Brake Bleeding/Pressure Bleeding

[JIMOCO]

Hi Guys. I know there have been many threads on bleeding brakes, maybe someone with better search skills can point me in the right direction. I have FF5 complete kit Ford GT brakes with 11" front and 11.65" rear rotors, PBR calipers, stock pads. I have tried bleeding the brakes several times using the conventional pump and bleed method. I have a firm pedal but cannot lock up the brakes on a hard stop. (I have seen a thread on this issue and can't find it). I feel I must have an air pocket somewhere. I have considered trying to pressure bleed and have found a system on line. Has anyone used the Motive Products Bleeder and is it effective. Does anyone recommend an alternative system?

[Avalanche325]

Air in the system will give you a spongy pedal. If your pedal is firm, bleeding is done.

Have you done a proper bedding in procedure for the rotors / pads? Without that, some brakes will not do much.

[JIMOCO]

I did so during my go cart stage. I now have 12,000 mi on my car. I would think that any bedding issue would have resolved itself. True?

[Ponymedic]

Saw a post on youtube and made a simple pressure bleeder with a decj spayer. Easy peezy and cost about $30121467

[rich grsc]

You say you have a firm pedal, so bleeding isn't the problem. Have you properly adjusted the parking brake? It makes a huge difference, because if it hasn't been adjusted, you are stopping with only the fronts brakes.

[CraigS]

What pads are you running?

[JIMOCO]

I am running stock pads. I know there are more aggressive pads available but don't understand why these pads could stop a much heavier car and are less effective on a Cobra. Granted, I do not have any power assist but I should still be able to lock them on a hard stop. I spent a fair amount of time working on the bias. On a gravel road, I got the balance to a point where the front locked sooner than the rear but was able to lock all with moderately more pressure. I am seeing even wear on the front and rear pads. In addition to my initial question, does anyone have suggestions of a better technique for achieving proper bias? Rich, please explain the parking brake suggestion. I don't understand why that would be an issue. I thought the mechanical actuation of the parking brake was independent of the hydraulic action of the braking system.

[rich grsc]

The parking brake mechanism is connected to the caliper pistons. If it isn't adjusted to remove excess slack, it doesn't allow full movement of the pistons. The master cylinder runs out of volume to move the piston completely against the pads. The pistons on disc brakes, only retract enough to release pressure on the pads, they can retract too much if the parking mechanism isn't adjusted.
That may or may not be what is going on in your case. I know this because I had similar problems with my own car, very poor stopping power, after adjusting the parking brake it was a big improvement.

[JIMOCO]

Thanks Rich, I will give it a try. Car is up on jack stands for the winter so this will be a project on my list get done before spring. I was in O'Fallon this past summer for a wedding. Very nice area.

[egchewy79]

Rich
shouldn't the pistons automatically advance as the pads wear down? you don't need to continually adjust your parking brake tension as the pads get thinner, right?

[rich grsc]

Once you have it adjusted, you should have quite a bit of miles before they wear that much, also you should use the PB occasional.

[tonywy]

Jimoco, if you have a firm pedal air is not your issue. I just tackled this issue myself on my car. Is your brake pedal arm modified or are you using a Wilwood pedal assy. What brake master are you using ? I found on my car that has manual Wilwood setup on it is that they used MP Brakes master cylinder with a 1 1/8" bore. Way to big for manual brake car. Just installed a Wilwood 7/8" bore with a adjustable proportioning valve. I haven't driven the car yet so I don't know if its fixed. There is good posts here on brake pedal arms if yours isn't modified.

[JIMOCO]

Tonywy, I have the Wilwood pedal assembly without modifications. I used the supplied Wilwood masters at 5/8" and 3/4" bores. I do not have a proportioning valve and I adjusted the bias using the balance bar. Based on the responses so far it seems to be coming down to pad quality. I believe my parking brake is properly adjusted. I may just get more aggressive pads and see what happens. I know dust is an issue but the stock pads I am using generate a fair amount of dust anyway.