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I’m having a great time getting my hands greasy on my new toy but I am a bit stumped. I had never gravity bled a system before so thought I would have a go. Here’s my process.
Removed, bench bled and replaced MC.
Removed MC lid, topped fluid.
Jacked car with front a bit higher than back as described.
Opened two bleeders on drivers rear caliper. Not a drop.
Gently probed openings with mechanics wire. Seems clear.
Out of curiosity I removed plug on rear of caliper, some fluid drained then stopped.
Replaced lid on MC and gently pushed brake pedal while leaving one caliper bleeder open. A healthy spurt of fluid.
Removed MC lid and opened bleeders again. Still no drips.
What am I missing?
Last edited by Williamhibberd; Oct 27, 2020 at 09:13 PM.
What is the condition of the rubber brake hoses, could they be collapsed from age? How long are you waiting to see fluid? What prompted you to want to bleed the brakes? For my money, I would start with just one bleeder at a time, tap on the caliper with a rubber hammer or 2 x 4, might loosen something up. And start with the passenger inside bleeder, then outside bleeder, then move to the driver's side, inside bleeder, outside bleeder. Then move to the passenger side front and finish with the driver's side front. Best of luck, glad you enjoy getting your hands greasy, helps when you own one of these classics....
What is the condition of the rubber brake hoses, could they be collapsed from age? How long are you waiting to see fluid? What prompted you to want to bleed the brakes? For my money, I would start with just one bleeder at a time, tap on the caliper with a rubber hammer or 2 x 4, might loosen something up. And start with the passenger inside bleeder, then outside bleeder, then move to the driver's side, inside bleeder, outside bleeder. Then move to the passenger side front and finish with the driver's side front. Best of luck, glad you enjoy getting your hands greasy, helps when you own one of these classics....
I will look at the hoses tomorrow. I did not see any fluid. Driving the car home from the seller the brakes went away. I guess I could try tapping on the caliper.
all bleeding threads that i've seen indicate the proper sequence is...copied from another thread... "The correct bleeding sequence for 1965-82 Corvette's with disc brakes is as follows: RR-(outer), RR-(inner), LR-(outer), LR-(inner), RF, LF."
and, i got the impression that when gravity bleeding, it can take alot of time for the dripping to start...haven't done it yet so no actual experience yet
i'm sure once the experienced fellow's get wind of this thread they will chime in to help
all bleeding threads that i've seen indicate the proper sequence is...copied from another thread... "The correct bleeding sequence for 1965-82 Corvette's with disc brakes is as follows: RR-(outer), RR-(inner), LR-(outer), LR-(inner), RF, LF."
and, i got the impression that when gravity bleeding, it can take alot of time for the dripping to start...haven't done it yet so no actual experience yet
i'm sure once the experienced fellow's get wind of this thread they will chime in to help
The vids I’ve watched all have the fluid dripping almost immediately. I look forward to illumination.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
sassc3 has the order to bleed the brakes correct but on the rear, you have to bleed the 'INNERS' first then the 'OUTERS'.
The fronts only have one bleeder.
If you didn't replace your brake hoses yourself, or have a receipt from when it was done within the past 10 years, the best way to test your brake hoses is to cut through them in the middle. Heavy shears should work, or large wire cutters. Then look at the cross-section.
At this point, replace your hoses, and carry on as usual (though a pressure bleeder may make your life easier).
Is your "Brake" light illuminated? If so, the combination valve may be locked on one side, preventing flow to either the front or rear part of the circuit.
Last edited by Bikespace; Oct 28, 2020 at 02:47 AM.
It seems to me since you had an issue with the brakes, and the lines are possibly original, gravity bleeding may not be the best way. Was the brake fluid old, dark, and nasty? If so, the lines may be gritty and gummy, so gravity may not do the job.
On my Dodge pickup, I had a “gummy” pedal, so I had my 16-yr old work the calipers using the plastic bottle with the hose extending into the fluid while I SLOWLY pushed the pedal about 7/8 of the way down never bottoming our. I was thinking it was just my 10-yr old fluid and gummy master cylinder (quit yelling at me). Yep...brakes like brand new for 3 months now. I doubt gravity would have worked on mine.
I can tell you from past experience and hundreds of posts on here, you will be farther ahead if you never touch the brake pedal on a C3. Lock yourself out of the car until you are sure the brake job is done. LOL
In your post, you mentioned a new MC. Is this a specific year MC or a general GM, fits all Vettes from blah-blah-blah to ????
There is a huge difference in the back of those MCs, not only over the different yrs but also with std brakes & P.B. Its all about the very important and critical gap, between the booster rod and the MC piston. If you buy or were sold the wrong MC, you will never get a firm pedal.
Next: When bench bleeding, how far did you shove the MC piston in with your screwdriver? If you went more than 1 3/8" you just ruined your brand new MC and voided the warranty.
If you didn't replace your brake hoses yourself, or have a receipt from when it was done within the past 10 years, the best way to test your brake hoses is to cut through them in the middle. Heavy shears should work, or large wire cutters. Then look at the cross-section.
At this point, replace your hoses, and carry on as usual (though a pressure bleeder may make your life easier).
Is your "Brake" light illuminated? If so, the combination valve may be locked on one side, preventing flow to either the front or rear part of the circuit.
apologies for my ignorance. where is the “brake” light you refer to located. Receipts tell me that the rear brake adjustment valve was replaced this past year.
Thanks for your advice everyone. To clarify, my MC is not new and I have no receipts for new hoses and yes the fluid is murky. I have recent receipts for proportioning valve, booster and front calipers. The pads and rotors look very good. The e- brake does not work. I thought I would deal with that after I get the brakes sorted.
my strategy going forward:
replace m/c, hoses and perhaps change bleeders to ones with check valves.
bench bleed nw m/c careful to only depress 1 3/8”
bleed lines in appropriate order with tube in bottle
I will order parts from one of the vendors here. So if I understand correctly I need to be sure to get a year/marque specific m/c. Any thoughts about rubber vs stainless hoses or just common sense?
Last edited by Williamhibberd; Oct 28, 2020 at 10:17 AM.
Thanks for your advice everyone. To clarify, my MC is not new and I have no receipts for new hoses and yes the fluid is murky. I have recent receipts for proportioning valve, booster and front calipers. The pads and rotors look very good. The e- brake does not work. I thought I would deal with that after I get the brakes sorted.
my strategy going forward:
replace m/c, hoses and perhaps change bleeders to ones with check valves.
bench bleed nw m/c careful to only depress 1 3/8”
bleed lines in appropriate order with tube in bottle
I will order parts from one of the vendors here. So if I understand correctly I need to be sure to get a year/marque specific m/c. Any thoughts about rubber vs stainless hoses or just common sense?
what do you mean the brakes went out when returning? that doesnt sound like a bleeding issue..i would first inspect everywhere.. also post pics..
when i brake bleed gravity the right rear was SLOW.... with new lines.. i like to get it started sometimes and let it drip.. may take up to an hour..or until clear.. keep fluid in it..
As usual, the further into this I go the more questions arrise. Looking at rebuild kits vs a new m/c if I go for a kit am I likely to run into bigger issues that require specialized tools?
Gravity bleeding takes a while.....crack a bleeder.....put a hose on it into a mason jar of brake fluid......the fluid will eventually come out and push the air out which will show up as bubbles in your submerged hose. When the bubbles are gone......that caliper is done. I am usually at about 45 minutes per caliper......it doesn't happen immediately, especially on the rears.....
For me it is a 6 pack job.....as I don't drink when I work on things usually and it is a brainless task so I can get shitfaced while claiming to be "working" on something.......I usually have some British Murder show streaming in the background......point is: Don't think about it too hard......hydraulic fluid always finds its way out.....count on that.
Last gravity bleed I did was on a Wilwood disc conversion kit for a 71' Demon with Dakota retro-fit master cylinder, Wilwood adjustable proportioning valve and my own lines......both sides bled out in about 15-20 minutes and I didn't even get to drink 2 beers
You said you just obtained this car. Has it been idle for a long time? If so, and perhaps even if not, I'd suspect the master cylinder first based on your description of a brake failure. Test the MC by disconnecting the lines and putting pipe plugs in the MC. You should get a firm pedal. If not, you found your problem.
You said you just obtained this car. Has it been idle for a long time? If so, and perhaps even if not, I'd suspect the master cylinder first based on your description of a brake failure. Test the MC by disconnecting the lines and putting pipe plugs in the MC. You should get a firm pedal. If not, you found your problem.
that’s my next step. Hiking down to the parts store momentarily
The plot thickens. I have determined that my master cylinder needs replacement. New one ordered. Because the shop that did recent work has not earned my trust I am going over some of things they changed. My research on line leaves me to believe that the new booster is incorrect for my car. See photo. Anyone able to confirm either way by looking? Also the adjustment valve they installed looks a bit sketchy, held on by zap strap. Should I be concerned?
Bleeding brakes
