After yanking the interior, one of the first things to go in almost every GM metric bodied car being turned into a race car is the rearend. That's because stock GM rearends use a C-clip to retain the axles. So, if either the C-clip or an axle breaks, you not only wind up with a broken axle but you can also wind up with a missing rear wheel and your car backed into a wall.
One option is to install a C-clip eliminator kit, but you still won't have the benefits that come from racing a Ford-style 9-inch full floater rearend. Plus, by the time you've rebuilt the stock rearend to proper racing specs it often makes better financial sense to use a new aftermarket rear anyway. That's why most Street Stock racing classes allow a full floater 9-inch rearend--the safety and economic benefits are just too great.
Quick Performance (QP) offers a wide range of gearing and rearend options for all types of racers. Its line of 9-inch full floater rears includes mounting options so that they will bolt right up to GM "metric" chassis like the mid-'80s era Monte Carlos and Regals. Quick Performance has put together complete rearend kits designed specifically around the needs (and the rule books) of Street Stock racers, so we decided to try one out for a car being built by racer Jason Gulledge. The kit we ordered up includes absolutely everything needed except for the gear oil of our choice, bearing grease (if you choose to use it) and silicone or a gasket for sealing the center section to the housing.
Possibly the best part of the deal is QP can build the center section for you to the specs you require including the gear ratio you need. We spec'ed a 583 gear ratio with a spool for racing on a half-mile track with long straights and tight turns. Being able to order up a complete center section built ready-to-race with the correct backlash and gear mesh eliminates one of the biggest hassles when it comes to building a new rearend. The rest of the build can be handled by just about anyone in their shop with standard handtools.
Besides the center section, we were also very interested in checking out Quick Performance's new Extreme Floated axle housing that uses a new "banjo" section of the housing that, according to Quick Performance, has been redesigned to be both stronger and lighter. QP claims that the new Extreme housing design chops 9 pounds of unsprung weight off the rear versus a standard G-body floater rearend. We also wanted to get a look at QP's new adjustable lower brackets which allow you to adjust the height of the lower control arm mounting points. Just like the adjustable bars on a Late Model, adjusting the height can help control how the car handles as the track changes. The adjustable brackets work with stock stamped steel G-body suspension components, so they should be legal at most tracks.
When using the adjustable lower brackets, QP recommends running the left-side lower control arm in the bottom hole and the right side in the second or third hole down (there are five holes total). If the track gets dry slick, dropping the right-side bar down a hole or two will help tighten the car back up, and doing the opposite will help the rearend turn more when the track is tacky and hooked up.
Although the Quick Performance Extreme Floater rearend kit can be assembled by practically anyone, we had gear specialist Gary Medlin of G.M. Racing give us a hand on the assembly--and his expert opinion in the process. And while we went with the complete kit, if you already have some of the components you need, like brake calipers and rotors for example, QP can put together just the parts you require.
We were also surprised by how affordable QP makes installing a new rearend in your car. For example, the full floater housing set up for a G-body, or Metric chassis, sells for just $950. That includes a new housing, axles, hubs, bearings, studs, and quality Wilwood rotors. For $30 more, you can have the adjustable lower brackets added. Brake calipers complete with pads and all the brackets required for installation can be had for $100, and finally, assembled center sections with a mini-spool start at a manageable $399. Now follow along as Gary gets to work.
1 QP uses Motive Performance...
1 QP uses Motive Performance gears for the ring-and-pinion. We chose a 583 ratio and a lightweight spool for racing on dirt.
2 Assembling a center section...
2 Assembling a center section requires special skills and a few specialized tools to ensure the gears mate in correctly and work trouble-free for a season for more. QP’s specialists handle the center section assembly to make your life a little easier.
3 QP’s newly designed Extreme...
3 QP’s newly designed Extreme Floater rearend housing design is fabricated from all new materials in-house. The redesigned banjo section increases strength while cutting weight. And QP also welds in all the suspension mounting points to fit the metric chassis, making this a direct bolt-in.
4 We asked Gary Medlin of...
4 We asked Gary Medlin of G.M. Racing to lend his expertise as a gear specialist and help assemble the rearend. The first step is to assemble the hubs and Wilwood rotors.
5 After adding a drop of...
5 After adding a drop of red Loctite to the included fasteners, Medlin torques the 5/16 cap screws to 25 ft-lb. Make sure to tighten the fasteners in a star pattern to help spread the loading equally around the diameter of the hub.
6 The brake caliper brackets...
6 The brake caliper brackets must be welded to the housing’s axle tubes, which is why the rotors and hubs need to be assembled. In order to properly locate the caliper brackets, you have to first install the rotors and hubs on the tubes. Slide on the inner bearing over the tube, but because this is just a pre-fit no axle grease is necessary.
19 QP provides the outer...
19 QP provides the outer seal, but it sits below the lip of the hub so you will need a seal driver.
20 A spiral lock helps keep...
20 A spiral lock helps keep the seal locked into place. Install it by slowly walking the lock into the groove.
21 Here’s the completed assembly...
21 Here’s the completed assembly ready to go onto the axle tube.
31 Medlin bolts back down...
31 Medlin bolts back down the brake calipers for the final time.
32 QP includes a few nice...
32 QP includes a few nice touches with its rearends like a jack pad in the center of the housing that also protects the drain plug.
33 Here, you can see how...
33 Here, you can see how the lower control arms mount up to the adjustable lower brackets.
22 Slide the locking ring...
22 Slide the locking ring over the axle tube.
23 Now thread on the hub...
23 Now thread on the hub nut.
24 You don’t have to have...
24 You don’t have to have a specialized hub nut socket to install the nut correctly. The hub nut has slots cut into it, use a screwdriver to tighten it down properly.
7 Other than laying off the...
7 Other than laying off the grease for now, assemble the hubs and tighten them down as you normally would. If you aren’t sure how, check the steps for final assembly. Don’t worry about drag on the bearings, you just want to make sure the bearings and hubs are fully seated on the axle tubes.
8 Begin by installing the...
8 Begin by installing the brackets onto the calipers using the two mounting bolts. Make sure the pads you are going to use are installed in the calipers.
9 Medlin installs the calipers...
9 Medlin installs the calipers onto the rotors and positions them where you want them to be once everything is welded up. We chose to mount the calipers so that they are behind the axle, slightly above the 9 o’clock position. Exactly where you place the calipers is up to you as long as the bleeder screws are at the highest point on the caliper body.
10 Lock the caliper onto...
10 Lock the caliper onto the rotor by blowing compressed air into the caliper body at the brake fluid inlet hole. Now the caliper bracket is correctly aligned so that the caliper is square to the rotor when the brakes are applied.
11 Use a scribe to mark the...
11 Use a scribe to mark the position where the brackets meet the axle tubes.
12 Medlin tapes the machined...
12 Medlin tapes the machined end of the tube to protect it and sands away the paint in the area to be welded. Make sure not to cut so deep you lose the scribe marks.
25 Tightening the hub nut...
25 Tightening the hub nut increases the drag. Medlin recommends 25 ft-lb of drag for new wheel bearings and 15 when rebuilding a rearend where the bearings have already had a chance to seat. Medlin has developed a feel for how much drag is appropriate, but you can set up a beam-style torque wrench on the pinion nut to get a feel for how much drag is produced.
26 Once the drag is set,...
26 Once the drag is set, bend over one of the tabs in the locking ring to lock the hub nut so that it can’t spin.
27 One of the included axles...
27 One of the included axles includes a bolt and locking nut to help set the axle depth.
28 Now slide the end plate...
28 Now slide the end plate on making sure the included O-ring is properly seated in the groove.
29 Ideally, you want the...
29 Ideally, you want the bolt in the end of one of the axles to be threaded so that both axles sit 1/8-inch inside the end plates. This allows a little bit of room for expansion when everything gets hot during a race.
30 The hub caps also have...
30 The hub caps also have O-rings to help eliminate leaks.
13 Now you can begin welding...
13 Now you can begin welding up the caliper brackets. Make sure to jump around and slowly stitch the weld together to avoid the change of heat warping either the bracket or the tube.
14 QP also provides two gussets...
14 QP also provides two gussets for each bracket. Weld them in place on the inside of the bracket in line with the caliper mounting holes.
15 Medlin checked over the...
15 Medlin checked over the center section but it required no attention before installation.
16 QP uses thick plate steel...
16 QP uses thick plate steel for the mounting face for the center section, so a bead of silicone is all that’s required to seal it up. Notice the beefy inner brace, there’s no inner seal to install on the floater housing because you want oil to be able to get to the inner bearings.
17 The housing comes with...
17 The housing comes with new studs installed, so Medlin is able to drop the center section right into place.
18 Finally, we’re ready to...
18 Finally, we’re ready to install the hubs for the last time. You can get by with simply oiling the wheel bearings, but we knew this housing may have to sit a bit before the car is ready so we packed the bearings with grease.