disc brake questions???
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disc brake questions???
Posted: March 27 2008 12:50 PM
 
BigAl Breland (aka BigAlBre) [ View ] [ bigalbre ] [ Car Ads ] [ Blogs ]
Saint Petersburg Beach, Florida
(866) 787-6337
 Big Al sittin back pickin & grinning in paradise.
 
Having changed the rearend to a disc setup I would expect more stopping power than I have. The master cylinder is one of those 7 inch booster under the floor equal chamber size units. I still have the red and blue residual valves in place and I opened up the Wildwood proportioning valve all the way. I also put all new brakes and and calipers on the rear. Last time I checked I had 18 inches of vaccum.... I know I need to swith the one residual valve but what else could be wrong???
 
 
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Posted by bigdude  -  03/27/2008 01:17 PM
Take the prop valve off completely make sure your master cyl is for disc brakes.
resident know it all [ View ] [ Email ] [ Blogs ] [ Car Ads ] Three Rivers, Michigan Charter Member since January 2004
 
Posted by ol bear  -  03/27/2008 01:18 PM
take that wilwood vale and through it as far as u can ,ol bear
OL BEAR [ View ] [ Email ] [ Blogs ] [ Car Ads ] crown point, Indiana
 
Posted by lildude  -  03/27/2008 01:33 PM
you need to take the red residual valve off and replace it with a blue one ( 2 lb. )
lildude [ View ] [ Email ] [ Blogs ] [ Car Ads ] kalamazoo, Michigan Charter Member since March 2005
 
Posted by BigAlBre  -  03/27/2008 01:48 PM
Thanks for the input, how do you tell if the master cylinder is for disc brakes ? I never asked when it was purchased (years ago)....
Big Al sittin back pickin & grinning in paradise. [ View ] [ Email ] [ Blogs ] [ Car Ads ] Saint Petersburg Beach, Florida Charter Member since June 1999
 
Posted by Crazyhorse Rod Shop  -  03/27/2008 02:54 PM
equal size bowls. chunk the adj valve and get a proportioning valve.
dont poke the porchdog........he bites [ View ] [ Email ] [ Blogs ] [ Car Ads ] BLUFF DALE, Texas Charter Member since March 2003
 
Posted by aosborn  -  03/27/2008 03:32 PM
If it is a Lincoln Versailles 9" rear axle with stock disc brake set-up, the pistons need to be adjusted to the proper clearance in order to get a decent pedal. As far as checking your master cylinder, the most fool-proof way I found is to probe the outlet ports of the master cylinder with a small allen wrench or something similar, if you feel a blockage, that is a check valve and that port goes to the drum brakes, if there is no check valve in either port the master cylinder is for 4 wheel discs. I have had good luck with the Wilwood adjustable proportioning valves, they are nice because they enable you to fine tune the brakes for different weight vehicles and different tire size combinations. Something you can't do with an off -the-shelf proportioning valve.
aosborn [ View ] [ Email ] [ Blogs ] [ Car Ads ] Olympia, Washington
 
Posted by bigdude  -  03/27/2008 04:05 PM
Dont need a prop valve with disc does he?
resident know it all [ View ] [ Email ] [ Blogs ] [ Car Ads ] Three Rivers, Michigan Charter Member since January 2004
 
Posted by aosborn  -  03/27/2008 04:44 PM
You have to have some way of balancing the front to rear brake bias. Either via a factory style fixed proportioning/metering valve or an adjustable valve. Installed in the rear line, an adjustable valve set properly, works well to keep the rear brakes from locking up before the fronts. If the master cylinder is lower than the calipers/ wheel cylinders, a check valve must also be used at each port of the master cylinder to keep fluid from bleeding back into the master cylinder. A 2 pound for disk brakes and a 10 pound for drums.
aosborn [ View ] [ Email ] [ Blogs ] [ Car Ads ] Olympia, Washington
 
Posted by Crazyhorse Rod Shop  -  03/27/2008 04:54 PM
proportioning valves do a lot more. they react to pressure. in a panic stop they keep the rear from locking up. an adjustable can not tell the difference. i use a matching brake set up on each of my builds.
dont poke the porchdog........he bites [ View ] [ Email ] [ Blogs ] [ Car Ads ] BLUFF DALE, Texas Charter Member since March 2003
 
Posted by aosborn  -  03/27/2008 05:29 PM
http://www.chevyhiperformance.com/techarticles/71398_install_brake_proportioning_valve/index.html

Copy and paste the above link to your address bar for a good article on this exact subject...
aosborn [ View ] [ Email ] [ Blogs ] [ Car Ads ] Olympia, Washington
 
Posted by ronhotrod  -  03/27/2008 09:06 PM
one more item make sure you aere using 3/16th line to rear as well as the front. need the smaller line to acquire the correct pressure. can't use the drum 1/4 " line.
ronhotrod [ View ] [ Email ] [ Blogs ] [ Car Ads ] Mount washington, Kentucky Charter Member since July 2001
 
Posted by sellersrodshop  -  03/27/2008 11:28 PM
al, definately change to a disc/disc master cylinder. most of the disc/ drum master cylinders have an internal residual valve that will not let fluid return back to the system on a disc change. here is a site with almost all you need to know about brake systems. take note in the master cylinder section as to bore sizes in the master in relation to pedal pressures etc which helps in fine tuning the feel of your system. really a good reference guide:


http://www.hotrodheaven.com/tech/brakes/brakes1.htm
sellersrodshop [ View ] [ Email ] [ Blogs ] [ Car Ads ] old hickory, Tennessee
 
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