Author Topic: 1969 Mustang disc brakes  (Read 3756 times)

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cjshaker

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Re: 1969 Mustang disc brakes
« Reply #15 on: May 15, 2021, 01:49:03 PM »
If you're having trouble with excessive travel on your manual disc set-up, it sounds like you're missing the residual pressure valves. That keeps the calipers from sucking back in and having to take up that distance with the pedal on the next stop.
Doug Smith


'69 R-code Mach 1, 427 MR, 2x4, Jerico, 4.30 Locker
'70 F-350 390
'55 Ford Customline 2dr
'37 Ford Coupe

Stangman

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Re: 1969 Mustang disc brakes
« Reply #16 on: May 15, 2021, 07:24:36 PM »
Ya know Doug I had thought about that but didn’t say anything cause how do you figure out which to install. I had seen a 2 lb a 10 lb. Is there a way to figure it out or is it trial and error. Is this something you have done before? I’m just so used to pumping the brake once before I make a stop. And do you just do the rears.

driveamerican

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Re: 1969 Mustang disc brakes
« Reply #17 on: May 16, 2021, 01:28:35 AM »
I used a master cylinder from a bronco 2 with manual disc drum system and all the Granada stuff on my 64 fairlane, might have been lucky but I could put lip prints on passengers windshield when ever I wan ted. Mark

sixty9cobra

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Re: 1969 Mustang disc brakes
« Reply #18 on: May 17, 2021, 10:57:35 PM »
where does the residual pressure valves live? I had discs before I went manual disc is this something I should have added? The electric steering unit is from a Prius 150 on eBay some cutting and welding and it lives under the dash.
« Last Edit: May 18, 2021, 08:40:24 AM by sixty9cobra »

67xr7cat

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Re: 1969 Mustang disc brakes
« Reply #19 on: May 18, 2021, 11:29:01 PM »
where does the residual pressure valves live? I had discs before I went manual disc is this something I should have added?

There is a residual check valve on the port for the rear drum brakes. It is behind the seat.  To access it you would use a screw to remove the seat.  It will have a rubber check valve and a spring.  This is only used on the drum side. You do not need this for disc and would make the calipers drag.  Only time you have a residual valve on disc is if the master cylinder is mounted below the caliper which you do not have.

Now there is also a proportioning valve which is part of the metering block and is plumbed into the line to the rear brakes this is used to keep the rear brakes from locking up in a hard stop.  If your setup was the stock disc/drum from the factory your stock one is fine. If you have different rear brakes you can get an adjustable proportioning valve, but it does not sound like this is your problem.

I would verify that the master cylinder is a disc/drum type and has the residual check valve on the drum side. If it does not you will have excessive pedal travel.  That all said the manual setup will have more travel since the manual brake pedal has more leverage and the master is a smaller bore.  This is required to still be able to generate enough braking force without assist.  If you go to a bigger bore master cylinder your pedal travel will be less, but the effort will go up.

Considering you went from a Hydraboost to manual brakes I am not surprised you are not happy, as is said  "there is no free lunch".  The old manual Ford disc/drum setup works, but will not match what you had. If you want to get rid of the hydroboost next best would be the factory vacuum booster and 1" master cylinder setup.  You can add a vacuum tank and there are OE vacuum pumps that can also keep the vacuum up if you have low vacuum because of a long duration cam.  Other option is electric, but that seems to still be an expensive option, have not heard of any DIY setups yet.

67xr7cat

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Re: 1969 Mustang disc brakes
« Reply #20 on: May 20, 2021, 02:24:54 AM »
So came across this page has an interesting new electric brake booster the iBooster.  Wonder if Apple will sue Bosch over that one... LOL 
Page has some good info as well as the links. I'd say it has some good DIY potential, just have to wait for all those EV cars to hit the junkyards.

https://www.evcreate.nl/electric-power-brakes/

Here is the Bosch video

https://youtu.be/lJzbCA6qrBw