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Simple Master Cylinder Conversion


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11 replies to this topic

#1 john65/64 (converted)

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Posted February 7, 2005 at 11:57 pm

What master cylinder is recommended to use whan converting a '65 valiant one line master cylinder to a 2 line master cylinder? The present one line master cylinder has four bolts to the body. I'm not looking to perform a disc brake conversion. Just to have the added safty of a dual output master cylinder. What does the proportioning valve need to be off of? Would a '67 dual chamber master cylinder work? If so, does the proportioning valve need to be off of the same vehicle?

#2 Bearhawke

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Posted February 8, 2005 at 09:57 am

What master cylinder is recommended to use whan converting a '65 valiant one line master cylinder to a 2 line master cylinder?  The present one line master cylinder has four bolts to the body. I'm not looking to perform a disc brake conversion.  Just to have the added safty of a dual output master cylinder.  What does the proportioning valve need to be off of?  Would a '67 dual chamber master cylinder work?  If so, does the proportioning valve need to be off of the same vehicle?

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ANY 1967+ A body or equivalent manual drum brake master cylinder will work; as for the F/R brake line split, simply run the front brake lines directly to the 'front brake' reservoir on the MC and ditto for the rears. Being an all drum system, no proportioning valve is needed.
Admittedly, to look 'factory' you can use a brake line junction block from probably any 1967+ drum brake MoPar car or light truck. :)

#3 gearhead

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Posted February 8, 2005 at 11:25 am

And note that the rear brakes are fed by the front section of the master cylinder, and the front brakes are fed by the rear section.

#4 Bearhawke

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Posted February 8, 2005 at 04:47 pm

And note that the rear brakes are fed by the front section of the master cylinder, and the front brakes are fed by the rear section.

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Good point there Gearhead:

I attempted to explain that the 'front brake' reservoir was not necessarly the actual front chamber of the master cylinder............
But I was not 100% sure here.
Every dual reservoir MC conversion that I have done involved the complete disc brake changeover with the 'disc' side being significantly larger whether on the back or the front of the unit. :blink:

#5 gearhead

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Posted February 8, 2005 at 06:58 pm

Good point there Gearhead:

I attempted to explain that the 'front brake' reservoir was not necessarly the actual front chamber of the master cylinder............
But I was not 100% sure here.
Every dual reservoir MC conversion that I have done involved the complete disc brake changeover with the 'disc' side being significantly larger whether on the back or the front of the unit.  :blink:

<{POST_SNAPBACK}>

I've always just done the single-to-dual M/C upgrade (3- '61 Chevs, '62 Valiant, '64 D-100, '66 Barracuda). Drums have always worked OK for me, so unless a car already has discs, I don't worry about swapping to them.

#6 68RT

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Posted February 8, 2005 at 07:48 pm

If doing a single to dual m/cyl. you have different size cylinders front and rear, you need a combination valve to insure equal pressure front and rear as was designed originally but you get the safety of the circuit protection in case of hose/line failure. You must utilize a m/cyl with equal size piston area or you have volume problems.

http://www.hotrodssu...alresmanma.html

#7 Bearhawke

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Posted February 8, 2005 at 08:16 pm

If doing a single to dual m/cyl. you  have different size cylinders front and rear, you need a combination valve to insure equal pressure front and rear as was designed originally but you get the safety of the circuit protection in case of hose/line failure. You must utilize a m/cyl with equal size piston area or you have volume problems.

http://www.hotrodssu...alresmanma.html

<{POST_SNAPBACK}>


For the record:

The drum brake A bodies even through 1976 simply used a brake line junction block to accomodate the brake light warning switch..........and the plumbing configuration was the same as the disc brake proportioning valve versions to make manufacturing easier----------as in a single set of hard lines for both disc and drum cars. :)

#8 john65/64 (converted)

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Posted February 8, 2005 at 09:23 pm

I've always just done the single-to-dual M/C upgrade (3- '61 Chevs, '62 Valiant, '64 D-100, '66 Barracuda). Drums have always worked OK for me, so unless a car already has discs, I don't worry about swapping to them.

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Thanks for all the input. I was not sure of the plunger rod off the '67+ cars would be the same length. The info about the need for a proportioning valve is great. Maybe I can get this '65 valiant on the road. It's going to get a A-833 overdrive tranny. I'm trying to make this one a daily driver and leave the convertible for the other days.

#9 gearhead

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Posted February 8, 2005 at 09:41 pm

If doing a single to dual m/cyl. you  have different size cylinders front and rear, you need a combination valve to insure equal pressure front and rear as was designed originally but you get the safety of the circuit protection in case of hose/line failure. You must utilize a m/cyl with equal size piston area or you have volume problems.

http://www.hotrodssu...alresmanma.html

<{POST_SNAPBACK}>

The proportioning on single MC cars was engineered at the factory by using different size wheel cylinders front and rear. A combination valve IS NOT needed if using a drum brake MC, and almost all drum brake MC's have the corredt residual pressure valve built-in. If I'm converting from a single-to-dual MC, as long as I get a drum brake dual MC for a later model car with the same size wheel cylinders as my earlier model car, I'm good to go. '61 Chevy Impala/Biscayne/Belair have the same size wheel cylinders as a '67, 68' 69, 70 drum brake Impala/Biscayne/Belair. Same thing with Mopar A-bodies. The drum brake MC's have the same bore sizes for the front and the rear.

#10 USA-aok

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Posted February 14, 2005 at 11:31 am

Excellent info, gentlemen. B)
Now, to confirm that the same rules apply to a '66 Satellite; manual drums and the desire for a later 'dual-reservoir' unit?

#11 gearhead

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Posted February 14, 2005 at 01:35 pm

Excellent info, gentlemen. B)
Now, to confirm that the same rules apply to a '66 Satellite; manual drums and the desire for a later 'dual-reservoir' unit?

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Same thing. Get a MC for a '67 Satellite with manual drums.

#12 john65/64 (converted)

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Posted February 15, 2005 at 09:25 pm

Same thing. Get a MC for a '67 Satellite with manual drums.

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I've now purchased a '67 dual line master cylinder. It appears to bolt up. Now all I have to do is plumb the system. I used a Dart for comparison. Darts came with both 9 and 10 inch brakes. Both use the same master cylinder. The wheel cylinders from the 9 inch system are the same as in my '65 model.


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