don't know when it was last repalced. I've never encountered this as a problem before, so don't know what it might feel like.
Agree with Kermit. If you don't know how old it is them changing it would be a good starting point. Brake fluid absorbs moisture and should be replaced about every two years. (Which reminds me mine needs doing) :confused:
 

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Discussion Starter · #4 ·
I've driven soft brakes from air trapped in the calipers. But I have just never encountered this feeling in the brakes before. There's not pulling, one caliper doesn't lock before the others... So you may agree that the fluid could cause similar symptoms. I'm gonna have it changed (It's too cold here for me to deal with this myself outside), but my theory isn't totally baked? It would be great if something this simple is the root of the problem.

Any good catastrophic theories. There's usually someone who'll chime in that the whole system needs to be replaced. ;)

Thanks,

Chris
 

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echrisconnor said:
There's usually someone who'll chime in that the whole system needs to be replaced. ;)

Thanks,

Chris
Erm the whole..................

Nah, change the fluid ;)
 

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echrisconnor said:
However, hard you press though (pumping doesn't make a difference) you can't get these things to lock.
Err.....that's what supposed to happen.....if you could I'd say there was something wrong, rather than being something wrong because you can't:roll:
 

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Discussion Starter · #7 ·
Aero,

*Lock* maybe I should be more specific: Engage the ABS system. If your calipers donot have enough power to engage the ABS system -- or otherwise begin to lock the wheels, then I surmise there's a problem. I'm not expecting an ABS car to lay big stripes, nor to never get into ABS mode at all.

Thx,

chris
 

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echrisconnor said:
*Lock* maybe I should be more specific: Engage the ABS system.
That.......and this

echrisconnor said:
nor to never get into ABS mode at all.
are contradictions.....:confused:

What I'm saying is that on dry tarmac, even in a panic stop the ABS modulation will be less than on a reduced friction surface, so you will be less likely to 'feel' the ABS doing it's job...even though it is.

I've got the massive Hirsch/Brembo 4-pot calipers on mine, and I've never even felt the wheels begin to lock on dry tarmac even when in a emergency stop......:confused:
 

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aeropilot said:
I've got the massive Hirsch/Brembo 4-pot calipers on mine, and I've never even felt the wheels begin to lock on dry tarmac even when in a emergency stop......:confused:
Same here, 4 pot Brembos, decent tyres and the thing just plain......stops!
 

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My brakes are standard and i agree with the two posts below, dry road plus hard braking, stops quickly with no drama - i did expect the pedal to vibrate like mad when i first bought the car, but it is very refined under hard braking.

Change fluid, see how it is. But i reckon you must have pretty grippy front tyres hence you stop quick without fuss. And rememebr thats a heavy engine bearing its weight over the front wheels.
 

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Discussion Starter · #11 ·
I'm hoping the fluid change will resolve things.

Regarding locking and ABS, we may be getting into semantics. The system needs to have enough power to *lock* the brakes to engage the ABS. Even if it's for a microsecond. We all know how ABS works from there. So, I believe my statement is not a contradiction, just misiterpreted. Apologies for not making that clearer. Also, it's pretty obvious when an ABS system is doing its thing. Whether through simply feeling a vibration in the pedal to the big flashing light on the dash. My two other cars, a 911 Carrera, and a Subaru Outback both are abundantly obvious as to when you're braking hard and when you get into ABS land.

Thanks to all for the problem feedback and discussion.

Chris
 

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Discussion Starter · #12 ·
Problem fixed

Brake fluid changed this morning. The problem is now gone. The brakes have plenty of power and the car is stopping nicely, ABS and all.

Thx all,

Chris
 
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