1998 F150 Supercab Long Box 2wd, I have a vibration when slowing down the vibration occurs at 40 mph, no vibration when accelerating. The vehicle has new tires, u-joints, rear end and axle bearings, limited slip rear end. 120000 kms, any ideas , I was told it may be the center hanger bearing in between the 2 driveshafts.

 

Does anybody have any input regarding this problem??

 

Look on the door code B-piller sticker. Are you coasting or on the brakes? I have heard about the two piece drive shaft bearing before, that could be right. Keep the inforation coming and maybe someone can chime in.

 

The transmission code on the door is U, the vibration occurs on slowing down when the speed declines to 40 mph weather you apply the brakes or not.

 

you have a vibration while coasting and then at 40 it goes away. So then from 39 to 0 it is fine? if that is the case I would almost bet it is the hanger bearing. See if it wiggles around up there. Unbalanced drive shafts do strange things like that too.

 

Actually it starts when coasting from about 45 down to 38 and dissipates, and I called it a vibration however it is more of a shake or shudder. I will check the bearing for play.

 

Sounds to me like the carrier bearing (hanger bearing) Mine did the same thing. It was shot.

 

Found the problem this morning, one of the balance weights on the drive shaft at the front end is missing. Going to replace and I will post results.

 

Use large hose clamps to balance the shaft.
1)Put rear axle on jack stands.
2)Get a helper to spin shaft to vibration speed.
3)Use chalk and lightly touch shaft while vibrating.
4)Put two clamps with screw mechanism 180 Deg from chalk mark.
5)Clean off chalk spin to check for balance.
6)Still vibrating chalk mark again adjust screw location or add third clamp
7)Repeat process till balanced.
8)Drive shaft run out should also be checked.

 

Than you very much for the info regarding balancing, will post results

 

I had the drive shaft balanced and still have the shake/vibration at 40mph, bumps in the road make it worse, may be coming from the front end but it is difficult to tell. Anyone have any ideas.

 

I have a 98 Lariat 2wd w/limited slip diff and 95k miles - I have been battling the same issue since replacing my original Goodyears at 85k. They are Michelins and have had 2 replaced which could not hold their balance. This improved the high speed vibration significantly but still have a slight "thumping" at EXACTLY 40 mph! The Michelins are supposed to be highest quality so I'm still not sure whether to suspect another tire or the alignment....

 

if it started when they put in new u-joints they may have not put the drive shaft in the right way the bolt holes will match but it will vibrate, try to rotat the shaft

 

P.S. I m still lfinding out more abouit fords but when i put new joints in my Jeep, this fixed it.