As our Chevys get faster, we more often find ourselves dipping into the tech found on race cars. One of these technological tidbits to recently migrate over to our street cars is floating axles.
The problem solved by a floater rear mostly revolves around brake pad knockback. In a traditional flange-axle rearend the weight of the car is supported by the axletubes, and under hard cornering, they flex. The amount of flex can be made even worse by large wheels and brake rotors. This flexing, besides causing wonky geometry changes, can force the rotors to push back on the brake pads, which knocks the pistons back into the caliper bores. The result is that when you hit the brakes, the first pump only resets the pistons back against the pads (and hence the rotor). This necessitates another pump to actually cause the braking action you expected on the first slap of the pedal. Now, you can get used to this, but double-pumping your brakes after every hard turn can get a bit old.
A floater is also safer than a traditional flanged axle since there’s no way a wheel can exit the vehicle if an axle snaps. In a traditional flanged axle arrangement, the constant flexing of the axletube also beats the crap out of the bearing, causing additional play, which worsens the knockback problem. Is it necessary for everyone? No, but if you plan on pushing your ride hard, then it’s an option you should really consider.
Several companies have started selling race-bred floater kits designed for street-driven Chevys. These kits have features not found on race cars, but are necessary for street duty. Items like parking brakes and ABS capabilities. One of these companies is Baer Brakes. They’ve melded race tech with their street-friendly brake kits to put out a system that lets you have your proverbial cake and eat it to. The Baer Tracker Floating Axle Conversion kit has everything you need for the street combined with the safety and rock-solid performance of a race-bred floater.
We heard one was getting installed over at Currie Enterprises, so we grabbed our camera gear and headed over to see what’s involved.
01. Here is a traditional flanged axle arrangement. The problem with this is that the weight of the car is carried by the axletube and supported by a single bearing. It’s this flexing of the axletube that contributes to pad knockback in the rear brakes. This constant stress also causes the bearings that support the axle to loosen, which makes knockback even worse. A common band-aid is to frequently replace the bearings, especially before a big track day.
02. Whether you modify an existing housing or start with a new one, the first task will be to do math, lots of math. If you’re using an existing housing, then you’ll most likely want the wheels to end up in the same spot, so be sure to take note of what distance you started out at. Just like building a house, measure twice, cut once.
03. The next step on a pre-existing rear housing would be to cut off the ends. If you mess up and cut the housing too short, you’re stuck. And if you make it too long and weld in the spindles, then it will be nearly impossible to fix. Given this, measure as many times as it takes to get it right the first time.
04. We didn’t have an existing rear housing for this project, so Currie decided to stitch together one of their fabricated pieces. After grabbing a center section from the rack, they cut some 3-inch tubes to length and, using a jig, inserted them into the center case. The entire circumference of the tube inside the case was then welded.
05. It was then time for the hard-core welding. This was done on a rotary jig, which helps make for some beautiful and consistent welds.
06. And here you can see the welds of the axletube to the center case. When all the welding was done, the flange, where the third member seals to the case, was machined flat and true to prevent fluid leaks.
07. At this point the procedure would be the same if we were working with either a used or new rear housing. After being cut to length, the axletubes were chamfered and four 5/8-inch holes were drilled around the circumference about 1.5-inches from the end of the axletube.
08. Since the spindle will support the weight of the car, it has to be made of stout material. The steel spindles shipped with an OD larger than 3 inches, which means they needed to be turned down on a lathe to match the ID of the axletube. This allows the shop to make corrections to the fitment for housings that are out of shape or have other issues.
09. After doing more math, the wizards at Currie put the spindles in the lathe and milled them down to match our axletubes. Since we’re dealing with a new housing, we didn’t have to worry about getting fancy with offset milling.
10. With the tubes welded on, we had Currie do a few extras. The first was making provisions for fill and drain holes in the casing.
11. To maintain rigidity, an iron housing was bolted to the centersection. After that, the spindles were inserted into the axletubes and properly aligned so that the holes for the Baer brake calipers would be orientated in the right spot.
12. Using a long steel bar to line the spindles up dead center in the housing, we checked all the measurements one final time. When we were sure everything was perfect, the spindles were tack-welded in place.
13. The whole housing then went back to the welding shop where the axletubes were fully welded to the spindles around the entire circumference, and the eight holes (four on each end) were filled with welding rosettes. Once cooled down, the housing was sent back out and straightened since the tubes tend to distort under heavy welding. This is critical since a floater needs to have the axles riding straight and true to prevent bind and accelerated wear.
14. Here you can see the spindle fully welded to the axletube. The end was wrapped to prevent it from being contaminated by welding spatter.
15. This is the Currie housing after getting the reinforcing nameplate welded on and the fill bung TIG-welded in place.
16. And this is the drain plug we had welded to the bottom of the case. Some people skip having a fill and drain added, but it sure makes life easier down the road.
17. Keep in mind that some sort of axle seal will be needed to keep the differential fluid from traveling down the tube and washing out the floater bearings. One option is this sweet O-ringed double-seal piece sold by Currie.
18. The hub assembly was fitted with the inner bearing then slid onto the spindle. You can also see the ARP 1/2-inch race studs that came in the kit.
19. Baer’s Floater Conversion kit adapts rear flanged axles with single bearings to a double-bearing configuration that relieves the axles from directly supporting the vehicle weight. The outer bearing was given a generous coating of high-quality bearing grease, then the hub assembly was secured to the floater with a spindle nut and lock ring. Keep in mind the kit doesn’t include the socket needed to torque down the spindle nut, so you’ll have to buy or borrow one.
20. The steel drive plates, built by Speedway Engineering, are what actually transfers the power from the diff to the wheels. They’re held to the drive hub by five countersunk Allen bolts, but the load is carried by the wheel studs. The drive plates had O-rings on the back to help seal in all the bearing grease. One nice feature of the Baer kit is that they kept the diameter of the register small to fit street wheels.
21. And with that, the floater part of this rear was done. The axles, which we’ll have to order from a specialty shop like Speedway Engineering, will have 31-spline ends on the differential side and NASCAR-spec 24-spline ends on the drive plate side.
22. The Baer Tracker Floater kit doesn’t include any brake parts, but will work with a variety of Baer systems, including their Extreme+ 14- and 15-inch as well as their Pro+ 13- and 14-inch kits. The brake package is very compact (only 5/8-inch wider than their normal Ford 9-inch brake system) and can be ordered to be fully ABS compatible. It also incorporates a parking brake system.