68 Brakes-Bleeding

[Kurt B.]

My master cylinder is presently being resleeved and will soon be ready for installation and then can proceed with bleeding the brakes.
After I "bench bleed" the master cylinder, can I begin the wheel caliper bleeding process by opening all the bleeder screws at all the calipers to remove most of the air and make it wasier to them bleed each caliper with the old "pump it up and hold it" method?
I was planning on running a clear plastic tube from each bleeder into a glass bottle with the end of the tube submerged in clean brake fluid and just keep an eye on the master cylinder so it doesn't get empty and watch the bottles at each wheel.
What say you all? Can this be done or am I wasting my time.
Calipers were rebuilt several years ago and have not yet had fluid in them, only small amount used for assembling the rubbers inside each caliper.
Will I encounter problems?
Thank you in advance for any input.
Kurt Butning #26406

[Clem Z.]

Re: 68 Brakes-Bleeding

JMHO but nothing works better that a pressure bleeder. you can buy them for less than$100 or some large chain auto parts will rent them to you.

[Joe L.]

Re: 68 Brakes-Bleeding

Kurt-----

For a 65-82 Corvette brake system, I've tried every bleeding method imagineable save for the factory system of injecting the fluid under high pressure into an air-evacuated system. I think that the factory system would work best as it's "tried-and-true". However, it's impractical for use in the field.

I have found that the gravity bleed system that you described gives the "best shot" at complete evacuation of air from the system. Some further bleeding using pressure, vacuum, or "pedal" bleeding systems may be required, but the gravity system does the best for initial fill of the system. If you're lucky, it's all that you'll need. Tap the calipers with a rubber mallet from time-to-time during the gravity bleeding process and do watch the master cylinder. If it goes dry, you start all over again.

You may need to apply a very slight overpresure to the master cylinder to get the gravity bleeding process started. I use a master cylinder cover with nipples epoxy-attached to the domes and a hand pump (hand vacuum pump used in "reverse") to apply the over-pressure, if needed.

[Craig S.]

Re: 68 Brakes-Bleeding

Kurt and Joe - I bought one of these but haven't tried it yet on my 67, they have a reverse flow injection process (RFI) described. I saw this on Shadetree Mechanic several years ago, and they had good luck with it. Since this company is based in Tucson, I went down to the facility where they make them, seemed like a good outfit. It is a professional caliber unit for sure, very high quality, but pricey. Time will tell how it works......Craig




Phoenix Systems

[Al S.]

Re: 68 Brakes-Bleeding

Kurt,
I did the gravity thing on my '72 at the same time converting to silicone fluid. It took all weekend (started Friday evening & finished Sunday afternoon) but it worked like a champ. One thing not to do, is pump the pedal when you start the bleeding process, just step on it once, hold it down, then crack the bleeder screw, starting with the furthest wheel from the master cylinder and working your way to the closest. (Pumping the pedal agitates the air and usually makes it worse) Using clear tubing will enable you to actually see plugs of air exiting the system into the jars. Once you stop seeing air plugs you should be ready to bleed. Remember to keep your eye on the fluid level in the master cylinder the entire time. You're on the right track.

[Mike M.]

Re: 68 Brakes-Bleeding

agree with craig. Local Vo-tech auto school put me on to it. They send a video with the bleeder. One man bleed jobs, perfect results. Phoenix system made a believer out of me. mike