Redoing the Brake System
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Joined: Feb 2014
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Redoing the Brake System
I need to pick you guys brains here on braking systems.
Ancient Chinese proverb: Go fast car, need stop fast brakes!
I have been tinkering around with my brake system trying to get better performance out of it. Ever since I got the car running, the brakes have been lacking a bit. The car is a 68 Coupe with power brakes. Originally the came came with a manual system, but when I did the frame off, I switched it over to a power brake system. Fast forward to putting the motor in and discovering the engine only makes 8" of vacuum at idle and does not have enough volume to run all the odds and ends that vacuum is supposed to power. I converted the headlights to electric, the WW wiper door is next. But I also added an SSBC vacuum pump to fix this, but at times, the pedal goes to the floor almost in stop and go traffic and causes some pucker factor issues for me. All parts on the braking system are brand new, but could be bad at this point.
I recently found myself at local boneyard and found a hydro boost system I scored for 13.00 buck, 120.00 worth of parts later, I tried it out and it made a huge improvement. However, I could only lock up one wheel under hard braking. (Safely did this in my work parking lot when no one around)
But, the rest of the system seems to be lacking. I rebuilt the calipers and could not believe the amount of crap that came out of each one. Put them back on, no leaks and they bled fine. Hard braking had the same results. The proportional valve seems to be pushed over to one side or the other now as that dash light is on. I unplug it and the light goes out.
So long story short, I am looking to upgrade my master cylinder and add an adjustable proportional valve for the brakes. As far as I can tell, the brakes and rotors are good, just what is controlling them needs help.
I looked at the Wilwood MC and adjustable valve, but its twice what GM or comparable units are. So, for you Autocross and Racer types, or anyone who knows brake systems well, what would you recommend and why?
Also, the hydro boost feel is a lot different from the vacuum feel and I plan on keeping it hydro boost.
Ancient Chinese proverb: Go fast car, need stop fast brakes!
I have been tinkering around with my brake system trying to get better performance out of it. Ever since I got the car running, the brakes have been lacking a bit. The car is a 68 Coupe with power brakes. Originally the came came with a manual system, but when I did the frame off, I switched it over to a power brake system. Fast forward to putting the motor in and discovering the engine only makes 8" of vacuum at idle and does not have enough volume to run all the odds and ends that vacuum is supposed to power. I converted the headlights to electric, the WW wiper door is next. But I also added an SSBC vacuum pump to fix this, but at times, the pedal goes to the floor almost in stop and go traffic and causes some pucker factor issues for me. All parts on the braking system are brand new, but could be bad at this point.
I recently found myself at local boneyard and found a hydro boost system I scored for 13.00 buck, 120.00 worth of parts later, I tried it out and it made a huge improvement. However, I could only lock up one wheel under hard braking. (Safely did this in my work parking lot when no one around)
But, the rest of the system seems to be lacking. I rebuilt the calipers and could not believe the amount of crap that came out of each one. Put them back on, no leaks and they bled fine. Hard braking had the same results. The proportional valve seems to be pushed over to one side or the other now as that dash light is on. I unplug it and the light goes out.
So long story short, I am looking to upgrade my master cylinder and add an adjustable proportional valve for the brakes. As far as I can tell, the brakes and rotors are good, just what is controlling them needs help.
I looked at the Wilwood MC and adjustable valve, but its twice what GM or comparable units are. So, for you Autocross and Racer types, or anyone who knows brake systems well, what would you recommend and why?
Also, the hydro boost feel is a lot different from the vacuum feel and I plan on keeping it hydro boost.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I need to pick you guys brains here on braking systems.
Ancient Chinese proverb: Go fast car, need stop fast brakes!
I have been tinkering around with my brake system trying to get better performance out of it. Ever since I got the car running, the brakes have been lacking a bit. The car is a 68 Coupe with power brakes. Originally the came came with a manual system, but when I did the frame off, I switched it over to a power brake system. Fast forward to putting the motor in and discovering the engine only makes 8" of vacuum at idle and does not have enough volume to run all the odds and ends that vacuum is supposed to power. I converted the headlights to electric, the WW wiper door is next. But I also added an SSBC vacuum pump to fix this, but at times, the pedal goes to the floor almost in stop and go traffic and causes some pucker factor issues for me. All parts on the braking system are brand new, but could be bad at this point.
I recently found myself at local boneyard and found a hydro boost system I scored for 13.00 buck, 120.00 worth of parts later, I tried it out and it made a huge improvement. However, I could only lock up one wheel under hard braking. (Safely did this in my work parking lot when no one around)
But, the rest of the system seems to be lacking. I rebuilt the calipers and could not believe the amount of crap that came out of each one. Put them back on, no leaks and they bled fine. Hard braking had the same results. The proportional valve seems to be pushed over to one side or the other now as that dash light is on. I unplug it and the light goes out.
So long story short, I am looking to upgrade my master cylinder and add an adjustable proportional valve for the brakes. As far as I can tell, the brakes and rotors are good, just what is controlling them needs help.
I looked at the Wilwood MC and adjustable valve, but its twice what GM or comparable units are. So, for you Autocross and Racer types, or anyone who knows brake systems well, what would you recommend and why?
Also, the hydro boost feel is a lot different from the vacuum feel and I plan on keeping it hydro boost.
Ancient Chinese proverb: Go fast car, need stop fast brakes!
I have been tinkering around with my brake system trying to get better performance out of it. Ever since I got the car running, the brakes have been lacking a bit. The car is a 68 Coupe with power brakes. Originally the came came with a manual system, but when I did the frame off, I switched it over to a power brake system. Fast forward to putting the motor in and discovering the engine only makes 8" of vacuum at idle and does not have enough volume to run all the odds and ends that vacuum is supposed to power. I converted the headlights to electric, the WW wiper door is next. But I also added an SSBC vacuum pump to fix this, but at times, the pedal goes to the floor almost in stop and go traffic and causes some pucker factor issues for me. All parts on the braking system are brand new, but could be bad at this point.
I recently found myself at local boneyard and found a hydro boost system I scored for 13.00 buck, 120.00 worth of parts later, I tried it out and it made a huge improvement. However, I could only lock up one wheel under hard braking. (Safely did this in my work parking lot when no one around)
But, the rest of the system seems to be lacking. I rebuilt the calipers and could not believe the amount of crap that came out of each one. Put them back on, no leaks and they bled fine. Hard braking had the same results. The proportional valve seems to be pushed over to one side or the other now as that dash light is on. I unplug it and the light goes out.
So long story short, I am looking to upgrade my master cylinder and add an adjustable proportional valve for the brakes. As far as I can tell, the brakes and rotors are good, just what is controlling them needs help.
I looked at the Wilwood MC and adjustable valve, but its twice what GM or comparable units are. So, for you Autocross and Racer types, or anyone who knows brake systems well, what would you recommend and why?
Also, the hydro boost feel is a lot different from the vacuum feel and I plan on keeping it hydro boost.
We just did the brakes on a 1971 and just like mine, if you hammer the brakes it'll toss you for a loop.
Are you sure the booster and/or the master cylinder are okay? Are you sure you have all the air out of the system. Are you sure you don't have a vacuum leak somewhere?
Something has to be failing in the system because like I said, when everything is right the stock brakes will work just fine for any horsepower car. And considering your running a vacuum booster you really should be having any issue.
IMHO,
Willcox
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Joined: Feb 2014
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Oh yeah I agree, something on the brake system has failed. I have bled the thing time and time again. Got all the air out using Motive power bleeder. No leaks on any caliper. Found leak on the master cylinder where it connects to the booster. Brake fluid was in the booster as well. Pretty sure the MC killed the booster and or I killed it with the power bleeder. Either way, I have narrowed down the failed part to the MC, plus the distribution block under it causes the dash light to come on, there is a problem there. I am thinking I messed it up and pushed it too far over to one side when I bled it. Options are to repair what I have, or replace it. Just wondering if there is a better system to replace it with?
Last edited by Lobzila; Oct 13, 2017 at 09:45 PM.
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 343
From: Allenton Wisconsin
Your 68 is a small spindle car, [same spindles used from 65 to 68] in 69 they got bigger. Small spindles flex under hard cornering and cause brake pad knock back. My 6t8 got a lot of track days and a few auto xs., running a Wilwood M/C and adjustable proportioning valve and DOT 4 fluid. You ask why, once installed and adjusted they preform flawlessly.
P/S, the 6t8 got a electric wiper set-up, if you want info contact me. T
P/S, the 6t8 got a electric wiper set-up, if you want info contact me. T
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Two things, number one is to ditch that switch that everyone thinks is a prop valve, just put a line splitter to the fronts/same as on rear....run the line to the forward section of the m/cyl.....rear line straight to the back section which is first actuated when you hit the brakes.....those switches are prone to leaks and are very devious on sucking air into the systems....don't ask how I know this
Second off, is to replace all the hoses, clean out the calipers, nice and new, and use DOT 5 fluid...NAPA carries it, for some stupid reason the other parts houses here do not, anymore...... DOT 5 don't RUST....not that with stainless calipers and fresh/new m/cyl there should be much of a problem, but long as it's apart, may as well do it right....
Second off, is to replace all the hoses, clean out the calipers, nice and new, and use DOT 5 fluid...NAPA carries it, for some stupid reason the other parts houses here do not, anymore......
DOT 5 don't RUST....not that with stainless calipers and fresh/new m/cyl there should be much of a problem, but long as it's apart, may as well do it right....
