Brake master replacement - ZR-1 Net Registry Forums

secondchance · 10-03-2016

Recently at two occasions my brake pedal would drop and engage maybe about ¼-1/2” below normal and then go back to normal as if nothing had happened. I discussed this with a few friends and concluded this condition could be caused by air in the system, worn out master cylinder (although random occurrence makes this a suspect), brake booster (I have a spare just in case), or ABS pump failing. Besides, brake master was looking grungy and fluid reservoir was stained and had crud build up – not surprising after 150,000 miles and 22 years of service. So, to start with, I decided to replace the master, reservoir and flush the whole system with Wilwood ESP 600 plus recommended by Jim Jandik. Also, decided to replace caliper bleeder valves with Gunny recommended Russell one-way bleeder valves. If this was temporary ABS pump malfunction, I am hoping, brake fluid flush may resolve the issue.

Notice how grungy the master and the reservoir look? Inside the reservoir had black sludge with no way to get to.

Reservoir and the master out of the car. Notice rags strategically placed to catch any brake fluid drops. Interestingly, flare nut facing the front (rear) has 9/16” nut. Nut closer to the bulkhead (front) was smaller and I thought would be ½” – Wrong! This one was 12 mm – once again proving Darrin was right – “all fasteners on ZR-1s are metric except for those that are SAE”.

Checking around, I concluded that master cylinder can be bench bled on the car. So, I bolted the new master in the car. So, I bolted the new master in the car to be bench bled.

When I sucked the fluid out through the reservoir opening fluid in the front chamber would not evacuate leading me to suspect these were two separate chambers. So, just in case, I cut a small opening above the front chamber to fill with fluid and run the hose from the rear brake line port for purpose of bench bleeding. This turned out to be unnecessary. Temporary lines from the brake line ports can be immersed into single fill opening. Once set up, I pumped the brake pedal about ¾” each stroke until air bubbles were not visible in the clear plastic tube.

After the bench bleeding connected front and rear brake lines, electrical connectors and fluid level sensor.

Bled the rear right, rear left.

Front right followed by front left.

Brake fluid flush was soooo easy with Gunny recommended one-way bleeder valve. Thanks, Gunny!

RussMcB · 10-03-2016

Good work.

One tip I've heard (and the Russel bleed valves help a lot with this) is to use a two step bleed in front/rear pairs (as opposed to four separate corners). The first pair should be the furthest rear caliper along with the furthest front caliper, then do the closest rear caliper along with the closest front. This way you'll get more travel for each pedal pump (since the other system half is not closed off). Hope that makes sense.

Another (admittedly more anal) tip - Tap the calipers with a small hammer to dislodge any air bubbles. Probably not necessary but I can't resist doing it "just in case". I always have my wife or a friend help, and it's reassuring to hear the tap tone change when they depressed the pedal, letting me know when it's safe to open the bleed screw.

secondchance · 10-03-2016

I can see how you can bleed a pair of calipers at one time. Perhaps, even all four simultaneously since you are pushing fluid out without dealing with air being sucked in. In my case, working with one jack (one stowed behind the passenger seat), best I could do was one corner at a time.
With one way bleeder I was able to do the whole thing without turning to whining wife or sons.

Mystic ZR-1 · 10-03-2016

Brake bleeding with Wifey can
lead to divorce court... 😩

GOLDCYLON · 10-03-2016

Quote:

Originally Posted by Mystic ZR-1

Brake bleeding with Wifey can
lead to divorce court... ��

I've done it. No Divorce Court occurred. LOL

Of Course it was her car LOL

One of the reasons I like the 90-01 Brake master two cup system easier to clean.

RichS · 10-04-2016

Finally getting mine back together and had to use the wife to bleed the brakes. Couldn't get the rears to bleed with a Mity vac or Motive bleeder. She's used to it. lol

Paul Workman · 10-04-2016

The Russel bleeders...#639630 from Summit...worth every cent!

Buy 4; one for each corner, and leave them in place.

(playing it forward from Mark Horner)

George Maz · 10-04-2016

http://www.speedbleeder.com
stainless, put them on my Yukon Denali

Billy Mild · 10-04-2016

When my brake lines from my master cylinder to my ABS pump sprung a leak I did something similar. Painted my calipers, put new Hawk Pads on, stainless steel lines, new master cylinder, and speed bleeders. The speed bleeders helped out so much. Took only a few minutes per caliper vs. hours. I have them in every car I do a brake job on now.

10-03-2016	#1
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,717	Brake master replacement Recently at two occasions my brake pedal would drop and engage maybe about ¼-1/2” below normal and then go back to normal as if nothing had happened. I discussed this with a few friends and concluded this condition could be caused by air in the system, worn out master cylinder (although random occurrence makes this a suspect), brake booster (I have a spare just in case), or ABS pump failing. Besides, brake master was looking grungy and fluid reservoir was stained and had crud build up – not surprising after 150,000 miles and 22 years of service. So, to start with, I decided to replace the master, reservoir and flush the whole system with Wilwood ESP 600 plus recommended by Jim Jandik. Also, decided to replace caliper bleeder valves with Gunny recommended Russell one-way bleeder valves. If this was temporary ABS pump malfunction, I am hoping, brake fluid flush may resolve the issue. Notice how grungy the master and the reservoir look? Inside the reservoir had black sludge with no way to get to. Reservoir and the master out of the car. Notice rags strategically placed to catch any brake fluid drops. Interestingly, flare nut facing the front (rear) has 9/16” nut. Nut closer to the bulkhead (front) was smaller and I thought would be ½” – Wrong! This one was 12 mm – once again proving Darrin was right – “all fasteners on ZR-1s are metric except for those that are SAE”. Checking around, I concluded that master cylinder can be bench bled on the car. So, I bolted the new master in the car. So, I bolted the new master in the car to be bench bled. When I sucked the fluid out through the reservoir opening fluid in the front chamber would not evacuate leading me to suspect these were two separate chambers. So, just in case, I cut a small opening above the front chamber to fill with fluid and run the hose from the rear brake line port for purpose of bench bleeding. This turned out to be unnecessary. Temporary lines from the brake line ports can be immersed into single fill opening. Once set up, I pumped the brake pedal about ¾” each stroke until air bubbles were not visible in the clear plastic tube. After the bench bleeding connected front and rear brake lines, electrical connectors and fluid level sensor. Bled the rear right, rear left. Front right followed by front left. Brake fluid flush was soooo easy with Gunny recommended one-way bleeder valve. Thanks, Gunny!

10-03-2016	#2
RussMcB Join Date: Jan 2015 Location: Marietta, GA USA Posts: 1,148	Re: Brake master replacement Good work. One tip I've heard (and the Russel bleed valves help a lot with this) is to use a two step bleed in front/rear pairs (as opposed to four separate corners). The first pair should be the furthest rear caliper along with the furthest front caliper, then do the closest rear caliper along with the closest front. This way you'll get more travel for each pedal pump (since the other system half is not closed off). Hope that makes sense. Another (admittedly more anal) tip - Tap the calipers with a small hammer to dislodge any air bubbles. Probably not necessary but I can't resist doing it "just in case". I always have my wife or a friend help, and it's reassuring to hear the tap tone change when they depressed the pedal, letting me know when it's safe to open the bleed screw.

10-03-2016	#3
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,717	Re: Brake master replacement I can see how you can bleed a pair of calipers at one time. Perhaps, even all four simultaneously since you are pushing fluid out without dealing with air being sucked in. In my case, working with one jack (one stowed behind the passenger seat), best I could do was one corner at a time. With one way bleeder I was able to do the whole thing without turning to whining wife or sons.

10-03-2016	#4
Mystic ZR-1 Join Date: Jan 2010 Location: Mystic CT Posts: 2,625	Re: Brake master replacement Brake bleeding with Wifey can lead to divorce court... 😩

10-04-2016	#7
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: Brake master replacement The Russel bleeders...#639630 from Summit...worth every cent! Buy 4; one for each corner, and leave them in place. (playing it forward from Mark Horner)

10-04-2016	#6
RichS Join Date: Nov 2013 Location: Wilkes-Barre, PA Posts: 148	Re: Brake master replacement Finally getting mine back together and had to use the wife to bleed the brakes. Couldn't get the rears to bleed with a Mity vac or Motive bleeder. She's used to it. lol

10-04-2016	#9
Billy Mild Join Date: Aug 2014 Location: Kansas City, MO Posts: 835	Re: Brake master replacement When my brake lines from my master cylinder to my ABS pump sprung a leak I did something similar. Painted my calipers, put new Hawk Pads on, stainless steel lines, new master cylinder, and speed bleeders. The speed bleeders helped out so much. Took only a few minutes per caliper vs. hours. I have them in every car I do a brake job on now.