dual master brake cylinder

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Zorm
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dual master brake cylinder

Post by Zorm »

Picked up one off Summit discount shelf, can someone shoot me the center to center measurement for the mounting on our brake booster? this would be a 65 Corsa. thanks

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terribleted
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Re: dual master brake cylinder

Post by terribleted »

Corvairs have no brake booster.
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Zorm
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Re: dual master brake cylinder

Post by Zorm »

ok, I said that wrong, the single brake reservoir not booster, sorry.

erco
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Re: dual master brake cylinder

Post by erco »

Corvair brake parts are still surprisingly cheap and widely available at your LAPS, even if specal order. It feels like a win anytime I can buy a part locally. I just flushed/rebuilt/replaced my whole brake system. Hoses, hardware, wheel cylinder kits & honing, etc. Even rebuilt the brake pressure differential warning switch. My rebuilt master cylinder from Pep Boys was around $20 with limited lifetime warranty. Hopefully you didn't pay more for Summit's discount deal. Shipping costs often eat up any savings on heavy parts.

erco
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Re: dual master brake cylinder

Post by erco »

Zorm wrote:
Sun Nov 08, 2020 4:54 am
ok, I said that wrong, the single brake reservoir not booster, sorry.
Now I'm totally confused. The only match here is that '65s have single master cylinders. You might consider editing your post's title.

Are you asking about mounting dimensions for an unboosted (manual), integral reservoir, single master cylinder to confirm fit?

Does your new one look substantially like your old one in a side by side visual comparison?

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terribleted
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Re: dual master brake cylinder

Post by terribleted »

If you have the correct dual master cylinder it will bolt right in place of the original single master cylinder. All that remains is replumbing the system so that the rear brakes are fed from the front reservoir of the new cylinder and the fronts from the rear reservoir. adjusting the pedal pushrod length is also often needed so there is proper clearance allowing the master cylinder piston to fully return when foot is off the pedal and have a little 1/8" or so clearance to the rod.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
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Zorm
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Re: dual master brake cylinder

Post by Zorm »

OK I’m driving and using speak and text so I apologize for any misspelled or wrong words. I picked up a dual master brake cylinder from the summit racing discount been at the store in Akron Ohio. I was up in Cleveland for some training. I just need to know center to center measurements for the bolt holes on the regular single reservoir master cylinder for the Corvair‘s. I just want to see if the one I bought I can use, Or find another one that’s got the correct dimensions this is for the mounting it to the firewall. I guess you can’t call the firewall anyway you guys know where it goes. Thanks

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Deadwolf
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Re: dual master brake cylinder

Post by Deadwolf »

Looks to be about 3.5" with a quick tape measure and having to eyeball it since the master is installed.
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66vairguy
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Re: dual master brake cylinder

Post by 66vairguy »

Master cylinders vary by bore size and stroke, just not how they are mounted.

The dual master 67-69 Corvair master cylinder was used on a number of GM cars with manual brakes and as others said "it's available and relatively inexpensive". It bolts up in the single master cylinder 65-66 cars and only needs some added brake line hardware.

Just me, but brakes are too important to be experimenting with unknown parts.

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azdave
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Re: dual master brake cylinder

Post by azdave »

66vairguy wrote:
Mon Nov 16, 2020 9:37 am
Just me, but brakes are too important to be experimenting with unknown parts.
I'll choose a well-maintained factory single MC over the endless number of problems people have trying to switch to dual. Even my V8 Corvair has a single MC and I don't lose any sleep over that. If the last time you checked your brake fluid or did a "hard, harder, hardest test" was over 5 years ago then I guess you should install a dual MC right away.

All Zorm wants to know is the spacing between the two studs on the "firewall". I'm at work so can't go measure it and can't find that info online.
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Re: dual master brake cylinder

Post by 66vairguy »

azdave wrote:
Tue Nov 17, 2020 5:51 am
66vairguy wrote:
Mon Nov 16, 2020 9:37 am
Just me, but brakes are too important to be experimenting with unknown parts.
I'll choose a well-maintained factory single MC over the endless number of problems people have trying to switch to dual. Even my V8 Corvair has a single MC and I don't lose any sleep over that. If the last time you checked your brake fluid or did a "hard, harder, hardest test" was over 5 years ago then I guess you should install a dual MC right away.

All Zorm wants to know is the spacing between the two studs on the "firewall". I'm at work so can't go measure it and can't find that info online.
I have no problem using a single MC, but Zorm specifically said he had bought a "dual MC" at Summit. So he apparently wants to go that route. If so why not use a part that works. I'm not sure why folks have "problems" with switching to a dual MC. I've done a number of Corvairs and they all worked as well as the old single MC. Most of the brake issues I run into are worn out brake systems and bad repairs.

However I've been around too long - LOL, and I've had a few single MC failures AND dual MC failures and even with a dual MC the braking action when one circuit fails is GREATLY reduced. I also use the hand (emergency) brake often when I park a car so if I need it in an emergency I can react quickly.

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terribleted
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Re: dual master brake cylinder

Post by terribleted »

Yes indeed. If there is a leak when running a dual master cylinder braking action is SEVERELY reduced. People think oh well I will have 1/2 my brakes. In practice is is more like a weak 1/3 of braking. I like dual master cylinders, since a weak 1/3 of braking power is way better than zero.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

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