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dual master conversion
Posted by: petalumacorsa ()
Date: March 02, 2014 09:48PM

Preparing to convert my single master cylinder on a 65 vert with Air to a dual.
Looking at piecing it together myself, A/C and all. It's a drum / drum brake set up.

Adding a second distribution block for ease of plumbing the brake lines.

I'm using a new dual master that has pressure valves installed. I'm assuming Clarks dual master has this as well if I go the Clarks route? Parts Geek has a good quality dual Wagner brand. Not sure if it has the pressure valves or not so I'll have to check this out.

Do I need a proportioner valve?

Will the brakes function properly with just the new master cylinder with pressure valves, separating the front from rear on the two circuits? I concerned the front/ rear braking pressure will be wrong.

It's the last piece of restoring the trunk.

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Re: dual master conversion
Posted by: MattNall ()
Date: March 02, 2014 10:01PM

If not buying from a Corvair Vendor.....are you ordering a 1967-9 Corvair MC?


All drum brake MC's have "residual pressure valves" to keep the seals from leaking when not in use.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
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Re: dual master conversion
Posted by: cnicol ()
Date: March 02, 2014 10:07PM

Just get a drum/drum master cylinder (67 Camaro etc) and plumb the rear bowl to the front brakes and the front bowl to the rear brakes.

You do not need "pressure valves" or switches. Pressure valves are used to limit rear pressure in a front engine car. Not used on a Corvair. The switch indicates failure in a circuit. It does not affect the brakes or hydraulic circuits.

Kits from vendors provide the right fittings to isolate the front and rear circuits. No doubt the details are in the CORSA tech guide but this is gist of it.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: dual master conversion
Posted by: gnvair ()
Date: March 03, 2014 06:10AM

I used an original set up from a 69 on my 66. GM used brass pass through blocks between the trunk and the interior. On the 65-66 there is just 1 block and it connects the front and rear lines together.
On a 67-69 there is a similar block in the same exact position but it only connects the front wheels. GM added another block just for the rear wheels.
The 67-69 set up has a block in the trunk close to the master cyl that some people mistake for a proportioning valve. That block has a switch to work the brake warning lamp they had on those model years incase there is a hydraulic failure in the system. You can buy a kit from clarks that eliminates most of what I listed OR you can accumulate the parts as I did and do it the way the factory did.
I went one step further and used the rear line from a 67-69 as well buy you can bend or shorten your 65-66 rear brake line.
A word of advice. Trying to save a buck usually doesn't turn out well. I found this out when trying to buy a master cylinder. I found a deal on an A1 Cardone brand reman. It was advertised as a Corvair master cylinder. Well the core they used was NOT the correct one for a Corvair as the port fitting sizes are different. Again, I was using original 69 lines and the casting had the port sizes reversed. This was after I cleaned and painted the master cylinder so now I didn't have an option of returning it. All was not lost as I ended up rebuilding the original GM core I had using the guts from the reman.
But my advice is to buy from a Corvair vendor to make sure you get the correct part.

Lee J



Edited 1 time(s). Last edit at 03/03/2014 06:16AM by gnvair.

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Re: dual master conversion
Posted by: coleslaw31 ()
Date: March 03, 2014 07:36AM

I will be doing the same thing. I have a 69 I am parting out and going to put the duel MC into a 66. Seems pretty straight forwards.

gnvair Wrote:
-------------------------------------------------------
> I used an original set up from a 69 on my 66. GM
> used brass pass through blocks between the trunk
> and the interior. On the 65-66 there is just 1
> block and it connects the front and rear lines
> together.
> On a 67-69 there is a similar block in the same
> exact position but it only connects the front
> wheels. GM added another block just for the rear
> wheels.
> The 67-69 set up has a block in the trunk close to
> the master cyl that some people mistake for a
> proportioning valve. That block has a switch to
> work the brake warning lamp they had on those
> model years incase there is a hydraulic failure in
> the system. You can buy a kit from clarks that
> eliminates most of what I listed OR you can
> accumulate the parts as I did and do it the way
> the factory did.
> I went one step further and used the rear line
> from a 67-69 as well buy you can bend or shorten
> your 65-66 rear brake line.
> A word of advice. Trying to save a buck usually
> doesn't turn out well. I found this out when
> trying to buy a master cylinder. I found a deal on
> an A1 Cardone brand reman. It was advertised as a
> Corvair master cylinder. Well the core they used
> was NOT the correct one for a Corvair as the port
> fitting sizes are different. Again, I was using
> original 69 lines and the casting had the port
> sizes reversed. This was after I cleaned and
> painted the master cylinder so now I didn't have
> an option of returning it. All was not lost as I
> ended up rebuilding the original GM core I had
> using the guts from the reman.
> But my advice is to buy from a Corvair vendor to
> make sure you get the correct part.

South Carolina Upstate



68 Monza convertible 140 4spd A/C (coming soon)
66 Corsa coupe 140 4spd

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Re: dual master conversion
Posted by: vairmech ()
Date: March 03, 2014 10:16AM

If you can find a donor car for the brake fittings it is the way to go. After putting in a Clark's dual master kit at this past year's convention for a tech show, I was not impressed with the routing of the line going through the firewall. It is to easy to hit it with something and bend or kink it, then there is the grommet that the line goes through the firewall. The kit is simple and easy to do but if I had the time I would have rerouted the line through the firewall to a different spot closer to the factory spot.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: dual master conversion
Posted by: petalumacorsa ()
Date: March 03, 2014 06:36PM

Definitely not trying to do it on the cheap, I'm just not all that crazy for the routing of the brake lines with the Clarks kit.

I found the the best MC brand (Wagner) I could that has the same part number for the 67-69 corvair as the 67 camaro. Also, it looks the most non aftermarket with the double bales. Has 3/8" female brake line outlets. Skipping the brake warning lamp set up. Also, I'm going with Napa poly black brake lines. Easy to bend and the local Napa parts store stocks them in the shorter lengths 8", 12" and 20".

I was inspired by another poster (the $30 dual conversion poster) on this forum who made the conversion look great by installing a second stock corvair distribution block for the other brake circuit just to the back of the existing one. Inside the car, it cleared the e brake cable perfectly and avoided A/c routing issues.

I haven't been able to find an aftermarket matching second distri block. So I might have to accept that it may look a bit different from the stock set up from the trunk side.

Any ideas where to find a stock used distribution block. I'll cap off any extra ports.

Thanks for all the ideas. It's reassuring to know that i don't need to worry about unbalanced brake line pressure as long as I go with the correct MC.

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Re: dual master conversion
Posted by: Seth Emerson ()
Date: March 03, 2014 10:35PM

You will run into another problem on a 65. The line to the rear of the car is smaller on a 65 than the 66-up. You can still plug the brass fitting for the front lines to make it feed just the fronts. Look for a SAE inverted flare plug - not particularly common. But the original 67-69 fitting cannot be used with the 1965 line to the rear, without an adapter of some type to the smaller line. You could change over to the 66-69 line, it is painful to install, and you will then have to change the splitter at the rear as well to the 66-69 size fitting! Some 1966 Corvairs were actually punched for the second line/fitting. I have seen several with the "not-round" hole already punched. As far as valves. GM installed residual pressure valves in the original master cylinders. These have nothing to do with proportioning front to rear, they just retain a small pressure in the line. Most rebuilts and even aftermarket replacements didn't use them, so you are safe either way. The only reason to add the factory valve is if you will be adding an indicator light in the dash (at the bottom of the 67-69 dash indictor cluster) If you are not adding it, just run the lines from the master to the fittings in the firewall, as you plan. If you are going to use the original line to the rear, you can just make up a firewall fitting to match it to the feed line you choose.

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Re: dual master conversion
Posted by: gnvair ()
Date: March 04, 2014 04:25AM

I used Clark's stainless hard lines on my car. The rear line I used was for the 67-69 even though my 66 already had the larger rear line. I did this so I could do the swap EXACTLY as GM did it on the 67-69 models. In the trunk I used the factory lines with the block and switch although I don't have the switch hooked up electrically.

Lee J

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Re: dual master conversion
Posted by: 66vairman ()
Date: March 04, 2014 08:50AM

vairmech Wrote:
-------------------------------------------------------
> If you can find a donor car for the brake fittings
> it is the way to go. After putting in a Clark's
> dual master kit at this past year's convention for
> a tech show, I was not impressed with the routing
> of the line going through the firewall. It is to
> easy to hit it with something and bend or kink it,
> then there is the grommet that the line goes
> through the firewall. The kit is simple and easy
> to do but if I had the time I would have rerouted
> the line through the firewall to a different spot
> closer to the factory spot.

Yes the Clark's routing is not good and requires you to bend the long main line to the rear brakes and possibly kinking/ruining it! Also if the car has A/C the washer bottle bracket goes exactly where Clark's routes the line. Many have simply put a second "T" behind the factor "T". This requires NO modification/bending of the long rear line. Myself and many others posted pictures here in the past. The only downside is you have to bend a line from the master cylinder to new second "T".

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Re: dual master conversion
Posted by: petalumacorsa ()
Date: March 04, 2014 07:01PM

As long as smaller line to the rear of the works function wise I'm not going to replace it. I already have enough hassles in my life!

All roads lead to installing the T, since my wife would kill me if I bought a donor car just for the factory distribution block. Although, I have done worse thing and gotten away with it.

The trunk is almost ready for the final finish. I just have to remove the MC (now that I'm mentally committed to it) and prep/ prime that area. Most of my parts are ready to install. See the pic of the before and after fan assembly. Couldn't have gotten this far without all the great info on Corvaircenter. This is my first vair less than a year since I've owned it.

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Re: dual master conversion
Posted by: petalumacorsa ()
Date: March 04, 2014 07:04PM

trunk progress

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Re: dual master conversion
Posted by: petalumacorsa ()
Date: March 04, 2014 07:12PM

fan assembly resto

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Re: dual master conversion
Posted by: gnvair ()
Date: March 04, 2014 07:32PM

I personally would do it the way the factory did it. Remember 67's had the dual res master cyl and could be had with a/c.
Why not contact Corvair Ranch and get the pieces you need and just use an inverted flare adapter on your rear brake line where it hooks to the connector?

Lee J

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Re: dual master conversion
Posted by: petalumacorsa ()
Date: March 04, 2014 08:32PM

Good idea, I didn't know anything about them. I'm going to send them a message tonight.

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Re: dual master conversion
Posted by: JimBrandberg ()
Date: March 05, 2014 05:34AM

I tried a few Corvair Vendor kits and was unsatisfied with the appearance so I started making my own. I like a clean appearance with nice routing and absence of brass adapter fittings which I think look amateurish. The Vendor kits were quite different from each other and I'd be happy to support them if I was completely happy. It took a lot of unbillable time to come up with my own deal.
I use the Dodge passenger side exiting MC on Earlies using the stock firewall fitting for the fronts and drilling an adjacent for rears.
There's less room on Lates so I use the Chevrolet drivers side exiting MC on Lates and pass under the MC with the same sort of firewall arrangement.
I generally use a brass Tee and plug one side to hook up the rear line with a little bending. I haven't found an L fitting.
I'm fortunate to be able to visit Brake and Equipment Warehouse. They have tube nuts to fit 1/4" line to the large 9/16 and 5/8 MC ports without the dreaded brass adapter look. They just get them from Brake Quip.
I like to mask and paint the MC satin black to avoid rust.
I don't think it's worth the small margin vs large risk to sell kits to be installed by others.
I haven't seen an advantage to using the stock dual MC arrangement, maybe because I don't have enough to go around.
I've yet to find a good bulkhead fitting, it's hard to find the time to look ahead.
There's nothing wrong with brass adapters out of the MC, it's just a personal quirk for me, same with carb lines made from brake lines with one short tube nut and one long one. I could probably benefit from Counseling as the junk collector/perfectionist sides of my brain are often in conflict.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: dual master conversion
Posted by: 66vairman ()
Date: March 05, 2014 07:49AM

Here ya go - a discussion with pics and part numbers to install a separate "T" for the rear line - either the larger 1/4" rear line or the smaller 3/16" rear line.

see [corvaircenter.com]

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Re: dual master conversion
Posted by: petalumacorsa ()
Date: March 05, 2014 03:39PM

Hey gnvair. I followed your advice! Corvair Ranch has the part I'm looking for with the odd pressed original nut. $20. I think I'll go that route as it will be easy to plumb and look kind of original...well at least matching with the current one. Thanks for the tip! Todd

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Re: dual master conversion
Posted by: gnvair ()
Date: March 05, 2014 04:04PM

No problem Todd. Glad to help. I'll snap some pics of mine and post later so you can see.

Lee J

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Re: dual master conversion
Posted by: gnvair ()
Date: March 05, 2014 04:29PM

Here are some pics. The master cyl was clean 2 months ago. The rust is from the nice dry New Jersey climate in the garage eye rolling smiley

Lee J

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