Adding big power to your car regularly comes with consequences.
Hardware that normally doesn’t flinch is suddenly hard pressed to keep up with the demand. Add big, sticky tires and before you know it—unanticipated carnage.
Rear axles are regularly taxed to the max under such circumstances.
If your car has a narrowed rear end or you’ve swapped in a rear end from another car, then it’s nearly impossible for even the best tech guys to figure out what the axle dimensions should be over the phone.
So before ordering your custom axles, it’s of paramount importance that measurements are taken correctly, and we’re going to help.
We’re going to show you exactly how to measure a rear housing for custom axles. It’s a pretty straightforward process. Once the dimensions are established, there’s no need to worry about axles being too long or too short.
Why custom axles? Because of the many possible spline combinations for spools and limited-slip differentials can complicate matters, as well as measuring the housing differently than a particular axle manufacturer, or running into an offset pinion.
Some vehicles incorporate an offset pinion. Some don’t. When a housing is set up with pinion offset, each axle will have a slightly different length.
Information the Axle Manufacturer Will Need to Make Proper-Fitting Custom Axles
1. Bare housing dimensions
- “X” = Housing, flange to flange
- “Y” = Driver-side housing, flange to pinion center
- “Z” = Passenger-side housing, flange to pinion center
2. Brake type
Many will be using a disc brake configuration, but for our example, the rear axle is set up with a standard small General Motors backing plate and a conventional 9½-inch small-car (Nova/Camaro/Chevelle) steel brake drum. These drums typically measure 3.200-inches wide to the outside of the axle register. Most manufacturers also require a brake drum thickness measurement. Take a reading at the register.
In the accompanying photos, we’ll measure a Strange Engineering S60 housing for axles. It’s easy. Just be sure to double-check your measurements.