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Brake pedal slow returning

Old November 25th, 2015, 07:51 PM
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Brake pedal slow returning

Hi all,

Bled the lines with a mitivac. When I press the brake pedal, it takes a while to come back up.

'62 88, drums all around, single master cylinder, power brakes. The booster is not new - but the pedal is sinking a bit when the car is started, which makes me think there's some vacuum.

Any ideas what this could be?
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Old November 26th, 2015, 08:53 PM
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No ideas, huh?

This is pretty maddening. Bled the brakes twice, bench bled the MC twice. Still need to wait 20 sec after flooring the brake pedal til it comes back up again.

Weird. Guess I'll ask the HAMBers if there are no suggestions here.
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Old November 26th, 2015, 09:08 PM
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I'm thinking your MC needs to be rebuilt. You can buy a kit and do it yourself.
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Old November 26th, 2015, 09:11 PM
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I'll throw one idea out there..I don't know if this will stick. This sounds like a master cylinder problem, but for some reason I think brake hoses up front, debris in the system or poor hoses.

I've never worked on anything like your model. Hope you find a solution.
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Old November 26th, 2015, 09:38 PM
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Originally Posted by don71 View Post
I'll throw one idea out there..I don't know if this will stick. This sounds like a master cylinder problem, but for some reason I think brake hoses up front, debris in the system or poor hoses.

I've never worked on anything like your model. Hope you find a solution.
This could be but when ever this type problem occurs usually you have a stuck brake at the same time. Left a lone it will after a time free up as the pressure drops off. Is the brake drum (wheel) sticking?....Tedd
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Old November 27th, 2015, 09:18 AM
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Originally Posted by Tedd Thompson View Post
This could be but when ever this type problem occurs usually you have a stuck brake at the same time. Left a lone it will after a time free up as the pressure drops off. Is the brake drum (wheel) sticking?....Tedd
Interesting. I'll take a look. It felt like the left rear wheel was a bit sticky.

I haven't been driving this car though, as there is no exhaust - typically I work on it late in the evening and don't want to drive my neighbors nuts. I really need to get an exhaust on it
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Old November 27th, 2015, 09:31 AM
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Brake booster weak or broken spring internal.
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Old November 27th, 2015, 10:05 AM
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weak shoe return springs and/or sticky wheel cylinders? Have the brake pieces been refreshed or at least lubed up?
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Old November 27th, 2015, 11:24 AM
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Originally Posted by Octania View Post
weak shoe return springs and/or sticky wheel cylinders? Have the brake pieces been refreshed or at least lubed up?
- Booster is old.
- MC is rebuilt but has been sitting around.
- distribution block is old
- I made all new brake lines
- brake bits (springs etc) in the drums are new

thanks

Justin
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Old November 27th, 2015, 01:19 PM
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Originally Posted by justinj View Post
- Booster is old.
- MC is rebuilt but has been sitting around.
- distribution block is old
- I made all new brake lines
- brake bits (springs etc) in the drums are new

thanks

Justin
62 didn't have a distribution block???
Sounds like BOOSTER to me.
Good luck

Johnny
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Old November 27th, 2015, 08:18 PM
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A bad booster wouldn't make it return slower, something is causing the fluid to not have enough pressure. Plus if it were the booster leaking you'd know it in other ways by the engine running really lean. Either there's a leak somewhere or air in the lines would be my guess.

EDIT: I forgot to ask, in this car do the drums have their own cylinders in addition to the master cylinder?

Last edited by illumined; November 27th, 2015 at 08:22 PM. Reason: forgot something
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Old November 27th, 2015, 08:21 PM
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Originally Posted by toymobile View Post
62 didn't have a distribution block???
Sounds like BOOSTER to me.
Good luck

Johnny
By distribution block I mean the little block that the 4 lines (plus MC line) connect to. Not sure what that's called.
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Old November 27th, 2015, 08:25 PM
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Not to hijack my own post...(but I will)

Can anyone suggest a replacement brake booster / dual circuit MC combo that would be relatively easy to adapt to this car ('62 olds 88)?

I'm not concerned about 'correctness' or originality.

It's kind of a Might-As-Well, but I guess it makes sense safety-wise for me to consider upgrading to a dual MC.

Last edited by justinj; November 27th, 2015 at 08:28 PM.
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Old November 27th, 2015, 08:34 PM
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Originally Posted by justinj View Post
Not to hijack my own post...(but I will)

Can anyone suggest a replacement brake booster / dual circuit MC combo that would be relatively easy to adapt to this car ('62 olds 88)?

I'm not concerned about 'correctness' or originality.

It's kind of a Might-As-Well, but I guess it makes sense safety-wise for me to consider upgrading to a dual MC.

I'd suggest making sure the MC is actually the problem before spending money on it. Evidently based on what I've been reading toymobile might be right, it could also be the booster.
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Old November 27th, 2015, 09:38 PM
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The brake booster will make the pedal return slowly,it should return even if the master cylinder is not attached,that's how you diagnose it.
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Old November 28th, 2015, 01:59 PM
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Originally Posted by justinj View Post
Not to hijack my own post...(but I will)

Can anyone suggest a replacement brake booster / dual circuit MC combo that would be relatively easy to adapt to this car ('62 olds 88)?

I'm not concerned about 'correctness' or originality.

It's kind of a Might-As-Well, but I guess it makes sense safety-wise for me to consider upgrading to a dual MC.
I think anything from a G M after 67 will bolt on in place of your single , If you can go to a UPULL would be the best, otherwise you need someone to remove the complete system from the firewall down to the equalizer valve and ship it to you, You can do the plumbing from the wheels.
Good luck.

Johnny
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Old November 28th, 2015, 02:47 PM
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Anyone know how much travel there should be between the floor and the pedal? Service manual seems to only refer to non manual brakes...
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Old November 28th, 2015, 07:57 PM
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Originally Posted by nsnarsk65cutlass View Post
The brake booster will make the pedal return slowly,it should return even if the master cylinder is not attached,that's how you diagnose it.
I took off the MC and the pedal returns quickly at first, then slow.
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Old November 29th, 2015, 06:07 AM
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Very often, the old leaky master cylinder will have been leaking brake fluid
into the booster. I think you will find brake fluid, and rust in the power booster, even if it is still sort of working.
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