I bought an '89 zilla last summer. The front wheels bounce up and down when riding on hard, flat surfaces. I thought the wheels or tires were out of round. I bought new wheels and tires and the problem still exists. The ball joints and all the bearings in the front end are good. I just finshed restoring another '89 and it has the same problem. The less weight on the front end the more it bounces. Anyone know what it could be?

 

Thats a tuffy,but my guess would be that your front shocks are to stiff.

 

I've seen this before also.... look at the shocks! Usually need rebuilt/replaced when this happens. (The stockers can be rebuilt if you have machine shop access... otherwise, you'll need to replace)

 

I had that problem when I first bought my '88 LT500R. I replaced the nuckles at the end of the A-arms and also replaces a slightly bent rear axle. The problem went away. Have you checked the axle (maybe the problem just feels like it is in the front)? Are your front wheels aligned? Have you looked at your spindle (I bent mine last year and it put the whole front end out of whack)?

 

Triple, my axle and spindles are straight. How did you align your front end? The manual says to set the toe-in with a rider sitting on the bike. I've got about a half inch of toe-in. The quad pulls to the right slightly. Which tie rod needs to be adjusted and which way(in or out) does that wheel need to go to straighten it out?

 

I set mine up with as close to zero toe in as possible. It seems to work fine even wide open on pavement. I don't use any elaborate method.

!) Turn the handlebar straight and keep it straight
2) Looking from above and from the front and the rear, I check each of the front wheels to see if they are aiming straight with the rest of the atv (or I turn the tie rods untill they are).
3)Once the wheels apear to be straight, I measure the distance between the center of one front wheel to the center of the other front one. I make the measurements on both the front sides and the back sides of the front wheels (you should have a second person to ensure an accurate measurement). These measurements should be equal for zero toe-in. Again, use the adjustments in the tie rods for this procedure. If you loosen the locking nuts at the end of the tie rods and turn the rod itself, you will quickly discover how they operate.

How do you know your axle is not bent. Mine had a very slight bend that could only be seen with the axle removed and rolled across the kitchen counter (or equally flat surface). Also, are you positive that there is not any slop in the ball joints at the end of your A-arms? A small amount of play seems to have a large effect on front end stability.

 

I decreased the preload on the front shocks. This got rid of most of the shaking. I rolled my axle on a flat surface and its strtaight. There is no play in the balljoints.