SOLVED - Odd brake pedal issue while driving

dang

dang

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I drove my coupe about 40 miles the other day, some stopping at signal lights and some on the freeway. About halfway through I noticed the brake pedal was engaging HIGHER than it normally does and by the time I got back to my shop it was engaging right at the top. Fluid levels are fine and no obvious problems were visible. It sat for about ten minutes before I drove it home and the pedal was still at the top. My drive home was only about 8-9 miles and it made it home with the engagement point still high but the brake function never gave me a problem. The brakes work normal except for the high engage point.

I haven't had a chance to check it since but thought I'd ask if anyone else has experienced this before.

FYI, within the last six months I went through (cleaned up) all four calipers and replaced all the rubber hoses. I've only put about 200 miles on it since then. I'm thinking some kind of vacuum/booster problem or master cylinder acting weird.
 
bfeng said:
Caliper Pistons which are sticking in their bores ( and thus not retracting) may cause similar symptoms. Feel each wheel after a drive and see if any are warmer that the others.
John
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This was my first thought since the reason I went through the calipers was because one was binding, but they all work fine now. No binding, wheels are not hot, if I stop at a very slight incline and release the brakes the cars rolls. The only thing that seems different is the engagement point.
 
Mike Goble said:
This is God's way of telling you that you should have driven the E3...
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I just made the comment to someone at work that my coupe seems to be acting up after I got the E3. Jealousy I'm guessing.

I drove the E3 Tuesday after changing the power valves and there's definitely a difference, but the engine started running hot fairly quickly so I didn't get to drive it very long. The engine temp is on top of my list now.
 
sfdon said:
Rust/corrosion in master cylinder?
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Mechanically, how would this cause the pedal to engage higher? I'm trying to picture how everything works but I know I'm missing something. Seems like air or fluid is expanding somehow.
 
There’s release valving in the master- crack one of the fittings on the master.
 
Perhaps the locknut on the pushrod from pedal to booster is loose and rod has lengthened? If the brakes don't ever bind up, then...it's a feature, not a bug.
 
andyleonard said:
Perhaps the locknut on the pushrod from pedal to booster is loose and rod has lengthened? If the brakes don't ever bind up, then...it's a feature, not a bug.
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I considered that too although I figured it would be a low percentage. Easy to check though.
 
I had a similar issue on a 2002 once. I had installed the dished retaining washer in the master cylinder the wrong way round and it was enough to slightly reduce piston rearward travel and stop the fluid from exiting the vent hole back to the reservoir properly. After about 10-20 applications of the brakes they would eventually lock up
 
Time to test bleed each caliper. Find out if one doesn’t bleed.
 
I had the brake booster rebuilt and the brakes work awesome now. I think the booster had a small leak that was causing the weird pedal issue and it must've gotten worse over time very slowly because I didn't notice how bad the brakes had gotten. First time I hit the brakes after replacing the booster I locked up all four. LOL

Thanks for the help Don.
 
I have a Saab (Sure Ain't A BMW) with a clutch that does nothing until the pedal is depressed 1/2 way, engages as soon as you lift off the pedal. Never occurred it might be a booster problem (everything else is new...) Not sure how though...
 
bill said:
I have a Saab (Sure Ain't A BMW) with a clutch that does nothing until the pedal is depressed 1/2 way, engages as soon as you lift off the pedal. Never occurred it might be a booster problem (everything else is new...) Not sure how though...
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How about bleeding the clutch system? Got fluid in the reservoir?
 
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