Hi all , first time gravity bleeding brakes .. Can I jack up the rear tires one at a time to gravity bleed and leave the front wheels on the ground. I know the sequence R/R, L/R, R/F, L/F. Thank you

 

I am fairly sure this is OK. Just remember that the caliper you are bleeding should be below the level of the master cylinder.

 

that was my question .. if I take rear tire off will I still be lower than master

 

That depends on how high you jack the rear up. I usually lift the car up all around. This allows me to fill the master cylinder easier and reach the bleeders easier as well. You can expedite a slow process by pumping the brake pedal as well. I suppose you could use a tape measure to ensure the rear bleeder is lower than the master cylinder if you are concerned.

 

you may be assuming the following is understood, but if you pump the brakes, once you let off of them, it will pull air back in the caliper/lines so I'm not sure how much time itll save during the process overall. If I misunderstood something, just ignore this haha

 

According to the service manual,

left rear inner, left rear outer
right rear inner, right rear outer
left front
right front


The most common error that arises when bleeding these brakes is overlooking the extra bleeder screws on the rear calipers. There are two bleeder valves located in the front as we’ve come to expect, but there are four located in the rear. Two on each rear caliper. Most people never expect to look for those extra bleeder valves.
When bleeding these brakes it is important to bleed in the proper order to ensure air is removed from all the brake lines. Deviating from this order could lead to spongy breaks. The correct sequence for bleeding is: left rear inner and left rear outer, right rear inner and right rear outer, left front and right front.
The following instructions are in excerpt from the Corvette shop manual on how to bleed the brakes:

Bleed the brakes in the following sequence: left rear inner and left rear outer, right rear inner and right rear outer, left front and right front.
With the proper size wrench over the bleeder valve, attach bleeder tube. The discharge end must hang submerged in a clean container partially filled with brake fluid.
Open the bleeder valve at least 3/4 turn and allow flow to continue until no air is seen in the fluid.
Close the bleed valve; be sure it seals.

Check the pedal feel for “sponginess” and repeat the entire procedure if necessary.
Dispose of all removed brake fluid.
Disconnect bleeder equipment from the brake bleeder adapter.
Remove bleeder adapter. Wipe all areas dry if fluid was spilled during adapter removal.
Fill master cylinder reservoir(s) to proper level and install master cylinder diaphragm and cover.

 

Just consider that the master is about groin level whereas the calipers sit about knee level. You'd have to jack up the rear substantially to get the rear calipers higher than the master. Be a bit cautious of doing any significant jacking of just one wheel at a time if you are opening and closing the doors - especially with a convertible. Just enough to get the tire off the ground is all you need.

 

Gravity bleeding can take quite a while - it can take a day or overnight for each bleed screw, and even then you're not assured all the air is really out of the system. Why in the world don't you just pony up the $18 for a bleeder kit and do the job right..? There's no reason or excuse to do gravity bleeding. Amazon delivers next-day. Just get the right tool for the job and don't be a cheap-***. If you own a C3, this won't be the last time you need to bleed your brakes:




Lars

 

well appreciated

 

Gravity Bleed isn't the best option, but will confirm there isn't a blockage any where in the lines. VERY SLOW PROCESS, and doesn't bleed the master cylinder.

As for the order, it doesn't matter if the goal is to remove air. It does matter if your goal is to replace the old fluid. The correct order only reduces the amt of fluid required for a complete flush of clean fluid.

But for bleeding in general, most use pressure bleeding, such as Motive 0105 - Early American Rectangular Power Bleeder - Motive Products

or you can make a DIY Bleeder as I have used for many years.


I use the air compressor with 15-20 PSI at the MC, then attach clear hose to the bleeder screws to collect the fluid into a jar. Clear hose is ~ 6-10ft length and bleed about total 24-30ft of fluid at each bleeder, and then ~ 10ft at the second bleeder on the caliper.

But befor I bleed the lines, I bleed the MC while on the car like this.

Get the last bit of air out from the brake master cylinder. - CorvetteForum - Chevrolet Corvette Forum Discussion

 

Tip # 1. Don't touch the pedal.
Tip #2 Don't touch the pedal.
Tip #3 You guessed it.

Usually you will "trip" the proportioning valve piston / warning light using the pedal method.

About those Mity Vac kits. I use them, they work. They are wonderful if you are only doing one or two calipers. More than that, I get the Motive tank kit loaded up.
The glitch with vacuum bleeding is, sometimes you can pull air past the piston seals. And secondly, you can pull air past the bleeder threads.
Both scenarios trick you into thinking there is a lot of air, still there. So you run to the store and get another 55 gal drum of DOT3

Mity Vac. And, Amazon is so backed up right now you are looking 8-10 days to get orders shpd.

For some reason, bleeder screws seem to manufactured a little on the loose side. I have bought several from different stores with different tolerances. This compounds the false bubbles in the clear lines when vacuuming. Sometimes a little a dab of anti-seize compound around the threads will help seal and only open the bleeder a smidge with the Mity Vac.

The beauty of gravity bleeding is you can do four bleeders at once. (rear). Just need four clear tubes, four plastic bottles. Pull up a stool next to the master cyl.
Grab a car magazine and a big bottle of DOT3.

 

flushing out old fluid

 

thank you brakes are great actually I am flushing the old fluid out .. hoping it won’t take that long

 

Buy a Motive Power Bleeder and be one and done, easy button. Use a C-Clamp vice the chains in the picture.

 

One person, 10 minutes, no hassels

 

Or....... You get a helper and bleed the brakes efficiently every time.

My wife and I have been bleeding the brakes on our 78 for 32 years, no fancy self-bleeders, or gravity.

We used to jack and remove one wheel at a time. I use a clear rubber hose, a nice tight fit on the bleed screw. Begin with the master reservoir filled, with the lid clipped on. Start at the furthest bleed screw from the master, so the order is:
R/R outer, R/R inner, L/R outer, L/R inner, L/F, R/F.
Release the bleed screw and have the helper simultaneously depress the brake pedal, evenly, and not too fast. You say "Down", the helper depresses the pedal. You will be able to see any air bubbles in the clear tube as they exit the calliper. When the pedal is down, the helper says "Down". You re-tighten the say and say "Up". The pedal is released. Repeat this until no air bubbles are visible. Re-fill master, replace cap, move to next bleed screw.

It's also worth saying that before O-Ring piston seals we usually needed to do this each year. The O-Ring seals mean that is no longer necessary, but still a useful exercise to keep the fluid fresh.
Even before the arrival of our QuickJack we could do all four callipers in under and hour, and never had anything other than a firm pedal at the end of the process.

 

I had to chuckle at that last post. I too have done it this way many times on my 77 over the years and never had a problem. I have used a neighbour lady twice. Young son a couple times. Friends and yes once the missus who normally refuses to help out with the car.

 

51 years ago and up to about 1985 my wife would help me bleed brakes using your (old fashion) method. She told me she retired from that job! Now I use a Mighty Vac and it works great for bleeding brakes and changing brake fluid. And the best part is....it doesn't complain.

 

It may bean old fashioned way, but if it ain't broke......

I'm pleased (should that be proud?) to say my wife never complains and in fact is only to keen to point out that she knows what she's doing around cars! And, for years we worked together on the car in a lock-up garage, with no power, heat or light.

 

from lack of a helper to do a conventional bleed
I created a vacuuming method.
still use it combined with gravity and move a lot of fluid thru the system.