After a fairly rough day of trail riding, on the way home I noticed a strange front end shimmy.

At say 40 mph, every 5-7 seconds I get a hard right or left pull. If I wasnt holding the bars good it would be enough to send it off the road. I jacked up all four, ran it, no strange vibrations. No bent wheels. The only thing mentionable is the left side boot on the inner axle is torn, has been for a few rides now.

Any ideas? Thanks, Chad.