Phaeton :: Brake Pulsing At High Speed Between 60 And 80 Mph

When I apply the brakes moderately at speeds between 60 mph and 80 mph, the brakes pulses and the car shakes. If I press harder, the intensity gets worse shortly and then disappears the harder I press. The front steering wheel does not shake so I believe it is the rear brake or wheels. This problem started after I changed the rear VW brakes rotors and rear VW pads and changed all four wheels with remanufactured VW Phaeton wheels. The issue must be with the wheels,brakes, or lug nuts. The tires have not been changed but they are fairly new from what I can tell. The front rotor and pads was changed by the prior owner and I've never had issue with them, they are fairly new and look to be OEM.

Prior to reinstalling the new wheels, I cleaned the rust off of the front rotor surface that makes contact with the wheel and applied high temperature paint. One of the wheels I had a run in the paint (and there is no way I can make the paint 100% the same thickness) so perhaps this has slightly misaligned the front wheels to the rotors.

When I did the brake job, I cleaned the driver side rear hub of surface rust prior to installation of the rotor. I did not clean the hub on the rear passenger side because the hub and wheel bearing was changed a few months prior. I did snap the plastic for the speed sensor for the abs on the rear passenger side. I epoxied the plastic back together and have no ABS errors when the car is scanned. Everything was torqued per VW recommendations. I also checked the calibers sliding mechanism (for left to right movement if rotor slightly warped or out of true) and they moved freely and was not locked up. The only part of the job that was not 100% by the book is I used a hand made tool to push the pistons in on the calipers so I could install the pads (I had to push and turn the piston roughly at the same time but was not 100% at the same time because the tool was hand made).

I've had the wheels professionally rebalanced balanced at a tire shop with a fairly modern balancing machine (digital computer flat screen readout). Originally the wheels was balanced with an older balancing machine and when they rebalanced it it was noted the wheels was way out of balance. I had a bad steering wheel shake and the car vibrated significantly prior to the new balance. The shaking improved greatly with the rebalancing but I could still feel a subdued shake in the seat of my pants (steering wheel shake is gone). Yesterday, I retorqued all of the lug nuts and found the driver side rear and passenger side front had one loose lug nut. Also it appeared that the lug nuts may have been installed with an impact driver and probably not torqued because some were very tight. I used a dial gauge to check both the rear tires and I have about 15-20 thousands of movement in each wheel when rocked side to side and top to bottom. Prior to tightening the lug nut on the driver rear, I had 100 thousands of side to side movement. Car now runs much smoother (maybe not as good with the original wheels and brakes but pretty good) after retorquing all the lug nuts, but the same 60-80 mph pulsing / shaking happens when apply the brakes at speed, perhaps even worse.

I've also checked the rear rotor and wheel runout with the dial gauge and I didn't have anything over 4 thousands on the rotor or wheel when rotated. My jig for the dial gauge was not the best since it was hand made and was attached to the ground instead of the car, so any dial gauge measurements could be off, but I would think they tolerances would be even better if I had a proper jig mounted to the car (not floor). The only thing that I haven't replaced is the lug nuts. Tightening them did seam to change the brake pulse behavior for the worse but did make the car run smoother. Could it be possible that the lug nuts are stretched and this is producing the behavior I'm seeing? I've head the ABS can cause a shake if the speed sensor is damaged.