When driving down the road and you hit a bump, and it causes the front end to begin to bounce violently.... what part is causing that?

Seems to me an old friend had a truck that did this, and it was a steering dampner? What would cause this on an old truck? Bad spring? Or I spose it could be a bad motor mount also? I have not had a chance to get up under the truck yet.

The only way to stop the wheel hop/bounce was to come to almost a complete stop.

 

try this. Get on one of the front corners of the truck and start to push down really hard on that corner, then let off really fast and immediately get back on it. You're trying to bounce the truck like a giant ball. Once you get it going about as much as you can take 2 steps back and once you have see if the truck is still bouncing. Dosen't have to be complete tire off the ground, but if still bouncing around replace the shocks.

 

The shocks are pretty much brand new.

I remember hearing this happening to a friend. It is something serious like a motor mount, ball joint, or steering part I am pretty sure. I just can't remember the part.

Anyway... thanks for the idea. I will check them anyway (the shocks).

By the way..... this is not a mild hop here. This is a VERY VIOLENT bouncing of the front end. The only way to stop the bouncing is to come to a complete stop. If it happened at high speed likely you would be in some serious trouble. It feels like the entire truck is coming apart. The bounce is brought on by hitting a bump in the road. The truck drives great, and this was completely unexpected. But VERY serious bouncing here. Not like an unbalanced wheel, etc..

 

yeah that's why I'm thinking shocks. It seems that only an untended spring could bounce that hard, but i did hear of another guy with a stuck e-brake saying that his truck had the shakes like he thought it was gonna come apart. said it shook so hard the wipers vibrated off the windshield. Just another thought

 

I really don't think it is a shock. No other vibrations are present at any other time.
I am pretty sure it is a known problem.

Here is a post I found while searching the net. Same exact problem.

"Whole Lot Of Shaking Going On(Posted October 17, 2003)

Please help with areply if you could.I have a 2002 Dodge ram quadcab 3500 4x4 with a HO Cummins,LWB.I only have 27k miles on it and I am having a very bad problem with a VIOLENT,UNCONTROLLABLE shake after hitting a small bump in a road,a R/R track,or a pothole on interstate.This will happen either loaded,unloaded,or while towing. And it is very sudden.I took it back to my dealer,and they ordered parts.I need to know why this is doing this shake,and what I can do correct the problem. I have had a number of large trucks,4x4's,and none less than 3/4 ton since 1979,but I have never had this type of problem!!!!The dealer is unsure of what is causing this,and "maybe these parts will take care of it!"My fiance,and my Chow refuse to even get in this truck,and I'm sure if my intended had been driving on our last trip,we would have crashed,as it was all I could do to keep straight.Even my vision blurs while this shaking is in effect,and I have to stop to make it quit.The sensation is like a blowout on BOTH front tires.ANY suggestions???HELP!

Our comments-Never had it before? You must have been living large (just teasing). It really is not that uncommon, at least to us old guys who have driven worn out equipment. First of all, as far as we know, your truck is not known to have that problem, (i.e. there is no recall) and since it did not happen when new (we assume) most likely something in the steering components is bent or worn, assuming that alignment has been checked first.

Thanks for writing


The staff @ MRO"

I am pretty sure it is something bent in the steering or worn.

Thanks for any ideas though. I appreciate it.

 

just hope it helps. I haven't had that bad a vibration from the stering, but then again I haven't had every problem possible with a truck, let us know what you find out.

 

Is it bouncing up and down? Or is the steering wheel shaking as the wheels lurch side to side? What you are describing sounds like death wobble. Usually caused by bad balljoints or tie rod ends.

 

Oldjeep... I am thinking you are on the right track. This would defenitely fall under a "death wobble". I was thinking maybe a ball joint or tie rod end also.

I am going to get up under the truck later today.

 

Adjust the toe in! as much as 1/4 inch toe in will not scrub your tires but will stop the side to side motion.

 

Wheel ballance and toe would be my guess.

 

I would suggest king pins and wheel bearings unless you have already replaced them.

 

Don't think this is your problem, but I had a ball joint that was so worn the ball would vibrate really badly in the socket on right turns - especially sweeping right turns. Got so bad the ball popped out of the socket in a parking lot. I was young and foolish at the time and was lucky it didn't come apart on the road. At any rate, this was definitely a steering wheel shake and happened only when the turn caused the spring force on the worn ball joint to back off enough that it would bang back and forth. Normally, the spring would force the ball to one side of the socket and it drove OK.

As I said, since you don't have ball joints on a stock front end, it would have to be some other component. I suspect a really badly worn tie rod end or drag link could cause the same sort of symptoms as I had. Man, it would just about shake the steering wheel out of your hands.

 

Well, as Earl noted no ball joints. I just went under the truck. Everything looks perfect. I am going to look closer.

This is not a vibration problem. Again the ONLY time this has ever happened was caused by hitting a bump in the road (some road construction was going on). The truck drives and handles fine with no noticeable steering problems of any kind.

The bump causes the oscillation to start and it gets to the point the steering wheel is being ripped from your grip. VERY violent. The only way to get it to stop was to come to a complete stop.

I have driven the truck across town a few times since with no problems (albeit very carefully).

I have seen this before in a friends truck. I just can't remember what caused it.

Anyway.... I defenitely want to locate the culprit. I expected to see something major wrong up underneath the truck.... it was that bad. It feels like the truck is coming right off its frame and goes from tire to tire (across the front), in a hopping/bouncing motion.

I will keep investigating and call a few front end shops.

 

Blue Dolphin, I hope you found your problem. It's been a long time ago but this sounds like my Dad's old truck problem. His was the spindle bearings got worn out and all of a sudden made the front end feel like it was shaking apart. Now that I think of it the front end was shaking apart. If you find the problem on one side you know the other is next. Good Luck

 

Still sounds like you have shimmy, which can be caused by too little toe in. Easy enough to check - just measure across the sidewall of your tires - once before the axle, once after. The front measurement should be around 1/8 inch shorter than the rear.

You can do the same thing using a couple of sticks.