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02-19-2024, 12:14 PM | #21 |
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Re: dual master cylinder
I can verify that a dual system should be well engineered and ideally, each circuit should be tested independently. I say this because of my experiences with a factory system. I have a "beater" '99 Ford F150 that I purchased new. Being in the Twin Cities area in the beginning of its life, it has encountered the usual rust problems, including brake lines. The first to go was one of the rear lines. While it was apparent that there was a problem, the truck was drivable and I was able to get to my shop with no problem and replace the rear lines. A quick bleed, and I was back on the road again.
A few years later, a front line rusted through and it was a completely different story. The brake system was so compromised that there was very minimum stopping power. Luckily, I was less than a couple of miles from my shop (which is on a county road out in the country) and was able to creep back to it. I replaced the front lines, and after a bleed, the brakes were back to normal. I was surprised by this because I did not expect the almost total failure unless something else went wrong. Maybe it was a design problem on this particular model of truck, but ever since, I have lost the confidence I once had in dual systems. Last edited by tubman; 02-19-2024 at 01:08 PM. |
02-19-2024, 03:52 PM | #22 | |
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Re: dual master cylinder
Quote:
V8 Bob ..... First thing I'm gonna do here is apologize profusely to Bob for ASSUMING that "Pickup's" math was correct. I started to check it last night, but got lazy ..... SHAME!! Anyway, V8 Bob's math is irrefutable after checking and tells the story in real life terms. I believe the big point here is bringing to light just how important it is to know what you're doing when fooling around with changing M/C bore diameters (or wheel cylinder bore diameters). It's also necessary for folks to realize that DUAL M/Cs require a GREATER stroke distance than normal to operate sufficiently once one of the circuits becomes compromised. And there are so many other details that need to be figured into these upgrades, like pedal ratios, or even the thickness of carpeting or padding below your brake pedal. And most importantly, take the time to create a TEST LEAK in each circuit of your newly-plumbed dual M/C to make sure that your new configuration will actually stop if a leak occurs in one side of your system. Coop . |
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02-19-2024, 06:35 PM | #23 |
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Re: dual master cylinder
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02-19-2024, 06:46 PM | #24 | |
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Re: dual master cylinder
Quote:
Thanks. I'll give that a try. |
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02-19-2024, 09:23 PM | #25 |
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Re: dual master cylinder
Thanks Coop.
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02-20-2024, 07:55 AM | #26 |
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Re: dual master cylinder
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Last edited by Ron_r1959; 02-20-2024 at 08:03 AM. |
02-20-2024, 09:09 AM | #27 | |
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Re: dual master cylinder
Quote:
I do not recall any brake system design problems with any F-150 while performing D.O.T. partial system (Failed primary/secondary) stopping distance testing, part of the D.O.T. braking performance requirements. Stopping with rear brakes will result in much longer stopping distance vs front only braking, but is still a whole bunch better than loosing all braking! |
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02-20-2024, 09:46 AM | #28 | |
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Re: dual master cylinder
Quote:
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02-20-2024, 11:40 AM | #29 | |
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Re: dual master cylinder
Quote:
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02-20-2024, 12:02 PM | #30 |
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Re: dual master cylinder
I think we should limit this particular discussion to include only those that have experienced a brake failure on this particular series of F150's.
(Brake system analyses from reputable sources are also acceptable.) |
02-20-2024, 01:05 PM | #31 | |
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Re: dual master cylinder
Quote:
Ron ...... Just about the time you begin thinking that you understand the issue(s) better, you might want to re-think it all once again. Brakes is one very deep subject. You mention possibly looking for a M/C with a bigger bore. You must remember that increasing the diameter of the M/C bore will directly affect how much pressure that you need to push the brake pedal. Increasing the M/C bore will INCREASE the amount of foot pressure necessary to produce the same stopping power as before the change. You will likely be surprised at how much increased foot pressure will be required. Just one of the laws of hydraulics. Coop . |
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02-22-2024, 08:03 PM | #32 | |
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Re: dual master cylinder
Quote:
Should have been 1.130 to arrive at 1 ci of volume and then the piston travel difference of about an 1/8" (0.14) between the two master cylinders would have been evident. |
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