45-50mph vibration

What I do is, jack up front end. Pick all stones out of the tires, (just for safety). Visually inspect the entire tire for any obvious signs of a broke or shifted belt, or irregular wear that will junk the tire. Anything like that, we are already done. Anyway, we have a spin balancer that is basically an electric motor with a flywheel on it that butts up to the tire and spin up the tire to actual highway speed, (now you know why I pick out the stones, LOL). Sometimes you don't have to spin it up that fast, what ever it takes. But as it is spinning I take a tire crayon and hold it to the tread face of the tire as close as it can so the crayon barely touches. The part of the tire it is touching and leaving a mark is the high spot. Now I stop the tire from spinning and move the high spot to the top or 12 o'clock. Now I inspect the locate tabs on the hubs and usually you will see a small gap between the hub finger and the inside of the rim. Next will simply loosen the wheel nuts and let the wheel resettle and retighten and test again. 90% of the time this is all that is needed. Sometimes it is trial and error and may take a few attempts. There are some really great products out there to help center wheels properly, the self centering wheels nuts are the easiest.

 

si i had the same problem on my 05 volvo..45-50 mph i felt like somebody is shaking me like the wind is hitting me or the road has bumps..i replaced the steer tires got it balanced and 3 wheel alingmant and that was it..no more shaking..i hope this helps..

 

Your toe in needs adjustment. The front tires have a gyroscope effect that can make the wheels shake at the speed you describe if the toe in is wrong. The pull against the tie rods is fighting the gyroscopic pull at that speed causing the shake. As you go faster the gyroscopic pull takes over and the shaking quits. Hope I described that right, the alignment book is at home, couldn't reread that section to answer your question.

 

I know everything seems tight but there is play in the bearings and king pins.

 

I agree for the most part, but if he is going to get it aligned have them focus on caster and set back. Both of these could cause a shimmy.

 

Put a piece of tape on the back of the steer tires as high up as you can and still get a tapemeasure thru to theother side and put a mark on it. Measure between the marks,drive ahead til the marks are on the front and remeasure. Should be 1/16 inch less on the front, no more than an 1/8 inch. Loosen clamps on ends of tie rod and turn 1/8 to 1/4 turn for each 1/16 inch you need. You can order the alignment books from md alignment. They're from the Des Moines, IA area.

 

alignment and bearing check. Consider a slightly twisted driveshaft.

 

Check wheel bearings first.