My '97 E350 (5.4 & E40D) has a serious vibration between 65-74 mph. It has been doing this for the last 35k. I have balanced and rotated the tires myself (225/75/16 Goodyear Wrangler HT's) but it makes no difference whatsoever. I know that these vans have a reputation for vibration issues, but this gets bad enough to shake the suction cups on my radar detector loose from the windshield. I'm inclined to think its the pinion bearing or driveshaft, but the pinion bearing feels tight as do the U-joints. The left front lower ball joint has some play in it, but I doubt that's the culprit because this has been going on for the last 35k.

I have searched this forum and found a lot of good suggestions, so I am going to have my friend who is a tech at a shop with a Road Force balancer try rebalancing these tires. I did them myself on a John Bean balancer at a friends shop, so I know that they were done as well as the machine would allow for.

Any help or suggestions will be greatly appreciated.

Thanks,
David

 

You are on the right path. Road force balancing will expose any tire issues,and hopefully solve your problem. good luck and let us know what fixed it
Dave