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My wife came home the other night complaining about her brakes. She was driving home on the interstate and all of a sudden the traffic slowed in front of her and she had to get on the brakes. She said they were going "thunk, thunk, thunk..." and she said she didn't slow down very fast. Then every time after that for a while, they did the same thing even when slowing down normal and she had to stay way back for fear she wouldn't be able to slow down in time. Then, before she got home, they started working normal. She said she didn't see any dash lights like the ABS light on the dash. I scanned it for codes and it was clean.
I told her that was the normal ABS operation to keep the car from locking the brakes and going into a skid. I am not sure why it was doing it after the first hard stop when she was slowing normal, but it sounded like the ABS to me. She was skeptical.
I am wondering as well. What do you guys think?

I was thinking of going out on the highway and slamming on the brakes to test it. Good idea or bad idea? I would know if the "Thunk thunk thunk...." was indeed just the ABS and if it was working as designed. I just hate the thought of locking up brakes "on purpose".
 

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Empty parking lot would be a better place, this way you can get out and check stuff. But you really need to verify for her safety.
 

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It's not really going to hurt the brakes, as long as you let them cool (with the car in park, or neutral, with your foot off the brake) properly, so you don't hot-spot the rotors (aka "warping" them).

How many miles are on the car? The ABS could be working properly - but if the brake fluid is old and gross, it's possible the brake pressure just isn't there.
 

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??? GOD man get it serviced..... Putting out $100 here and there while running a vehicle should not be a shock.
 

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170,000 miles and the brake fluid is probably factory.
Jesus, that's even worse than my 115k mile numbers-matching brake fluid :)laugh:) which has the compressive properties of silly putty and is a nice black color (instead of clear).

Brake fluid absorbs water over time, so it loses the ability to act like intended (since water compresses easier than brake fluid - this is also why bleeding your brakes is crucial, because air compresses even easier).
 

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Do you have a shop or someone you take it to regularly that you trust? Some places might just tell you "Oh you need this flushed" when it's fine (my friend bought a Cobalt and a shop told him he should get the power steering fluid flushed - I quickly let him know our cars don't have power steering fluid, as we have EPS). Take a quick peek inside the master cylinder and A) make sure you see some fluid and B) check what color it is. When brake fluid needs to be replaced, it's usually not clear anymore.

So, with that, if you have a good shop/mechanic and they indeed agree it should be changed (they likely won't use the term "flush"), it shouldn't be more than $80-150, as it's not a very difficult job.
 

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If you do have the brake fluid changed, check the level before you drive away. When I had mine done, they WAAAAAAAY over-filled it. Like, all the way up to where it touched the cap. Better than under-filling it, but I had to remove some fluid when I got home.
 

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Yeah, you don't want that sloshing around, since it's very good at removing paint. :laugh:
 
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