About two weeks ago, I installed new wheels tires and lowering springs on my coupe. After everything was said and done, I took it out for a drive and the abs, vdc and slip lights all came on. I know the issue already for these lights - my front tires are too short and its throwing off the wheel speed sensors. However, the first time I braked at the first stop light i noticed that my brakes felt a little weak (I have brembos btw). When I hit about 5-10 mph I feel a shudder in the car and the brake pedal sinks further down. Granted, my front two pads need replacing and I was actually planning on changing them today, but ever since this has started happening I've seen my front wheels become caked in brake dust while my rear wheels are virtually clean. My theory is that since the front wheels are spinning faster than they should be, they are making the front pads where down much faster. This doesn't really explain the lack of brake dust in the rear, nor does it explain the shudder and sudden sinking of the brake pedal at a low speed. If anyone has experienced this or has any insight, I would appreciate it since I need to change my front pads but don't want to wear them completely out in a month..

 

Maybe an ABS sensor? Kinda doubtful though.. Pull the calipers off and check if they need rebuilding. Re-lube everything it doesn't hurt to have your brakes preform better

 

Ya I checked the calipers and they seem to be in good shape. I just changed the pads but the problem seems to persist. I'm starting to think that the abs sensor may be at fault as well. I'm going to take it into some Nissan shop to see if I can get a good diagnosis on it...

 

Re-bleed them in correct order.

 

in my opinion it sounds like your ABS is kicking in. the car is thinking it is sensing slip do to the different outside diameters of the wheels/tires. how drastic is the size difference? does it shudder mostly when turning a corner at slow speed?

 

Ok so I bled all of the brakes, replaced the pads, and its still happening. I've been engine braking a lot to save my brakes..which doesn't bother me because of my exhaust
I'm starting to think that it is the ABS. Right now I have a 255/40/19 in the back and a used 235/35/19 in the front. Technically it's supposed to be about a 1.5" difference but it looked more like 2"+. I'm about to throw on some 225/40/19 on the front to see if it fixes some of the issues. I guess that's a consequence of running a drag car set up on my G