Violent Shudder
Thread Starter
|
New User
Joined: Apr 2003
Posts: 5
Likes: 0
From: New Mexico
Violent Shudder
I have a 91 F350 crew cab 4x4. Today while I was driving down the road about 35 mph one of my front tires hit a bump that sent the front end into a violent shudder. The steering wheel was oscillating back and forth so badly that the truck was hard to control. The only way to get it to stop was by slowing down to a stop. I had noticed something similar at much slower speeds but nothing like this. I routinely drive to work at speeds of 55 to 60 mph on smooth roads and have had no problems. There is no front end vibration or wobble. The truck has 127000 miles but I have only owned it for the last 6000 miles. Before I bought it I jacked up the front end, checked for any slop and everything seemed to be tight. I haven't had it off road for any of the last 6000 miles. Any suggestions? Can bad shocks cause this? I hate to take it to a shop without some idea as to what might be wrong. Thanks!
Fleet Mechanic
Joined: Sep 2003
Posts: 1,716
Likes: 15
FWIW, I once had a car that I thought the shocks were in good shape. One day at about 25-30 MPH I hit a dip&bump in the pavement. It was a road in a flood plain where the soil under the asphalt softened, so there was a depression in the pavement, followed by a rise where the soil pushed the pavement up. I hit that with a front wheel, and that wheel just took off in a violent shake up and down that slowly damped out down the road.
Obviously a bad shock, right? Well, I did the bounce test many times, always passed. But I could go back to that road and duplicate it. So I went ahead and replaced the front shocks anyway. Then went back to the bump... problem solved.
I learned from that that a shock may act normal for a bounce or two, but if hit hard enough it may give up damping for a while. And an undamped suspension can go wild if struck hard enough.
With a heavy solid axle like you have, you have a lot more unsprung weight up there, once that weight gets bouncing up and down with a weak shock, look out!
Obviously a bad shock, right? Well, I did the bounce test many times, always passed. But I could go back to that road and duplicate it. So I went ahead and replaced the front shocks anyway. Then went back to the bump... problem solved.
I learned from that that a shock may act normal for a bounce or two, but if hit hard enough it may give up damping for a while. And an undamped suspension can go wild if struck hard enough.
With a heavy solid axle like you have, you have a lot more unsprung weight up there, once that weight gets bouncing up and down with a weak shock, look out!
Thread Starter
|
New User
Joined: Apr 2003
Posts: 5
Likes: 0
From: New Mexico
Thanks
Thanks for the responses. I was hoping the solution would be new shocks and not something more expensive. When I have the shocks replaced I'll be sure to have the rest of the front end checked out.
