Today CARspec had an Eden Prairie guest’s GX470 with just north of 100k miles, the owner concerned over a pull when he used the brakes.  The technician test drove the vehicle and confirmed the condition, also noting that the vehicle didn’t like to roll when in gear.  Something was amiss.

Upon inspection the tech noted that the right front wheel wouldn’t spin freely when off the ground.  The wheel was so hot to the touch the tech had to wait several minutes for the wheel to cool down before further inspection.  The cause?  A seized front caliper, something we see often as a Lexus repair shop.  In this case, both front calipers were seized, the right front stuck partially applied (hence the heat) and the left only partially working.  This perfectly explains the symptoms: the right front would only drag and not apply, the left front would apply and pull the vehicle left.  The right front rotors showed signs of significant overheating:

Overheated Rotors

The dark spotting of the rotor in the foreground indicates the rotors and pads were getting extremely hot – the brake caliper dragging being the root cause.  The rust color (lighter on the overheated rotor than its counterpart, towards the outer edge) also tells the tech the rotor was overheating.

The repair is straightforward: replace the seized calipers and any other heat-damaged components.  In this case the pads were ashen and crumbling on the right side, so the technician recommended replacing all front brake components in conjunction with the calipers and rotors.

GX470 brake caliper

Above is the left front brake caliper.  The most common point of failure is the inner bottom piston, but in this case all of the pistons were either seized or extremely hard to move.  The guest opted for aftermarket replacement calipers vs. factory new at considerable cost savings.  After caliper replacement and new Lexus rotors, pads, shims, fitment kits and pins the brake system was bled and the vehicle test driven, being return to service the next day.