Brake Caliper (Front) Replacement & Fluid Flushing


Created:  04 February 2004

Last updated: 


Author/source:  Rich Acuti & Mike Cohee. Photos by Rich and Mike. DeLorean Workshop Manual excerpts used by permission of  DMC Houston.


Disclaimer:  Use this procedure at your own risk. I provide no warranties expressed or implied against personal injuries, damaged tools or vehicles.

Preface: Like my father told me regarding my first car, “You’ve got to stop before you can go”. Brakes are one of the single most important systems on any vehicle. This article is provided so that even the least mechanically inclined owner can keep his DeLorean safe. A total caliper replacement is not necessarily the most cost effective method of brake repair, but it is one of the simplest. On DeLoreans, a complete hydraulic fluid flush is recommended at least every two years.  DOT 4 is specified and either Lucas Girling or Castrol GTLMA are the most common recommendations. In a pinch, I’ve found that Valvoline SynPower is also an acceptable substitute.  The reason for the (relatively) frequent flush is because the fluid absorbs moisture which contaminates and rusts the brake system from the inside out. Once the calipers are contaminated, the pistons no longer move freely. This causes: Uneven braking (pulling to one side), delay in braking, or “grab”,  a condition where the caliper won’t let go of the rotor. This can cause rotor warping, observed by a pulsing felt in the pedal. The rotors can be ground flat again if grooves or warping are noted.


Procedure:

1.      Disconnect and Drain:  Open and empty out the boot. Remove the carpet. Remove the access plate for the brake master cylinder. If you’ll open your bible to page L:04:01 and sing along you’ll notice Fig. 5

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which shows the back of the front caliper. Jack the car, put it on stands and remove the wheels. Start with the driver’s side. It’s the

shortest distance from the reservoir. The front brake line is made of a flexible, braided section attached to a short steel section. There are several disconnect points. I recommend the final point where the rigid line screws into the caliper.

Warning: Failure to use the proper tool may result in a stripped line fitting. I highly recommend a “line wrench” as shown here:

 

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Commonly available at any tool or hardware store, the more closed box prevents rounding the fitting off. Unscrew the fitting.  Next, remove the two large bolts from the caliper as indicated in the figure by the black arrows. Note:  The manual says to remove the pads but you can remove it all as a unit and pull the pads on your workbench. Next, use a mallet or hammer with a block of wood and gently tap the caliper free from the rotor. Be careful not to let it just fall and bend the brake line. Do not let the caliper hang suspended from the brake line. Remove the unscrewed brake line from the hole in the caliper.  Set the old caliper aside.

Have a friend pump the pedal while you collect the fluid in a jar. Once drained, remove the master cylinder cap. Remove the red catch-cup/filter inside the master cylinder. With a clean cloth, wipe it clean. There was a lot of black sediment in mine. Wipe the inside of the reservoir clean. Remove the passenger side caliper the same way, use a jar to catch the last remaining  fluid as it gravity drains out of the line.

2.      Flush and Installation:  The lines may still have some sediment in them so you can pour fresh fluid in the reservoir and have a friend hold the pedal down and allow it to drain into jars or pump for forced flushing. I think there may be a special tool for this but I haven’t been formally introduced to it. Once you’re satisfied that the fluid coming out of the lines is about as clean as it is going in, stop. Fit the proper side caliper with a brake line (they mount up one way). Do NOT tighten it up yet. Align the brake line bracket and fit the bolts. Slip the caliper over the rotor and tighten the large bolts down. Next, tighten the brake line down. Make sure you’re not cross-threading it. If the new calipers are “loaded” with pads, you’re done with this part. If not, we’ll cover pad installation. Repeat for the other side.

3.      Pad installation:  On the new caliper, remove the small jesus clips, then the retaining pins shown here:

The pads are universal so don’t worry about which is left or right. Compress the pistons just enough to slip the pads in (metal plates against the pistons). Align the retaining pinholes and install the retaining pins. Install the jesus clips.  Repeat for the other side.

4.      Bleeding:  Warning: Failure to properly bleed the air from the brake system may cause increased stopping distance resulting in a crash.  Cleanliness must be observed to prevent system contamination. Do not re-use brake fluid.

Top off the reservoir to the max mark. The following pattern MUST be observed: Right rear, left rear, Right front, Left front, in accordance with manual page: L:11:01. There are several ways to bleed air from the system. There are a variety of one-man bleeding kits available on the market or you can do it manually with an assistant. That method will be covered here.

Following the pattern outlined above, have an assistant pump the pedal 5-10 times and hold the pedal to the floor. Using the line wrench, open the bleed screw on the caliper. Initially, due to low system pressure only a small amount of air and fluid will come out. Close the screw. As you repeat this process the system will pressurize, resistance will be felt at the pedal and air/fluid will more forcefully vent from the bleed screw. Once you have a steady stream of fluid, move on to the next wheel in sequence. A short length of tubing may be attached to the bleed screw to facilitate draining the fluid into a container instead of dumping it on the ground. While bleeding, carefully monitor the fluid level in the master cylinder. Don’t allow the master cylinder to drain and intake air, or the entire procedure must be repeated.

A slow, cautious test drive with a few hard braking maneuvers is recommended to test the system. Ensure that the brakes to not pull, pulse, grab or grind. Check for leaks. Inspect fluid level everyday for few days afterward.


Post-Mortem:

As always, I recommend owning a copy of the DeLorean Workshop manual as sold by your favorite vendor. This procedure is not meant to replace the vehicle manuals, but only to translate some of the “mechanicspeak” into everyday language.  Any questions about, or suggestions for this procedure may be addressed to me, at racuti1@delorean.com


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