The ABS 5mph dry pavement problem...

srlbotanical · February 26, 2006

OK, I know the problem is the front sensors. I've have read all about the low speed ABS problems that plagued our OBS trucks. I need help accessing the darn sensors.

I have a 97 silvey and today I pulled the wheels, lifted the calipers, pulled off the rotors and attempted to get at the ABS sensors.

On my truck the sensor is held on the hub with two small allen screws. The problem I had was the d**n hood/guard that covers the sensor. This guard is held on by two of the three 15mm bolts that hold the bearing/hub assembly together.

I sprayed the three bolts with penetrating oil and could not get them loose with my regular 10" socket wrench. In fact I spun the square end of my short socket extension right off (It was a no-name piece of chit). What can I expect to find when I get these three bolts loose? When the front triangular plate on the hub assembly comes off will this reveal a cogged wheel that the abs sensor reads?

I am getting tired of the ABS coming on at 5mph on dry pavement. Any one with a 97 cleaned up your front abs sensors?

This is driving me nuts!

bronyaur · February 26, 2006

A good quality 6-point 15mm socket and a long breaker bar should get those bolts out. If you remove all three of them the hub assembly should come right out, but sometimes it requires a puller. If you pull the hub, grab the bearing on the back and check it for play. If there's anything but a tight spinning bearing, it's worn, and it's probably the reason your ABS is activating. Not convinced? Clean the mounting surfaces of the hub assembly and ABS sensor, put a small amount of dielectric grease on them, and put it all back together. If the ABS problem persists, you'll need to replace one or both of your hub assemblies. It's happened on my '95 burb and my '99 OBS K1500 truck. It was an easy job on both, but all my bolts came out easy and the hubs fell out without a puller. New hub assemblies with new ABS sensors cost me about $225 each at NAPA.

If you're lucky, cleaning the sensors mounting surfaces will solve the problem.

srlbotanical · March 20, 2006

Do I have to remove the large central axle nut as well to remove the hub? Or will the hub come off after removing the three 15mm bolts?

Thanks,

Steve

larry arizona · March 20, 2006

I consider myself an expert at replacing these wheel bearings as I have done 3 on my 02 Z71.

Like stated above a GOOD 6 point socket like a snap on, mack etc (not craftsman will do it with the breaker bar approach. 1/2 drive will not fit and neither will impact on at least two of the three.

Once you get the bolts out you will have to take the large center nut (36mm socket will do) off. Then either use a puller (they are rusted in there bad) or a trick is to use a wedge and a large hammer and work your way around the perimeter if the bearing and where it mates to the spindle. It takes some hammering but it will wedge out.

One easier but sloppy way of doing it is to bend the shield over enough to get the sensor out and then bend it back in place when done. You likely will not hurt anything.

Good luck

By the way I know on the new body style trucks if you go into the dealer and ask for a discount they will sell you GM bearings with the sensors for $122 plus tax.