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1992 Regal ABS


Solarboy
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Are you sure the diving isn't related to struts in poor condition?

Rear calipers are new, and work fine. Brakes engage with pedal at rear, but I suspect they are not holding very much when applied during driving. Just feeling how the car nosedives as if the fronts were doing 90% of the work. I operated the parking brake about 30 times or more over the course of bleeding and adjusting the rear brakes. I didn't bleed at the ABS...I only opened the back lines for as long as it took to disconnect the banjo bolt and transfer it plus two new copper washers to the new calipers, losing very little fluid. MC reservoir never got low...kept it topped up. But, it looks like I'll be pulling the fronts off, so I'll do a full system bleed then. Is there a manual bleeding procedure for ABS that will do the job? I don't have a pressure bleeder.
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The rear calipers/rotors/pads are new. Parking brake wasn't working, bad cable replaced and works fine now. Rear calipers are working...how "good" is the issue. It may be as simple as needing to be bled better. Pedal doesn't feel too soft...actually feels hard...like it's taking more foot pressure than it should to stop. Front rotors are hot after a few stops, backs are hardly warm. Struts may be bad...yep...but it "feels" like the diving is cuz the front brakes are doing 90% of the work. I'm thinking of getting or making a pressure bleeder...I'm thinking go to pick-a-part and get a cap, empty the miracle grow out of the missus sprayer when she isn't looking...

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From another post, I learned some curious things about this system...and I can see I need to re-do the bleeding...and maybe found the reason this car has (according to the owner) "always" had crummy brakes. Maybe even the reason for the flashing ABS light...the learning curve on this system has some hairpins in it! Introduced in 1991 as an option on Saturn, Buick Skylark, Oldsmobile Cutlass Calais and Pontiac Grand Am models, the Delco ABS-VI anti-lock brake system has been used on a wide range of General Motors front-wheel-drive vehicles, including Chevrolet Lumina and APV, Chevrolet Beretta, Corsica and Cavalier, Pontiac Grand Prix, Sunbird, Oldsmobile Cutlass Supreme and Buick Regal.

 

The Delco VI system is a nonintegral ABS system with a conventional master brake cylinder and power booster. It has four wheel-speed sensors, but is a three-channel system. The front brakes are controlled separately, but the rear brakes share a common ABS circuit. Attached to the master cylinder is the hydraulic modulator and motor pack assembly. The modulator is held by two banjo bolts at the master cylinder upper outlet ports, and two transfer tubes at the two lower outlet ports. An important service point to note here is that the two lower transfer tubes and O-rings must be replaced if the master cylinder and modulator are disconnected from one another. This is necessary to prevent leaks that could cause the brakes to fail.

 

The modulator assembly has fluid chambers for all four brakes, two isolation solenoid valves, four check balls, a motor pack containing three bidirectional direct current motors with electromagnetic brakes (EMBs) and/or expansion spring brakes (ESBs), three ball screw assemblies, four pistons, a gear drive set and gear cover. The modulator motor pack, isolation solenoid valves, gear cover and individual gears are all serviceable parts and can be replaced separately.

 

The brakes on GM cars equipped with Delco ABS-VI may be bled using manual, vacuum or pressure bleeding. The usual bleeding sequence is right rear, left rear, right front, left front.

 

Before you begin, however, you must make sure the rear pistons in the Delco ABS-VI modulator are in the home position so the check balls are unseated. If this is not done, you won't be able to bleed the rear brake lines. There are two ways that this can be accomplished: With the Tech 1 or similar scan tool, select the F4 ABS Test mode, then select the F0 manual control option. You can now command the rear motor to drive the pistons to the home position.

 

Without a scan tool, open the front bleeder screw at the modulator. There are two, so be sure you open the front one. Then bleed the modulator. Close the screw, then bleed both front brakes starting with the right one first. After checking for a firm pedal, drive the vehicle above three miles per hour. The controller will automatically reset the system by commanding the rear motor to run to the home position. Once this has occurred, you can stop the vehicle and bleed the rear brakes.

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Not yet...almost had the front brakes done, and noticed that the right caliper bleeder was snapped off, and frozen in. After playing the "easy-out" game, I got a new caliper. So...maybe today I'll get to bleed things. Pretty apparent that right caliper hadn't been bled for a long time. In "theory", if the caliper/line was never opened in it's service history, it shouldn't need bleeding...but with 180K, I think it's overdue for a good bleed. I'll see if O'Reilly's has some Buick Leeches.

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A number of things:

1) If you're not willing to spend $75 for a Dealer Service manual, imho, you shouldn't bring any tool within 1,000 feet of your car. Yes, it makes so much sense (and $$$ cents) to pay a mechanic $100/hr for stuff you can do for yourself. And/or, get bad, and often dangerous, advice from the interweb.

 

 

So far I have done my oil and my transmission fluid without a dealer service manual with no ill results...

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The regular driver says the brakes are a helluva lot better, but I don't like the way they feel. Too much freeplay before good braking. Seems even and smooth, but I don't like the slack. The ABS light is still on. Haven't tried pulling the fuse or anything. Looking at crow recipes if I have to take it in to have the codes read, etc. I need to go to pick-a-part and get a wheel sensor wire to make a test rig, plus a new hood cable lever bracket assembly.

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