Author Topic: Brake Proportioning Valve Adjustment  (Read 380 times)

rockhouse66

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Brake Proportioning Valve Adjustment
« on: October 01, 2019, 01:08:27 PM »
I failed to take note of this when I had the valve apart.  If you want to "back off" the rear brakes, do you turn the threaded part into the valve body or out of the valve body?  I think I read that the standard Mustang disc brakes had the valve set at 11 threads showing (?) and the Shelby with the larger rear brakes had 9 threads showing, so turning it "in" reduces pressure to the rear?  And I would also deduce that 2 turns (11 threads to 9 threads) made a noticeable difference?
« Last Edit: October 02, 2019, 08:03:09 AM by rockhouse66 »

Kent

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Re: Brake Proportioning Valve Adjustment
« Reply #1 on: October 03, 2019, 07:48:37 AM »
do you have a picture of your p valve?
SAAC Member from Germany and Owner of a unrestored 1967 Shelby GT500, 1968 1/2 Cobra Jetīs and some nice Mustang Fastbackīs 67/68

rockhouse66

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Re: Brake Proportioning Valve Adjustment
« Reply #2 on: October 03, 2019, 08:03:35 AM »
Just the standard 65/66 valve but here it is disassembled.


CharlesTurner

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Re: Brake Proportioning Valve Adjustment
« Reply #3 on: October 03, 2019, 09:06:51 AM »
Google is your friend here...

From this page: http://www.stangerssite.com/brakevalve.html  (Page 2)


Unit can be adjusted by loosening adjuster lock nut and screwing adjuster sleeve in or out to desired effect. Be sure to tighten down adjuster lock nut each time. Threading the sleeve outwards will increase the pressure going to the calipers on the front wheels, threading in will decrease it.
Charles Turner
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rockhouse66

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Re: Brake Proportioning Valve Adjustment
« Reply #4 on: October 03, 2019, 09:18:11 AM »
Thank you Charles.  For some reason, I didn't find this web page when rebuilding the valve. It is oddly worded to say that adjusting this valve changes the pressure to the front brakes, because it actually only controls the pressure to the rear brakes, but I get the message.  Unscrewing the threaded part from the body reduces pressure to the rear brakes.

CharlesTurner

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Re: Brake Proportioning Valve Adjustment
« Reply #5 on: October 03, 2019, 10:20:23 AM »
Thank you Charles.  For some reason, I didn't find this web page when rebuilding the valve. It is oddly worded to say that adjusting this valve changes the pressure to the front brakes, because it actually only controls the pressure to the rear brakes, but I get the message.  Unscrewing the threaded part from the body reduces pressure to the rear brakes.

Because the 65-66 setup is not a dual bowl master cylinder, the amount of fluid pressure to the valve is still affected by the amount of pressure/fluid required to the front brakes.
Charles Turner
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