1965 L76 Non Power Brake Car - Brake Bleeding Issue

[Joe L.]

Re: 1965 L76 Non Power Brake Car - Brake Bleeding Issue

3 days on and off bleeding, still spongy pedal! A couple of questions. I like to identify a problem before I just start rebuilding and replacing components. I'm thinking that I'm going to rebuild the master cylinder and replace the rubber hoses to the calipers. That's about all that is left to do.

Questions:

When the brake pedal is pressed and released or just pumped, should there be visible movement of fluid in the MC reservoir (cap off)?

Using push and hold of brake pedal for bleeding. Clear tube on bleeder into vented jar. Only get a couple of inched of brake fluid flow in tube at bleeder. If I leave bleeder open and pedal is pushed again, nothing comes out of any bleeder on any caliper. I'm thinking MC isn't holding pressure. On other cars I've bleed, I could fill the jar with fluid using this method. Of course, I would close bleeder once the flow of brake fluid into the jar was clean and clear.

This is an extremely original car! I don't like to just start taking things apart w/o identifying the problem first. Would appreciate comments on what I'm finding. Thanks.

Ted------


I'd focus on the master cylinder first. Rebuild and bench bleed. Make sure there is no damage, at all, to the bore. If damaged, do not hone; have it sleeved. If your rubber brake lines are original to the car, replace them whether they're related to your problem, or not.

Beyond that, let me say this: brake bleeding on a Corvette is one of the jobs I fear most, maybe even THE job I fear most. I've always had problems just like those you are experiencing. I've never figured out why. On other cars I've had no trouble bleeding, at all; on a Corvette, nothing but problems.

[Ted F.]

Re: 1965 L76 Non Power Brake Car - Brake Bleeding Issue

Thanks Joe - took the master cylinder off today. Definitely one of my problems. Bore looks good. Seals were worn and starting to leak. Half the holes in the end of the piston were plugged solid. Thanks again - Ted

[Paul J.]

Re: 1965 L76 Non Power Brake Car - Brake Bleeding Issue

Ted,

Early on you mentioned that the peddle went to the floor. This is always the MC. On Chevrolets (especially full sized trucks) a soft peddle is brake lines. 65's are tough to bleed, but I think that you've thoroughly chased the problem. I would have started with the MC, and I think most of your problem lies there.

Paul

[Ted F.]

Re: 1965 L76 Non Power Brake Car - Brake Bleeding Issue

Ted,

Early on you mentioned that the peddle went to the floor. This is always the MC. On Chevrolets (especially full sized trucks) a soft peddle is brake lines. 65's are tough to bleed, but I think that you've thoroughly chased the problem. I would have started with the MC, and I think most of your problem lies there.

Paul

Appreciate the reply Paul. Looks like I had a couple of problems. This car never ceases to amaze me. Pulled the MC, sure enough, date code on the MC lines up with build date for the car. The MC was obviously rebuild before me as it has the newer style snap ring. Since I'm at it and based on comments to this thread from other members, I'm going to replace the rubber brake hoses also.

MC piston was plugged pretty good. Seals were worn, however everything else looked good. MC started to leak down the inside firewall. Glad that I caught when I did!

[Ted F.]

Re: 1965 L76 Non Power Brake Car - Brake Bleeding Issue

Installed new master cylinder, jacked up rear of car, bleed all six bleeders using the press and hold brake pedal technique. Have a firm/hard pedal now!!! We'll see if it holds overnight. My bet is it will.

Thank you to all for your posts, ideas and advice. Ted

[Leif A.]

Re: 1965 L76 Non Power Brake Car - Brake Bleeding Issue

Installed new master cylinder, jacked up rear of car, bleed all six bleeders using the press and hold brake pedal technique. Have a firm/hard pedal now!!! We'll see if it holds overnight. My bet is it will.

Thank you to all for your posts, ideas and advice. Ted

Good job, Ted, working through the process. Hope you get to drive it some more before winter sets in.