GM Metro/Sprint 1985-1993 Repair Guide

Brake Pipes

Print

The brake pipes run from the proportioner valve (except the left front brake pipe, which runs directly off the master cylinder) to the wheels. The rear pipes are routed under the left side of the vehicle and along with the fuel pipes, are protected by metal guard plates.

REMOVAL & INSTALLATION



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Brake pipe routing

  1. Clean dirt and foreign material from pipes and fittings.
  2.  
  3. For front pipes, remove pipe to be replaced at proportioner valve and/or master cylinder and from brake hose fitting.
  4.  
  5. For rear pipes, remove pipe to be replaced at the four way junction and from the proportioner valve.
  6.  
  7. Remove pipe from guide brackets and clamps.
  8.  

To install:
  1. Prepare hose ends using the double flare method.
  2.  
  3. Install new pipes and tighten connections to 12 ft. lbs. (16 Nm).
  4.  
  5. Tighten brake pipe clamps to 124 inch lbs. (14 Nm).
  6.  
  7. Flush and bleed brake system.
  8.  

BRAKE PIPE FLARING



See Figure 2

Use only brake line tubing approved for automotive use; never use copper tubing. Whenever possible, try to work with brake lines that are already cut to the length needed. These lines are available at most auto parts stores and have machine made flares, the quality of which is hard to duplicate with most of the available inexpensive flaring kits.

When the brakes are applied, there is a great amount of pressure developed in the hydraulic system. An improperly formed flare can leak with resultant loss of stopping power. If you have never formed a double-flare, take time to familiarize yourself with the flaring kit; practice forming double-flares on scrap tubing until you are satisfied with the results.

The following procedure applies to most commercially available double-flaring kits. If these instructions differ in any way from those in your kit, follow the instructions in the kit.

  1. Obtain the recommended tubing and steel fitting nuts of the correct size.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Double lap flare identification

  1. Cut tubing to correct length. Correct length can be determined by measuring the old pipe using a string and adding 0.125 in. for each double flare.
  2.  

Do not use single flaring tools. Double flares must be used to produce a flare strong enough to hold the system pressure. Using single lap flaring tools could cause system failure.

  1. Square the end of the tube with a file and chamfer the edges.
  2.  
  3. Insert the tube into the proper size hole in the bar until the end of the tube sticks out the thickness of the single flare adapter. Tighten the bar wing nuts tightly so the tube cannot move.
  4.  
  5. Place the single flare adapter into the tube and slide the bar into the yoke.
  6.  
  7. Position the yoke screw over the single flare adapter and tighten it until the bar is locked in the yoke. Continue tightening the yoke screw until the adapter bottoms on the bar. This should form the single flare.
  8.  

Make sure the tube is not forced out of the hole in the bar during the single flare operation. If it is, the single flare will not be formed properly and the procedure must be repeated from Step 1.

  1. Loosen the yoke screw and remove the single flare adapter.
  2.  
  3. Position the yoke screw over the tube and tighten until the taper contacts the single flare and the bar is locked in the yoke. Continue tightening to form the double flare.
  4.  

Make sure the tube is not forced out of the hole in the bar during the double flare operation. If it is, the double flare will not be formed properly and the procedure must be repeated from Step 1.

  1. Loosen the screw and remove the bar from the yoke. Remove the tube from the bar.
  2.  
  3. Check the flare for cracks or uneven flaring. If the flare is not perfect, cut it off and begin again at Step 1.
  4.  

 
label.common.footer.alt.autozoneLogo