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Anyone else have a "dead zone" in their brake pedal?

nik12937

nik12937

New member
Just as the title asks, does anyone else have a dead zone of sorts in their brake pedal travel? I got my 05 Grand Prix at around 58k miles, sitting at 105k now, and as far as I can remember it's always been there, possibly a little worse now than at first.

I've got plenty of meat on the pads, rotors have never been cut and are above minimum thickness, and the caliper slider pins are well greased. All the rubber portions of brake line have been replaced with braided stainless steel lines (the 5th rubber line was already braided SS on my GP... weird), and I recently bled out all the old brake fluid for fresh fluid. So I've got all the basic maintenance/upgrades covered.

A dead zone is really my best explanation. There's about an inch or so of pedal movement where the brakes don't react at all, but once they begin to apply the pedal is very firm and feels great, so it isn't due to air in the lines. I'm beginning to wonder if there's possibly slack somewhere in the linkage from the pedal to the master cylinder, so I'll have to take a peek up there on the weekend.

This issue is surprisingly irritating in stop and go traffic when I'm trying to apply the brakes gently, because I'll try to push past the dead zone quickly and wind up making the car sort of "lurch" forward once the brakes apply :th_tongue2:

Edit: Forgot to mention that the master cylinder is in good shape as well, oops!
 
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It's worth me checking considering my only vacuum line is for the brake booster, I'll spray some carb cleaner around there after replacing my spark plugs.

I'll report back with pictures if I manage to find anything loose in the linkage. I know there are a few bushings up in there so maybe they've just worn out.
 
master cylinder bore and seals are worn, you may notice under light pressure the pedal will slowly sink...then probably stop once you increase pressure enough to force the seals against the bore firmly. usually due to a lack of brake flushes/purge during pad change

i need to replace mine, ****it though i know what it is, when it get bad enough maybe ill change it out
 
My pedal doesn't sink when I let my foot sit on the pedal actually, I don't think it's a master cylinder issue. Luckily I covered braking systems last year in school (I'm getting a two year degree for an auto tech job) so I do understand the internals of most things brake-related. I completely forgot to mention ruling that out, my bad! I'll add it to my OP :D

I'm going to be disappointed if it's just the nature of the pedal design. At some point I'm planning on getting some dual-piston Impala calipers as well as the Impala brake booster, so I may wind up adding the pedal assembly to the list. From the exploded diagrams I've seen it's very similar or possibly identical to the GXP pedal, and I really enjoyed the feel when I test drove a GXP.

You know, this didn't even bother me enough to get into it until I helped my buddy replace his Subaru's brake fluid. When I test drove it after I was amazed by how firm his pedal was considering his brake setup is 100% stock :O
 
Mine has had that little bit of dead zone since the day I bought the car from my parents. Hasn't got better or worse with age. Have destroyed many a brake rotor with my driving antics so the dead zone isnt effecting my stopping power. I just have a bad habit of getting myself into situations where im going 140mph and suddenly need to be going 70mph.
 


There is a certain amount of travel that the pedal needs to move to fill the caliper piston and engage it against the rotor. When I read your post.. I thought about normal pedal travel.
 
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