Quick question - Braking problem
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Quick question - Braking problem
I'm posting this for my father. He's sent his 2001 A4 1.8T to a few garages, but they all told him they couldn't find the problem, so I'm hoping someone here might have some insight.
Basically what's happening is that whenever we apply the brakes, the brakes will randomly decide to do a "springy" sound and we'll feel the car brake stronger when that sound happens.
Has this happened to anyone? TIA!
Basically what's happening is that whenever we apply the brakes, the brakes will randomly decide to do a "springy" sound and we'll feel the car brake stronger when that sound happens.
Has this happened to anyone? TIA!
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Joined: May 2005
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a comment......
Well, on our 00 it did not have a "springy sound" but the pedal changed consistency which I traced down to a faulty booster/master cyl. Its felt as if sometimes the booster would work and others it would not or could not moderate it. I replaced them both which vastly improved brake behavior.
A couple other maintenance items that really changed the brake behavior on our car:
-cleaning all the abs sensors:
Comment: After this one would have thought a new brake system was installed. The threshold for the abs was raised tremendously. It also felt as if it was biasing differently as well. There is so much debris that collects in those wheel wells. It binds up caliper carriers, coats the sensors, and coats the inside of the rim.
-cleaning caliper carriers, lubing the pins and contact areas.
-replacement of the rear calipers & hoses.
Comment: We all acclimate to aspects of daily life. The internal binding of the caliper pistons really took away alot of initial bite to the brake system.
If you do have to replace the booster/master cyl., I'll warn you or the tech working on the car that there is a factory release tool that is needed.
A couple other maintenance items that really changed the brake behavior on our car:
-cleaning all the abs sensors:
Comment: After this one would have thought a new brake system was installed. The threshold for the abs was raised tremendously. It also felt as if it was biasing differently as well. There is so much debris that collects in those wheel wells. It binds up caliper carriers, coats the sensors, and coats the inside of the rim.
-cleaning caliper carriers, lubing the pins and contact areas.
-replacement of the rear calipers & hoses.
Comment: We all acclimate to aspects of daily life. The internal binding of the caliper pistons really took away alot of initial bite to the brake system.
If you do have to replace the booster/master cyl., I'll warn you or the tech working on the car that there is a factory release tool that is needed.
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that's good info....
I'll have to dig through my files, I know I have a test guide somewhere to test a brake booster.
Update from my father though. He tells me that the "springy" noise only happens at low speeds (when getting close to stopping). He suspects the ABS, so he's been trying to get a garage to put the car on a oscilloscope, but I don't think that any of the garages had one.
The 4 wheel sensors are ok (they were tested/replaced recently) and the sound seems to come from the front, but it's hard to tell.
Update from my father though. He tells me that the "springy" noise only happens at low speeds (when getting close to stopping). He suspects the ABS, so he's been trying to get a garage to put the car on a oscilloscope, but I don't think that any of the garages had one.
The 4 wheel sensors are ok (they were tested/replaced recently) and the sound seems to come from the front, but it's hard to tell.
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a response.......
Thanks, I make my best attempt. You might consider providing more detail on what sensors where replaced exactly and which ones were removed and cleaned. Testing is fruitless on these, the parameters were talking about are not pass or fail. The problem with those sensors is when the magnetic elements get dirty(and they do) with debris, it changes the behavior of the signal sent. Having said that, the abs modules on the 1.8's don't exactly have steller reputations either. By cleaning the sensors and wheels on the joint you'll get rid of 95% of that abs kick at low speed stops. In combination of the afore mentioned, clean the caliper carriers and the pins. You'll find it really will change it. They corrode and bind up.
The problem you might find as I did testing the booster is that the problem is intermittent. So, its hard to get concrete results. You might try and trace down the spring noise. It might be something completetly different , like the driveline loading and unloading or a faulty control arm.
The problem you might find as I did testing the booster is that the problem is intermittent. So, its hard to get concrete results. You might try and trace down the spring noise. It might be something completetly different , like the driveline loading and unloading or a faulty control arm.
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Joined: May 2005
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a response.......
Well, when your completely dyslexic and can't form a cohesive or intelligible sentence, it avoids having to form one. ; ) I find it easier to just format some structure of facts in what hopefully is remotely useful. Thanks.