I noticed this summer a sort of rythmic bounce to my truck as it drives down the road this summer. The truck is a 1994 F150 long bed, single cab that I have owned since new. In the last few weeks the bounce has gotten noticebly worse to the point that what began as a little shimy has now turned into a damned bone shaker. My first thought was the tires. The tires ARE old but I see no bulges or other damage that might be the cause of the bouncing. The brakes and rotors are old too and due for a change, along with the tires but the motion of the bounce seems to up and down. In the past when driving cars with, say, warped rotors, the shimy motion was sideways. I have checked the spare tire, it is secure, the exhaust system seems solid, the drive shaft also SEEMS to be OK (I can't see it turn as I am driving so I cannot SAY it is good). I do not get the motion when in neutral as at one point I thought maybe it is crapped out motoro mounts. I am handicapped so I cannot actually repair my truck any more but I would like to have a clue as to where to go looking before I hand the truck over to a mechanic. Someone please give me some ammo to use to look for causes of this motion? Thanks in advance!

 

Maybe its related to ball joints or tie rod ends.

Another place to look is the transmission crossmember. Its fairly common for the bolts to need retightening.

 

Forgot to ask. Are you sure its not just worn out shocks?

If you replace them, I suggest Monroe gas magnum.

 

Thanks for your thoughts. I should add that this is happening on regular city roads, no pot-holes, etc. It has gotten so bad that I have stopped driving this truck for the last month or so as I am worried about dropping the drive shaft or something like it. The shocks WERE replaced about 10 years ago so I reckon they are up for replacement soon if not now. What makes me think this is NOT suspension related is that this is going on despite driving on flat, well maintained roads. My suspicion is that this connected to the transmission or drive shaft. The truck still runs fine, with the exception of the bounce but I am just so worried about being left on the side of the road, handicapped and really unable to do something about it that the truck is not being driven. The transmission mount is something I have not thought about and will most certainly will have my mechanic look into once I get the nerve to drive it to him. Any other thoughts? The differential looks a little oily with old crusted dirty oil that has dirt on top so there is no glisten to it. We replaced the lubricant inside the differential about 7-8 years ago. I don't think the differential is a problem (although I am thinking it is time to repack it with new lubricant) as the truck rolls just fine, albeit with a bounce. Again, any suggestions or help would be appreciated.

 

X2.. seen this happen more than once on E40D trucks.

So when in neutral it goes away? I'd be looking at the universal joints at the driveshaft ends also. That's usually the first thing I check at the first hint of a vibration that goes away in neutral. The tranny mount and motor mounts are another suspect. Although in my '94, when one motor mount went, the other soon followed and then I just did the trans mount for the hell of it.

I've learned with my 17 year old truck, anything that goes shouldn't surprise me, but those are the things id start with. If the rear end was out of fluid itd probably be more of a violent vibration or whining, but Id check the fluid level anyways if you have concerns about it.

 

I would jack up the front and check for play in the steering components.