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Re: Disc brakes
Posted by: Dave Decker ()
Date: December 11, 2018 07:55AM

Thanks all. Hey Mike, was that without a vacuum booster? TIA Cheers, Dave

Dave, Kamloops, B.C. '65 Crown V8, 2017 Mazda CX3

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Re: Disc brakes
Posted by: moomba32 ()
Date: December 11, 2018 04:42PM

I have metric calipers on the front and drums on the rear, I have the stock 66 MC and I'm very pleased with the way it performs. I had thought I would upgrade to a dual but I like the stock one so much I'm now planning to keep it that way. I know there is a chance there'll be a complete loss of pedal brakes if there's a failure but hasn't happened yet so I'm guessing my chances are low if I keep relatively new rubber hoses and I have the hand brake as backup. I've experienced complete loss of pedal brakes on my 2002 Tahoe so even a dual is not fool proof.

Don Marlowe
66 Monza 2Dr 140/pg
64 Spyder convertible now, 110/pg
Eutawville SC



Edited 1 time(s). Last edit at 12/11/2018 04:56PM by MattNall.

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Re: Disc brakes
Posted by: marcus66 ()
Date: December 29, 2018 06:13PM

I have them with a bracket kit from scarebird I think that's the name , out of Washington , got s10 calipers and rotors of a 4x4 s10 had to have hubs turned down a bit , they work great and still using stock master, 1966

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Re: Disc brakes
Posted by: 65180 ()
Date: December 30, 2018 08:37AM

I am running the Scarebird brackets, S10 calipers and rotors along with a 77 Monte Carlo 1 1/4 MC. I also run an adjustable proportioning valve installed under the dash and within easy reach for adjustment while driving. My setup provides a firm pedal with minimal travel and straight, positive braking. My fellow club members who have driven my car always phrase my cars braking ability.

Mike Lake
Tucson, Az
65 Corsa 180
65 Corsa 140 sold
66 Monza PG
66 Monza 4sp sold
61 Lakewood sold
61 La[corvaircenter.com]

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Re: Disc brakes
Posted by: jimc ()
Date: December 30, 2018 09:30AM

Interesting read and maybe my experience can be of some help.

Last winter, my work truck, a 1996 S10 2wd with 159,000 original miles suffered a rear brake failure, brake system is front power discs and rear drums.

The pads/linings were nearly new and proper fluid level maintained. As I was backing out of the garage and applied the brakes, the pedal went to the floor. I still had relatively hard brake pedal, but it was on the floor so at first it was hard to determine.

My first reaction was to pump the brakes again and again and though the pedal did not come up I did still have some pressure. I stopped put the trans in park and applied handbrake and got out to check for problems, but no fluid was on the ground - yet.

After confirming I had some brakes, I decided to "carefully" drive to our family wrencher, about 1/2 mile away, using the hand brake if needed at full stops. I took back streets and arrived without further issues. The mechanic found that the left side main rear brake line just above the gas tank had broken. Fluid was collecting atop the tank and was now dripping on the ground. We found the front reservoir was full and rear was empty.

In this failure scenario, I had previously thought that with dual MC reservoirs would have kept the pedal off the floor and stopped the car, maybe with some increased stopping distance or pedal feel.

A repaired line and I was back in business, minus a few $$.

Jimc
1965 Corsa
HACOA Member

CORSA 2017 Concours Senior Gold Award
AACA 2015 Award

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Re: Disc brakes
Posted by: veverlove ()
Date: December 30, 2018 02:40PM

65180 - I plan on a similar conversion w/ Clark's dual MC and Scarebird adapters, etc. Would like to know how you routed the brake lines to get the proportioning valve under dash? Sounds awfully handy to have in-cab access to that. Thanks in advance.

Victor

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Re: Disc brakes
Posted by: MattNall ()
Date: December 30, 2018 11:09PM



[www.ebay.com]





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: Disc brakes
Posted by: Seth Emerson ()
Date: December 30, 2018 11:19PM

Good descriptions of Valves and how they work:

[techtalk.mpbrakes.com]

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Re: Disc brakes
Posted by: hjackson3149 ()
Date: December 31, 2018 10:57AM

good afternoon all and Happy New year.

with the talk of brake failures with duel master systems of b0th drum and disc brakes.
I have a question on testing a failure scenario.
if I drain either the front or back of all fluid and test the brakes to see if the peddle hits the floor or you have half a system that will stop the car will that damage the master cylinder??. or can I then just fill and bleed.

Hank Jackson
South Florida
69 Monza PG
everybody has to believe in something and
I believe I will have another.
one for the Road!

The Three Stages of Christine

;;

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Re: Disc brakes
Posted by: joelsplace ()
Date: December 31, 2018 12:29PM

No, but it can uncover a problem that you didn't know about. If the master cylinder is damaged or has crud in it where the piston doesn't normally travel then you can damage the seals from the travel to that area. But you really needed to know that anyway so go for it.

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Re: Disc brakes
Posted by: CoCoCo ()
Date: December 31, 2018 08:24PM

Wouldn't the same result be arrived at by opening up the bleeders in the back instead?
You could attach tubing and bottles so that you don't make a mess, and if prepped appropriately, even do the whole test without letting air into the system.
Maybe?

Not sure if either method, or any method that lets the master piston potentially reach full travel is more or less detrimental to the master, but seems like it would be an easy test at least.

I've had plenty of dual-master failures in other vehicles over the years and it's a pretty scary proposition. While there was some minuscule amount of braking ability left, the pedals all went straight to the floor. Or almost to the floor, where some little bit of stopping ability was met.

Paul

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Re: Disc brakes
Posted by: MattNall ()
Date: December 31, 2018 10:33PM

First... remember.... Older cars have 7" pedal travel to ONE inch of piston rod travel.

'67 and newer with Dual Chamber MC's have 5" to 1"

Per SanMan1st's FC test ['61] he opened ONE bleeder and still had a fairly high pedal... not near the floor.

Cars are different!! Our pre '67 Vairs FAIL!!

============================================


To Answer Victor's question;

A Vair with Discs up front would normally need the P-Valve in the REAR's's line

BUT due to variances... you always TEST FIRST!! to see which wheels lock up first.



The SIMPLE P-Valve I linked to is just a piston with a spring and a bolt to limit it's travel... thereby controlling the amount of fluid going past 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: Disc brakes
Posted by: hjackson3149 ()
Date: January 04, 2019 09:23AM

good afternoon all

lets start with what I have
69 monza pg lowered 2 coils.
front discs rear drums, s10 rotors and calipers on brackets I got from one of our suppliers, master cylinder from a 68 chevelle manual front disc rear drums autozone part number NM1372.

I drained the master cylinder for the rear brakes and tested went to about an inch from the floor and had decent front brakes was able to lock them up, then i refilled and tested again all good. then drained the front and tested again this time the peddle almost hit the floor bur did have half ass rear brakes but would stop the car. refilled and all good
I imagine if the rears were readjusted they may have more peddle.

this may or may not be what happens with all setups but thought I put it out there

Hank Jackson
South Florida
69 Monza PG
everybody has to believe in something and
I believe I will have another.
one for the Road!

The Three Stages of Christine

;;

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Re: Disc brakes
Posted by: MattNall ()
Date: January 04, 2019 11:16AM

Hank... as I noted earlier... your pedal has a 5" to 1" ratio.... they are fine.





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: Disc brakes
Posted by: Dave Decker ()
Date: January 04, 2019 03:49PM

BobV66Vair Wrote:
-------------------------------------------------------
> I am running them on all four wheels. No need for
> power brakes, they are easy to pedal. Much easier
> than the drum brakes were. I run a single 1-1/8"
> MC. I found that the extra fluid was needed to
> make the pedal stay higher under braking.

Hey Bob. What kind of master are you running? TIA Cheers, Dave

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Re: Disc brakes
Posted by: jmaechtlen ()
Date: January 04, 2019 08:28PM

That link was to an explanation of combination valves, one kind having a kind of limit valve in it.
I wouldn't call either of them 'proportioning valves' - unless I totally misunderstand what a proportioning valve is.
Of course, that's entirely possible!

oh, well...

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Re: Disc brakes
Posted by: Seth Emerson ()
Date: January 04, 2019 09:01PM

Wander around on Master Power Brakes site. Lots of tech.

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Re: Disc brakes
Posted by: Ron62 ()
Date: January 07, 2019 01:40PM

Im just really surprised that no one makes a direct bolt on front disc brake kit that requires not machining of spindles or odd group of misc. parts. You can find them for pretty much every other car from the 60's. I would love to put them on my 67 but am afraid of a mixed parts solution etc.

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Re: Disc brakes
Posted by: 66vairman ()
Date: January 07, 2019 04:12PM

jimc Wrote:
-------------------------------------------------------
> Interesting read and maybe my experience can be of
> some help.
>
> Last winter, my work truck, a 1996 S10 2wd with
> 159,000 original miles suffered a rear brake
> failure, brake system is front power discs and
> rear drums.
>
> The pads/linings were nearly new and proper fluid
> level maintained. As I was backing out of the
> garage and applied the brakes, the pedal went to
> the floor. I still had relatively hard brake
> pedal, but it was on the floor so at first it was
> hard to determine.
>
> My first reaction was to pump the brakes again and
> again and though the pedal did not come up I did
> still have some pressure. I stopped put the trans
> in park and applied handbrake and got out to check
> for problems, but no fluid was on the ground -
> yet.
>
> After confirming I had some brakes, I decided to
> "carefully" drive to our family wrencher, about
> 1/2 mile away, using the hand brake if needed at
> full stops. I took back streets and arrived
> without further issues. The mechanic found that
> the left side main rear brake line just above the
> gas tank had broken. Fluid was collecting atop the
> tank and was now dripping on the ground. We found
> the front reservoir was full and rear was empty.
>
> In this failure scenario, I had previously thought
> that with dual MC reservoirs would have kept the
> pedal off the floor and stopped the car, maybe
> with some increased stopping distance or pedal
> feel.
>
> A repaired line and I was back in business, minus
> a few $$.

That exactly the way a dual MC system works when one circuit looses pressure due to a leak. The piston springs in the MC compress to allow for front/rear variation. A leak in one circuit causes greater movement of the pistons before the good circuit develops pressure via pedal movement. That causes the pedal to go ALMOST to the floor with a properly designed system. A dual MC only prevents total brake failure, but as you found out the braking action is reduced considerably. NORMAL.

This presents a problem for brake design as the dual MC must still be able to supply enough piston movement when one circuit goes open to activate the other circuit with regard to the available pedal travel.

I've test a few disc./drum conversions with a dual MC during bleeding the brakes and found a few were opening one circuit caused the pedal to go completely to the floor with very little or no effect on the other closed circuit. Basically no better than single MC that fails.

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Re: Disc brakes
Posted by: Seth Emerson ()
Date: January 07, 2019 09:30PM

Ron - Corvair vendors are walking a thin line. Many of the Corvair enthusiasts like to do their own work and pride themselves in their ability to tweak stuff onto their cars. (This is a good thing.) Sometimes a vendor goes the whole way, with every nut/bolt/bracket/etc. Too often they get criticized for "inflating" the cost of a kit. I have noticed that the "nothing other than stock" folks are becoming a little less vocal, as the cars get older and older. I admit I have been guilty of "adapting" parts, instead of buying the "right" part. I take it as a challenge. I do realize that not everyone is as "enterprising" and would prefer the whole thing, all tested and ready to go. Finally, one problem with kits is that there are some external variables that cannot be addressed in a kit. The examples in the front disc kit, would be: Which year spindle is on the car. 65 and 66-later have a different upper bolts. A complete kit, to me, would include a hub with new bearings and longer studs. Also, which replacement brake hoses? The tube fittings on the 69s are different in some way, as I recall. So, the kit needs to be tailored to the customer. Not doing that creates unhappy customers, as things don't "fit" exactly. Believe me, I have been on both ends of that situation, over 40 years of supplying stuff.

PS - I don't think any of the kits require the spindles to be machined, just the hubs.

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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