Crazy brake pedal problem - Impala Tech
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post #1 of 12 (permalink) Old 04-26-2019, 08:25 PM Thread Starter
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Crazy brake pedal problem

Here's a new one. On my 62 Impala, only with the engine compartment warm, once in awhile the brake pedal won't quite fully return allowing the stop lights to stay on. With a little nudge with my toe or by hand it'll come the rest of the way up (less than 1/2") to allow the switch to open and the lights to go off. This never seems to happen with the car cold. The problem is definitely not in the pivot pin of the pedal, so what's happening?? Could something be expanding and sticking and if so what?? Don't know where to begin...master cylinder or booster! Also not sure exactly what I'm looking for!! I've replaced the brake light switch thinking it was the culprit but it's still doing the same thing. Any thoughts appreciated!!
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post #2 of 12 (permalink) Old 04-26-2019, 09:25 PM
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That is a new one. Brain is too foggy to think through this now but will give it somne thought tomorrow.

Big Dave
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post #3 of 12 (permalink) Old 04-27-2019, 10:40 AM
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Heat obviously causes things to expand. So the question is what is expanding to the point were the return spring doesn't have enough force to lift the pedal? My guess is that it is inside the master cylinder where tolerances are super tight anyway.

Big Dave
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post #4 of 12 (permalink) Old 04-27-2019, 09:14 PM
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I had the same issue on my 68 and kept messing with the brake switch and pedal adjustment to no avail. I got a new return spring from 4speedconversions and that did the trick.
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post #5 of 12 (permalink) Old 05-02-2019, 11:11 AM
 
 
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Ive been living with this problem for a couple of years now. After doing a disc brake conversion (front and back) it has become a normal driving habit to pull my pedal all the way back up with my foot after every stop. Brakes work fine, they dont lock up or anything but the pedal sometimes wont return all the way, just enough to keep my brake lights on. Ive tried many different things but I cant figure it out. Ive found other post that have the same problem but cant find any solution. Whats weird is that sometimes the pedal will return on its own. This leads me to believe that a spring is not the correct solution. About a month ago i changed out my front rotors and calipers so i can fit a different wheel size. On my first test drive the problem seemed to be gone but after a few drives it came back. idk anymore. Hopefully someone comes up with a common solution for us. Ive asked around for the past couple of years and cant find anything.
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post #6 of 12 (permalink) Old 05-02-2019, 02:16 PM
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Springs sag with age. If your brakes work fine except for returning up against the pedal stop (a rubber bumper on the pedal assembly), then you probably just need a stiffer spring to replace your worn out spring.

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post #7 of 12 (permalink) Old 05-03-2019, 08:38 AM
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Guess??

Do you think it could be the lack of a 1 way residual pressure valve??? I've seen a similar situation with a Chevelle I had. Installed a 10lb pressure valve and the brake pedal creep went away.

Brian

1968 Impala SS Fastback 383 stroker
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post #8 of 12 (permalink) Old 05-03-2019, 01:12 PM
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I had a similar issue recently and found that my brake pedal switch was only working about 80% of the time. (bench testing, with multi-meter)
I took it out, spent several minutes blasting it with electrical cleaner (brake cleaner probably ok too) and using a paper towel to catch the drips I got a LOT of nasty dirt out of it. It takes a bit of effort to try to get the blasting spray inside that sucker!
It's been fine since then.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #9 of 12 (permalink) Old 05-03-2019, 02:37 PM
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Quote:
Originally Posted by BA. View Post
I had a similar issue recently and found that my brake pedal switch was only working about 80% of the time. (bench testing, with multi-meter)
I took it out, spent several minutes blasting it with electrical cleaner (brake cleaner probably ok too) and using a paper towel to catch the drips I got a LOT of nasty dirt out of it. It takes a bit of effort to try to get the blasting spray inside that sucker!
It's been fine since then.
He stated in his initial post that he had replaced the switch with a new one. I think the heating up is a red herring in this case and the issue is just a lack of sufficient force to pull the pedal back up. A new/stiffer return spring or an added booster spring from the hard ware store might fix his problems.

Big Dave
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post #10 of 12 (permalink) Old 05-03-2019, 02:51 PM
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Quote:
Originally Posted by Big Dave View Post
He stated in his initial post that he had replaced the switch with a new one. I think the heating up is a red herring in this case and the issue is just a lack of sufficient force to pull the pedal back up. A new/stiffer return spring or an added booster spring from the hard ware store might fix his problems.



Big Dave
My bad, I missed that in the first post.

Agree with you on the red herring and need for a spring.




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HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #11 of 12 (permalink) Old 06-13-2019, 09:23 PM
 
 
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Quote:
Originally Posted by rbwinston View Post
Here's a new one. On my 62 Impala, only with the engine compartment warm, once in awhile the brake pedal won't quite fully return allowing the stop lights to stay on. With a little nudge with my toe or by hand it'll come the rest of the way up (less than 1/2") to allow the switch to open and the lights to go off. www.airclaim.comThis never seems to happen with the car cold. The problem is definitely not in the pivot pin of the pedal, so what's happening?? Could something be expanding and sticking and if so what?? Don't know where to begin...master cylinder or booster! Also not sure exactly what I'm looking for!! I've replaced the brake light switch thinking it was the culprit but it's still doing the same thing. Any thoughts appreciated!!
It could have been something else then.
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post #12 of 12 (permalink) Old 06-13-2019, 10:13 PM
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Quote:
Originally Posted by jimmy06 View Post
It could have been something else then.



Thanks for dropping by and spamming us with your website links. Hope you never come back.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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