1964 brake bleed

[Larry M.]

Re: 1964 brake bleed

Jack:

When I mounted the MC to the booster and VERY LIGHTLY pushed it together, I could see a approx 1/8 inch gap between MC and booster.. Then as I pushed a bit more, the gap disappeared...........as the MC piston(s) were being depressed. I could feel the added resistance when closing this 1/8 inch gap.

Now you have to be really watching for this, when mating the MC to the booster. The difference in resistance is very slight........and most folks would miss it..........and just bolt the two components together. If you do this, you are depressing the MC piston(s) inward and likely covering or restricting the MC bottom ports. If you have a helper nearby with a strong flashlight, and the MC cover off, you can see this movement in the larger MC port opening(s).

My friends 69 car has the dual front and rear reservoirs....with a small port and a slightly larger port on the bottom of each reservoir. Total of four. If you have a single reservoir, it will have only two ports.

Larry

[Jack J.]

Re: 1964 brake bleed

Larry, yesterday Afternoon I emptied MC, removed it from the car and checked with a wire down through the port opening and everything looked OK. Bench bled it and installed it back on the car. Late last night, I disconnected the main brake line from MC (no brake fluid flowing) removed both nuts and lock washers and let the MC hang right at the end of the studs. This morning, NOTHING with regards to gravity flow. Jack J.

[Larry M.]

Re: 1964 brake bleed

If MC is original type and you still have all drum brakes, it may contain a "Residual Pressure" valve that is designed to hold a few psi residual pressure on the brake shoes. Disc brake MC do not have this.

This could be the issue with MC not wanting to gravity bleed. Since it will bench bleed, you may just need to install it on the car, make certain the booster rod length is correct, and then bleed it using the brake pedal and a helper. Or pressure bleed it with a MOTIVE Pressure Bleeder System.

Larry

[Jack J.]

[Jack J.]

Re: 1964 brake bleed

If MC is original type and you still have all drum brakes, it may contain a "Residual Pressure" valve that is designed to hold a few psi residual pressure on the brake shoes. Disc brake MC do not have this.

This could be the issue with MC not wanting to gravity bleed. Since it will bench bleed, you may just need to install it on the car, make certain the booster rod length is correct, and then bleed it using the brake pedal and a helper. Or pressure bleed it with a MOTIVE Pressure Bleeder System.

Larry

Larry, any particular model you can recommend in the Motive line? Thanks, Jack J.

[Larry M.]

Re: 1964 brake bleed

Larry, any particular model you can recommend in the Motive line? Thanks, Jack J.

Jack:

Here is the MOTIVE website for domestic cars. https://www.motiveproducts.com/colle...t-bleeder-kits

The 0101 is probably what you want for your car ...........but check out the other offerings as well. The only differences are for the MC top lid that adapts it to the MOTIVE pressure tank. C2 cars with the dual MC reservoirs take a different design than the 0101. I think they use the 0105. The j-bolts and small chains that MOTIVE supplies don't work well for most folks. They typically use a large C-clamp to hold the lid securely in place. Also many will only fill the MC with fluid, and use the MOTIVE supply tank for air pressure only..........although it is possible to fill the MOTIVE tank with some brake fluid to replenish what is bleed out of the system. But this is just too messy in my opinion.

You could also buy a cheap MC cap from NAPA, etc. and make your own custom cap with the air supply connection. Many do this, and use the original clips on the MC to secure the revised service replacement cap.

I have never used a MOTIVE bleeder, since my (late) wife was always able to help me with the brakes. She was not always happy, but she did an excellent job at this task. But I am a widower now, and so I will buy and use a MOTIVE bleeder the next time I do any brake work. A similar (but much more expensive) system is used by the Chevrolet Garages for pressure bleeding modern brake systems. I just had this done (brake fluid flush) last week to my 2011 Grand Sport when I replaced the tires.

If you search a bit you will likely find a better price. Just Google the words "Motive Pressure Brake Bleeder" or something similar.

Larry

[Owen L.]

Re: 1964 brake bleed

...make your own custom cap with the air supply connection.

Just last week I made my own cap and hose line because I have an air compressor and just can't justify spending $60 or so on a Motive to use as a plastic pressure tank. Made from clear, 1" thick, scrap plexi so that I can monitor the fluid level in the reservoir, 1/8" neoprene to seal, and a 1/4 turn pressure release valve. Attach with a couple of woodworking clamps and dial back the shop compressor to only supply ~10-15 lbs. My system was not completely empty as it had been gravity bled to fill the new lines and calipers; that said, I could bleed a complete caliper without any risk of running the reservoir dry which was easy to monitor with the see through cap.

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[Paul S.]

Re: 1964 brake bleed

I have both the mighty-vac and the Motive bleeder and neither impress me. The I bought this bleeder and that changed everything. Hooks up to your air compressor and vacuums the fluid out. When I restored my car I had all new lines, calipers and MC and it took about 20 minutes to bleed the entire car including the MC which I did not bench bleed prior to installing. Highly recommended and well worth the $85.
Tom

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That's an interesting alternative--I have the Motive Power Bleeder and just finished flushing and refilling my 67 this past Saturday. I always have issues getting the plate on the Motive to seal up against the top of the master cylinder, using a pair of C clamps (the chains and J hooks are junk). Once I do get it sealed with an empty jug/air, then I add the brake fluid and keep the pressure at 8 PSI and it works great. My other more modern cars (c7 Corvette and 997 Porsche) have master cylinders with screw on caps and those are easy-peasy to get sealed. I may try the Capri in 3-4 years when it's time to flush the 67 again.

I take it the nipple that attaches to the bleeder screws is really tight to create a good seal?

As for the rest of this thread, put me in the camp where DOT5 would not work; when I converted my 67 standard brake to power brakes back in 2013, I could not get the DOT5 to bleed out and quit seeping from the driver's side front caliper and from the master cylinder (all new parts from CSSB who also sold me the DOT5). Ended up sending all the stuff back to them (other than the power brake booster) and starting over with new parts (other than the hard brake lines) from Lone Star Caliper Company here in TX. Went with DOT 4 that time, and never looked back. Before I returned the calipers and MC to CSSB I used my Motive Power bleeder to run denatured alcohol through the entire brake system to clean out the DOT 5 from the brake lines. I really wanted the DOT5 to work but could not.

Frankly given the pain in the neck of pulling a MC or calipers if the seals in either are harmed/would go bad from the DOT5, I'd be tempted to return the the parts the OP has, starting with a new ones that hasn't had DOT 5 in them (although will confess I don't have a deep understanding of the seals in the MC's/calipers to know if the DOT5 would have got to them, even for a short time).

[David G.]

Re: 1964 brake bleed

The discussion about silicone fluid may never end, but the military has been using it worldwide
since the early 40s.

[Larry M.]

Re: 1964 brake bleed

The discussion about silicone fluid may never end, but the military has been using it worldwide
since the early 40s.

David:

We are very aware of this fact. And the Parker o-ring company says their EPDM o-rings are very compatible with DOT 5. So then why do our Corvette Caliper Rebuilders not like it and do not recommend it??

Larry

[Jack J.]

[Owen L.]

Re: 1964 brake bleed

Nice! Like the clear cap feature.

[Jack J.]

Re: 1964 brake bleed

Nice! Like the clear cap feature.

[Owen L.]

Re: 1964 brake bleed

Owen, YOU get ALL the credit!! Great idea. I was thinking of making a pressure bleeder, I just did not know what material to use. YOUR clear plexiglass window into the MC was perfect! With all of the “stuff” in my basement, I knew I could come up with something starting with the the 3/8 plexiglass.

The u-bolt is slick - I may have to look into what width is required to span the double MC on the later cars instead of the F-clamps I used. I'm a little surprised 3/8" plexi is not too flexible. That's good to hear because it should be much more available on the cheap than thicker acrylic. When I mounted my acrylic, it leaked out the far end of the clamp so a second was needed - maybe I used too much clamping pressure and warped the plastic into the reservoir void.

[Jack J.]