Hi guys, whenever I use brake hold on the LS. For some reason the front driver side caliper has a problem holding the brake. The front driver calipers are F Sport Brembo Brake Caliper and the symptoms are such :

1- When stopped on and using brake hold, sounds as if the front left caliper is losing grip over the rotor but very slowly and does not completely disengage the rotor; when in brake hold I depress the brake peddle all the way down and it makes this noise again.
2- When aggressively using the brakes on a spirited drive the front driver caliper pulsates as if the rotor is warped but when I aggressively stop from over 130+ to 20 mph getting of the ramp, the brakes work just fine but again sometimes the front left brake caliper would feel like its "wobbling"
3- When turning at very low speeds, the car makes squealing noises that are sometimes high pitched or low pitched; even when brakes are not being applied.

Questions:

1- Could there be air in the system that is specific to the front left caliper?

2- Could this be a sign of premature caliper failure?

3- Could this be a wheel bearing? as there is squealing noises when no brakes are being applied only when wheel is being turned.

Note* I did grease the brake calipers with the proper high temp greases and have bled the brakes using tech stream but noticed the front left caliper would pump out air bubbles just before I closed the bleed valve

All inputs are appreciated!

 

Start with checking brake caliper seals. If one those was damaged it will eventually cause a so called "sticky caliper". I had to replace front left seals and one of cylinders on my non-f-sport LS. LS calipers are re-buildable, if you have a sticky caliper you might have replace some pistons and seals and not the whole thing.

 

Sticky caliper sounds close but I do not see any leaking fluids or difference in brake fluid reservoir. What symptoms did your calipers show before you narrowed the problem down? At how many miles did this happen to you? What year is your car?

 

I didn't have any fluid leaks either but one piston was corroded at very end due to a failed seal. It caused a sticky caliper - uneven motion of the cylinder during operation. Though, you might have a different reason for the brakes behavior.

I have 2010 AWD, it uses different caliper size than RWD.