Brake Gurus I need help!!!!!!

[nats68]

OK Gurus I've got a problem that maybe you can help me solve.
I've got a 1968 Camaro with Wilwood forged dynalite brakes. All new brake lines from Right Stuff.
I can't get fluid to the rear brakes.
I disconnected the flex line over the rear end and attached a pressure bleeder on the end of the hard line. I was able to suck fluid from the master cylinder. I then went to the brake cylinder and pushed fluid through the flex line, when it was disconnected.
When I connect the hose to hard line it won't let fluid pass that fitting. Both the hose and hardline are from Right Stuff and appear to be correct, as far as the flare and inverted flare. The flex line is a braided stainless steel one. I also tried a standard rubber line and it did the same thing. I figured the flared end was bad so I cut the line and flared it again. It did the same thing.
I'm lost as to what the problem could be.
Thanks for any help you can give.

[Hydratech®]

I'm willing to bet that your MC pistons are preloaded, not allowing a full state of release against the snap ring in the back side of the Wilwood MC. When this happens, you can (believe it or not) suck fluid out of the rear brake line (as the cup seals in the MC are designed to balloon and hold pressure, but have little to no effect against vacuum). This would be very simple to "nail", as all you would do to verify this is loosen the MC mounting bolts / nuts up some and then you should be greeted by capillary / gravity bleed actions (as a result of allowing the preloaded MC pistons into a full state of release). Our BRAKE BLEEDING 101 online tech applies to manual and power brake scenarios - read it over thoroughly:

http://hydratechbraking.com/braketech1.html

If my hunch is correct, you will have to adjust your MC mounting scenario to allow for definite full release of the MC pistons when the brakes are not applied. You can temporarily rig it by installing washers between the MC and its mounting to shim the MC further away. In some cases these means taking a carbide burr on an air motor and removing a few thousandths of material from the MC piston apply area (surmising you likely have the Wilwood spacer bullet installed into the deep MC pushrod hole in use with a short rod vacuum booster). BTW - FYI - we have observed that Wilwood has very recently started supplying an updated spacer bullet / plug design that addresses this issue (removing MC piston pushrod preload in vacuum booster installations).

Or? Start using compressed air testing of your brake lines to see what in the world is going on. If you can use a (preferably rubber tipped) blow gun to get compressed air through your lines, then brake fluid will also certainly flow through. I certainly hope that you haven't used any Teflon tape anywhere in your installation...

[nats68]

I will definitely check this out as a possibility. If I disconnect the pushrod from the brake pedal, will this do the same thing? I forgot to mention I have a power brake booster also.

Thanks for the info.

[Hydratech®]

Disconnecting the brake pedal rod connection under the dash may only tell part of the story. You may indeed find a brake light switch or rubber pedal stop adjustment not allowing the vacuum booster to go into a full state of release. It is actually much more likely that you will find the output pin / pushrod versus the MC pistons to be the problem. Since both are related, I say loosen the MC mounting nuts up first, verify that you can achieve gravity bleeding actions in the rear brake circuit, THEN do your underdash dive second (to insure no brake pedal preload condition may exist there)(correct if / as needed), THEN see if you still may have a MC piston preload condition existing and correct further if / as needed.

[nats68]

Disconnecting the brake pedal rod connection under the dash may only tell part of the story. You may indeed find a brake light switch or rubber pedal stop adjustment not allowing the vacuum booster to go into a full state of release. It is actually much more likely that you will find the output pin / pushrod versus the MC pistons to be the problem. Since both are related, I say loosen the MC mounting nuts up first, verify that you can achieve gravity bleeding actions in the rear brake circuit, THEN do your underdash dive second (to insure no brake pedal preload condition may exist there)(correct if / as needed), THEN see if you still may have a MC piston preload condition existing and correct further if / as needed.
That's what I did and sure enough I was able to pressure bleed the calipers. I called Right Stuff this morning to ask a few questions and found out the 8" booster I have has an adjustable piston. I guess some do and some don't, it depends on the size and style. I just have to get that adjusted and should be fine, along with the pedal adjustment and brake light switch. Too may variables on the brake pedal for a novice like me. lol
Thanks for the response.

[Hydratech®]

This seems to happen way too often, and I am glad that you are all set now. :cheers: