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Brake question (odd one)

Never had any brake issues. Always stop on a dime. In fact they are better than my wife’s new CRV. I have always been able to “brake late” and aggressive per say when approaching a stop sign and am pleased with the response.

This morning I was spacing out and had to “stab” the brakes as the truck in front of me was suddenly stopping. The pedal felt totally different and the brakes only felt about 75-80 percent. by different I mean the pedal felt like it had a stiffer level of resistance but without the effectiveness. It seemed as if I couldn't even lock up the wheels if I had tried too.

Anyone ever experience something similar? Thoughts?

Old 11-06-2012, 12:49 PM
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Air in the brake lines? Old brake fluid? Cylinder problem?
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Old 11-06-2012, 01:03 PM
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Did you check your fluid level? Was it low, any leaks? When was the last time you did a fluid flush and bleed?
Old 11-06-2012, 01:03 PM
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Not sure, but it sounds like your booster may not be assisting your braking effort. Could be a loose vacuum line, stuck check valve, or a vacuum leak in the booster itself. Do you notice anything different in the way your car idles, maybe when you apply the brake whilst idling?
Also, is your car an ABS model? Are pads and discs in good nick? is your fluid level OK and the fluid 'fresh'?
Good luck!
Old 11-06-2012, 02:10 PM
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Yeah, when's the last time the fluid was replaced? ATE Super blue ftw
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Old 11-06-2012, 02:11 PM
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Fluid level ok and no leaks. really dirty thought and it has been over a year. guess what i will be doing this weekend:0
Old 11-06-2012, 02:27 PM
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Cold brakes? What linings are you running, and what was the ambient temp?
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Old 11-07-2012, 05:31 AM
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If you never had a similar problem and all of a sudden you experience this then it may be indicative of a failing failing component. If the type pads/discs etc. would be the problem there wouldn't be a sudden change in the functioning of the brakes under normal circumstances I think.

contaminated brake fluid leads to malfunctioning brakes when very hot, as in (repetitive) high speed braking. In normal traffic it will not be so noticeable as there is not enough heat to evaporate the contaminants. as long as the fluid remains fluid, it's non-compressible and functioning.

If there is air in the system the pedal will be spongy, almost to the floor.
stiff pedal feel and reduced braking can indicate either fading due to more than normal heat (long braking from high speed or repetitive hard braking) or a malfunctioning vacuum assist. I think this last one is most likely. Also, if a car is equipped with ABS, a fault in this system can cause a similar symptom but is often earmarked by the 'clicking' feel typical of ABS.

I would suggest you go about inspecting the check valve, the vacuum lines between check valve and booster, as well as the booster itself. Maybe a connection came loose, maybe there's a rip somewhere.
I don't know how to check the check valve's function, maybe someone else has a suggestion?

Put your hand/foot on the brake pedal when the engine is running, listen for hissing from the foot well. there shouldn't be any. If there is, it's indicative of a vacuum leak in your booster. I recently fixed this exact problem on my own car.

I hope you'll find out what's wrong, and that you don't have to change the booster!
Old 11-07-2012, 06:23 AM
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Providing its a non ABS car, I'm throwing in a vote on the vacuum assisted brake booster as well. All it does, is reduce the force to depress the pedal, if the pedal was still firm, it just took a lot of force, than it wasn't doing as much to help you.
Old 11-07-2012, 07:09 AM
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Your brake system is 25 years old. If you like to drive hard and brake hard, replace it all if it has not been replaced. Replace the master and the short rubber line to the calipers. Bleed and forget about it.
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Old 11-07-2012, 07:59 AM
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Quote:
Originally Posted by kfanazini View Post
Your brake system is 25 years old. If you like to drive hard and brake hard, replace it all if it has not been replaced. Replace the master and the short rubber line to the calipers. Bleed and forget about it.
I agree with you that preventative replacement of certain components is a good idea when you intend to drive the ***** out of it. However, blindly replacing parts without taking into account the 'symptoms' and implications of those symptoms, is not going to help the 'patient'
Old 11-07-2012, 09:50 AM
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wow thanks for ALL the feedback. it is a lot to digest. there is no ABS, it is an 83. i did change to all silicone vacuum lines a couple of weekends ago. i will double check everything. have not heard any hissing or change in idle etc. all has been good. could also be contaminated fluid. i have been bad about changing this as i dread bleeding brakes.
Old 11-07-2012, 01:18 PM
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Definitely look for vaccum leaks, I agree about the power braking system.

If you drive hard, I also reccomend braided stainless lines at the calipers. They are stronger, safer, and are less prone to expansion and help with a firmer feel.

The fact that you just changed a bunch of hoses to silicone screams vaccum leak!

Jeff
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Old 11-07-2012, 01:26 PM
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Wouldn't you see the classic idle surges with a vacuum leak? mine idles perfect
Old 11-07-2012, 03:58 PM
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Maybe.

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Old 11-07-2012, 04:17 PM
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