disc brake question
05-02-2012, 10:24 AM
#1
2nd Gear Member
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Location: cali
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disc brake question
Ok, i installed disc brakes on my 68 mustang about a year ago. The car was all non-powered drum brakes. I replaced the front with baer 12" disc brakes on the front and kept the drum in the rear. The master cylinder i replaced with a stock disc brakes master cylinder for 68. Kept the orginal porportion valve. The question is the brakes work, but it seems like you have to push pretty hard to stop fast. Just normal driving its no biggie, but when it comes time to stop on a dime. You have to put ur leg into it. What would be the cause of this? Bigger mastercylinder or porportion valve? thanks.
05-02-2012, 10:36 AM
#2
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05-02-2012, 12:59 PM
#4
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To my knowledge, the adjustable proportioning valves do not incorporate residual pressure valves. I've seen residual pressure valves either incorporated in aftermarket master cylinders or separate (cylindrical) inline attachments.
Perhaps you have both, but just confused them in ezstang's question? You said you "kept the original proportion valve" but later mentioned you had an "adjustable one".
Perhaps you have both, but just confused them in ezstang's question? You said you "kept the original proportion valve" but later mentioned you had an "adjustable one".
05-02-2012, 01:16 PM
#5
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when i installed them, i was reading if the rear brakes locked up first then you had to add this to the rear brakes http://www.summitracing.com/parts/WIL-260-8419/
so this is hooked up to the rear brakes.
so this is hooked up to the rear brakes.
05-02-2012, 01:33 PM
#6
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Personally i think i have my setup wrong. I think i need to remove the EXISTING porprotion valve, run line from master cylinder to front brakes. Then put adustable porportion valve for rear. does this sound correct?
lets just say im all confused!! lol..
lets just say im all confused!! lol..
Last edited by 68dustin; 05-02-2012 at 01:55 PM.
05-02-2012, 02:47 PM
#8
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+1 didn't see a mention of a brake booster being plumbed for or added. Also the proportioning valve for drum/drum vers disc/drum is different because disc/drum brakes have a different bias of front to rear for stopping power.
On Disc/Drum setups a usual proprotion is anywhere from 60 to 70% front versus 40 to 30% rear. A Drum/Drum setup can be 50-60% front versus 50-40% rear.
On Disc/Drum setups a usual proprotion is anywhere from 60 to 70% front versus 40 to 30% rear. A Drum/Drum setup can be 50-60% front versus 50-40% rear.
05-02-2012, 03:07 PM
#9
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ya i have a aftermarket power booster on it, bought it a long time ago to convert my non-power drums to power. when i went to disc, i then bought a power disc/drum mastercylinder. I think i need to ditch the drum/drum porportion block.
05-02-2012, 03:32 PM
#10
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The drum/drum distribution block should work fine. The plumbing of the proportioning valve (in this case the adjustable proportioning valve) should be on the rear brake line AFTER the distribution block.
You should remove the original proportioning valve from the system. I don't know what the consequences are for having two proportioning valvees in sequence. Did/do you have them both plumbed in now???
You should remove the original proportioning valve from the system. I don't know what the consequences are for having two proportioning valvees in sequence. Did/do you have them both plumbed in now???