Dual break circuit conversion

[AW-100]

Just discovered my -65 Cuda has only one single break circuit. Any thoughts on converting it to a dual circuit? Now I see that just below the master cylinder there is a "pipe junction" where I have one tube from the master, one to each front wheel and one to the rear of the car. Just thought that I'd might hook up a dual circuit cylinder to this junction, either one circuit front, and one rear, or one left front and rear, and one right front? Thoughts? Comments? Concerns? maybe I'd have to add one more circuit to the rear, so I can hook up LH front with RH rear and vice versa?

Anyone done this before?

 

[toolmanmike]

I really should do this to mine too. I think you should split the fronts from the rears. The cross splits (RF to LR etc.)were used on disc brake systems where the fronts do the majority of the braking. toolmanmike

 

[furydan]

Just discovered my -65 Cuda has only one single break circuit. Any thoughts on converting it to a dual circuit? Now I see that just below the master cylinder there is a "pipe junction" where I have one tube from the master, one to each front wheel and one to the rear of the car. Just thought that I'd might hook up a dual circuit cylinder to this junction, either one circuit front, and one rear, or one left front and rear, and one right front? Thoughts? Comments? Concerns? maybe I'd have to add one more circuit to the rear, so I can hook up LH front with RH rear and vice versa?

Anyone done this before?

The way I did mine was to run the front through the junction block and run the back directly from the master cylinder to the rear brakes.

 

[tedsweet]

simply removed rear line from the junction, pipe plug in the hole. run the 2 new lines from the dual mc as follows. line for fronts to the junction, rears to the rear line u removed from the junction.

 

[RustyRatRod]

My recommendation would be to get a M/C and proportioning valve from say about an 88 Fury. That M/C is the same as one of the MP units. You'll need the 4 stud to 2 stud adapter plate, too and of course plumb accordingly.

 

[dusterglenn]

Actually a really easy upgrade. All you really need to do is:
1-use a master cylinder from a 67 & later car
2-bend your existing line so it'll reach the rear port on your dual mc
3-unthread the line that runs from the junction block to the rear brakes, then plug that port
4-extend the rear line up to the front port on the mc
5-live happily ever after
I left out benchbleeding, cutting, bending & flaring lines, etc. But you get the idea.
If you get stuck, I can probably even help you out with some part numbers.

 

[cudamark]

Any '67-72 A-body drum brake car would be a good donor also. What tedsweet said will work fine too if you don't need a brake warning light.

 

[AW-100]

Thanx guys. Then I'll have something to fill the winter with... Any dual circuit master cylinders that are bolt-on? Or where might I find an adaptor plate between the new mc and the old pattern? Can I make one out of 4mm steel?

 

[DonPal]

I was able to directly bolt a 71 demon dual master cylinder into my 65 Dart (no power brakes). I ran the rear line right up to the dual master cylinder.
The front lines go over to the junction block from each wheel. The master cylinder front line outlet goes down to the junction block.

Selecting a dual master cylinder with the correct piston size is important if you want to avoid high pedal forces.

The 71 demon dual master cylinder for a combination of discs in front & drums in the rear comes with the smallest diameter piston...15/16 dia.
This gives you the lowest pedal pressure. Along with that low pedal pressure you have to expect added brake pedal travel to provide enough volume of fluid to displace the brake cylinders.

If you think someday you'll be going to disc brakes upfront then the above master cylinder is a must since discs require higher pedal pressure than drums generally. My dart has the scarebird conversion to discs with the above dual master cylinder.

The NAPA number for the master cylinder use to be 36338 however they may have change suppliers recently & will give you the crossover number if that's the case.

 

[AW-100]

I'm finally doing my brake swop, found a Dorman M71258 master cylinder for the 1967 Barracuda. At the same time I ordered some new brake lines from RockAuto, but as it seems, my -65 has brake lines of 5/16" on the single circuit, but I was recommended 1/4" to the -67. I am only swopping the pipes from the cylinder down to the junction block below the firewall, is it OK to reduce the diameter of the pipes, as I am swopping from one pipe to two?

 

[amx364]

I would tease about "waking the dead" but you are the original poster.
I like the Willwood combination valve and mount it next to the master cylinder. Either way you must replace some brake lines and this valve replaces all the connections

 

[BillGrissom]

Since your original question in 2011, I posted how I did this w/ photos, as have others. I kept the factory distribution block for the fronts only. I plugged the rear port w/ the correct inverted flare plug (not a pipe thread!). I added an adjustable proportioning valve to the rear circuit.

Yes, you could spend a day making an adapter plate, but only $30 on ebay for an anodized aluminum one.

The tube from your MC is 1/4"D, not 5/16"D. All newer MC's use 3/16"D tubing. I put a 1/4 M-INV_F to 3/16" F-INV_F in the top port of the dist. block. I gave the Autozone PN. Don't screw a 3/16" tube directly into that port!