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Brake problems
Posted by: joelsplace ()
Date: February 09, 2019 01:14PM

I was driving the Phil Sport Sedan the other day, parked it for about an hour then the brake pedal went almost to the floor but still stopped. Pumping did nothing. Decided to work on it today and now they are normal again. ???
Ideas?
I'm guessing it has to be a bad master cylinder but I can't imagine what could make it act like this.
My experiences with bad master cylinder failure modes are:
1) go to the floor randomly but pumping helps - bad seals
2) leak down with steady pressure - bad seals
3) go out completely - no pressure - bad seals
4) won't return - bad spring or stuck piston
5) leak - bad piston o-ring

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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Re: Brake problems
Posted by: MattNall ()
Date: February 09, 2019 01:27PM

Just take it apart and Clean / inspect... bet it just goes back together.... piece of grit...one time...





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Brake problems
Posted by: joelsplace ()
Date: February 09, 2019 01:36PM

I read my description again and left out one very important detail. When it went to the floor I had to drive it another 20 miles home and it was bad all the way.
Sorry about that.

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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Re: Brake problems
Posted by: ctcorvair ()
Date: February 09, 2019 02:33PM

I think there's a leak somewhere and eventually the air bubble makes it's way to the MC. If you bleed the valve on the MC a bunch of air should come out...the pedal won't go to the floor now and it's temporarily fixed. Then the problem will eventually rear it's head again until you find the leak in the brake lines



Edited 1 time(s). Last edit at 02/09/2019 02:34PM by ctcorvair.

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Re: Brake problems
Posted by: Wagon Master ()
Date: February 09, 2019 03:30PM

Am I the only one that doesn't know how the Phil Sport Sedan is equipped as far as a master cylinder goes?
LM 65-66 single pot
LM 65-66 converted to dual pot
LM 67-69 stock dual pot
Almost on the floor but still able to stop makes me ASSUME dual of some sort. I've had one piston seal on my two seal 69 fail and act as you discribed.


'29 Ford Model A Tudor
'61 700 Lakewood 110 4 speed
'69 Monza Convert. 140 Auto.
'70 Dodge Challenger R/T 440 4 speed

Been aircooled since 1973
Northwest Ohio

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Re: Brake problems
Posted by: joelsplace ()
Date: February 09, 2019 05:15PM

Sorry. I must keep thinking people can read my mind. '66 single.
Bled the master cylinder today. Didn't get any air out of it.

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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Re: Brake problems
Posted by: MattNall ()
Date: February 09, 2019 05:54PM

Clean it!





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Brake problems
Posted by: joelsplace ()
Date: February 09, 2019 07:20PM

That will be the next step. Maybe Monday.

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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Re: Brake problems
Posted by: joelsplace ()
Date: February 16, 2019 02:36PM

I took it apart and it looks new inside. I was examining it and discovered that it was manufactured incorrectly. The piston seal was slightly past the fill hole so it couldn't self bleed at all. I machined a little off of it so the hole was exposed and it helped but not enough. Has less travel now but still too much and pumping the brakes doesn't bring the pedal up at all. It also has about double the pedal travel when it's cold outside. 2 days ago when it was 80 degrees the pedal went about half way to the floor. This morning when it was about 35 the pedal went about 3/4 of the way to the floor. Seems solid where it stops. Not mushy just extra travel.
???
As a side note I've read that EM and LMs have different pedal ratios. Does anyone know if '60-'61 is different from '62-'64? My Lakewood's pedal doesn't seem to have any travel but requires more effort than my '63-'64s.

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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Re: Brake problems
Posted by: MattNall ()
Date: February 16, 2019 05:30PM

Pedals are different 60-61, '62-4, '65-66 , and '67-9 [ dual MC ].


For your problem adjust ALL FOUR wheels tight... no rotation possible... now see what the pedal does..

Note: usually to fix the inlet hole problem... all you do is shorten the rod from the pedal to MC.... just enough that there's SLOP in the static position.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Brake problems
Posted by: Frank DuVal ()
Date: February 16, 2019 08:03PM

Without slack you will find the brakes lock up after several brake applications. BTDT. Somehow left a 1/2” spacer off (between master and firewall, no power brakes) my aunt’s 65 Chevelle. She called me from her friend’s house to tell me the problem. Ah, tht’s what that piece of metal is on the workbench, I drove right over to install it.grinning smiley

Frank DuVal

Fredericksburg, VA

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Re: Brake problems
Posted by: joelsplace ()
Date: February 16, 2019 08:06PM

The inlet hole was covered with the master cylinder out of the car.
I've got them tighter than they should be but not locked up. Sounds like a good thing to try.
Thanks!

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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Re: Brake problems
Posted by: joelsplace ()
Date: February 16, 2019 08:08PM

My Malibu had a piston in the master cylinder that was too long. It would lock up the front brakes when they got warm. Had to machine that one also.

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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