Wheel bearings

Tiny
LSUFAN05
  • MEMBER
  • 2001 PONTIAC BONNEVILLE
  • 150,000 MILES
I asked a question earlier about bad wheel bearings triggering my anti lock light. This may be a silly question, but do those wheel bearings have to be replaced or is this something I don't have to worry about?
Tuesday, April 5th, 2016 AT 7:42 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Any time the yellow warning light is on, the anti-lock brake system is turned off. The ABS system is an optional add-on to the regular brake system. These systems didn't even exist on cars before the late 1980s except for a few Chrysler models in 1969. When your system is turned off, you are left with the standard brake system like we all had many years ago. To say that a different way, you do not need the system as long as you understand you're driving only with regular brakes.

I have to stop for a minute and add a comment for anyone researching this problem. While your wheel speed sensors are a real poor design that cause a lot of problems, the hydraulic controller, (with the valves that modulate brake fluid flow to the wheels), on these GM front-wheel-drive cars are relatively inexpensive, easily repairable, and quite effective. Part of the reason they're so inexpensive is they have nothing to do with power brakes. Your power brake assist comes from a large vacuum canister between the firewall and brake master cylinder, and that system has been around since the 1940s or '50s. You will have power brakes regardless of whether the anti-lock function is turned off or functioning properly.

There are many car models that take advantage of the brake fluid that is pumped up to and stored at real high pressure to provide the power assist. My '93 Dodge Dynasty has that system. The advantage to my system is if the engine stalls or is turned off, I get over 40 brake pedal applications with power assist before that pressure bleeds off. On all cars with normal vacuum boosters, you only get two or three pedal applications before it becomes real hard to push, and that is much harder to do on most GM cars, but that is supposed to be sufficient to stop safely on the side of the road.

Now, you're asking about not having the ABS system fixed right away. On my car, if the ABS system is not working, it won't be long before I do not have power brakes. The car can still be stopped but doing so smoothly will be very difficult. Pedal effort will be very high. You will still have power brakes, but I don't want other people to think that unless they know for sure.

The other issue with not having the system fixed is the potential for a lawsuit. First you must understand that for reasons I won't go into right now, the ABS feature on my car makes it stop REAL quickly, even on sand, but that is not their purpose. Their only purpose is to maintain steering ability. Skidding tires have no traction and prevent you from steering away from obstacles. If the other guy runs a red light and causes a crash, a lawyer or insurance investigator will find out you have a feature that could have prevented the crash, but it wasn't working and you knew it. They will use that to shift part of the blame for the crash onto you. They'll argue you were less able to avoid the crash, and they will be right. Every mechanic has that potential for lawsuits in the back of their mind when they work on your car.
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Tuesday, April 5th, 2016 AT 9:58 PM

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