Hydraboost brakes

[XSS 454]

Hi guys I've recently fitted a hydratech system with the cpp m/c and couldn't get a pedal no matter how I bled everything, anyway after rebuilding the m/c and still no pedal I gave the cpp unit the flick and now have a wilwood m/c, although the pedal is better it still goes about 3/4 to the floor before working. Now trust me Ive done a sh1tload of research via the net and have tried everything recommended, I've triple checked everything, leaks, pedal rod length, calipers, wheel cylinders etc. you name it and I reckon I've done it, bled the system for hours and hours, but still not happy.
The car is:
68 camaro
BBC
Disc/drum setup
Standard gm type prop. Valve
Hydraboost system and m/c as recommended by hydratech

Any ideas would be appreciated
Thanks Brett

[69x22]

If you are not running a small bore master cylinder (which has allot more pedal travel compared to a large bore) you can disconnect the lines and put plugs in the master cylinder once you bleed it at the plugs you should have a very firm pedal that stays high. This will eleminate the M/C and hydraboost. If you have a nice pedal I would make sure the drum brakes are adjusted properly, this will also eat up pedal travel. If you don't have a firm pedal I would look for air in the M/C and bench bleed it again until there are no bubbles. I tap on the M/C while I'm bench bleeding it to help remove the air.
Brakes can be aggrivating.

[Hydratech®]

Hydratech Braking Systems has a HIGHLY EXPERIENCED circle track veteran, Jim Petty, that can directly work with you over the phone to nail down where your issues may be:

http://www.hydratechbraking.com/contact.html

5 minutes with Jim can truly get you directly on the right path, so don't hesitate to call him and discuss your installation. He will clearly identify your issue by concisely interviewing / analyzing your specific build details, and then get you headed on a clear path to success.

Until you get Jim on the horn, read this article to get some further diagnostic tech "uploaded" into your mind:

http://hydratechbraking.com/braketech1.html

Summary? Call Jim - he is REALLY GOOD at what he does

[XSS 454]

Hi guys, I've done that and I don't believe it to either the hydraboost or the m/c but thought maybe elsewhere, not sure as every part in the brake system is either new or reco'd. I'll see what happens with this thread before I call hydratech as I work nights.

[Hydratech®]

With the 5 hour time difference between Australia and US Central Time, might that help get in touch with my guy Jim Petty to discuss (with you working nights)? At any rate, I have taken a very keen personal interest in your case, and will directly work with you to make it happen - I want to see a success story come of this. Can you tell me / us what the rest of your brake system consists of? To the best of my recollection, you are running one of our universal brake assist units (?)(or is it a direct fit model?), and have now installed the Wilwood 1.125" bore MC (in place of the 1 .125" CPP MCPV-1 design that was giving you some guff) - correct? What kind of brakes are at the wheels? Disc / Disc? E-brake possibly built into the calipers? Or Disc / Drum? Any guesstimate as to the mechanical brake pedal ratio? How long is the brake pedal from pivot point to foot pad, versus the distance from the pivot point connection point to the brake booster input rod? Likely in the ball park, though the more you can tell us = the more we can collectively work with your diagnostics.

Regardless of what types of brakes at the wheels, have you actually performed any of the port plug testing suggested in our "advanced brake bleeding problems..." discussion lower down the "Brake Bleeding 101" page on our website? It sounds like hell taking line connections apart and installing brake line port plugs into various places throughout the brake system, though it goes a long way into determining just where your gremlin is truly hiding. As a matter of general brake hydraulic dynamics, we are either dealing with air (stubbornly) trapped in part of your brake system *OR* something in the brake system "eating up volume" produced by the master cylinder (before achieving proper clamping / apply pressure). The task at hand is to figure out which one of these issues we are dealing with. I recall a case from years ago where a guy had everything right on paper, yet we ultimately found a bent caliper support bracket that was sucking up all of the MC produced volume before allowing pressure rise (by the time the caliper straightened itself out in relation to rotor, all effective volume produced by the MC was "sucked up" by excessive caliper piston apply travel).

Do tell us everything you can that you feel may be relative to the brake details, and all of us here on Lat-G will work with you to get your braking issues squared away as quickly as possible. It is my understanding that your area is now in its summer time, and that means you are missing out on cruise nights! So let's "gitter done" !

Tobin from KORE3 + all other gurus - let's get this chap from down under on his way!

[Apogee]

Paul and Jim are the guru's when it comes to troubleshooting hydroboost units, so I'll let them do their thing and make suggestions regarding the rest of the system. Paul mentioned the Brake Bleeding 101 on his site which is worth reviewing if you haven't already.

That said, I would start by isolating the front and rear circuits of your system and try to narrow down where your problem lies. I assume that you have confirmed that the master cylinder is fully bench bleed prior to installing it by plugging both outlet ports and making sure that the MC hydraulically locks at minimal travel, but if not, then you should do that before you do anything else. Once the master cylinder has more or less been removed from consideration as the culprit, I would connect the front brake circuit, bleed the hard line at the MC and then each caliper, and check the pedal feel/travel...it should be high and firm. If it's not, then you have an issue in the front circuit as the rear circuit has not been added to the equation yet.

Next, attach the rear circuit and repeat the process. This way you at least be able to begin to narrow down wher the potential problems may be which should help everybody here help you with more specific suggestions.

Most importantly, try not to get too frustrated and be methodical about what you do...whenever I have issues getting a good pedal on a car it's usually because I made an incorrect assumption early on in the process...I could probably start a thread on the subject and I'm sure everybody could contribute something.

Tobin
KORE3

[XSS 454]

Hi guys sorry I haven't replied, been a bit busy but I really appreciate you helping me with this, anyway I haven't done any work on car for a week or so but hope to get into it this weekend, I'll keep you posted but once again thank you for your help.
Regards Brett