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Brake line advice?

Old May 11, 2022 | 06:31 AM
  #1  
Rallye469's Avatar
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Brake line advice?

I'm about to order my brake lines from Right Stuff.
I'll be running non-power disc up front, drum rear.
However, I don't want their proportioning valve hanging off of the MC...and I don't want it INSIDE the frame.
Any tips on keeping it low and out of the way without header interference?
(65 f-85)

THANKS!
Old May 11, 2022 | 06:47 AM
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I put mine on top of the frame rail when I had one. The Wilwood roundy-round I have now doesn't use one (removable residual valve).
Old May 11, 2022 | 06:58 AM
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Unfortunately I doubt you'll be able to get a pre-bent line with the combo valve in a non-stock (or not offered by the aftermarket company) location. The variables in line bending are infinite. Invest in a good set of bending and flaring tools and don't look back.
Old May 11, 2022 | 07:40 AM
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Yes, I had to make lines from the master to prop valve.
Old May 11, 2022 | 08:45 AM
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Flemming...what kit or lines did you use to get the prop valve on top of the frame?

Joe...I'm thinking to get the stock disc brake conversion kit(which puts the proportioning valve up by the MC)
and modifying the last 2 feet. So yeah...I need a nice bender and flaring set.
Old May 11, 2022 | 08:59 AM
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Originally Posted by Rallye469
Flemming...what kit or lines did you use to get the prop valve on top of the frame?

Joe...I'm thinking to get the stock disc brake conversion kit(which puts the proportioning valve up by the MC)
and modifying the last 2 feet. So yeah...I need a nice bender and flaring set.
When you say "stock" disc brake conversion kit, are you talking about the 1967 cars? If so, be aware that those cars did not use a proportioning valve. The device mounted under the M/C is a metering valve that only introduces a slight delay in the application of the front disc brakes, to allow the linkage in the rear drums to take up any slack before applying the fronts. The front/rear "proportioning" in the 1967-70 cars was done by using smaller wheel cylinders at the rear on disc brake cars as opposed to 4wheel drum cars. This precludes premature rear wheel lockup. Note that these cars also used the rectangular distribution block (with the differential pressure switch) that mounts to the inside of the frame rail.

The 1971-up cars used a combo valve that incorporated the distribution block, differential pressure switch, metering valve, and proportioning valve all in one common housing.

A couple of takeaways from this information.

First, in every case, the factory REDUCED braking force from the rear wheels with disc brakes - both the smaller wheel cylinders on the 67-70 cars and the proportioning function in the combo valve in the later cars limits the force applied at the rear drum brake shoes and thus limits the braking available from the rear wheels. While I realize you are not planning rear discs for this car, one has to wonder at the wisdom of people spending all the money on a rear disc conversion then using the prop valve to limit their performance to the same braking the original drums provided.

Second, the factory tailored the front/rear brake bias for each model, body style, and application. There were a plethora of differently calibrated combo valves listed in the parts book. Today every aftermarket kit uses the same one-size-fits-none Chinesium brass combo valve and you have no idea what it's calibrated for.

Third, the optimum front/back brake bias depends not only on car weight and weight distribution, it also depends on tire size and compound. Unless you have the original tires for the application, your front/back bias requirements will be different from whatever valve you install is designed for. An adjustable prop valve is a far better choice for any modified car, but that requires you to know how to properly set the front/back bias through testing.

Where all this is going is that you're likely better off with an aftermarket adjustable valve, locate it where you want, and bend the lines yourself. Just a thought.
Old May 11, 2022 | 09:07 AM
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^^^^Great write-up^^^^
Old May 11, 2022 | 09:18 AM
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Originally Posted by Rallye469
what kit or lines did you use to get the prop valve on top of the frame?
I used most of a Right Stuff kit. Then, I raided the "wrong" kit I ordered from IT because they wouldn't return it. IIRC, I bent the front to rear line to put the shuttle valve on top, then made my own out of the IT front lines from there up.
For what you're doing, it might be better to just get the front and rears prebent, then make your own front to rear and master lines.
Old May 11, 2022 | 11:33 AM
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Yes, that IS a great write up. Lots to think about and soak in.

Joe, my apologies...I simply meant that it is THEIR(Right stuff's) "stock" kit.
But thank you for all the tech info!
Old May 12, 2022 | 12:02 AM
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Originally Posted by Rallye469
Joe, my apologies...I simply meant that it is THEIR(Right stuff's) "stock" kit.
My point was "stock" for what? The lines for a stock 1967 are different from those for 1968, which are different from those for 1969-70, which are different from those for 1971-72.
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