Q: How to replace flexible and metal brake lines on Chevrolet Avalanche,Silverado,Suburban,Tahoe,GMC Sierra,Yukon,Yukon Denali and Yukon XL?
A: When replacing flexible hoses, it is important to clean the ends of the hose and disconnect the brake line from the hose fitting, being careful not to bend the frame bracket or line. The U-clip should be removed from the female fitting at the bracket and the hose should be removed from the bracket. Any mounting fasteners for brackets that secure the hose to other components should be removed, and on models where the hose is connected directly to the caliper, the hose fitting should be disconnected from the caliper by removing the banjo bolt. The copper washers on both sides of the fitting should be discarded and new copper washers should be used to attach the new brake hose to the caliper. The hose should be routed exactly as the original one was and any hose brackets that secure the hose to other components should be mounted, as equipped. The female fitting should be passed through the frame or frame bracket and installed in position with the least amount of twist in the hose. The U-clip should be installed in the female fitting at the frame bracket and the brake line should be attached to the hose fitting using a backup wrench on the fitting. The tube nut should be tightened securely and the replacement hose should follow the same path as the original one to avoid contact with moving suspension or steering components. Finally, the brake lines should be bled. When replacing metal brake lines, it is important to use the correct parts and not use copper tubing for any brake system components. Prefabricated brake lines, with the ends already flared and fittings installed, should be used and carefully bent to the proper shape if necessary using a tube bender. The new line should be well supported in the brackets and have plenty of clearance between moving or hot components. After installation, the brake fluid reservoir level should be checked and fluid added as necessary. The brake system should be bled and the brakes should be confirmed to be fully operational before resuming normal driving.