The Difference Between D52 and D122 Brake Pads: Why it Matters

D52 and D122 brake pads look pretty similar. In fact, many auto parts retailers say D52 and D122 pads are interchangeable. But they’re not exactly the same. This article explains the difference between these pads, and why that difference is important.

D52 vs D122 Brake Pads

While D52 and D122 brake pads are roughly the same, there’s a small difference in the brake pad backing that has a big impact. Specifically, the D122 brake pad has a “nub” on the back of them that mates to a recess in the piston. This “nub” is not found on the D52 brake pad. The D122 “nub” is part of a locking feature that keeps the piston from twisting when the brake is applied.

If you have a brake caliper with an integrated emergency brake (aka parking brake), you need this nub. This is because the calipers with the integrated emergency brake (also known as “Eldorado calipers” or “1976-78 Cadillac Eldorado rear calipers”) have a screw mechanism on the back of the piston that is used to adjust the piston precisely. If the piston were to rotate, it would recede slightly into the caliper, and come out of adjustment. Once out of adjustment, it won’t function well as a parking brake.

Unfortunately, a lot of the companies selling e-brake calipers with disc brake conversion kits don’t know about the nub. They’re selling D52 brake pads with these kits, which don’t work nearly as well when the parking brake is set.

Buy Only E-Brake Calipers Loaded With D122 Pads

It’s important to pay attention to the type of brake pads you’re getting when shopping for e-brake calipers. If you find someone selling a set of e-brake calipers with D52 brake pads, it’s a good idea to keep looking…If you’re buying a set of disc brake calipers with the integrated e-brake, you need a set of D122 pads. Double check any orders you receive as some retailers will put D52 pads in D122 packaging.

Also, if the seller doesn’t specify which type of brake pad they’re including with their e-brake calipers, it’s a good idea to ask.

Of course, all our Eldorado style calipers come with D122 brake pads. And, you can choose between semi-metallic or ceramic D122 brake pads too. Be sure to check them out.