scranage

When I changed my D36 2.59 to a D44 3.07, I changed the VSS driven gear to a purple, and all was well. The speedo jives when I drive past a radar sign.

I was just looking in the parts manual and noticed I was also suposed to change the VSS sensor from a 10456091 part (for use with the old 2.59 white gear) to a 10456092 for use with the new purple gear. Now I was under the car on my back at the time, but I recall the new gear was a comfortable slip fit on the old VSS shaft, and my calibration seems to be right on, so does anyone know why the different VSS part number is called out?

Is not a big deal to change out the part, but I'd like to know why I need to. TIA

WVZR-1

There are two speed sensors and yours is for driven gears with tooth counts 39 or less. The other part 10456092 is for tooth counts 41-45. The housing is somewhat of an eccentric to allow the pitch of the gears to mesh properly similar to a ring and pinion. You've got a mesh of sorts but it likely won't last! I'd try to locate a sensor of the proper part# so you don't wear out the tooth cut on the drive gear, attatched to the outputshaft and need to do a replacement of it. A great deal more work! On the end of the sensor in the ceramic housing you might see 35-39 on yours and the one you want is cast 41-45.

The sensor you need is '91 and newer only. There's other #'s with similar ID's 35-39 and 41-45 but it's a different PM generator. Yours needs to be from an A4 I believe.

CentralCoaster

The two speedos are eccentric to get the proper gear mesh for different ranges of gear sizes.

To use a small-gear speedo with larger (40+) driven gears, simply rotate the speedo sensor 180degrees and reinstall it. You'll also have to pull the holddown clamp off and snap it on the other side of the speedo.

It surprises me that it works now, but it will still wear out quickly if everything is as you stated.

WVZR-1

On the ZF's with a different style sensor, rotating the sensor that you've got is likely the only solution but his situation and the availability of the correct parts it might be more practical to do it right. I've got both of the earlier '90 style sensors new, the ones used in the ZF's and haven't inspected them for a confirmation of the 180 degree rotation. I've certainly seen it done and apparently with relative success.

WVZR-1

The new "correct" sensor is quite inexpensive and I'd replace the driven gear again also. The drivens are very inexpensive.
It is somewhat surprising that it does work "consistently". I believe I'd get it "done now"! Both the drive and driven will likely fail if you leave it "as is"! How long has it been together as it is?