Full-Floating Rearend - Trickle-Down Engineering

Race car Floating Rearends Get Street Car Practicality

Camp 1301 01 The Full Floating Rearend 31 Spline Axle Graphic 1/10

Hot rodding has a long tradition of adapting race car parts to street rides. In the last few years, thanks to the increase in performance driving events, the trend has really accelerated. After all, it only makes sense that parts built strong enough for the track are perfect for guys wanting to push their street-driven Camaros harder and harder. Racing harness systems, huge six-piston brakes, two-piece rotors, three-piece forged wheels, safety cages, fire suppression systems, and Watt’s links are just some of the tidbits once reserved for track-only cars but are now increasingly common on hard-driven street Camaros.

Camp 1301 02 The Full Floating Rearend Blue First Generation Chevrolet 2/10

Another race part that has recently trickled down to us hot rodders is the full-floating rearend. What we typically deal with are non-floating axles. In the case of GM and smaller Ford 8.8-inch rearends, the units use a C-clip to retain the axles. If this clip breaks or the axle snaps, then the wheel has an excellent chance of exiting the vehicle. Another popular rearend is the Ford 9-inch, which uses the bearing near the wheel flange to retain the axle and wheel assembly. Here, if the axle breaks, it may or may not be retained. In a full-floating rearend, the axles are splined on both ends instead of splined on one end with a wheel flange on the other. Because of this, the axle has nothing to do with the wheel, so if there’s an axle failure, the wheel stays put. Obviously, this is far safer.

Aside from this safety benefit, the axles in a floater are much stronger since they don’t have to support the weight of the vehicle. The only force placed on the axles is rotational, as the differential transmits power though the axles to the drive plates. They are also easier to service, which is another big selling point for racers. Due to the design, a broken axle can be pulled and replaced without even having to remove the wheel from the car.

For the added strength and safety, floaters have been used in drag racing and off-roading for years. For cars that corner hard, a floater can also help solve the problem of rear brake pad knockback. With a traditional non-floating axle there’s axle deflection. This bending and bowing of the axles occurs as lateral (cornering) forces rise. While you may look at a typical 31-spline axle and think there’s no way it can flex, it does due to the tremendous leverage effect of cornering at high speed—a problem compounded by large wheels. The result is that the rotor pushes the pads into the pistons, forcing them back into the caliper, which in turn creates a space between the rotor and pads. Hit the brakes and the pedal goes to the floor until the calipers are pumped back up. Repeated axle deflection also dramatically decreases bearing life, which causes pad knockback to get even worse.

So why wouldn’t you run a full floater? The number one reason is cost. A floater is going to set you back more than a typical rearend, and to be honest, if you’re just cruising around town, it falls into the overkill category. But if hanging it all out around your favorite road course is in the plans, then a floater should really be factored into your build.

01 As you can see in this cutaway drawing provided by Baer, the axle’s only job is to turn the drive plate where the wheel is attached. Since it no longer has to support the vehicle’s weight, it isn’t subject to knockback-inducing axle deflection.

Camp 1301 03 The Full Floating Rearend Axle Cutaway 3/10

02 With a traditional axle, the wheels are bolted directly to the axle by way of the flange. Because of this, the axle has to support the weight of the car in addition to turning the wheel. Add in high loads from cornering, and even the stoutest axles can flex. Most differential companies like Currie, Strange, and Moser will make you floater axles in whatever length and spline count your heart desires.

Camp 1301 04 The Full Floating Rearend Traditional 4/10

03 Moser is another company that is now offering a floater system for Camaros. Their bare floater package (housing, axles, and hubs) starts at only $879 and is made from all-new materials. The kit comes standard with 28- or 31-spline axles, steel hubs, steel drive flanges, steel or aluminum rotor adapters, hardware, and bearings. Keep in mind the kit doesn’t include provisions for a parking brake.

Camp 1301 05 The Full Floating Rearend Wilwood Disc Brake 5/10

04 For those going even more hard-core, floater rearends can be set up to have negative camber. To pull this off, the outer ends of the axles are “barreled” or “crowned” so that they can run at an angle other than perfectly parallel to the drive plates. The downside is that there’s more wear, and more maintenance is required due to metal particle buildup in the hub grease, which needs to be cleaned out frequently. The drive plates also become “wear and tear” parts that need to be replaced occasionally. Personally, this is where you go from a street car that visits the track, to a track car that visits the street.

Camp 1301 06 The Full Floating Rearend 6/10

05 Speedtech recently released their new Chicane 9-inch floater assembly. It uses sturdy ZR1 Corvette rear hubs, which will accommodate any standard Vette brake package. It also has GM wheel speed sensors if you want to retrofit ABS and traction control. Unlike some of the more “race” systems, the one from Speedtech incorporates a parking brake. Given the sealed bearing design, there’s also no regular maintenance required. This kit is sold with a housing and isn’t available as a retrofit kit.

Camp 1301 07 The Full Floating Rearend Speedtech Chicane 9 Inch Floater 7/10

06 Strange is also introducing their own version of a floater for corner-carving street cars. This retrofit kit features 4130 spindles, steel drive plates, steel hubs, and high-quality Timken bearings. They also have bulletproof ARP ½-inch, or 5⁄8-inch, wheel studs. The inner axle end can be 31- or 35-spline, and the outer end is a NASCAR-style 24-spline deal. The axles themselves are made of Hy-Tuf steel. It will offer ABS compatibility and accepts Wilwood brake systems with a parking brake.

Camp 1301 08 The Full Floating Rearend Strange Retrofit 8/10

07 Baer was one of the earlier companies to offer a floater system designed specifically for Pro Touring cars. Their kit is designed to be retrofitted onto existing housings. The end of the axle tube is cut off and a new steel spindle is welded in place. It also uses two very large bearings spaced apart for maximum load capacity. The system does include a parking brake and can run either 31- or 35-spline axles. The kit is ABS-compatible and starts at around $1,500, not including calipers and rotors.

Camp 1301 09 The Full Floating Rearend Baer Steel 9/10

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