Here are the top ten brake job mistakes made by rookie mechanics when replacing brake pads, rotors and calipers.
1. Not cleaning the brake slides and hardware: Just slapping new pads where the old pads once resided never works. The slides and abutment clips should be cleaned and/or replaced.
2. Not lubricating the guide pins: Caliper guide pins on floating calipers should be cleaned in solvent and new grease should be applied. The grease is under extreme heat and pressure so always use a caliper specific grease. NEVER put a torn boot back on a car.
3. Installing the brake pads backwards: It happens more often than you would think!
5. Not machining the rotor: New pads almost always require a fresh rotor surface so the pads can deposit a thin layer of friction material to increase braking performance. If old deposits of the previous material are on the rotor, it can contaminate the new pad and lead to performance and noise issues.
6. Not properly torquing the caliper bracket bolts: Not all caliper bracket bolts are the same. Torque ranges can vary from 30- to 110-ft/lbs. Also, some bracket bolts can be torque-to-yield or require liquid tread lockers.
7. Over torquing the caliper guide pin bolts: Caliper guide pin bolts typically need a 13mm wrench to remove. It is a rookie mistake to go nuts on these bolts and break the heads off. Typically these bolts require only 25- to 35-ft/lbs of torque. Be gentle!
8. Installing a caliper upside down: Nothing is worse than going to bleed a new set of calipers on a vehicle, only to find the bleeders are on the bottom of the caliper and not the top. The bleeder needs to be at the top of the caliper to remove all the air. Always check the box to make sure you have a left and a right before you start the job.
9. Using cheap brake pads: This is the most common mistake for the rookie is to shop for a pad on price and not quality, features and reputation. Features like NUCAP’s NRS mechanical retention system, Clip-on/floating shims and extras thrown in the box like abutment clips do not come cheap, but the can mean the difference in the long run.
10. Hanging the brake caliper by the hose: Nothing is more painful than to watch a brake caliper do a bungee jump from a control arm or knuckle and watch it dangle by the brake hose. This can cause damage to internal structure of the hose that can cause a soft pedal or a rupture.
What was your biggest mistake while doing a brake job? Please share in the comments!