chirping noise but only at highway speeds

[MechBob]

There is a reluctor inside your brake rotor,for the ABS.

[gordo999]

There is a reluctor inside your brake rotor,for the ABS.

Sorry, Bob, I should have known that. I'm going to pull the wheel apart, including brakes and wheel bearing to have a look. Thanks for tip. I am a bit slow getting at it because I don't have access to a place to work on the van. Sometimes I have a driveway but right now I'm parked at the side of the street and it limits my work...for safety's sake.

Some guy has already smashed his passenger side mirror into my open door and had the nerve to claim I hit him. Called a cop to help out and I handed her the mirror assy which was at the side of the road. Saw where he lived when he pulled in his driveway. She knocked on his door and asked, "Is this yours"? The guy came clean and admitted he got a bit too close to my door. He had about 2 1/2 car widths to pass me and he did it within hitting distance of my open door. You take your life in your hand around here working on the street.

[sixsix]

Geez, one of 'those' threads... ya know.

Hi 66 ...

Well, really, you should know what I mean - trying to describe sounds and where they are coming from...
Sound File, Video... NO. Hello... so... yup, "one of those threads".

Pull off the rotor and dump the rock out of the reluctor.

Are we still talking alternator? Don't see any smileys so I presume you are serious or have a very dry sense of humour.
The only reluctor would be in the distributor housing and no rock is going to get in there. Already listened to the front and rear bearings on the alternator with a long vinyl tube, no rock sounds, quiet as a mouse with heavy breathing issues. No noise at high RPM either.

Not a big Gen II Motor nut, but isn't there a Reluctor on the Crankshaft - timing something or other - CPS, I dunno.
The one in the Dist for the rotor/etc - they are a type of inductive coupling w/o touch. Maybe it is sometimes called a reluctor, but not heard of it.

Someone will surely ( and politely ) come to our/your rescue.

I hear that noise just now... yeah, turn a little and lift that leg, hold the tongue right... LOL

[Leeann_93]

You can't go by the outer pad. The inner pads on my '05 were toast though plenty of meat on the outer pads. PO had neglected the slides and they didn't slide.

And yeah, rocks and rust and crap get into the reluctor wheel for the ABS and make a helluva noise.

[gordo999]

Not a big Gen II Motor nut, but isn't there a Reluctor on the Crankshaft - timing something or other - CPS, I dunno.
The one in the Dist for the rotor/etc - they are a type of inductive coupling w/o touch. Maybe it is sometimes called a reluctor, but not heard of it.

I had never heard the term either and I'm an electrician. MechBob could likely explain it better than me.

Reluctance is a term that applies to magnetic circuits and is the equivalent of resistance in an electrical circuit. In an electrical circuit, the electromotive force drives a current through a resistance. In a magnetic circuit, the magnetomotive force drives a magnetic field through a reluctance. The reluctance could be an air gap or a metal pole piece.

When you have a bar magnet with a coil of wire wrapped around it, and you cause the magnetic field to change, it induces a voltage spike in the coil. From what I saw of the ABS sensor it has a single pole piece in a package and it likely has a coil wrapped around a magnet. Alternately, you could use a plain metal rod with a coil wrapped around it and a DC voltage fed to the coil. That would create an electromagnet.

A reluctor is defined as a geared wheel where each tooth interferes with a magnetic field as the metal gear tooth passes it. On my 2001 Safari, the geared wheel teeth for ABS, attached to the rotor hub, run past the pole of a magnet, attached to the rock shield behind the rotor. Each time a gear tooth passes the magnetic pole piece it changes the reluctance of the magnetic circuit which cause an electrical pulse in a coil that is wound around the magnet with the pole piece.

The speed sensor, on the other hand, located in the transmission extension housing has a geared wheel rotating past a horseshoe magnet pole pieces, according to the Haynes manual. Maybe someone with a real manual could post the ABS reluctor circuit and I could interpret it. Or Bob.

The older distributors used points, as everyone knows. and the points were activated by a cam on the distributor shaft. Each time the cam operated the points, they would interrupt the primary of the coil causing a high voltage pulse in the secondary. That was fed via the rotor cap centre pole to whichever spark plug was connected by the rotor.

I am not up on modern systems, but I understand there is a sensor on the camshaft and another on the crankshaft. Each sensor is a Hall Effect sensor which is a semiconductor circuit that responds to a magnetic field. Both signals are sent to the computer (VCM) and it decides when the coil or coils should fire.

The Hall Effect sensor is not really the same as a reluctor but similar. Apparently the vehicle speed sensor is mounted on the transmission tail housing and has a gear/sensor system that seems to be a reluctor. It sends a series of pulses to the PCM and the pulses are conveted to mph or kph.

There seems to be a sensor in the distributor housing on the 2001 Safari but I don't know what it is for. It may serve as a reference marker for the distributor shaft position.

[gordo999]

You can't go by the outer pad. The inner pads on my '05 were toast though plenty of meat on the outer pads. PO had neglected the slides and they didn't slide.

And yeah, rocks and rust and crap get into the reluctor wheel for the ABS and make a helluva noise.

There was nothing in the reluctor wheel unless it fell out during disassembly. My brake pads looked somewhat grotty. They are metal-based and the surfaces seems pock-marked.

You are right about the inner being a bit more worn than the outer. I guess that's because the caliper piston is pushing on it directly. I noticed that the inner pad assy had one of those depth gauges that wipe against the rotor when the pad gets too low. I did not see a general worn edge on the indicator but one edge seemed to be worn. Maybe it was just starting since the indicator gap was close the the thickness of the pad.

I was surprised at the condition of the pads since it seems as if I replaced them recently. I bent the indicator out of the way and I will have to change the pads soon. Don't know how long they are expected to last. I don't drive the van much so I think the pads will likely last till spring.

[gordo999]

There is a reluctor inside your brake rotor,for the ABS.

Found it Bob, thanks. Did not see any rocks in there, I took a fine metal brush and ran it through the gaps between the teeth. The problem may have been the pad depth gauge. It seemed to be just beginning to hit on one edge. I won't know for sure till I get out on the highway again.

[gordo999]

Squeak/squeal seems to be gone. Thanks to everyone who offered advice.

It was definitely in the front passenger side wheel and most likely related to the brake pad level indicator. As I said, the metal device is on the inner pad and seems to be on a slight angle with the rotor and one edge was shiny. I did not think it would make that much noise.

While I was in there I examined and repacked the wheel bearings. I rotated each roller in each bearing to make sure none were damaged or sticking. All of them turned freely.I also stuck some lube on the area of the inner pad where the piston contacts.

The long guide bolts that go through the pads were pretty gunked up as well. Cleaned them and applied some lube.

The wheel was turning freely before disassembly but there was considerable drag from the brake pads. After reassembly, the wheel turned much more freely with the brake pads still contacting the rotor. I am wondering if maybe the piston had gunk around the edges which prevented it retracting. To get the pads back in I used a large c-clamp with a block of wood to drive the piston all the way in.

[Mmusicman]

I bent the indicator out of the way...
It was definitely in the front passenger side wheel and most likely related to the brake pad level indicator..

Two pages and ALL this work and discussion over a brake pad wear indicator??? ...
Well at least thanks for sharing the solution.

[sixsix]

Geez, one of 'those' threads... ya know.

Hi 66 ...

Well... see, there ya' go. Brake Chirper... really!

[gordo999]

Two pages and ALL this work and discussion over a brake pad wear indicator??? ... Well at least thanks for sharing the solution.

You're a music man, your ear should be well atuned to resonance. I've heard the brake chirper sound before but it was a distant sound, nothing like this. I reckon the chirper has a mic with a 100 watts Marshall stack.

Did you hear about the Tacoma-Narrows suspension bridge that started vibrating like guitar strings and tore itself apart? That's a case of natural resonance causing amplification of forces so strong they had the bridge deck vibrating like a guitar string. I'm wondering if the chirper started vibrating in a resonance mode and amplified its importance out of proportion.

https://www.youtube.com/watch?v=j-zczJXSxnw