Dave_D solved the bumpsteer problem!
 

Dave is the man! :tup: He pointed out that the tie rod was upside-down on the Gio 150 GY6 quad, which caused terrible bumpsteer.

For the unfamiliar, bumpsteer is when a wheel hits a bump and changes direction in the process. The wheel should remain straight throughout the range of suspension articulation, but it's not always like that in the real world (cars and trucks included). It usually results from a tie rod that is a dissimilar length to the control arm, but it can also be due to a dissimilar angle, as Dave pointed out. Read his thread here.

To complement his thread, I took pics of the tire from the top view (before and after) to show just how dramatic the difference is.

This is the wheel unloaded, with the front of the quad on a jackstand. Even at full droop, the wheel remains straight. This is before I moved the tie rod.

http://i158.photobucket.com/albums/t...psaeba9203.jpg

When you jack the wheel up, this is what it does.

http://i158.photobucket.com/albums/t...ps9385766b.jpg

You can see how much the wheel turns to the left when the shock is compressed. To be clear, the handlebars are still pointed straight ahead! :wtf: If you're travelling at a good speed and hit a bump, the quad will dart around on you.

One end of the tie rod was upside down, so I removed it and placed both tie rod ends upside down. The gives the tie rod the best clearance all around.

This is the newly-corrected tie rod.

http://i158.photobucket.com/albums/t...ps7f88903d.jpg

This is the front wheel at full compression; you can see that it still points straight ahead.

http://i158.photobucket.com/albums/t...ps815bb1c3.jpg

After I got the tie rods sorted, I set the front wheels to about 1/8" of toe, and called it done. Thanks Dave! :thanks:

Looks good
Glad to see some before and after pics as I forgot to take them
What a difference

Dave

I forgot to take pics of the tie rod before, because I was focused on the amount of steering angle at full compression. It's severe.

Thanks again! :D

I did take note of dave's thread and had a look at all of ours and they are all mounted from the top.
thanks Dave and Weld.

Midlife, are they mounted from the top on both the inner and outer?

yes they are....all of them all atv's

You're lucky. I've had my 150 since 2007, and it was only recently that Dave figured it out for me.