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Canadian Poncho Homepage -> Canadian Poncho -> 65-70 Full Size Chassis Tech Forum -> Dual master cylinder conversion on 66 grande
Post Info TOPIC: Dual master cylinder conversion on 66 grande
66 Grande guy


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Dual master cylinder conversion on 66 grande
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Hi guys I've been thinking about doing a slight upgrade on the 66 Grande to the extent of putting in a 67 dual master cylinder.  I wasn't going to go the disc brake route as my drums system is freshly rebuilt with allnew lines etc and I don't plan on actually having to do repeated panic stops here in the prairies.

(As P.J. O'Rourke says,"If you find yourself having to do repeated panic stops in normal driving, you have more problems than just your brakes.)

So figuring that some of you guys have already done this, I'll ask,  is the 67 master cylinder a direct bolt on to the bendix vacuum pot and do you really need to put in the valve thingy as it is still all drum brakes front and back? 

As far as i know the only purpose for the all drum brake manifold assembly valve thing is to activate the brake warning light so do you really need it  or can I just hook the dual cylinder to the front and rear lines directly.

 

 



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ken from northern Alberta

38 Willys pickup electric

39 Buick (327 with 700 r4)

66 Beaumont 4 door hardtop

69 Chevy CST pickup

1976 GMC 23'  motorhome

1994 Impala SS 

1968 Citroen Fourgonnette (Yeah Carl!)
dualquadpete


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Ken, I swapped out the 64 Catalina to dual M/Cyl. & didn't use the Porportioning valve. I used a Chevelle drum M/cyl. & it bolted to my booster,only thing I couldn't use was the "rubber" dust boot on back of M.cyl. not enough room inside booster & it shortened up the stroke, fired it in the "BIN" as soon as I figured out the problem. Feel much "safer" now w/dual system!!!!!

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67Poncho


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 I took everything off of a '69 Laurentian to put on my '66 Chief. The master, booster and combination valve. Very easy conversion with just some elongating of the booster mounting holes.

 If you take the valve with the cylinder, unbolt the lines and just remove your existing splitter on the frame and just mount the combination valve in the same hole with the same bolt. Refab the front lines to fit.

 The only fix you will have to do is to the flare nut that comes out of the combination valve to the rear brakes. DO THIS WITH THE CYLINDER AND COMBINATION VALVE OUT OF THE WAY. More room!! You will have to cut the flare off the original line, remove that nut and use the '67 nut. The line is the same size but the nut is a larger thread size... Then reflare!

 Then run the wire from the valve and tie into your park brake lamp wire to turn (ground) on the "brake" bulb in the dash if you have a failure of the hydralic system!

 Easy as pie.................. wink



 



-- Edited by 67Poncho on Tuesday 20th of December 2011 05:48:48 PM

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Vincent Jr.
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  1. I'm planning to install a dual master cylinder (probably leave car with non-power brake set-up since my motor only makes 12" of vacuum). I've looked but can't find a drum/drum mc that has integrated residual valves. I've been looking at '67 thru '69 GM mc's.

    Has any body found a source for dual reservoir mc's that have integrated residual valves? Thanks.

  2.  

    I bought the dual master cylinder for a '67 Impala manual drum brakes several years ago and it works great. Must have the residual valves built in because I have excellent brakes. Hard pedal about 1" from the top. If necessary, I can look up my part #. BTW, the plumbing part is not too difficult. Leo

  3.  

    You probably won't find one with valves inside. I have never had problem not using residual valves, the theory is they keep slight pressure on drum brakes to help over come the initial shoe spring pressure. I always use the dual 1" bore 67-76 Corvette manual brake (1" bore) for any brake combination, has work flawlessly for me.


  4. Can you share the differences between the Corvette and the pass. car master cyl? Thanks for the previous info. Leo

  5. drc409 

    1958 delivery said:
    You probably won't find one with valves inside. I have never had problem not using residual valves, the theory is they keep slight pressure on drum brakes to help over come the initial shoe spring pressure. I always use the dual 1" bore 67-76 Corvette manual brake (1" bore) for any brake combination, has work flawlessly for me.
    Interesting (and good) to hear since I started this thread because according to Master Power Brakes, no residual valves results in a soft pedal:

  6. 1958 delivery

    That's what some same in theory. I have never experienced that. You can always add the inline residual valves if you encounter that. Most vendors just want to sell you more stuff. I have been selling and designing disc brake kits for many years and have always used the Corvette master, not one has said they had soft pedal.
  7.  
    Did a little research on the NAPA website and the Corvette and Impala master cylinders take the same 1" repair kit. The only difference that I can see is that the Corvette has a larger reservoir capacity for the disc brake calipers I assume. The whole casting just looks much beefier. Takes the same size brake lines on both castings. The Corvette one would be my choice if I ever had to replace my wimpy Impala unit. 


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66 Grande guy


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Thanks for the advice guys.  I have To admit I don't actually have a  67 combination valve which is why I was not planning to use one.

 

I seem to have sold all my 67  parts cars to some guy in Saskatchewan...

 

The only one I have is from a 69 chev pickup (All drums). I wonder if it'll make any differerence?



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ken from northern Alberta

38 Willys pickup electric

39 Buick (327 with 700 r4)

66 Beaumont 4 door hardtop

69 Chevy CST pickup

1976 GMC 23'  motorhome

1994 Impala SS 

1968 Citroen Fourgonnette (Yeah Carl!)
427carl


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The only one I have is from a 69 chev pickup (All drums). I wonder if it'll make any differerence?

         will work



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67Poncho


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66 Grande guy wrote:
 I seem to have sold all my 67  parts cars to some guy in Saskatchewan...

 

 wink... Ken, '67-'70 are the same! (or the truck one) But the cars would be a direct bolt on for sure!

    I can sent you one???? (lol)



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Vincent Jr.
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66 Grande guy


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Thanks again guys I'll just stick with what I have.  At least now I know

Once again the Canadian  Poncho guys  deliver the goods!



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ken from northern Alberta

38 Willys pickup electric

39 Buick (327 with 700 r4)

66 Beaumont 4 door hardtop

69 Chevy CST pickup

1976 GMC 23'  motorhome

1994 Impala SS 

1968 Citroen Fourgonnette (Yeah Carl!)
66 Grande guy


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dual master cylinder.JPGWorked out not bad...

 

 



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ken from northern Alberta

38 Willys pickup electric

39 Buick (327 with 700 r4)

66 Beaumont 4 door hardtop

69 Chevy CST pickup

1976 GMC 23'  motorhome

1994 Impala SS 

1968 Citroen Fourgonnette (Yeah Carl!)
4SPEED427


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Are you sure there's room for the Z bar when I put the stick in? Oh, never mind, I have my car to convert now!!!

I stayed silent on this because you were getting excellent direction from Pete, Vince and Carl. I did this on my 66 in the mid 70's, using a disc setup from a 68. When I swapped it back to drum, all I did was pull off the discs and put on the drums. I never touched the master cyl, etc. Everyone says it won't work right but I drove the car a few years after that and never had any issues.

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66 Grande guy


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Hi Carl, I think there is still room for the clutch stuff. I just wanted to get this done before I put the sheet metal back on as it is so much easier to work in there like this.  I checked the inner fender fit and it should work ok.

I figured the price of a rebuilt 67 dual master cylinder (like $60.00)and a bit of tubing bending and double flaring work would  be worth it for the piece of mind and (lets face it) better engineering than that marginal original setup.

its just another case of doing safety improvements like (dare i say it) replacing T3's or runnings radials that, if you're not just showing the car and actually drving it on a regular basis (like I know you will do) should be done, eh?

I hope it looks at least factory enough so the average guy would think that it is.

I must say having parts cars so does make it easy to find fittings etc.   I sure enjoyed the feeling when I  knew I needed a tee brass fittiing that I also figured I would never find in this small town and I went to one of my parts cars and had it off in like 2 minutes.

Now I just have to scrounge up a  terminal connecter for the warning light. Pretty sure I saw one of those up in my herd...



-- Edited by 66 Grande guy on Friday 23rd of December 2011 01:25:38 PM

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ken from northern Alberta

38 Willys pickup electric

39 Buick (327 with 700 r4)

66 Beaumont 4 door hardtop

69 Chevy CST pickup

1976 GMC 23'  motorhome

1994 Impala SS 

1968 Citroen Fourgonnette (Yeah Carl!)
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