esuarknod

90 CRX - DX (manual tranny)
my speedometer does not work consistently.

when engine/tranny cold, speedometer bounces up to about 20mph max, and then as the engine/tranny warm up, the needle drops back to zero and stays there

I have checked the following:
- replaced cable from speedometer to tranny
- speedo sensor (VSS) on back of speedometer pulses 4/rev correctly
- speedo works when cable spins (drove cable w/ electric drill, results consistent)
- replaced boot & clip on tranny, and cable is snugly plugged in properly
- checked speedometer assembly that pulls out of tranny (spins & gear teeth fine)
- speedometer gear on differential in tranny look okay (no missing teeth, etc.)

Only thing that seems strange is that when I had the speedometer assembly pulled out of tranny and was inspecting the speedometer drive gear on the differential, I could MANUALLY rotate that speedometer drive with my finger without the front wheels moving! It appears that they speedometer drive gear on the differential in the tranny has worked itself LOOSE!

Has anyone ever seen this problem before? Does this sound plausible? Is there an easy fix, or am I looking at having the pull the tranny to fix it? $$$

I have been looking for an aftermarket replacement speedometer, but can't find one that does not need to use the VSS already on the car. If my differential has a loose VSS drive gear, I don't have a VSS working, and will need an external one (ie. magnets mounted on drive shaft with magneto sensor to produce a speed sensitive pulsing signal). I installed such a sensor arrangement for a cruise control back in the early 80's, but they don't sell cruise controls like that anymore (they all want to use the built in VSS signal now ).

Any ideas? Any help with the tranny problem or suggestions on an aftermarket speedometer would be very welcome. THANKS!