SC_Highlander

I've had my racecar apart for the last 4 months making some upgrades that include:

swapping in an AP2 rear subframe
upgraded diff
fuel cell and new fuel plumbing

Well, last night, I fired up the car for the first time with the new fuel system. After chasing some leaks, I noticed that the speedometer fluctuates between 4 and 8 mph. This is with the car on a lift without any wheels mounted, and with the transmission in neutral.

I've checked the connection to the sensors on the transmission and everything looks ok visually. Any ideas what might be going on there?

SheDrivesIt

Living proof that "that car looks fast even standing still"?

AllHailKingHomer

Race cars don't need speedometers rip it out!

SpitfireS

The rear hubs do not spin?
(handbrake on)
The propshaft does not spin?

Otherwise, check the ground connections.
At the driver's footwell area / ECU, engine & trans grounds, etc.

Do you still have the OEM final drive?
IOW: no Yellow Jacket or Yellow Box?
IOW(2): never messed with the speed sensor wire? (IIRC blue/white)

camuman

bwahahaahahaaa.

Slows2k

The VSS input is taken off a gear in the trans. Even if the trans is in neutral the gears inside are still spinning. Put the e-brake on at the speedo should read 0.