Anyone experiencing a rapid oscillation of brake power intermittently when lightly on brakes?

[dogunbound]

I haven't figured out exactly what is causing this yet, but I do see that my front brake calipers have torn rubber seal boots. Also the pads I ran at track have uneven wear from the top to the bottom as the bottom piston was activating more freely than the top piston. I think the oscillation comes from the "on/off" application of brake power from my top pistons, though I'm not totally sure.

I'm going to warranty it, but if they void it (because yes I did play around in there to try and figure out what's happening. I didn't damage any of the parts on the caliper itself, so hopefully they don't), then some advice would be good. I know for sure I will have to rebuild it. Found this seal kit from nissan https://parts.nissanusa.com/parts/n...9MjAyNCZ0PXBlcmZvcm1hbmNlJmU9My0wbC12Ni1nYXM=

But what could cause the top pistons, and only the top pistons from activating correctly?

 

[D2M]

What you are describing is normal wear for track. The Z calipers have 4 pistons that are all the same size, this will cause uneven pad wear no matter what you do on track. Racing calipers will have different size pistons to try to equalize the pressure and have more even pad wear. The oscillation is most likely coming from warped rotors or uneven pad material left over on the rotors. The Z is a fast and heavy car with brakes left over form the 370Z that was lighter and slower. A more track oriented pad compound will help along with a full floating rotor upgrade.

 

[ujnx2000]

Kinda sounds like how a warped rotor might act, if the speed you are driving affects the rate of oscillation.

 

[BigBlue]

Research on how to check your rotor run out. If it's bad enough you can eyeball it

 

[dogunbound]

I don't think it's warped because it does it intermittently. Actually, for the past 2 days, it has been smooth sailing . I still need to fix the torn dust boots, but the brakes feel ok.