Jim Smart
October 17, 2012

In addition to building in extra camber, there's also the added benefit of reducing brake knock back. Brake knock back is when the axleshaft flexes or moves under cornering and the axle movement then pushes the brake pads outward, moving the brake caliper pistons into the caliper. When you come to the next corner and hit the brakes, there's nothing there for a brief second or two, but depending on your speed into the corner, that can be enough time to put you off track or worse. While knock back is more prevalent in C-clip-style axles, it can occur in 8- and 9-inch rearends when the axleshafts become weak over time, often from the axleshaft supporting the load. In the case of a full floater, the brake package is fixed to the hub, so there is no movement.

For a competitive road race car, knock back can be costly over the course of an event, and while we won't be competing for any road racing championships with our project Mustang, we certainly don't want any braking surprises during a high-performance driving event or similar outing.

Speedway Engineering's full-floating 9-inch axle assembly consists of a custom-made axle housing designed specifically for full-floating axles. The axle's center section is CNC-machined to ensure concentricity at each of the bearing bores to reduce or eliminate stress issues. At each end are extended-length snouts, which prevent tube crush and provide good bearing/hub support. Under the close supervision of Frank Ferrell, Welding Manager at Speedway Engineering, these handcrafted housings and components are precision manufactured at the company's Sylmar, California, facility for your specific application, and based on information you provide.

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Is A Full-Floater For You?

We have to admit, this is the first time we've ever been presented with the opportunity to install a full-floating axle in a Mustang. What this has meant for us is the chance to learn something about race-ready axle technology. The beauty of a full-floating 9-inch Ford is its industrial strength demeanor--engineering that takes Ford's bulletproof rearend to a new level. Full-floating technology isn't for everyone and it can get expensive. For durability, easy service, flexibility, and the ultimate form of load distribution as we know it today, Speedway Engineering has the goods for brute street and racing performance.

Build any 9-inch housing you desire because there are four to choose from--Super Light NASCAR Style, Short NASCAR Style, Saturday Night Late Model, and the vintage Ford rounded 9-inch (1957-1966). Choice depends on how you're going to use your Speedway Engineering housing. With the exception being the rounded back, it's challenging to tell the difference, but important to know about when you order.

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Float For Your Hard-Earned Buck...

  • CNC machining throughout
  • Cooler, vent, and drain fittings
  • 3.0-inch diameter 0.250-inch wall axle tubes
  • V-notched welded seams
  • Laser cut truck arm pads and brake brackets
  • Longer end snouts
  • ARP housing studs
  • Every housing guaranteed plus or minus 0.003-inch toe and 0.03-degree camber
  • Complete assemblies are shipped with specification sheets that include camber, toe, width, pinion offset, and angle
  • Complete assemblies include housing, hubs, hub bearings, seals, nuts, drive plates, dust caps, O-rings, and axles
  • Wheel studs
  • Trailing arm mounts are located to fit the most popular frames
  • Each assembly is made to order though there are popular types in stock
  • Choose Your Center Section

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21 Hanging upside down in the paint booth, our new Speedway Engineering 9-inch housing is ready for paint (or powdercoat if you prefer). Be sure to check back as we stuff the 9-inch with a stout third member and add Wilwood's trick full-floater rear brake system.