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ABS damaged during wheel bearing repair?

Hi! I have a 2006 VW Golf with 140,000 miles. Last week took it to the shop to have a wheel bearing replaced. Mechanic also replaced the wheel hub. When I left the shop I discovered a new problem that had not previously been there. Now the Anti-lock brakes are kicking in at the very end of a soft stop on smooth, dry roads and even in my garage. This happens about 20% of the time, but never during a hard stop. I took it back to the shop on Monday and mechanic could not find anything and was perplexed. The question is whether the ABS sensor could have been damaged during repairs and is the car safe to drive?

Also, what is the remedy? Do I need a new ABS sensor or can this be repaired? I have another appointment on Monday.

Was this in the front or the rear?

The hub has a tone ring for the speed sensor and all of that is integral to the operation of the ABS system. So the work and the ABS activation are probably related. But how won’t be particularly clear. If something just went completely wrong then the ABS light would be on all of the time with error codes stored in the computer and the system wouldn’t work at all.

What the system actually does is monitor the speed of each wheel. If it detects any variation among the wheel speeds, the computer basically starts variably pulsing the brakes to try to keep each wheel spinning at the same speed. Low speed, dry surface engagement is not supposed to happen, but will often come from some small and possibly imperceptible problem. I once had this issue that disappeared when I got new tires. (The old ones were worn differently side to side).

It’s possible that it is a complete coincidence, but is more reasonable to assume that something is slightly off after the bearing / hub work. Do you know if the speed sensor tone ring was replaced? It may be integral to a new hub, but I’m not sure. A small defect in the tone ring might create this kind of problem.

What is the threshold speed for ABS operation on that car? At walking speed there should be no ABS involvement in the braking. Maybe that hub bearing is not fully seated.

Thanks guys for your feedback! I don’t believe the tone ring was replaced, as I wasn’t charged for it. As far as threshold speed, not sure what is normal for this car as it rarely kicked in before. But now it is happening when I am almost at a complete stop.

This might be a dumb thought, but I wonder if they forgot to plug the sensor back in?

I’m pretty sure that a new hub and/or bearing-hub assembly would have come with a new tone ring, so it wouldn’t be listed separately. Like I said, there is probably some really minor defect, or as Rod Knox noted, perhaps the hub didn’t get correctly seated. Either way, it is probably a symptom of the work.

If you only had one side done, then yo might actually consider the other side. Wheel bearings see the same stuff over their lifetimes and when one is gone, the other won’t be far behind. So I would also wonder about some small defect in the bearing on the other side

On some newer vehicles, the tone ring is INSIDE the bearing. If the bearing gets installed “upside down” . . . there will be problems with the ABS

I went and looked them up. These are outside.

I expect this is the result of the bearing repair. As mentioned above, the wheel’s ABS speed sensor gadgets are intimately involved with the bearing repair process. If the sensor were just left unplugged, the ABS or check engine light would almost certainly come on. Since that isn’t the case, the speed sensor must be mis-registering the speed. Perhaps the wrong part was used. Or the distance between the sensor and the ring is too great or cockeyed-aligned for some reason. Those are both possibilities. If the mechanic can’t figure out what is wrong, you’ll need to find a mechanic who can. And that means a trip to a dealership or to a VW specialty inde shop probably, the latter preferred. You need a mechanic with VW ABS repair experience and probably some VW-specific scan tool will be required too, so ask if they have this tool on hand before starting down the path with a new shop. Ah, 'twer it were before the days of ABS, life (shortened a tad perhaps) would be so good. Alas. Best of luck.


Thanks for the picture

For the record, I had no idea what the bearing looked like for this vehicle.

When I was at the dealership, my colleague installed a bearing upside down, and the ABS light wouldn’t turn off

These are the bearings I’m talking about

It’s actually very easy to install these incorrectly, if you’re not paying attention

@db4690, funky. I’ve never seen such a thing. (But there’s plenty I haven’t seen).

I didn’t know what these VWs looked like either. Just got curious. And I’m actually assuming they’re the same on the GTI and across all of the other finer model distinctions. We didn’t get the specifics about model and all.

Thanks again for the input. I am going to give my guy one more shot to make it right. He said he was going to do some research. If he can’t sort it out on Monday, I will be looking or a vw shop in Dayton or Cincinnati if anyone knows a good one. Thanks!

So my mechanic ran the scanner today and said everything looked fine. I believe he is a good guy and has done everything in his understanding, but the problem still exists. He said that it is not dangerous and that I should ignore it. I am not comfortable with that solution. Trying to figure out the best way to resolve this. I have already spent $500 on the wheel bearing repair. Sounds like I need a VW person to look at it, but the problem was clearly caused by the recent repair. Do I send them the bill after I get to the bottom of it with a vw repair shop?

Well, I don’t know what to say about it. It isn’t “unsafe” in the sense that you will get some kind of catastrophic brake failure from it. But it is unsafe in the sense that your ABS system isn’t doing what it is supposed to do. At 5 mph on dry pavement, it’s true that it doesn’t matter. But at 70 mph on a wet highway, it very well might.

If he is being a good guy about it, then I think you just have to start with something like “I get that you say it’s not dangerous. But look at it from my side. Ever since that work was done, my braking system isn’t working right. I can’t ignore that, and think it is safe. I am willing to accept that there might just be a coincidence, but if I take it to a VW dealer and they find it is related to the bearing work, will you help me out?” You now. Or something like that.

Whatever you do, document everything - just in case it comes to that.