4Runner wheel bearing vs. Tacoma question

That's not how the hall-effect ABS sensors used in 2nd gen Tacomas work. The magnetic tone wheel on the back of the bearing assembly is what the sensor reads speed and direction of rotation from, not the bearing rollers.

 

By personal experience with these bearing assemblies, and my knowledge of the ABS system in these trucks, I disagree. The way this system works is exactly as I described.

 

http://www.hella.com/ePaper/Sensoren/Raddrehzahlsensoren_EN/document.pdf

The lower half of page 2 says it better than I can. And there are plenty of other reliable sources on the internet on how "Active" or "Hall Effect" ABS sensors work. Then go throw a pinch of iron filings at the back of an old 2nd gen bearing assembly, and you just might learn something new.

Of course, you can blissfully continue in your ignorance if you choose, and I'll be content to know that the members can see the truth, rather than the misinformation you posted. Either option works for me.

 

That's not a magnetic tone wheel on the back of the bearing assembly. That is a plain old magnet of uniform polarity by itself. When placed on the bearing the ferromagnetic rollers alter the field so it has alternating intensity exactly as @BamaToy1997 describes.

EDIT: now I don't think it does, see down thread. Leaving rest of post so responses make sense.

Try actually learning how various automotive sensors and pick-up schemes work rather than Googling one document that isn't even model specific.

But of course if you want instead "you can blissfully continue in your ignorance if you choose" because the rest of us "know that the members can see the truth, rather than the misinformation you posted".

As to the larger issue of a potentially new bearing with a different number of rollers if that bearing doesn't use a uniform polarity magnet like the older one and instead uses a more conventional tone ring then that could be a way to make a bearing with a different number of rollers that is still compatible with the ABS system.

 

Let me guess...right rear is still going.

 

Im actually not sure. But it is one of the rear ones. Is there a reason why these would last longer?

 

So Toyota is wrong about how they work too??

http://www.customtacos.com/tech.old.../06toyrm/06toypdf/06rmsrc/rm2006ta/041006.pdf

 

Most weight is in the front, and our Tacos are left-side heavy (gas tank, driver, battery, steering) so right-hand turns put more wear/tear on front left bearing than front right. So, all all other things being equal, bearing will tend to wear out in this order: LF, RF, LR, RR.

 

Interesting.. never thought about this much but that makes sense

 

That doesn't say *how* the alternating field that the sensor picks up is created.

You are saying it is because the ring itself contains alternating pole magnets - which is definitely true for many "ABS rings" in many vehicles.

He's saying that at least for the front wheels on the Tacoma it is the combination of a fixed polarity magnetic ring with the rollers behind it. What he is claiming definitely creates an alternating field the sensor can pick up.

I don't have one apart in front of me to confirm one way or another, nor do you appear to. He does on the other hand assemble these all the time so I'm going to assume he's got the function of it down.

And as I said before, the claim that this prevents a bearing with a different number of rollers is not something I agree with. I believe you could make a bearing with a different number of rollers and then use a ring constructed as you describe to make the ABS sensor happy. But I don't know that for sure of course.

 

@landphil - thinking about it more I'm not sure the roller scheme would produce a signal that can distinguish forward and reverse - which I'm fairly certain the 2nd gen can do. I wonder if he's confused between 1st and 2nd gen bearings. I'll need to dig further.

 

I have in fact observed in person the alternating pole magnetic tone ring on these bearing assemblies, thus my suggestion to observe it with some iron filings.

But hey, maybe I just searched it on the internet. Maybe that's how I got to be the ABS specialist at the shop I work at, 15+ years of full time Googling. Or not. I'll let you assume.

 

First gens use a steel tone ring and an inductive pickup sensor, same as the first gen Tundra I'm working on at the moment.

And yes, the sensors on 2nd gens do read forward or reverse rotation.

 

And I haven't so I'll defer to you. The sensor location doesn't look right for a single magnet plus rollers to work as a good signal source either.

Iron filings is a good suggestion too because closely spaced poles on the ring would act on the large scale as a weak N/S pole magnet as he described in another thread I found. So it would be easy to get confused if you didn't examine it carefully.

Thanks for taking the time for a detailed response!