Rear Axle & Brake Swaps - A Pattern For Success

Owners of stock, pre-'73 Mopar A-Bodies all share a peculiar thing in common: that unique A-Body five-lug-on-four-inch bolt pattern for the wheels. Now, this may or may not pose problems, depending on which steps you are taking in your restore or rebuild. In the case of my rebuilt daily-driver '67 Barracuda, steps were made long ago to ensure it didn't end up under a truck on Califomia's stop-and-go freeways. The factory 10-inch drums got too hot, too fast, and were useless when it came to sailing in the sea of glowing taillights. Thanks to a boneyard '75 Dart and its front end, the fish now sports a single-piston disk brake setup and the remarkable ability to stop again and again.

Unfortunately, now that I could stop, one-wheel burnouts were deemed not nearly as fun as the two-wheel variety, so another boneyard Dart gave up its 8 3/4 rear. With a swap meet-found Sure Grip in place of the open 3.23, I was soon reveling in the joy of stab-and-steer driving, traction, and leaving twin black streaks in my wake.

And therein lies the real dilemma. Those front rotors off the '73-'76 A-Bodies have the "big" 5- on-4.5-inch pattern, while the replacement A-Body 8 3/4 rear has the "small" 5-on-4.0 pattern. This situation not only leaves you carrying two spares, but lacking in real choices as to what wheels you can put on your car. Since I already had a set of 15x7 cop wheels, the final decision was made to switch out the rear axles for the big bolt pattern all the way around.

There are a couple of options. Hit swap meets and hope you get lucky on a set of used stock 5-on-4-inch axles. Scour the junkyards for a C-Body 8 3/4, score the axles with enough spline length, send them out to be shortened, and then use the massive C-Body rear brakes on your A-Body. Or you could also pick up the phone and call Moser Engineering. For about the same price as scavenging boneyard axles and getting them shortened, resplined, and shipped, you could slap a set of new axles in your A-Body in a couple of hours. You will need to score a set of the bigger bolt 10x2.5-inch Mopar drums and backing plates at the boneyard for the swap (or you can go so far as to convert those to disc from an aftermarket supplier like Stainless Steel Brake Company). The brake hardware is still available at many auto parts stores.

Moser supplies the axles as either bare units or with non-adjustable "green bearings" pressed on. Should you decide to go with the old tapered bearings, you also need to save the adjuster off your original axles when you press them onto the new axles; these adjusters often get mangled while trying to get the bearings off, so you may not have to think too hard about which way to go. Since the front brake setup came off the aforementioned '75 Dart, we simply ordered the wheel cylinders, shoes, and hardware for the same car. Just get used to remembering what to say when the guy at the counter asks you, "What kind of car is it?" It's amazing how many parts they have when you say, "'75 Duster!"