SmokesGTP Posted May 20, 2003 Report Share Posted May 20, 2003 My brake pedal is really bad. It goes almost to the floor before the car stops and then it just kinda glides to a stop. I had the car at 2 mechanics including the dealer and the first said a rear caliper was the problem and the dealer said the caliper was fine and they couldn't see a problem. I asked the dealer about the booster hose and he said then I wouldn't have any power assist basically at all. I wasn't quite sure about this but beileved him at the time. They just changed the fluid and told me that they could try a new master cylinder because thats what he suspected. I have recently put on new pads and the calipers and rotors appear fine. Anyone got any ideas so hopefully I don't have to spend 350$ on a new master cylinder. Quote Link to comment Share on other sites More sharing options...
SmokesGTP Posted May 20, 2003 Author Report Share Posted May 20, 2003 I can't think of anything else except, i know it seems odd but the pedal will sometimes be better than others, thats what makes me think master cylinder. Although I still wonder about that booster hose, I felt it earlier and it doesn't seem to squishy. The dealer also said all the brake lines look good and no leaky calipers. Thats about as much info as I got Quote Link to comment Share on other sites More sharing options...
Slade901 Posted May 20, 2003 Report Share Posted May 20, 2003 Do you have an ABS? I assume you or the technician have bleed the brake system for air. If you have ABS, most ABS needs to be bleed as well. Bleeding the brake system would also confirm if the brake fluid is going to all the brake calipers. Bleeding an ABS equipped vehicle has a specific steps to bleed the brake system. Some pushrod on the brake pedal can be adjusted to prime the master cylinder. If there is an adjuster on the pushrod, then just loosen the nut and adjust the pushrod but make sure you don't adjust the push too far which might fall off the pushrod. Once you are satisfied with the adjustment then just tighten the nut on the pushrod. Quote Link to comment Share on other sites More sharing options...
SmokesGTP Posted May 20, 2003 Author Report Share Posted May 20, 2003 The dealer said on these newer brake systems its very hard for air to get in and he highly doubted it so I'm guessing he didn't bleed the system. I'd do it myself but I have no idea, if anyone has instructions that'd be great. Quote Link to comment Share on other sites More sharing options...
Slade901 Posted May 21, 2003 Report Share Posted May 21, 2003 Do you have ABS (Anti-Lock Brake System)? I need to know your car model and year and I'll see if I can paste the instruction on bleeding for your car. I recommend to purchase a brake bleeder wrench, 2 bottles of large brake fluid, get someone to assist you and if not purchase a one-man bleeder kit. I'd recommend getting two large brake fluid bottle. If you have a friend to assist you in bleeding your brake would be nice, but if you don't have someone to assist you then you can get can a one-man bleeder kit. One kit that I like best is a plastic bottle with a clear tube and comes with different type of fitting to connect to the bleeder screw. Get a brake bleeder wrench. Don't use a regular wrenches/socket because you WILL strip the bleeder screw. You can set the plastic bottle on a flat surface, loosen the bleeder valve a little bit and close it up but not too tight, then connect the other end of the plastic hose with the right fitting to the bleeder screw and then you can now loosen the bleeder screw about 3/4 turn. You can now push the brake pedal once and see if the fluid comes out and if not push of the brake pedal one at time until you see the fluid comes out clear and continous without bubbles and then tighten up the bleeder screw. It depends on your car but most car, you bleed the right rear, left rear, right front, left front. If you have ABS, you need to bleed the master cylinder. Usually there are two bleeder screw on the master cylinder. Bleed the bleeder screw closest to the firewall/booster and then bleed the other bleeder screw. Quote Link to comment Share on other sites More sharing options...
SmokesGTP Posted May 21, 2003 Author Report Share Posted May 21, 2003 It says in my sig 94' Grand Prix GTP, yes I have ABS. I think I can handle this any help you can give would be much appreciated. I'll get a buddy to help me. Quote Link to comment Share on other sites More sharing options...
Slade901 Posted May 21, 2003 Report Share Posted May 21, 2003 I would assume then that your car is equipped with Delphi Chassis (Delco Moraine) ABS VI. Bleeding: 1. The manufacturer specifies that it will be necssary to bleed the entire system whenever air is allowed into any part of the system. 2. The pistons in the hydraulic modulator must be raised to the home position before bleeding the system. This can be done with a scan tool if available; if not use the following procedure. 3. To raise the pistons to the home position without a scan tool, start the engine and let it run for 10 seconds. Watch the ABS light - it should turn off after three seconds or so. Warning: if the light doesn't go off, a scan tool must be connected to diagnose the problem. Have the vehicle towed to a dealer service department or other repair shop equipped with the necessary tool. 4. If the light turned off like it is supposed, turn the ignition off and repeat the procedure. If the light goes off again after three seconds, the brakes can no be bled. 5. Have an assistant on hand, as well as a supply of new brake fluid, an empty clear container, a length of clear plastic tubing to fit over the bleeder valve and a wrench to open and close the bleeder valve. 6. Remove the cap from teh brake fluid reservoir and add fluid, if necessary. Don't allow the fluid level to drop too low during this procedure - check it frequently. Reinstall the cap. 7. Bleed the master cylinder as follows: Models without bleeder valves on the hydraulic modulator: 8. Disconnect the two forward brake lines from the master cylinder with a flare-nut wrench. 9. Fill the reservoir with brake fluid until fluid begins to flow from the two forward outlets. 10. Reconnect the forward lines to the master cylinder and tighten the tube nut fittings. 11. Slowly depress and hold down the brake pedal. 12. Loosen the fittings again and allow any air in the fluid to be purged, then retighten the fittings. 13. Slowly release the pedal and wait 15 seconds. 14. Repeat this procedure until air is removed from the two front outlets. 15. Disconnect the two rear tube nut fittings and repeat this procedure until all air is expelled from those ports as well. Proceed to step 17. Models with bleeder valves on the hydraulic modulator: 16. Attach the bleeder hose to the rearmost bleeder valve on the modulator assembly. With the other end of the hose in a jar partially filled with clear brake fluid, open the valve slowly and have an assistant depress the brake pedal. Keep the pedal down until fluid flows. Close the valve and release the brake pedal. Repeat this until no air is evident as the fluid enters the jar, then repeat the procedure for the forward bleeder valve. After bleeding the hydraulic modulator assembly, bleed the rest of the braking system as described next. All models: 17. Check the fluid level again, adding fluid as necessary. WHen bleeding, make sure the fluid comign out of the bleeder is not only free of bubbles, but clean also. 18. Raise the vehicle and support it securely on jackstands. 19. Beginning at the right rear brake, loosen the bleeder screw slightly, then tighten it to a point where it's snug but can still be loosened quickly and easily. 20. Place one end of teh tubing over the bleeder screw and submerge the other end in the brake fluid in the container. 21. Open te bleeder screw and have your assistant slowly dpress the brake pedal and hold the pedal firmly dpressed. Watch for air bubbles to exit the submerged end of the tube. When the fluid flow slows, tighten the screw, then have your assistant slowly release the pedal. Wait 5 seconds before proceeding. 22. Repeat Step 21 until no more air is seen leaving the tube, then tighten the bleeder screw and proceed to the left rear brake, right front brake and left front brake, in that order. Be sure to check the fluid in the master cylinder reservoir frequently. 23. After bleeding the right rear wheel brake, repeat Steps 19 through 22 on the left rear brake, right front brake and the left front brake, in that order. 24. Lower the vehicle and check the fluid level in the brake fluid reservoir, addign fluid as necessary. 25. Check the operation of the brakes. The pdeal should feel solid when depressed, with no sponginess. If necessary, repeat the entire process. Warning: Do not operate the vehicle if you are in doubt about the effectiveness of the brake system. Quote Link to comment Share on other sites More sharing options...
91GranSport Posted May 21, 2003 Report Share Posted May 21, 2003 Not to stray off topic, but I heard that W-Body's ABS systems, particularly the ones on the Gen1 W-Body, were all crap. I guess I'm glad I don't have ABS! By the way, what was wrong with the Gen1 ABS anyways? Quote Link to comment Share on other sites More sharing options...
SmokesGTP Posted May 21, 2003 Author Report Share Posted May 21, 2003 Thanks alot, one part I don't underdstand is the part about the ABS light. It always goes off after 3 seconds unless something is wrong, how would just turning it off and starting it again cause it to stay on? and that you can't bleed it if it goes off? I'm a little confused about that otherwise pretty straight forward. Quote Link to comment Share on other sites More sharing options...
Slade901 Posted May 21, 2003 Report Share Posted May 21, 2003 Sorry for the typo. Look at this 4th procedure. 4. If the light turned off like it is supposed, turn the ignition off and repeat the procedure. If the light goes off again after three seconds, the brakes can no be bled. It is suppose to be 4. If the light turned off like it is supposed, turn the ignition off and repeat the procedure. If the light goes off again after three seconds, the brakes can "now" be bled. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted May 21, 2003 Report Share Posted May 21, 2003 Not to stray off topic, but I heard that W-Body's ABS systems, particularly the ones on the Gen1 W-Body, were all crap. I guess I'm glad I don't have ABS! By the way, what was wrong with the Gen1 ABS anyways? There's nothing wrong with the 92+ ABS VI system. It's an inexpensive system that works well, that's why GM used it for a long, long time, almost 10yrs. The 88-91 PowerMaster III system is what's crap. It's a very complex, overdesigned system that fails often. It was designed when ABS was so new, the engineers weren't sure how to go about it. They rigged up a system using a high-pressure nitrogen-charged accumulator and a special master cylinder. It's nothing like the typical braking system. ABS VI uses standard vacuum brakes, but has a modulator assembly that has motors and solenoids in it to pulse the pressure to the calipers. Quote Link to comment Share on other sites More sharing options...
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