running a redline 400, but the driver side spindle keeps loosing up. What can I do to keep them tight?

Do you have the correct spindle? Is the arm worn?

Issues are nomally due to worn parts or incorrect installation. Check parts for being worn, if ok then clean real good, use locktight on bolts and run down tight. I normally over tighten everything because I'm heavier and have incredible cranking power. ( at least for the first 10 feet. )

Post a pic of the spindle if you can, if it is not one of three special ones you wont be able to get it to work as a rider!