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Curing Tire & Wheel Fitment Problems with Narrow Disc Brakes

CPP “Drum Width” disc brakes offer a simple cure for tire and wheel fitment issues

Tommy Lee Byrd Nov 5, 2018
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Stance is a big part of giving your Chevy the right look, but sometimes we make sacrifices in the process. For our early Chevelle project car we nailed the stance with about 4 inches of total drop up front, but we ran into a tire and wheel fitment problem, mainly when the car was loaded down or in a tight parking lot. We originally used a standard Classic Performance Products (CPP) kit on our Chevelle (PN 6466CBK), which included 2-inch drop spindles and all of the necessary parts to swap our car from drum brakes to disc brakes. The kit functioned perfectly, but it pushed the wheels out toward the fenders a little too much for our application. This doesn’t normally create a tire and wheel fitment issue, but after we dropped it two additional inches with lowering coil springs, we noticed an occasional tire rub. We had a few options to fix the problem: 1. Replace the front brakes with CPP’s “drum width” rotors. 2. Raise the car up an inch (not happening). 3. Wheels with custom backspacing and/or smaller tires.

We decided early on that raising the car’s ride height wasn’t an option, so we narrowed it down to the CPP drum width kit or custom backspace wheels. We are already running Wheel Vintiques 15x5 OE-style Chevy front wheels that have 3 inches of backspacing. The narrow 5-inch rim doesn’t provide a lot of wiggle room for custom backspacing and new max-backspace wheels from Wheel Vintiques would’ve only given us an additional 3/8-inch per side. So, we opted for the CPP drum offset kit and held onto our off-the-shelf steelies and 185/70R15 front tires from Coker.

Since we had already installed a CPP kit on the car, the new drum width rotors and calipers offered an easy installation and gave us the instant results we needed. We gained 1/2-inch per side with a simple brake swap, and while that doesn’t sound like much, it made all the difference in the world. The front tires no longer rub in parking lot situations or when we have the car loaded down with dudes going on a lunch run. The swap took us about four hours in the garage, and now we don’t have to worry about those cringe-worthy moments when the front tires would rub on the fenders at full lock. The drum width rotors worked wonders on our early Chevelle, and CPP offers similar kits for many other applications.

Take a look at the steps involved to solve a big problem and make our Chevelle’s track width a little slimmer. CHP

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1. As much as we love a slammed stance, the cringe factor was pretty high when our front tires contacted the inner fender at full lock. This interference was due to the 4 inches of total drop in combination with a standard disc brake conversion.

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2. After lifting the Chevelle and securing it with jack stands, we can remove the front wheels and start disassembling the brakes. This kit positioned the front wheels 7/16-inch closer to the fenders than the original drum brakes. Our new CPP rotors will fix that.

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3. A large 3/8-inch Allen wrench is used to loosen the two caliper bolts.

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4. With the two bolts removed, the caliper should slide off of the rotor with ease. The new CPP drum width kit (PN 2711) comes with new calipers, so these can be placed in the spare parts pile.

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5. After removing the dust cap, we can straighten the cotter pin and pull it out. Then, it’s the simple task of loosening the large spindle nut.

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6. We carefully slide the brake rotor off of the spindle, bringing the wheel bearings and keyed washer along with it.

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7. With the rotor out of the way, we can access the caliper bracket bolts. We start with the 3/4-inch socket on a 1/2-inch ratchet to remove the lower bracket bolt.

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8. Next, we flatten the bolt locks, using a flathead screwdriver.

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9. Then, we use a 15/16-inch socket to remove the 5/8-18 upper caliper bracket bolt.

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10. The CPP drum width kit offers a narrower track width than its standard disc brake kit for Chevelles. The kit contains rotors, calipers (with pads), wheel bearings, and brake hoses. We also needed a left caliper bracket (PN 37053) and right caliper bracket (PN 37054).

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11. With the standard CPP rotor removed, we’re looking at 2 1/4 inches from the brake rotor surface to the wheel mounting surface.

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12. The new CPP drum offset rotor measures 1 1/4-inch from the rotor surface to the wheel mounting surface. While this is a full inch difference from the old rotor, the inner mounting surface is slightly different, giving us a final difference of 1/2-inch.

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13. After a little clean up, we installed the right caliper bracket on the CPP drop spindle. These calipers are typically used on Nova brake kits, but also work for this drum width system.

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14. CPP included the necessary hardware to install the caliper brackets. We started by installing the 5/8-18 Grade 8 upper bolt. Also note the spacer between the caliper bracket and spindle. This is necessary to properly align the bracket.

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15. After tightening the upper bolt and folding the locks into place, we can tighten the lower bolt using a new 1/2-13 Grade 8 bolt provided in the kit.

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16. Using the tried and true “palm” method, we pack the inner wheel bearings. We place a glob of high-temp bearing grease in our palm and roll the bearing across it, while also making sure to pack it between the race and cage.

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17. The inner bearing is placed in the backside of the rotor and then the seal is pressed into place. Sometimes the seal needs some light persuasion to fit properly.

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18. The outer wheel bearing gets the same treatment and fits into the outer side of the rotor.

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19. The rotor slides into place easily. Since we had to tweak the dust shield to fit the new caliper brackets, there was a clearance issue between the shield and the new rotor. The shield is pretty flexible, so a few gentle blows with a rubber mallet did the trick.

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20. We install the keyed washer and then the new castle nut. When adjusting wheel bearings, we typically tighten the nut until we start feeling tension on the rotor. Then, we can back the nut off slightly to align the holes for the cotter pin.

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21. The new calipers and pads slide into place with a little bit of wiggling. The new parts offer a snug fit, but we want to get at least one of the caliper bolts started before our next step.

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22. Now we can move onto the new flex hoses included in the CPP kit. We tighten the fittings using a 3/8-inch line wrench and 5/8-inch line wrench.

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23. The flex hoses feature a banjo fitting on the caliper side. This offers easy installation, using the supplied bolt and washers.

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24. Finally, we can tighten the two caliper bolts to finish the installation of the new components. We repeat the process on the other side of the car.

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25. As with any brake installation, it’s important to bleed the system starting with the wheel that is furthest from the master cylinder. A 10mm wrench is used to loosen the bleeder screw when pressure is applied to the system.

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26. Our Chevelle gets driven often, so it will make great use of the new rotors and pads, but the most important aspect of this swap is the narrower track width. It might not sound like much, but 1/2-inch is substantial when it comes to tire and wheel fitment.

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27. Although we could’ve ordered custom-backspace steel wheels, we stayed with our existing off-the-shelf versions and 185/70R15 tires from Coker. The Wheel Vintiques OE-style wheels measure 15x5 and feature 3 inches of backspacing.

Photos by Tommy Lee Byrd

Sources

Coker Tire
Chattanooga, TN 37402
866-516-3215
www.cokertire.com
Wheel Vintiques
City of Industry, CA 91746
800-959-2100
http://www.wheelvintiques.com
Classic Performance Products (CPP)
Placentia, CA 92870
800-522-5004
www.ClassicPerform.com

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