Ongoing Brake Issues

[colt45 gto]

i dont blame you on the speed bleeder thing. always done it manually.

[Austin@STM]

It is AWD ABS.

[Polygon]

It is AWD ABS.

Awesome, just let me know your PayPal address.

[Austin@STM]

Sales@StreetTunedMotorsports.com

leave a note "Austin's Master Cylinder"

[Polygon]

Payment sent.

[Austin@STM]

Cool, i'll send it out tomorrow, you should have it by Thursday.

[ChargerX3]

If its any consolation my abs has never kicked in on clean asphalt. Then again i run stock rotors w/ceramic pads.

[MR2]

I hit abs all the time...usually smashing the brakes mid corner or with all the weight to one side of the car

[Polygon]

If its any consolation my abs has never kicked in on clean asphalt. Then again i run stock rotors w/ceramic pads.

Ever changed the fluid?

Besides, not really. I know somethings wrong and now it's too late. Now it's just going to piss me off until I fix it.

[bluemax_1]

Polygon,

on the 'other' forum, you mentioned something about SCE caliper bolts. What are these exactly? And did you have these when you were experiencing problems with the old setup (btw, HPS pads suck a fat one. They aren't great to start with but they really start sucking when they're a little older).

Pedal travel under maximal braking should be minimal, i.e. the pedal should never get close to the floor. The pedal in general (with the engine running and a properly functioning booster) should feel like you're stepping on one of those rubber gym mats (not the kind people do Pilates on, but the kind they use to stop dropped weights from cracking the floor) covered with about 1/2" - 1" inch of medium density foam (I've noticed that unlike some platforms, 3/S brake pedals have some travel before the brakes fully engage). In other words, when you stomp on the pedal, you should get 1/2" to 1" max of softer travel before you feel a whole lot of resistance (like trying to crush a rubber gym mat with your foot, i.e. your foot isn't going to move more than 1/4"). If you're getting more than 2-3" of pedal travel, you either have air in the system, or a leak.

If the pedal travel is fine, then the problem is either internal in the MC or something else.

Outline your exact rotor installation and bedding-in procedure?

Carbotech Bobcats are fairly easy to bed-in. With zinc coated rotors, generally the first couple of stops is enough to wear off the zinc coating from the swept area.

Things to keep in mind when bedding in pads:
- You need to generate enough heat in the system to create and bond the pad layer to the rotors
- Done properly, brake torque WILL reduce significantly in the middle of the bedding procedure
- Full brake torque should be achieved by the last few deceleration events of the bedding procedure without really needing to let the brakes sit and cool (especially for street pads like Bobcats), UNLESS you've overdone things and have exceeded the pads' MOT.

To street bed Bobcats, I would find a clear stretch of road, accelerate up to 60-65mph and then brake at 60 - 70% of maximum pedal effort down to 15-20 mph (don't stop the car while bedding pads), accelerate hard, back up to 60-65 mph and repeat about 8 times. Don't drag the brakes with light/moderate pressure. Medium high pressure is essential to the bedding process. You need to alternate medium high pressure (to generate enough heat in the pads to transfer material to the rotors), with zero pressure as the cooling between braking events, while you're accelerating back up to 65mph, helps the deposit layer bond properly to the rotors. Dragging the brakes with light pedal pressure doesn't allow the cyclic cooling and the lower pressures can produce uneven pad material deposits.

Usually, with street pads like Bobcats (and even AX6's) by about the 3rd-4th (and potentially even up to the 6th) braking event, the pads will start smoking, you'll smell the brakes and you'll notice that for the same (or more) pressure on the pedal, the car is taking significantly longer distances to slow down to 15-20mph. This is normal with most pads. The heat is burning off the excess binder (even with newer compound pads, there will still be some excess binder burnt off during bed-in) and this excess binder reduces mu and brake torque while it bleeds out and is burnt off.

By the 7th to 8th braking events though, with the same pedal effort as the 1st through last, you should notice the brake torque getting significantly higher and the rate of deceleration increasing dramatically. At this point, you SHOULD (barring problems with the brake system) be able to lockup wheels or trigger the ABS (if still active) with maximum pedal pressure. The brake torque for similar pedal pressure should feel (in relative terms from a scale of 1 - 10 for a given set of pads), like this for bedding in:
- Braking events (BE's) 1-3 = Brake Torque (BT) ~6
- BE 3, 4, 5 maybe 6 = BT ~2-4
- BE 7, 8, 9, 10 = BT 9-10


Max