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Discussion Starter #1
Need some help here. 94 S4 with 48k I drove it last in July 45 miles got home all was fine parked her in the garage. In September made the plunge and put it up for sale took it out for a gas run and the front right brakes were locking up pedal got hard as a rock. Limped home .7 miles only to find the flex line on the right burst (still a puzzle) Got a line replaced it bleed brakes this past Sunday test drive the car and the pedal is as hard as a rock no boost. Under braking the car pull to the right very unstable. Any thoughts before I start looking in the wrong places Thanks all.:confused:
 

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Could the caliper be seizing? Jack it up, pump the brakes a few times, then see if you can easily turn the tire by hand. If not, you probably need a new caliper.

Is the ABS light on? Brake warning light?
 

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What did the old brake fluid look like? Was it thick and dark? Did you follow the correct bleeding procedure, it is not that simple for the Delco ABS system. It does sound like a stuck caliper at the very least. If you popped one hose you should consider replacing them all.
David Teitelbaum
 

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The car has Toyota brakes I have bleed them many times before hope I have been doing it to spec. The fluid is changed every 2 yrs and looked good to me. Last change was Dec 2012. I will try the caliper tonight and report findings. Thanks guys.
 

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The car has Toyota brakes I have bleed them many times before hope I have been doing it to spec. The fluid is changed every 2 yrs and looked good to me. Last change was Dec 2012. I will try the caliper tonight and report findings. Thanks guys.
You pretty much need two people to do a full bleed procedure on the ABS system. But, air in the system shouldn't cause one caliper to lock up. .

The Toyota calipers are cheap and available, just go ahead and replace them both, along with the brake lines. It is all 20 yrs old

Randy
 

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Discussion Starter #7
An update. Invested a week going through this entire brake system one component at a time, found two things. 1- one rear flex line with a partial block 2-a small fluid leak at the accumulator more like a sweat than a leak the O ring looked more compressed on one corner. I took the four calipers off and rebuild them, fit six new s/s braided flex lines, new pads front and rear, new accumulator and flush all the metal lines. Add fresh fluid and bleed the system did a 40 mile test run place the car back on stands gave it a full inspection and all is well. Thanks all off to test out the new tires:D:D:D
 

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I'm confused. Your S4 has Toyota brakes? I thought the S4 had Brembo. My S4s has them. Maybe the Brembo was one of the "s" model upgrades?

Also curious about your bleed procedure. I thought the ABS system required an electronic module to put the ABS valves in the right position for a bleed. I've avoided bleeding mine because I don't have that module. Can you bleed the GM ABS system conventionally?
 

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I'm confused. Your S4 has Toyota brakes? I thought the S4 had Brembo. My S4s has them. Maybe the Brembo was one of the "s" model upgrades?

Also curious about your bleed procedure. I thought the ABS system required an electronic module to put the ABS valves in the right position for a bleed. I've avoided bleeding mine because I don't have that module. Can you bleed the GM ABS system conventionally?
The manual details a slightly complex bleeding process. It involves one person pumping the pedal and another person systematically bleeding the various parts of the system. No special equipment needed.

Randy
 

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The manual details a slightly complex bleeding process. It involves one person pumping the pedal and another person systematically bleeding the various parts of the system. No special equipment needed.

Randy
Also, one person needs to hold the brake pedal down a bit to get the rear brake fluid flowing via the ABS pump. On the Powermaster ABS system, pumping the pedal with the engine off only flushes the front brakes.


FOLLOW THE MANUAL.

+++++++++++++++


An additional benefit is: with two people, you have someone to hear you cursing. :crazyeyes Otherwise it's the old "tree in the forest" scenario. :D

http://en.wikipedia.org/wiki/If_a_tree_falls_in_a_forest
 
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