Excess brake pedal travel with new power front discs - Page 4 - Vintage Mustang Forums
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post #46 of 65 (permalink) Old 04-14-2019, 09:33 PM
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When I did the conversion, I screwed the male end of the residual valve into the rear junction block, then, simply screwed the "removed" brake line into the female end the valve...easy peasy.

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post #47 of 65 (permalink) Old 04-15-2019, 08:00 AM
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Originally Posted by Nailbender View Post
OK, so is it better to put the residual valve before or after the proportioning valve? I checked my new M/C today and it did not have any restriction at the port so I ordered a 10 lb Wilwood residual valve. At this point it would be easier for me to put it between the master and the proportioning valve.
It will function fine installed right after distribution block. This way 10 pounds of pressure is kept in the full length of rear brake system. If you put at the rear, you have to push that fluid the length of the car for anything to happen at the wheel cylinders.
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post #48 of 65 (permalink) Old 04-17-2019, 10:51 PM
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The issue I found with my system was the aftermarket booster was poorly designed and is the primary cause of the low pedal. No matter what the OP does with his brake system (bleeding, residual pressure valves, etc) nothing will change if he leaves that booster in there. I reduced the sloppy feel slightly by moving my master cylinder pushrod pivot on the pedal arm down ~1” (mine was manual drum prior). But it wasn’t until I ditched the aftermarket booster (for a stock later model Mustang booster) and that’s when it finally felt normal.

Those boosters are flawed for this application, in my opinion. There is way too much play to activate the power booster, and this in turn gives a horrible pedal feel when vacuum is present. With the engine off you get a nice hard pedal, but once the motor starts it goes flaccid, and that’s the last thing you want!

OP is somewhat stuck because he has a manual transmission. It may be worth trying a larger diameter master cylinder, but he may just end up with a moderate amount of slop and too hard of pedal effort. How tricky is a hydraulic booster to install?
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post #49 of 65 (permalink) Old 04-18-2019, 04:57 AM
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OP is somewhat stuck because he has a manual transmission.
I have a manuel car with one of those aftermarket boosters that copy the original Ford booster design, by having a lever behind the booster. The lever change the pedal ratio and also move the booster a litttle up to make space for the clutch linkage. The pedal works and feels like any modern car. 🙂
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post #50 of 65 (permalink) Old 04-18-2019, 07:20 AM
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I have a manuel car with one of those aftermarket boosters that copy the original Ford booster design, by having a lever behind the booster. The lever change the pedal ratio and also move the booster a litttle up to make space for the clutch linkage. The pedal works and feels like any modern car. 🙂
I forgot about that style with the lever. From pictures it looks like that lever will double the throw over a direct connection, which would work nicely in this situation I think. The only other issue I see is using a dual reservoir master, in combination with the booster and bracket/lever, it will hit the shock tower in a 65/66 because of its overall length. Your only option would be a single bowl master (not ideal).

I’d be curious to see pics of your setup seeing that it works!

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post #51 of 65 (permalink) Old 04-18-2019, 07:51 AM
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Your only option would be a single bowl master (not ideal).

Iíd be curious to see pics of your setup seeing that it works!
No problems fitting an dual bowl MC, different complete bolt-on kits have been sold like that for years. But surely you can't just use any dual MC. Mine looks like on the pic below, I'm not sure if kits still are sold with this design. The lid on the booster does not get partly hidden under the export brace with this exact MC design, but are placed freely just behind.
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post #52 of 65 (permalink) Old 04-18-2019, 08:04 AM Thread Starter
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The issue I found with my system was the aftermarket booster was poorly designed and is the primary cause of the low pedal. No matter what the OP does with his brake system (bleeding, residual pressure valves, etc) nothing will change if he leaves that booster in there. I reduced the sloppy feel slightly by moving my master cylinder pushrod pivot on the pedal arm down ~1Ē (mine was manual drum prior). But it wasnít until I ditched the aftermarket booster (for a stock later model Mustang booster) and thatís when it finally felt normal.

Those boosters are flawed for this application, in my opinion. There is way too much play to activate the power booster, and this in turn gives a horrible pedal feel when vacuum is present. With the engine off you get a nice hard pedal, but once the motor starts it goes flaccid, and thatís the last thing you want!

OP is somewhat stuck because he has a manual transmission. It may be worth trying a larger diameter master cylinder, but he may just end up with a moderate amount of slop and too hard of pedal effort. How tricky is a hydraulic booster to install?
I think you may be right...I got the residual valve on, rebled everything and even backed out the rod to the master cylinder to make it as long as possible. The effect was that it is slightly better, but still takes a distance before things feel firm. I can live with it for now, but I'm open to booster suggestions for the future. I'd rather change that than the rest of the components. I think I can even sneak it out without unhooking the brake lines from the MC.
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post #53 of 65 (permalink) Old 04-18-2019, 08:05 AM Thread Starter
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Originally Posted by Westmus View Post
I have a manuel car with one of those aftermarket boosters that copy the original Ford booster design, by having a lever behind the booster. The lever change the pedal ratio and also move the booster a litttle up to make space for the clutch linkage. The pedal works and feels like any modern car. 🙂
Sorry, my car is an automatic...I've swapped the C4 for AOD.
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post #54 of 65 (permalink) Old 04-18-2019, 08:09 AM
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A quick pic from my car. A little black paint and it looks pretty "factory" to me.
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post #55 of 65 (permalink) Old 04-18-2019, 08:29 AM
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Sorry, my car is an automatic...I've swapped the C4 for AOD.
Yeah, but the original Ford lever design on the early cars, was also mounted on the automatics. The lever do the same ratio change that '67- was made by having a different lenght brake pedals for power/no-power brakes. I'm pretty sure engineers at Ford only made these additional changed, because they couldn't get the pedal to feel right with just mounting a booster on the manuel setup.
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post #56 of 65 (permalink) Old 04-18-2019, 11:18 AM
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I'm pretty sure engineers at Ford only made these additional changed, because they couldn't get the pedal to feel right with just mounting a booster on the manuel setup.
I think this is it. The early cars with high mechanical advantage pedal ratios don't play nicely with direct mount brake boosters. Halving the pedal ratio would halve the slop in the booster setup which is exactly what needs to happen to get a reasonable pedal feel.

We aren’t trying to reinvent the wheel here but the problem lies in these aftermarket kits which utilize a direct mount brake booster. That combined with a high ratio pedal gives us a very sloppy brake pedal.

I wonder if there is a way to do the mechanical/lever adjustment on the pedal side vs the firewall side? That would help the clearance issues in the early cars. Hmmm...

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post #57 of 65 (permalink) Old 04-18-2019, 02:16 PM
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Have we, as a collective group, reached the point where we now strongly discourage owners of 65 - 66 cars not to install power brakes? Manual disk yes, but power disk no? No real need for power assist on such a light car, and then all of the woe of crappy pedal feel and height.


When the booster on my converted car dies, I will not be replacing it, instead I'll be going to manual with the current disk conversion.
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post #58 of 65 (permalink) Old 04-18-2019, 03:34 PM
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Or buy this tool to get the pin set properly...what's another $26, right?
https://www.youtube.com/watch?v=qc6MgNNMQts

https://www.macsautoparts.com/ford_m...E&gclsrc=aw.ds
Thanks for posting this. I struggled a lot with setting this up on my car and this tool looks like it will really help. I tried to order it from macsautoparts.com and there would have been a $34.95 shipping charge (I live in Hawaii). Found it on Amazon with a $5 shipping charge

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

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post #59 of 65 (permalink) Old 04-18-2019, 10:22 PM
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I guess I'm the newest member of the club. I installed a CSRP booster and a 1967 drum master cylinder a year ago on my 1965 and pedal travel was fine on my all drum setup. This winter I installed the Mustang Steve 2008 Mustang GT brackets and 12.5" rotor and caliper assembly. The calipers are dual piston aluminum. I also installed a 1967 style disk drum master cylinder (China). A Ford style proportioning valve, also from China I assume, was installed. https://www.ebay.com/itm/231631393689 That was followed by a Wilwood 10lb residual pressure valve mounted immediately after the proportioning valve. I bench bled the MC for far longer than I have ever before. Probably a 100 strokes after the last bubble appeared. I ran 2 quarts of Dot 3 brake fluid using a pressure bleeder through the system to make sure there was no air present. No bubbles appeared in the clear tubing I use to capture the fluid into a bottle for the last quart. Pedal goes annoyingly close to the floor with a lot of travel that was not there with the drum setup. I won't be able to drive it until Saturday but I'm assuming it will stop fine with an uninspiring amount of pedal travel. I guess my first set will be to lower the pedal mount 5/8" Mustang Steve style.

PS. Rear drums are adjusted "tight" and will probably have to be backed off before driving.

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Last edited by Nailbender; 04-18-2019 at 10:26 PM.
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post #60 of 65 (permalink) Old 04-19-2019, 05:14 AM
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Have we, as a collective group, reached the point where we now strongly discourage owners of 65 - 66 cars not to install power brakes?
I drove my '65 for like 20 years with the stock non power discs and I never learned to really love it. Mounted a booster and now I like it much better.

It seems that even Ford realized non-power discs wasn't the best system for normal drivers, because it wasn't available after '66. Discs need by nature higher pressure than drums to give the same braking power. But power brakes have been the standard on road cars the last 50 years, it works perfectly. The problems usually starts when people think they can easily backyard engineer a brake system. 🙂
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