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Installing a Baer Floater System on a 9-inch Rearend

Installing a floater rearend setup cures the dreaded brake pad knockback

Mar 11, 2019
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If you’ve ever driven on an autocross or road course, you’ve most likely been a victim of brake pad knockback. It’s probably one of the scariest things you can experience on a track or even while driving on the street, for that matter. You go to hit the brakes and … nothing. The brake pedal goes to the floor and the car continues on its merry way. You panic, let the pedal raise, which feels like forever at that point, and hit the brakes for a second time when—thankfully—the brake pads squeeze the rotors and you are overcome with a feeling of relief as the car slows down as originally planned ... hopefully before hitting anything or missing a corner. But like all of us, we are accustomed to and expect the brakes to work on the first hit.

Due to the development of wider and stickier tires over the past decade or so, our muscle cars are pulling lateral g’s like never before … on street tires. Add in stronger and more functional suspension components that allow aggressive cornering along with larger diameter brake discs and you have a recipe for a big bowl of brake pad knockback.

So what exactly is brake pad knockback?

Bret Voelkel of RideTech explains: “Brake knockback happens when the spindle [or rear axleshaft] flexes and allows the caliper to flex with it. When the caliper moves in relation to the rotor, the brake pads are then pushed back into their bore, creating clearance between the pad and the rotor. When you hit the brakes the next time a large part of the pedal travel is then required to push the pads back against the rotor to begin the braking activity. While the flex and resulting clearances are small (a few thousandths of an inch), the result is a momentary butt-puckering loss of braking action. On a racetrack at over 100 mph with a turn looming in your future, this is heart stopping!”

Bret goes on, “There are several band-aids for this issue depending on severity, and a couple of real solutions. In mild cases, a simple RPV (residual pressure valve) can be installed between the master cylinder and the caliper. These typically come in 2-pound and 10-pound calibrations. The 2-pound is usually appropriate. Another band-aid is simply to get in the habit of double pumping the pedal in preparation for a turn. This can work OK on a road course where you may have some time to accomplish this, but it’s a terrible solution on an autocross where you have but a fraction of a second between turning events.

“There are some real solutions, as well. Some brake companies can incorporate ‘knockback’ springs that go into the piston and keep a small amount of pressure on the pad. Stronger spindles for the front may be required to minimize spindle flex and unwanted caliper movement. On the rear, a common solution is a floating brake system. This is where the axle is divorced from the wheel hub and ‘floats’ independently of any lateral load imposed through the wheel hub.

“We found that as soon as we started using a sticky tire, the lateral g loads increased to the point where we experienced brake knockback. As the cars got faster, the g loads increased and the problem got worse. At this point, our fast track cars use our recently developed Track 1 billet modular spindle that incorporates a C7 bearing hub and floating rear brakes. The street cars still use a pin style spindle and non floating rear brakes, even if they see some limited autocross use.”

Matt Jones, lead mechanical engineer at Art Morrison, tells Chevy High Performance, “We try to tackle the problem on the front end. We have the customer’s wheel/tire data, weights, wheel specs, etc., all up front. In the design stage, we look at what we can do to center the wheel bearing in the tire’s contact patch to reduce these issues.” Matt goes on, “For the more extreme loads (which isn’t too common, but more so than it used to be) we resort to a unit bearing up front as spindle pins will bend inevitably.

“The press-on bearing used on 9-inch axles do present some issues. A couple helpful ideas we have found are: matching bearing cup and races, thicker bearing retainers (the piece that bolts to the housing end that retains the bearing) of a quarter-inch or more and are a one-piece construction, full floater, and going with one of our independent rearend suspension systems.

“Obviously, full floaters and an IRS cure the issue, but minimizing loads on the bearing in the first place is key.”

Some of us just deal with pad knockback and have grown accustomed to tapping the brakes twice prior to approaching a hard corner while on an autocross or road course, but having to do the “double tap” only adds unnecessary time to our course laps. Adding a mere tenth of a second to your lap time can be the difference between winning and losing, and qualifying or sitting out the next round. Trust me, it’s not fun watching from the sidelines as the person that beat you by 0.01 of a second continues to race.

If you’ve ever experienced brake pad knockback for the first time, then you know it’s just about the scariest thing that can happen behind the wheel of your car. While autocrossing Orange Krate, our second-gen Camaro project, we were experiencing horrible pad knockback. Doing the double pump on the brake pedal was the norm and we just dealt with, but we knew it was killing our lap times, so it was time to make a change.

We went to Baer and looked into installing their Tracker full floating axle conversion system so we could fix the problem once and for all. Now, this isn’t your typical driveway installation piece, so we packed up our rearend and new parts then headed over to Currie Enterprises in Corona, California, to have them tackle the job for us. Their staff of professionals have done tons of floater rearends for customers in the street/track performance and off-road industry and have been in the rearend business since 1959 when Frank Currie started building differentials in his home garage. Needless to say, we were in good hands.

Follow along as the crew at Currie Enterprises shows what’s involved in taking our rearend to the next level of performance braking while knocking out knockback. CHP

002 Baer Floater Rearend Install Currie 2/30

This rear came out of our second-gen Camaro, Project Orange Krate. The goal is for the new floater rear setup to end up the same width. The first task was measuring where we were at and calculating how much we would need to cut off to get the proper length. We measured from the end of the housing to the inside bolt of the centersection. Our measurements indicated we’d need to be at 18 3/8-inches on the driver side and 19 1/8-inches on the passenger side.

003 Baer Floater Rearend Install Currie 3/30

It’s critical that the axletubes are perfectly straight with any rearend, but it’s especially critical when using a floater setup since deviation will cause the drive axle to side load and wear quicker. It would also cause premature bearing wear and seal leakage.

004 Baer Floater Rearend Install Currie 4/30

Our housing was fairly straight, but the crew at Currie tweaked it a bit in their hydraulic press to make sure it was perfect.

005 Baer Floater Rearend Install Currie 5/30

We could then make the mark where we would lop off the existing ends. According to Baer, if you’re converting an existing rear to the full floater, an additional 0.640-inch will need to be removed from the axletube in order to maintain the same wheel location. After doing the math, we found that they were right.

006 Baer Floater Rearend Install Currie 6/30

Once cut, the ends were cleaned up and drilled so rosette welds could be added during the final welding stage.

007 Baer Floater Rearend Install Currie 7/30

With the housing prepped, it was time to machine the Baer spindle. First up was measuring the axletube’s id.

008 Baer Floater Rearend Install Currie 8/30

With that measurement, Currie could then turn down the steel spindle to match. If the housing was warped beyond our ability to straighten, we could offset machine the spindle to compensate for the warp. Thankfully we didn’t have to.

009 Baer Floater Rearend Install Currie 9/30

We could then insert the Baer spindles into the housing. The floater snout has a flange machined into it to allow many systems using Big Ford ends (Torino) to bolt right to the snout.

010 Baer Floater Rearend Install Currie 10/30

A tape measure was used to confirm the new spindle was at the correct distance, and magnetic levels ensured everything was clocked properly.

011 Baer Floater Rearend Install Currie 11/30

The spindles were then tacked in place.

012 Baer Floater Rearend Install Currie 12/30

The housing was then sent to the rotary welding station to get finished up. Between the perimeter weld of the spindle to the axletube and the rosettes, this spindle isn’t going anywhere.

013 Baer Floater Rearend Install Currie 13/30

The rest of the floater install is a bolt-on deal. First up was bolting on the billet aluminum backing plate. The integrated parking brake’s one-piece shoe design is superior to a two-piece design and offers 35 percent more breakaway torque.

014 Baer Floater Rearend Install Currie 14/30

It was then time to assemble the hub. First up was pressing the ARP wheel studs into place. Currie has this cool hub tool they made to press in the studs.

015 Baer Floater Rearend Install Currie 15/30

Once in, they ensure the wheel studs are properly pressed in by putting the assembly on a level surface.

016 Baer Floater Rearend Install Currie 16/30

With the ARP studs in, we bolted the hubs to the rotors using the supplied hardware. Next was the messy job of packing the bearings with grease and putting them in place, followed by the seals.

017 Baer Floater Rearend Install Currie 17/30

The inner bearings were then greased and put in place. This floater kit allowed us to reuse our current Baer 6S calipers and rotors.

018 Baer Floater Rearend Install Currie 18/30

The rotor/hub assembly was slid onto the spindle and the locking ring was put in place.

019 Baer Floater Rearend Install Currie 19/30

With the locking ring on, we spun on the nut, which requires a special four-prong spindle socket (NAPA PN 3146) to torque it in place.

020 Baer Floater Rearend Install Currie 20/30

Once torqued down, one of the tabs from the locker ring was bent over to keep the spindle nut in place.

021 Baer Floater Rearend Install Currie 21/30

We could then put the drive plates in place over the wheel studs. These plates handle a ton of power and are made to NASCAR specifications. This 24-spline plate is 0.050-inch larger than a standard 35-spline axle.

022 Baer Floater Rearend Install Currie 22/30
023 Baer Floater Rearend Install Currie 23/30

You can get a measurement for the axles by either installing your third member or by using a jig like Currie did. Either way, you need the distance from the third member to the outer edge of the drive plate.

024 Baer Floater Rearend Install Currie 24/30

Using that information we were able to order our axles.

025 Baer Floater Rearend Install Currie 25/30

The axles came with the needed 31-spline end to mate with our Eaton Detroit Truetrac posi on one end and a 24-spline end to mate with our Baer drive plate.

026 Baer Floater Rearend Install Currie 26/30

On the inboard end of the axletube (nearest the centersection) it’s important to have an axle seal to keep fluid out of the tubes so that it doesn’t end up washing out the bearing grease on the outboard ends. We ordered these from Speedway Engineering based on the id of our axletube.

027 Baer Floater Rearend Install Currie 27/30

They were simply inserted in the tube and tapped in place. Here you can see how the axle passes through the new seal.

028 Baer Floater Rearend Install Currie 28/30

With the new floater-equipped rear installed in the car, and the third member in place, we could slide in the new axles.

029 Baer Floater Rearend Install Currie 29/30

As you can see, the measurements Currie took for the axles were dead on. We paid a bit extra and got the gun-drilled axles, which will save us a little rotating mass. Every little bit helps.

030 Baer Floater Rearend Install Currie 30/30

After smearing some bearing grease on the axle end, we installed the O-ring–equipped billet cap using the hardware supplied by Baer. The only thing left to do now was hit the track and enjoy some knockback-free braking!

Photography by Nick Licata

Sources

Currie Enterprises
Corona, CA 92880
714-528-6957
http://www.currieenterprises.com
Art Morrison Enterprises
Fife, WA 98424
866-321-4499
www.artmorrison.com
Baer Brakes
Phoenix, AZ
602-233-1411
www.baer.com
RideTech
Jasper, IN 47546
812-481-4787
http://www.ridetech.com
ARP
Ventura, CA 93003
805-650-0742
http://www.arp-bolts.com

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