Hub ABS Ring Teeth Greasy

[J_C]

I recently had my ABS sensor go out on my '98 4WD, front left wheel. No ABS light but it exhibited the typical activation of ABS when slowing down to a stop around 5 MPH.

I put a new ABS sensor in and haven't had the ABS activate since, but while doing that I noticed something. Looking down in the sensor hole in the hub, the sensor ring teeth had grease between each tooth, not a huge amount but never the less there.

It's not gooped up all around the ring, fairly neatly sitting between the teeth. It is the original factory hub. It has no play, no noise, and spins smoothly.

Does this mean the bearing has blown an internal seal and is throwing grease inside the hub, or is some grease between the teeth normal?

 

[imp]

I recently had my ABS sensor go out on my '98 4WD, front left wheel. No ABS light but it exhibited the typical activation of ABS when slowing down to a stop around 5 MPH.

I put a new ABS sensor in and haven't had the ABS activate since, but while doing that I noticed something. Looking down in the sensor hole in the hub, the sensor ring teeth had grease between each tooth, not a huge amount but never the less there.

It's not gooped up all around the ring, fairly neatly sitting between the teeth. It is the original factory hub. Does this mean the bearing has blown an internal seal and is throwing grease inside the hub, or is some grease between the teeth normal?

@J_C
I also found grease in there when I replaced the sensor. Figured they grease the sensor when inserting it, so went ahead and inserted the new sensor, which also had a daub of grease on it. No problems. imp

 

[fast_dave]

JC -

No worries, it's hub grease and it's normal.

Hub grease will get thrown when it's hot, and will gradually build up and coat the face of the abs sensor, which in turn will attract and hold all sorts of crud (i.e. worn down bearing steel), decreasing it's efficiency and thus your ABS System efficiency.

So, here's what you need to do - I do it every time I replace the front brake pads as normal brake system maintenance since I'm "right there".

Unbolt the one nut holding the ABS Sensor, remove it from the hole in the hub, and wipe off the face of the ABS sensor.

Then, when the ABS sensor is removed, turn the brake roter by hand, and through the abs sensor hole clean out the "valleys" (as opposed to the peaks) of the ABS sensor ring with either a long q-tip or a sharpened end of a wood chopstick.

I use the sharpened end of a wood chopstick, and wipe the grease off on a rag, and repete - proceeding to the next sensor ring "valley". It's tedious but eventually you will go 'round 360 degrees and it's done.

Whatever you do, DO NOT spray parts cleaner in there as you will break down the hub grease!

Hope my thoughts are clear and hope that helps!

Merry Christmas & Happy New Year!!!

PS - With regards to the rear differential, when I'm changing brake pads, I also remove the ABS sensor from the top of the "pumpkin" and also wipe off it's face. It will be coated with a fine mixture of gear oil and worn bearing metal.

 

[J_C]

Thanks. I guess it could be normal but I didn't see any reason why there would be grease in that cavity, doesn't seem to need any outside of the bearing or is the bearing not sealed on the inside at all?

There was a minor amount of goop on the end of the ABS sensor, but at that point I already had a new one and they were only $20 for a two pack on Amazon (warehouse deal). I might've tried cleaning it off and reusing it out of curiosity whether that would be all it took, but the old one broke the shell off and was stuck in the hole. I ended up picking a few small pieces of it out of the hole before resorting to heating a wood screw with a torch to turn into it, melt the plastic onto the screw and extract it.

It seems they were poorly designed, having only one o-ring 2/3rds of the way down in a hub hole facing upwards, so water gets in, sits there at the o-ring and rusts the hub hole till they get stuck. I did not detect any traces of grease around the old one but it was pretty gnarly looking after melted for extraction plus the rust on it.

I put a bead of thick silicone grease on the base of the new sensor to hopefully keep water out, and a trace on the sensor shaft to make removal easier. I might've tried putting an o-ring on the base too if I had a spare just the right size but I didn't.

 

[fast_dave]

J_C -

It's normal in the sense that the hub drivetrain heats up, a small amount of grease slips by the bearing seal, and works it's way out to the ABS Ring. And as that grease is thrown off the ABS Ring, it lands on the ABS Sensor face.

What's more important is to to clean off the face of the ABS Sensor, as well as the "valleys" of the ABS Sensor Ring.

The reason is that the hub grease isn't dielectric, and therefore it insulates (lessens) the signal between the sensor and the ring - resulting in lessened ABS performance.

HTH!

 

[J_C]

The more I think about it, the more the grease looked like it was put on the teeth when manufactured. It seemed very evenly distributed, and pretty clean (light golden color) not like it was being flung around. I mean if there was a ton of grease everywhere I could see it still clinging between the teeth but not so evenly deposited there in the first place.

Even so the grease coming out of the bearing seems plausible because I still can't think of any reason that they'd grease a sensor ring, unless that was cheaper than putting a rust-deterrent plating on it?

At some point I'll probably take the other front wheel off and see of the other sensor will come out without breaking. Even if it does break I have a 2nd sensor and can check whether that ring has a similar grease deposit.

Something else I've been thinking about is that when I pulled that sensor out, it came out VERY easily once the bolt holding it was out, leaving the broken shell in the hole. I don't think I pulled anywhere near hard enough to break it so I'm wondering if it was already broken off... yet it did still work to some extent, the ABS was only kicking in maybe 10% of the time and the element inside the sensor shell looked intact, relatively clean shiny enameled wire on it.

Just came across this:

GM found that it's not always the sensor that is the problem. Rust builds up between the sensor and the hub causing the sensor to lift slightly. This increases the air gap between the sensor and the tone ring causing the low speed activation you've described.

I might be putting too much thought into this, it was only a $10 sensor and not that hard to replace besides the broken off piece being stuck in the hole. Then again maybe the rust broke it as well as causing it to be stuck.

 

[fast_dave]

Hi J_C

FWIW - In my Ex's case as well, the golden colored grease is on the ABS sensor ring every time I've replaced the front brakes (and pull/clean the ABS Sensor) which according to my service records has been is 3 times. Each time I've cleaned it off the sensor and sensor ring it's re-appeared.

As far as the broken shell on your ABS sensor, I wouldn't doubt if some heavy handed tech, trying to solve an ABS issue, broke it while trying to get it out.

As you saw, the ABS Sensor is relatively fragile - it has a plastic body, surrounded by a thin o-ring providing some minimal "friction fit / water protection", all held down with one small bolt.

 

[J_C]

Topic update. Still don't have ABS false activations going forward, but now do turning in reverse backing out of my driveway with the brakes on, going 5 MPH if that. Odd, in that previously it didn't do it in reverse IIRC.

Figured the hub is probably shot, even though I didn't notice any play in it. It's the original so I got a new one. Could be that the passenger wheel sensor is going out but I got the hub on closeout at a good price so I figure I'll need it eventually anyway.

Haven't had a chance to put it on yet but took the ABS sensor off the new one and noticed there is (at least on this Timken aftermarket hub) grease completely filling the ABS sensor ring teeth, and liberally applied to the ABS sensor hole and end of the sensor.

Now something I hadn't thought about before. Is there a seal behind the front hubs on a 4WD '98, in the knuckle that needs replaced if it's missing? I see a Timken and SKF part # 25013 for "Front; 4WD" on Rock Auto?

I know there is a dust shield thing on the axle but what I'm talking about looks different than that (AFAICT)?

For some reason I had assumed the bearings themselves were sealed and there was no additional seal, that Rock Auto just made a listing mistake, but Rock Auto lists a different part # for front on a RWD (only) version of this model year, BUT the SKF part # above cross references to Motorcraft F57Z1S190BB on Rock Auto, which on the following ebay listing shows it is for a non-driven wheel bearing setup, not an integrated hub?

1998 FORD EXPLORER 4.0L V6 SOHC Wheel Seal | RockAuto

FORD OEM 1997 Ranger Brake-Front-Grease Seal F57Z1S190BB | eBay

 

[J_C]

Now I think I see the situation. There is a metal "seal" piece on the CV axle, and there is a rubber/other mating piece in the back side of the knuckle.

These two, can rub and create noise, should have some grease between them because all by themselves can become an undesirable noise source, but do reduce the amount of grime that gets to the sealed hub bearing so with less grime getting to it, less wear on the outside of the seal and less chance of it getting in the bearing.

 

[imp]

Now I think I see the situation. There is a metal "seal" piece on the CV axle, and there is a rubber/other mating piece in the back side of the knuckle.

These two, can rub and create noise, should have some grease between them because all by themselves can become an undesirable noise source, but do reduce the amount of grime that gets to the sealed hub bearing so with less grime getting to it, less wear on the outside of the seal and less chance of it getting in the bearing.

@J_C
These seals are not present on my '04 Gen 3, but were present on my '96 Gen 2. I thought them to be a worthwhile safeguard. imp