I pulled the sender out when I dropped my rear-end, and briefly
eyeballed it to try to determine how it worked. The sender looks a lot
like an ABS sensor. It just sits in the hole and has no moving parts.
Inside the diff, the mass of metal (ring gear unit) has big steps on
it (not a toothed wheel like ABS).
Clearly, you are unaware of the level of cluelessness out here! I
dunno what an ABS sensor looks like, and I dunno what an ABS toothed
wheel looks like. So, since we have finally identified someone who
has actually laid eyes on the parts we’re talking about, let’s start
slow:
Am I correct in understanding that the sensor installs in a hole in
the diff housing, so that removing the sensor leaves a hole into the
housing? Like, could you add oil through this opening?
Whereabouts is the sensor located on the housing?
Is the sensor a simple mount-and-forget item, or is the installer
expected to shim it properly to establish a clearance between the
sensor and the moving parts within the diff?
Am I to understand that the “big steps” you are talking about are NOT
the teeth on the ring gear? Must we conclude that the ring gear for
this car is therefore special, or are these steps on a separate part
from the ring gear? Or did the earlier gears have these steps, and
some smart guy just figured out how to devise a sensor to read speed
from them?
If anyone can make any sense out
of how it works, with this small amount of information, God bless
them.
Actually, it’s not all that difficult to devise ways this thing might
work. It could, for example, work the way the OPUS ignition pickup
works: a balanced transformer, and the “steps” cause an imbalance and
change the output. Or, they could work like the CEI pickup, in which
the flux changes caused by the steps opening and closing a gap in an
iron core of a magnetic field generate currents in a coil. Or, as is
most likely, they work the same way the ABS sensors work, however
that is. The difficulty lies in actually knowing which is the
correct answer!
Meanwhile, someone can answer this question: once ABS brakes were
fitted, why did the car need a sensor for the speedo at all?
Couldn’t a signal from the ABS sensors have been split off and used
for speed? Or, and this would qualify as a “DOH!”, is that what
we’re talking about? Is this speed sensor the device used to control
the rear brakes on an ABS car?
– Kirbert | Palm’s Postulate:
| If anything is to be accomplished,
| some rules must be broken.
| – Kirby Palm, 1979From: “Cohen, Peter” peter.cohen@unisys.com