In 2009, when the ZR1 became the top of the line C6, GM equipped it with the ultimate in road car braking hardware: massive, Brembo, six-piston, fixed-caliper brakes and racing-inspired, carbon-fiber-reinforced, ceramic brake discs. Known inside GM as “J57 Heavy Duty Antilock Brake System”, the “carbon brakes” were, also, a Z06 option in 2011, ’12 and ’13 as part of the Z07 “Ultimate Performance Package”.
Strangely, on a car with a $7500 set of brakes, General Motors used rubber brake hoses, like the ones on any Chevy Cruze. That’s just ridiculous. It’s cost savings gone crazy.
A brake system based on what Corvette Racing uses to win at LeMans ought to have the type of brake hoses used on race cars, that is: polytetrafluoroethylene (“PTFE” or “Teflon”) tubing covered with stainless-steel braid.
Rubber brake hoses expand slightly under brake pressure. That may give the brake pedal a slight soft feel under heavy braking. Teflon tubing with reinforcing stainless steel braid on its exterior does not expand. That lack of expansion improves brake pedal feel.
Fortunately, the aftermarket, specifically Corvette parts vendor Zip Corvette, has come to the rescue of C6ers wanting appropriate brake hoses for their carbon brakes with U.S. Department of Transportation compliant “braided brake hoses” for ZR1s and Z06es with Z07. To experience the improved pedal feel with braided brake hoses, we put a set of Zip’s hoses on a 2012 Z06 with J57 brakes.
Zip’s hoses on a 2012 Z06 with J57 brakes
Zip Corvette offers these hose kits two ways: 1) standard and 2) with a colored overlay on top of the stainless steel braid. The colored hoses come in red, yellow, blue and graphite. As the calipers on our Z06 are red, we ordered the hoses in red (PN# DB-905.red) to can also use our 06-13 Z06/GS Stainless Steel Brake Hoses (PN# DB-746).
All Zip Corvettes’s brake hose kits come with everything you need including: banjo bolts, banjo crush washers and retaining clips. Zip’s hose kits are bolt-on parts. You take off the stock hoses then replace them with the Zip braided hoses. No modifications or fabrication work is required.
Installation of a Zip Corvette’s braided stainless steel Teflon brake hose kit is fairly simple and can be accomplished by any DIY who has experience working on disc brakes. In addition to common hand tools, you need some flex-head, metric flare nut wrenches and a telescoping inspection mirror. We, also, suggest you have a pressure brake bleeder such as the 92-19 Motive Power Brake Bleeder. You may need some brake cleaner, too–we like Permatex Pro Strength.
You’ll need brake fluid, too. We like Willwood “570” for street use and for track use we suggest Willwood “EXP600” Racing Brake Fluid. Both these Willwood fluids are organic based and both are made in the US. Racing fluids need to have high boiling points and they need to have low moisture affinity to slow the natural absorption rate of water vapor. Both Wilwood fluids fill that bill.
Wilwood 570 fluid meets the DOT3 specification and has a 570 degree dry boiling point. It’s a great fluid for all kinds of sportsman racing and high-performance street use.
EXP600 fluid meets DOT4 and has a 626°F dry boiling point and a 399° wet boiling point. It is a professional-quality racing fluid for the highest levels of motorsports. It maintains its viscosity and lubricity under extreme temperatures which helps maintain brake system reliability and performance. The true test of any brake fluid is how well it resists aeration and compressibility after it has been heated and pressure cycled a few hundred times. The real test is at the track. EXP600 has proven to maintain firm pedal feel and quick response, long after lesser brake fluids have failed. For this article, and another brake project we have planned, we ordered a case of EXP600 (PN# DB-703) from Zip.
Please follow below on how to install your C6 ZR-1 and Z06/Z07 Corvette Brake Hose. There is a list on the bottom of the instruction of the tool list.
01: The chassis end of each brake hose has a 17-mm wrench hex and is also keyed to fit into the hose mounting bracket on the chassis.
03: A flex-head, flare nut wrench is required for the hose upgrade project because of the confined space around each chassis connection. A set of Gear Wrench flex-head, metric, flare-nut wrenches (PN 81911D) is in our rollaway but, if you can’t afford the whole set, since the flare nuts on the brake pipes which screw into the hoses are 13-mm.; you can get by with just the Gear Wrench, 13mm/14mm flex-head, flare nut wrench (PN 81688).
04: The first step is to get your Corvette up on a lift or on jack stands. You must “jacking pucks” to prevent damage to the Z06/ZR1 aluminum frame and any carbon fiber side skirts the car may have. These extra-tall jacking pucks are perfect for cars with side skirts. They are available from Zip here: 06-13 Z06/ZR1 Aluminum Jacking Pads.
05: Install the disc brake rotor protectors which came with all cars equipped with J57, then remove all four wheels.
06: The most time-consuming hose installation is the left rear, so that’s the place to start. Unplug the electrical connector. Remove the screws holding the MagnaRide (MR) sensor to the sensor bracket, then move the sensor out of the way leaving the bracket in place.
07: Pop the conduit retainer loose with a small screw driver then fold the MR sensor harness back and over the top of the CV boot.
08: Use an inspection mirror to locate the brake hose chassis connection.
09: Use your Gear Wrench flex-head, flare nut wrench to break loose the brake pipe fitting but leave it finger tight for now.
10: Remove the retaining clip which holds the brake hose to the chassis. We found the only way we could get the left rear clip off was to work from underneath the car. We used a long screw driver, inserted upward between the suspension parts and axle shaft, to push on the bottom side of the clip. That popped the clip off.
11: Observe and remember the angle of the hose coming out of the caliper banjo bolt. Mark the angle if necessary. Loosen the bolt, but leave it finger tight.
12: Place a small drain pan under the chassis connection. Unscrew the brake pipe fitting from the chassis end of the stock brake hose, then fold the hose off to the side such that the end is up as high as possible. That keeps the hose from leaking.
13: Quickly screw the brake pipe fitting into the chassis end of the Zip hose. Finger tighten the flare nut into the hose fitting.
14: Make sure the keyed fitting fits into the chassis bracket. The 17-mm hex end of the hose must be flat on the face of the brake pipe bracket. You may have to rotate or jiggle the hose end to get it flat on the bracket.
15: At the brake caliper, remove the stock banjo bolt and the hose. Select a new banjo bolt and two crush washers from the Zip hose kit. Place a washer on the bolt. Push the bolt though banjo fitting on the caliper end of the hose then add a second washer. Finally, screw the banjo bolt into the caliper.
16: Adjust the angle of the hose to the caliper which you observed previously. The hose kit instructions say to tighten banjo bolts to 30-ft/lbs., but using a torque wrench on those bolts can be difficult due to the restricted space. We ended-up using a 14-mm, flex-head Gear Wrench and our experience in feeling bolt tightness. If you don’t have that experience, a 3/8-drive torque wrench and a short, 14-mm socket may fit. While holding the banjo fitting at the proper angle, tighten the banjo bolt.
17: Install a retaining clip on the chassis end of the brake hose. The clips can usually be reinstalled with your fingers. Hold the hex on the chassis end of the brake hose with a 17mm wrench then, using the flex-head, flare nut wrench to reach the other side of the bracket, tighten the fitting on the end of the brake pipe.
18: Reinstall the MagnaRide sensor and reconnect its wiring.
19: Move to the right rear brake. Unplug the MR sensor connector. Unscrew the MR sensor link pivot ball from the sensor arm. Then, remove the bolt holding the MR sensor bracket to the rear cradle.
20: Push the sensor out of the way to gain access to chassis end of the hose.
21: To remove the left rear brake hose retaining clip and the clips for the two front hoses may require a set of needle nose pliers with angled jaws.
22: Install the right rear Zip Corvette braided hose in the same manner as you did the left rear hose. Then, reinstall the MR Sensor and bracket, reinstall the sensor link pivot into the sensor arm then reconnect the sensor harness.
23: Changing the two front brake hoses does not require removal of the MR Sensors, but you will need to disconnect them and push the wires out of the way. After you do that, changing the two front brake hoses is just like doing the two rears. After you install the new front hoses, reconnect the MR sensor harnesses.
24: Now, the brakes need to be bled. There are two ways to do it: manual or “foot” bleeding and pressure bleeding. We recommend pressure bleeding, but either way requires you bleed fluid though a clear plastic hose into a container which has the hose end submerged in brake fluid.
25: If you are pressure bleeding, which we recommend, check to make sure your pressure bleeder has an adequate supply of brake fluid. Wilwood EXP 600 brake fluid is the best choice for ZR1s and Z07 Z06es which are going to see a combination of street and “track day” use. Install the master cylinder adapter and the pressure bleeder hose. Pump the pressure bleeder up to about 25-psi.
26: Begin with the bleeder fitting on the inside half of right rear brake. Then, do the right, rear, outside bleeder. Once the air is out of the right rear, move to the left front brake and bleed that in the same manner, inside bleeder first, then the outside bleeder. Next, is the left rear, inside then outside and, finally, the right front, inside then outside.
27: Manual bleeding takes two people. You bleed the brake while an assistant pushes the brake pedal. With traditional, two-person, manual bleeding, you bleed until the air bubbles, which you can see though the clear tubing, stop coming out of the caliper.
28: Contrary to popular belief, when you manually bleed the brakes, you do not pump the brake pedal rapidly. Your assistant should stroke the pedal one time and hold modest pressure. Then, you open the bleeder but close it before the brake pedal bottoms. Wait 10 seconds before doing that, again. With as much air which will be in the system after a hose change, it will likely take many pedal strokes to get all the air out the brakes. Bleed the brakes in the same sequence: RR-I, RR-O, LF-I, LF-O, LR-I, LR-O, RF-I and RF-O
29: Now test the brake pedal feel. Stroke the pedal several times to exhaust the power assist then push the pedal firmly and hold for a while. Release the pedal and go to each wheel and check for leaks. This can be done either by feel–use your little finger to touch the lowest part of each brake pipe fitting which screws into to each hose’s chassis connection. If your finger gets wet with brake fluid, there’s a leak.
30: Or you can use an inspection mirror and a bright light. If you hold the mirror in just the right spot next to the chassis connection bracket and at the right angle, you can just barely see the bottom part of the fitting where it goes into the hose. If you do the feel test and see brake fluid on your finger or you see brake fluid in the mirror, tighten the each fitting some more. This can mean pretty darn tight and that’s why you must use a flare-nut wrench.
Sit in the car and check pedal feel again. If the pedal is still spongy but there is no air in the base brake system and no fluid leaks, you may have air in the electronic brake and traction control module (EBTCM), the device which gives the car its antilock braking system (ABS) functiuons. The only way to bleed the EBTCM is to command the ABS “auto bleed” function using a scan tester. Initially we tried a software-based scan tester, PC Scan Tool, from EASE Diagnostics, running under Windows 7 on a laptop PC.
Unfortunately, that did not work well. In spite of EASE Diagnostics’ sales and marketing information claiming PC Scan Tool is capable of the “bi-directional” communication required to enable the “auto bleed” function of a C6es EBTCM, the software apparently does not actually support that function.
31: The other way to run auto-bleed is with a hardware-based scan tester which supports the such as the GM TECH2 or the current GM dealer scan tester, the Bosch MasterTech VCI. Finally, if you believe your EBTCM has air in it and you don’t have access to the appropriate device for commanding the auto-bleed function, take the car to a GM dealer for service.
32: Once the bleeding is done, put the brake rotor protectors in place, reinstall your wheels and tires, remove your protectors and set the car back on the ground. Torque your wheel nuts in a star pattern, in three increments to 100-lbs/ft. Admire you work and enjoy your Zip Corvette brake hoses.
C6 ZR-1 and Z06/Z07 Corvette Brake Hose Installation: Installing the C6 ZE-1 & ZO6/ZO7 Brake Hose
Source: Zip Corvette Parts
8067 Fast Lane | Mechanicsville, VA 23111 | (800) 962-9632
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