help with wilwood brakes, can't get the combo right! [ordered hydroboost]

[joflaig]

The resto shop put in a 4 way Wilwood disc setup on my Charger, but after a huge amount of experimentation that just can't seem to get them working right and now they're hearing from their vendor to maybe switch to manual instead of power. They have tried 4 different boosters. The setup right now is 4 piston front discs and 2 piston rear discs, with an OEM master cylendar, hemi-booster, 1" bore.

I have not tried it myself, but they say the problem is the pedal pressure, there is initial pressure, then pedal drops an inch and I guess when the pedal is on the floor it's stiff with no play, though the breaks do engage, in fact so much the engine can stall when they've tested it hard. All the breaks lines are new and they've bled it to death.

Anyone have this combo working?

[Mike DC]

 
 
So the brakes are too "grabby," like they're either on/off without enough space in between?  And the brake pedal's travel distance is way too short before it really starts holding the wheels gripped very tightly?  (I'm assuming that the "pedal travel is only an inch" problem is not anywhere near bottoming-out the pedal and/or the MC?  The brake clamping action gets too stiff too EARLY in the pedal's total possible throw distance, right?)


Well, I'm not a big brake guy, but just off the top of my head I'm thinking maybe swapping the master cylinder.  If the booster itself was the only issue then I don't think the pedal-throw distance should be too short to use it well, as you're describing.  (The brake pedal linkage to the master cylinder wasn't totally redone for this brake swap, was it?  If so, that would be a relevant monkey wrench into the equation.)

Even if you're at a normal MC size right now, a whole set of smaller cylinders at the wheels could be adding up to much less piston area than stock in total.  So I'm thinking maybe leave the vacuum booster installed and just try a larger-bore master cylinder. 



So if I'm correct about all this, then the best solution is to either grow the MC size or else change the cylinders at the wheels.  And I don't think you wanna toss all the Wilwood calipers you've just paid so much to get onto this thing. 

If I'm right then this MC swap would be a better solution than any more monkeying with removing or changing the boosters.  And when the MC is sorted out, you can make the booster decision based purely on how difficult the pedal pressure is on your leg. 

[joflaig]

Well the shop has been on and off the phone with Wilwood for a week and the suggestion remains to go to manual breaks, so after getting some advice we ended up ordering the hydroboost kit from XV...$875 for the billet kit. This is same thing as on Mr. Angry. My resto guy had never even heard of it before so despite the expense at least it is something novel. XV was very helpful on the phone.

I will post pics when it's installed...who knows when...

[FLG]

Curious how the unit works..keep us updated 

[John_Kunkel]

  Even if you're at a normal MC size right now, a whole set of smaller cylinders at the wheels could be adding up to much less piston area than stock in total.  So I'm thinking maybe leave the vacuum booster installed and just try a larger-bore master cylinder. 

I don't see how "the vendor" can think that a pedal drop to a hard pedal is the fault of the booster. Whether it's a vacuum booster or a hydro booster the link between the pedal and the MC is continuous, if the pedal drops and is solid the problem is volume.

[joflaig]

  Even if you're at a normal MC size right now, a whole set of smaller cylinders at the wheels could be adding up to much less piston area than stock in total.  So I'm thinking maybe leave the vacuum booster installed and just try a larger-bore master cylinder. 

I don't see how "the vendor" can think that a pedal drop to a hard pedal is the fault of the booster. Whether it's a vacuum booster or a hydro booster the link between the pedal and the MC is continuous, if the pedal drops and is solid the problem is volume.

I know they've tried multiple MCs, but none have worked just right. I'm probably not describing the problem perfectly since I have not expereinced it first hand and am just going off their description.