dizwiz24

I am getting ready to install the DRM brake bias spring in hopes of improved hi-speed braking.

Installation calls for removal of fluid from the master cylinder, replacing the spring in the combination piston/proportioning valve with the DRM spring, reinstalling everything, and then bleeding the brakes.

Everything about bleeding the brakes seems straightforward for my 93 in the Chilton's manual (I have never bleed brakes before), except it mentions that if the entire system must be bled that you have to first bleed the system at the master cylinder prime pipe on the hydraulic modulator located in the left rear storage compartment?

Where is this thing? Do I need to bleed this modulator thing?, and how do I get to it on my convertible?

Any response would be appreciated!

M2001

I have an 88 convertible and I've installed a DRM bias spring on my car. While the master cylinder is is off the car, bench bleed the master cylinder after you install the new spring. Install the master cylinder on the car. Have someone pump and hold the brake pedal while you bleed the brake lines that connects to the master cylinder. I would wrap a rag around the fitting when you do this because if the brake fluids spills on the car, it will attack pianted surfaces so be careful when you do this. After you bleed the lines that connect to the master cylinder, bleed the brake calipers. The order I do this is the right rear, left rear, front right and then the left front. Once I did this, I repeated the bleeding of the brake calipers again. I never had the need to mess with the ABS unit and I came away with a rock hard brake pedal. If you really wanted to bleed the ABS pump, I think you need a scan tool that will activate your ABS pump while you bleed it. I don't have any experience with this scan tool but then again, I never felt as though I needed to go that route. Try my method, I think it will save you the headache of trying to bleed the ABS pump. It worked for me so it should work for you too. BTW, have a few pints of new brake fluid on hand for the job. With all that brake bleeding, you may go through 4 or more pints. Another side benefit is that you'll have flushed out all of the old brake fluid. When I bleed my brakes, I use the old fashion method to service the brake system. Have someone pump the brake pedal and hold it while you release the brake line pressure. If you are going to track your car, you're going to like the results of the DRM spring. You can't really notice it on the street but you will feel the difference under really hard braking. Let us know how you made out and good luck.

BBA

I did it in my car in about 1 hour from start to driving.
I removed the wheel cylinders from the rotors, placed a lug nut between the pads, then I pumped the brakes. This extends the wheel cylinder pistons. Next, I placed a peice of board between the drivers seat bottom and the brake pedal, then used the power seat motor to push the board forward to press the brake pedal. This closes the brake piston, so no fluid will go past the piston.

Then I removed theproportioning valve cover and valve from the master cylinder, changed springs and reinserted the valve and cover. Then I removed the board from the pedal, used my C-clamp to compress each wheel cylinder piston to fullly seated and put the wheel cylinders back on one at a time.

Then I took it for the test drive.

I did not even have to bleed the brakes. The fluid I forced into the wheel cylinders was enough to push any air back into the master cylinder resevoir and no bleeding was necessary.

M2001

That was very clever of you!

cajun86

I gravity bleed my brakes a trick an older gentleman showed me. Remove the top off the mastercylinder make sure it stays full of brake fluid. Then go to one wheel and open the bleeder valve let it drain untill its clear of bubbles then close it off. Go to the remaining wheels and do the same no pumping or anything. This doesn't work on all cars dur to the brake set up but it did work on my vette and the brakes are perfect.

dizwiz24

The 92 through 94 have something different in their braking system called a hydraulic modulator it has a prime pipe (looks like a 3rd brake line coming off the master cylinder).

This part needs to be bled first according to the Chilton's manual, when bleeding the entire system.

Does this sound right?