Premature wear and brake noise comebacks
Sometimes the cause relates to the quality of the cleaning and lubing
The amount and type of cleaning you will have to do will vary with the type of vehicle being serviced and the area of the country you live in. Some vehicles have only a few key areas that need to be cleaned when servicing the disc brakes while others require considerable more effort. If you work in the south or out west then you won’t have to deal with too much rust like those of us in the snow belt. We commonly have to deal with brackets that look like the one in Figure 14.1.
Failure to clean the highlighted surfaces will cause nothing but problems. When cleaning, make sure only to remove the corrosion and not to remove good metal. The bracket in Figure 14.2 has had a number of the surfaces damaged by too aggressive of cleaning using an angle grinder. This can allow too loose of a fit for the pads or cause other related problems.
A commonly missed surface, especially where rust is common, are the caliper “ears” that support the outboard pad. These flat surfaces can have considerable rust buildup over time as shown in Figure 14.3. Another source of buildup can come from the use of some of the brake quiet products on the market. If there are remnants of these products on the caliper‘s mating surface it will reduce the surface contact and could increase the chances for brake noise. Failure to clean these surfaces will not allow the outboard pad to sit squarely against the caliper increasing the chances for vibration.
Once all surfaces have been cleaned they need to be lubed. There are many choices out there for brake lube and as many opinions of which ones to use. I recommend the use of a high quality moly-lube on all metal to metal surfaces and a high quality silicone lube on all metal to rubber parts. The reason I like the silicone on metal to rubber is that silicone repels moisture and if used properly it will form a nice moisture barrier. There are some basic rules of thumb to follow when using both lubricants. One is – “a little goes a long way” or conversely – “too much is not always a good thing”. For example, the bracket in Figure 14.4 should first have a light film of moly-lube applied as shown. Next, install the anti-rattle hardware and apply a thin film to the surfaces that contact the brake pads as in Figure 14.5. The bracket can now be installed on the vehicle.
How about the brake pads? What if anything should be applied to the back of the pads? There are a number of different products available for this task so which one should you use? Again, most experts agree that a thin film of moly-lube is the best method to combat brake noise. The key here is to apply it where it will make a difference. Rather than apply it to the entire back of each pad try this, apply a thin layer to each caliper “ear” and then a small circle on the inboard pad where the piston contacts the pad as shown in Figure 14.6. What about pads that already have shims? Should anything be done to them? I say yes, do the same thing. On vehicles with multilayered shims put a thin layer between each layer. If you ever noticed this is how most of these vehicles come from the factory.
Keep coming back to our blog to get more Tech Tricks Tuesday info and you can read our previous Blog Posts to help solve those brake system problems you might be having.