I have a 1969 10 bolt Chevy rear getting ready to install in a '47 Chevy coupe. I sprang for the disc brake kit with emergency brake equipped calipers from Jeg's as it was only $35 more than all new drums. The brake kit comes with both full rotor backing plates (zinc plated and of good quality) and a spacer to use instead if you choose not to run them. Why or why not should I use the provided backing plates? The instructions say they are optional but do not say why. Thanks for the opinions.
They're not a bad thing to have as they'll keep water off the rotors if you run in the rain. Discs can get 'coated' with water and you'll have no brakes until it's cleared off. If you never run in wet conditions, you don't need 'em....
its mostly to keep the grease and oil from the engine and suspension components off them and help direct the hot air away from them ( makes the rotor surface act like a air pump ,like a tesla turbine ) so it pulls cool air over them , as for rain the disc pad is always in contact with the rotor , not heavily but still enough to cut the water off the surface and keeps the pad face warm . several of my daily drivers the backing plates have rusted away ,so I never replaced them . no effects on the braking performance of the vehicles .
Not needed. Back in 1996, I bought a brand new [OT Alert!!!] Chevrolet Caprice w/LT1. One of the mods the 94-96 Impala SS guys were doing was replacing their stock full backing plates with the factory 9C1 (Chevrolet RPO for police package) backing plates. The 9C1 backing plates were trimmed down to nothing, just enough to hold the anti-lock brake sensor. The inside of the rotor is fully exposed. This, along with a different airdam was done for brake cooling. All from the factory.
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