add rotation from float but object flips between 0 and 180 only

[t4d]

HI  I got a odd issue,. I'm missing something here  I have a locator that I'm rotating and a wheel mesh object as the child.

but the wheel mesh only rotates between 0 and 180 or -180 to 180 flips back

I need wheel rotations to follow the distance travelled. and hit this ?