Most of the four groove Jackson Racing pulleys had a 0.8" offset, however a few of them had a 1" offset.

Because the 4 groove Jackson Racing pulleys we offer are the more common 0.8" offset, this 0.2" spacer must be used with our pulley if your system has the 1" pulley offset or your belts will slip.

If you aren't sure which offset measurement your Jackson Racing kit has then you may want to purchase this just in case or you will throw belts due to the 0.2" offset difference.

Diagram showing how to determine your offset.