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Brake Bias Spring Installation


Some folks want to add more rear bias to their brake system, so they install this handy spring made by DRM. Here's how to do it.

Tools Required

The following tools were used to make the modification.

  • Felt tip pen
  • 19mm combination wrench
  • 13mm combination wrench

Do the Job

  1. You will need to bleed the brakes after you replace the spring so I jacked up the C5 and removed the wheels.
  2. Locate the brake proportioning valve junction box. It is located below the forward section of the master cylinder. Mark the junction box where the input pipe from the master cylinder enters. I put an old towel on the frame underneath to catch the small amount of brake fluid that leaked.
  3. Use the 13mm wrench to remove the brake pipes from the master cylinder to the junction box and the pipe from the junction box that goes toward the front brakes. You may need to put a piece of tape over the pipe from the master cylinder to keep fluid from leaking. Mine only leaked a tablespoon or so of fluid.
  4. Wrap the junction box in a rag and put in a vise with the 19mm retaining nut pointed up. Carefully remove the nut. There is a fiber retainer on the end of the nut. I dropped mine and had to get my flashlight to find it. The old spring should be protruding about 1".
  5. Remove the spring. If the valve comes out with the spring, you will need to reinstall the valve on the new spring in the same orientation.
  6. Insert the new spring/valve in the junction box.
  7. Here was the hard part. The new spring is considerably stiffer than the stock spring. You need to put the fiber retainer on the end of the nut and then the nut assembly over the end of the spring. You will have to compress the spring to get the nut to the threads. I used a small, flat bar to push down on the nut while turning it with the wrench. I didn't find a torque specification for the nut but it should not be much.
  8. Replace the proportioning valve assembly to the brake pipes. Attach the pipe from the master cylinder to the fitting you marked in step #1. Tighten the brake pipes to 13 lb ft.
  9. Bleed the brakes. I used one of the magic pumps to make sure all the air was removed from the pipes/lines and I got fluid only out of all of the calipers. If you have a friend/wife you can get them to help by pushing the pedal gently after you have loosened the bleed valves one at a time. As soon as fluid squirts, tighten the valve. Work from farther away toward the master cylinder. RR-LR-RF-LF. Replace the wheels and put the car back on the ground.
  10. Before you start the car, pump the brakes and after a couple of pumps the pedal should sit really high. Start the car and the pedal should drop back to normal position. Check the brake fluid level and top off if necessary.
  11. Make sure the brakes work before any high speed or emergency stops. I drove back and forth in the driveway until I was comfortable that the brakes worked. If you lose pedal, then you need to bleed the brakes again.
  12. Take it for a test drive. I went to a deserted stretch of road and did some 40 to 0 stops and then some 60 to 0 stops. I didn't notice much difference than the stock setup, but then I did a 100 to 0 stop and didn't feel much nosedive at all and it really stopped quickly. What I have read, says 5 to 20 feet shorter stops than stock. 5 feet can make the difference in missing or hitting that cone at the end of the straight.
  13. Check the fluid level again in a couple of days.

This page was last updated on 06/21/01 by Redshift


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