I have a 99' F150 extended cab. I replaced the tires with Michelin SUVs about 6 months ago. The ride has been great until recently. I have noticed an increase in the roughness over the past two months from both the rear and front. The best way I can describe the ride now is horrible. It seems whenever I hit even the smallest of bumps in the road, it feels like I am riding on no suspension at all, almost like the axel is directly attached to the frame. I replaced the shocks with the new Monroe sensa-trac but this made no difference. A friend thought it might possibly be the rubber bushings in the rear leaf springs and the bushings on the top and bottom of the front coil springs have hardened therfore they are not reducing road roughness. Anyone have any ideas? My truck only has 42,000 miles and has been a very smooth running truck up until now. I also had the same problem with a 1997 F150 when it reached about 45,000 miles.

Another problem I had was the drive shaft clunk. A mechanic suggested I add another leaf to the rear springs to stiffen up the suspension. This gave me a much more stiffer and somewhat uncomfortable ride but it elliminated the clunk for close to 3000 miles. Unfortunately this did not last long and the clucnk is back. I'm now thinking about replacing the rear springs bushings and shackles. Any suggestions would be greatly appreciated.

 

The bushings shouldn't have "hardened" this fast, nor should they be worn out in that mileage. It is possible that one has gone bad, but that would not give you a bad ride at all 4 corners. The extra leaf definately can give you a stiffer ride. Are your tires over-inflated??---just an idea. Your trans clunk could be the commonly reported slip yoke needing re-lubrication. I'd suggest a complete suspension analysis by a qualified suspension technician including your new shocks, all the bushings, and every suspension component.

 

Had the same experience except mine happened a lot sooner. The rear leaf spring bushing set needed replacing at 15,000kms. Now at 32,000kms the front lower control arm bushings are showing cracks. If you are experiencing a general harsh ride on small bumps and you've lost the isolated feel over rough roads then usually these bushings are to blame.