Bleeding brakes
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,474
Likes: 2,181
From: Loveland
You may need to get one of these tools.... ensure you get the appropriate one for your year.
https://www.performanceonline.com/GM...Tool-AC-Delco/
Follow the thread below for more info.
https://www.corvetteforum.com/forums/c3-general/4371698-bleeding-my-brakes.html#post1601008013
https://www.performanceonline.com/GM...Tool-AC-Delco/
Follow the thread below for more info.
https://www.corvetteforum.com/forums/c3-general/4371698-bleeding-my-brakes.html#post1601008013
Melting Slicks
Joined: Aug 2016
Posts: 2,346
Likes: 1,174
From: CLEVELAND STUCK IN OHIO
2024 C3 of the Year Finalist- Modified
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
What I still don't get. I have two lines coming from the MC, one to the rear, one to the front. Completely different systems. Two reservoirs. But when I open a bleeder in the rear, "have a rear leak" the pedal still goes to the floor. This is why I removed the distribution block.
None of my business but, why are you not using the stock brake line configuration from the master to the D. Block? You have set yourself up for two additional leaks with those spliced lines / joints.
If the new lines going into the MC ports are not flared, they will never hold a seal. Inside the MC ports is a matching flare that is part of the iron castings. Only a flared line should mate up to those ports.
The two ready made brake lines from the MC to the D. block are not expensive, are pre-bent to the perfect angle and fit correctly.
Also, by you removing the so called distribution block as a potential problem, you will have to re-bleed again when you reinstall the block.
I don't believe you should ever use a thread sealer on brake line fitting. DOT3 is a solvent and would destroy the paste soon.
And last but not least: Is your MC / Booster rod adjustable on your model yr? If so, what is your gap between the two? A gap of 0.060 or about 1/16 inch is ideal.
Last edited by HeadsU.P.; Mar 10, 2021 at 07:42 PM.
Race Director
Joined: Mar 2017
Posts: 11,948
Likes: 4,506
From: Virginia
So, just to clarify, this is for the bleeder valve threads only, never the brake line fitting. I've mangled enough of those without Loctite.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
When pedal bleeding the brakes properly, you can't get air sucked back into the caliper through the bleeder. Hence, no need for any teflon tape, grease, duct tape or whatever.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,474
Likes: 2,181
From: Loveland
Not to worry, My bubba lines are made correctly,,, yep with a flare, they don't leak. There are just as many chances as the "so called distribution block" to leak as these lines. Like I said again,,,,,, I removed the block to eliminate it as a source of my problem. Good idea to bleed the brakes again after breaking the system open. huh. If you do a little research you will learn the difference between a proportioning valve and a 68 distribution switch. Look it up in the 1968 Factory Assembly Manual, it's a part number, "3904303 switch". It's only designed to light up the brake light. This is a manual brake car,,, I don't think it has a "booster". I did check with the rear bleeder open if I get front breaking,,,,, I do.
Last edited by kodpkd; Mar 10, 2021 at 09:51 PM.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
To be honest from reading your posts, I don't think you know near enough about how a brake system works in order to make your brakes functional and safe. You can't pedal bleed brakes by yourself. When you crack open a bleeder, the pedal goes to the floor in a heartbeat. The brake distribution switch does more than complete an electrical circuit to illuminate a light on a loss of fluid pressure and does not need to be removed from the brake system for any reason unless it has failed, which is unlikely but can happen. And how did you test your front braking with the rear bleeder open?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,474
Likes: 2,181
From: Loveland
Hummmm.. Maybe the block has failed, 50 year old rubber orings.. Let me see,,,, jack up the left side of the car, open the rear bleeder, have someone push the brake pedal down, then see if the front wheel is locked up,,, easy peazy! You seem to know a lot about 68 distribution blocks. So you have had one off a car and had it apart to see how it functions? So tell me, how many brake line fittings does it have coming in and out of it?
Melting Slicks
Joined: Aug 2016
Posts: 2,346
Likes: 1,174
From: CLEVELAND STUCK IN OHIO
2024 C3 of the Year Finalist- Modified
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
What did you use for the MC lid may I ask? Because that "thing" that comes with the Motive for a MC lid is a joke.
The idea with the Motive is to pour two bottles of DOT3 in the tank, pump it up and bleed all four screws on the rear at one time.
Then do the fronts. Never touch the pedal.
The idea with the Motive is to pour two bottles of DOT3 in the tank, pump it up and bleed all four screws on the rear at one time.
Then do the fronts. Never touch the pedal.
Last edited by HeadsU.P.; Mar 11, 2021 at 07:39 PM.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,474
Likes: 2,181
From: Loveland
What did you use for the MC lid may I ask? Because that "thing" that comes with the Motive for a MC lid is a joke.
The idea with the Motive is to pour two bottles of DOT3 in the tank, pump it up and bleed all four screws on the rear at one time.
Then do the fronts. Never touch the pedal.
The idea with the Motive is to pour two bottles of DOT3 in the tank, pump it up and bleed all four screws on the rear at one time.
Then do the fronts. Never touch the pedal.
So, you are saying to have all 4 rear bleeders open at the same time? I can see that could help get air past the little block in the rear that divides the left from the right.
Melting Slicks
Joined: Aug 2016
Posts: 2,346
Likes: 1,174
From: CLEVELAND STUCK IN OHIO
2024 C3 of the Year Finalist- Modified
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,474
Likes: 2,181
From: Loveland
Melting Slicks
Joined: Aug 2016
Posts: 2,346
Likes: 1,174
From: CLEVELAND STUCK IN OHIO
2024 C3 of the Year Finalist- Modified
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Post 33
Yes. Not wide open, but all four bleeders "trickle" open into a clear hose, into a water bottle etc. Consider the procedure a semi-gravity bleeding assist process.
Closing the bleeders in the normal bleeding order RRO, RRI, LRO, LRI, when the bubbles cease. Then RF>LF done.
Yes. Not wide open, but all four bleeders "trickle" open into a clear hose, into a water bottle etc. Consider the procedure a semi-gravity bleeding assist process.
Closing the bleeders in the normal bleeding order RRO, RRI, LRO, LRI, when the bubbles cease. Then RF>LF done.
Last edited by HeadsU.P.; Mar 12, 2021 at 08:20 AM.
Race Director
Joined: Mar 2017
Posts: 11,948
Likes: 4,506
From: Virginia
While you are bleeding per @HeadsU.P.'s method, tap the junction block(s) and calipers with a wrench to dislodge trapped air bubbles. Even with the Motive I had to do this twice to get a firm pedal on my 79.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,474
Likes: 2,181
From: Loveland
I really need to see an original 68 distribution block that is different than these. There are a lot of retro fits, but not original fit.
https://www.zip-corvette.com/67-68-m...roduction.html
https://www.ecklerscorvette.com/1967...-162821-1.html
https://www.topflightautomotive.com/...oaAtoSEALw_wcB
https://www.zip-corvette.com/67-68-m...roduction.html
https://www.ecklerscorvette.com/1967...-162821-1.html
https://www.topflightautomotive.com/...oaAtoSEALw_wcB
Le Mans Master
Joined: Jan 2001
Posts: 6,741
Likes: 1,383
I'll try to remember and get a picture of my April 68 distribution block tomorrow. (send me a PM if I space--- I'm going to be working the car so I shouldn't space it....but you never know).
Are you getting really good flow out of your bleeders?
Have you replaced the hoses to the calipers?
I ask about flow because when I do pressure bleeding I get so much flow that it's the easiest way to replace all the fluid with new.
Are you getting really good flow out of your bleeders?
Have you replaced the hoses to the calipers?
I ask about flow because when I do pressure bleeding I get so much flow that it's the easiest way to replace all the fluid with new.
I really need to see an original 68 distribution block that is different than these. There are a lot of retro fits, but not original fit.
https://www.zip-corvette.com/67-68-m...roduction.html
https://www.ecklerscorvette.com/1967...-162821-1.html
https://www.topflightautomotive.com/...oaAtoSEALw_wcB
https://www.zip-corvette.com/67-68-m...roduction.html
https://www.ecklerscorvette.com/1967...-162821-1.html
https://www.topflightautomotive.com/...oaAtoSEALw_wcB
Last edited by carriljc; Mar 12, 2021 at 12:02 AM.