I have a t-56 from a 94 Z28 in a street rod that I own and have it hooked up to an after market speed o (STEWART WARNER). The problem that I have is that when it is in neutral the speed o is registering 10-20 miles an hour or faster when I rev it up. Is there any why to stop this??? I have tried to get help from Stewart warner but that is as useless as **** on a bull.
Thanks
Angelo

 

the electronic pickup on the T56 shouldn't generate any signal when the driveshaft isn't moving (rev'ing the motor should have no effect on the VSS signal) . I've seen elect-mech conversion boxes output noise if they don't have a good power and/or ground connection, this sounds like it may be happening to your aftermarket speedo. Check and redo all the power/ground connections to your speedo and see it that cures it. Make sure the engine/trans/body grounds are all present and in good shape. Finally, check the VSS wiring from the sensor on the trans, all the way to the speedo. It may have worn through and shorting out on the body.

 

All the wires are new. I got good grounds.The thing that I dont understand is that when I step on the clutch it stops. I first thought that was that it was picking up a signal from the distributer.

 

Did you happen to use "Ron Francis" hotrod wiring kit on your project? I had this exact problem on an old ******/TPI hotrod. It had a noisy power line. I know you said you have good ground, but there's definitely something puting noise on your speedo. Try to run a dedicated power and ground wire from the battery or fusebox just to test. If it is noise, you should also be able to unplug the VSS wire from the transmission and still see the behavior you describe..

 

i used American auto wire. I did try hooking up direct no change. Did yours stop when you stepped on the clutch?

 

It was actually an automatic I was working on. But as I've mentioned, unless your driveshaft is turning while you're troubleshooting all this, it has nothing to do with the transmission.