thbirdman

Hello Under the Hood. I have been having an odd issue lately with my front brakes on my s2000. Trouble started about a month after replacing my rotors and pads after I heard squealing following an autocross event. I noticed that the passenger side pads were much thinner than my driver side pad, but replaced sides of the car none the less.

I noticed after some time that my car's brakes were dragging lightly. If I would coast slowly you could feel the car "lean" forward at the stopping point, where normally this lean wouldn't happen. In other situations it wasn't noticeable. Shortly after I was slowing down and I felt a noticeable pulse, like one spot on my rotor was particularly good at friction. At this point I put my car up on stands and inspected the calipers. There seems to be nothing visibly wrong with the piston or boot seal. I bled a little bit of my fluid, which looked fine. I re-greased my slide pins, as this was a recommendation I came across and put my brakes back together. After re-greasing the pins the problem went away completely for a few months, until this week.

It is doing the same thing as before where the brakes would drag, and sometimes when braking I would get a pulsing sensation as if I have a bent rotor. The odd thing about this pulse is that it is not always there. Can a warped rotor only sometimes pulse under braking. This problem also seems to be happening with each wheel, as the 1st round of troubles was primarily the passenger side, this time it seems to be the driver side (determined by heat from the rotor). Does anyone have any clues as to what this could be?

Thanks

T-Smac

Here's what you can do. Jack up the front of your car and remove the wheels. Apply the brakes. Now try to turn each rotor by hand. If one is harder to turn than the other, crack open the bleeder screw on that caliper. If brake fluid comes out (as if pressure were built up in there, not a tiny dribble) and the rotor is now easier to turn than before, you have a restriction in your brake line (could be a bent line). If the rotor is still hard to turn, you have an issue with the caliper. Don't overlook pads that are stuck in place. To find these retract the caliper piston and simply try to wiggle each pad a bit. A seized pad wont move at all, which could be the root of your problems. If you think you have a seized pad, move the caliper, remove the pads and lubricate the parts of the pad that slide on the hardware / caliper bracket.

As for the intermittent pulsation, it is most likely a rotor with thickness variation (what people like to call warped), and it is being masked at times by your sticking caliper.

Let us know what you find.

SpitfireS

Pulsed braking = uneven brake pad material transfer onto the rotor = uneven friction.
Usually caused by bad (or non) brake pad bedding.

Do you feel a difference in rotor temperature after a drive?
Try not to brake too much before testing.
IOW: go for a drive where you know you do not have to brake too much and find a parking to test.

If your old pads were pretty thin, the piston is now in a completely different spot in the caliper bore, with the new = thick pads.
If there was some rust behind the dust seal, that rust could be pushed back in with the piston, making it stick a bit.

thbirdman

Hey guys thanks for the follow ups. Unfortunately I was sent out of town for a while on business so it will be a couple of weeks before I'm able to check into your suggestions. I will follow up after I've had a chance to get the car up on stands.