I have never had any issues with noise from Cobra front brakes, except when I had drilled and slotted, coated rotors. When the rotors were new, the coating must have been uneven or something and it felt like warped rotors for a few days, then went away.
Later, many years later, those same rotors did get warped a bit and caused some pedal minor pulsation and a bit of noise. I replaced with smooth rotors and have no more problems.

On the very first prototype brackets, the calipers were too close radially and would sometimes rub the Oad of the rotor, but that problem was solved about 20 years ago on all production brackets.  If you have rotors with severe radial runout, that might be something to check.  Also be sure no mounting bolts rub the back of the rotors, but that should be impossible if the bolts supplied with the kits were used.

Other than that, check the calipers or MAYBE some front end component that is now clunking under much better braking than it ever experienced before. Like strut rod bushings, UCA bushings, ball joints, tie rods, etc.

Final results?

Hello Again
I drived around a few times without any issues. But last night I made a hard brake and same problem returned. As soon as I got home I raised the car up and tried to spinn the front Wheels, there was resistance. I let the car sit for 2 hours came back and spinned the wjeels again. Now there was no resistance just normal sounds from the pads. Something is expanding with heat. I cant figure it out. There is no pinch in the flexlines, they are new.

¨There is a clonk noise when moving back and forth. I f I remove pads and reinstall Everything is gone. 

I hope this could give somebody some clue :-)

Thanks Rob

 

Last edited by Mach173 (8/08/2019 3:16 AM)

GPatrick wrote:

It sounds like you may not have the master cylinder push rod adjusted properly.  It may not cause a big issue with light braking  but with a hard apply, if the rod is too long, it will not allow the fluid to return and the brakes (front or rear or both) will remain in contact.  Numerous posts you can search on how to set the push rod properly.  As a test, if you can get it to repeat the symptoms, when you get back to the garage back the nuts off of the master cylinder a few turns and then see if your wheels free up.

Hi
This is checked and its at the right lenght. The dragging Went away after the brakes coolded down. Can there be an issue that the rotor is in Contact with the studs after hard breaking ? or maybe the Wheel does lock the rotor enough. This only accours after hard breaking.  Master cylinder is new, flexline new. No pinch.

Regards Rob
 

Be sure the OD of the rotor is not rubbing inside the caliper bracket.

Not to flog the dead horse but I have set things properly only to find that they weren't as proper as I thought over the years.  By not checking the rod length by backing of the nuts a few threads is a potential missed opportunity.  Not only is the system cooling over 2 hours but fluid will slowly bleed back into the master.  Go for the easy and obvious checks before looking for the obscure.