Brake pressure differential switch 67-69

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erco
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Brake pressure differential switch 67-69

Post by erco »

Does anyone sell just the switch that screws into the junction block? Shown in red in attached images.

brake switch.jpg
brake switch2.jpg
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azdave
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Re: Brake pressure differential switch 67-69

Post by azdave »

Don't think so from any Corvair vendor I know of but that small switch might be a part common to other GM vehicles of the era.
Dave W. from Gilbert, AZ

66 Corsa 140/4 Yenko Stinger Tribute
66 Corsa 140 Coupe w/factory A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5
64 Greenbrier 110/PG, Standard 6-Door
erco
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Re: Brake pressure differential switch 67-69

Post by erco »

Right again, azdave! Turns out it's a whole assembly with springs, pistons and O-rings. That screw-in part is just a fixed electrical contact. A rebuild kit is just $12, I've emailed this company to confirm it fits Corvairs. I'm surprised Clark's doesn't carry these (assuming they fit).

Info page: https://musclecarresearch.com/gm-pd-valve-kit-4

Rebuild instructions: https://www.musclecarresearch.com/gm-3956727-rebuild

$1 seat puller tool: https://www.musclecarresearch.com/brake-valve-seat-tool
brake diff switch.jpg
brake diff switch.jpg (119.33 KiB) Viewed 666 times
erco
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Re: Brake pressure differential switch 67-69

Post by erco »

Owner Scott replied to use a different one:

That looks like this one:

https://www.musclecarresearch.com/1972- ... ve-autopsy

This is the kit for the valve in my article:

https://www.musclecarresearch.com/gm-pd-valve-kit-1

Scott Hollenbeck
Muscle Car Research LLC
https://www.musclecarresearch.com/
erco
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Re: Brake pressure differential switch 67-69

Post by erco »

Just ordered a kit from Scott, will advise how it goes. I'm doing everything else to my brakes & front end so rebuilding this switch is the crowning touch. I'm surprised more people haven't chimed in here. Maybe since 90% of Corvairs only have single master cylinders then nobody cares. :chevy:
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azdave
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Re: Brake pressure differential switch 67-69

Post by azdave »

erco wrote: Wed Sep 09, 2020 9:19 am Maybe since 90% of Corvairs only have single master cylinders then nobody cares. :chevy:
Just not something I have ever needed myself. All of my Vairs are pre-67 and single MC.
Dave W. from Gilbert, AZ

66 Corsa 140/4 Yenko Stinger Tribute
66 Corsa 140 Coupe w/factory A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5
64 Greenbrier 110/PG, Standard 6-Door
erco
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Re: Brake pressure differential switch 67-69

Post by erco »

Yes, that's an enviable motor pool of "early" LMs you have there, azdave!
erco
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Re: Brake pressure differential switch 67-69

Post by erco »

I rebuilt mine today, Scott's kit and tool were easy to use with the instructions on his website. My brass piston was fairly seized in the cast iron block. Only change was that I opted to re-use my springs since the ones in his kit were stiffer. Can't test just yet since the rest of the car is scattered, but I am confident that all went well.
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nirvairna
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Re: Brake pressure differential switch 67-69

Post by nirvairna »

well done erco :clap: :clap: :clap:
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