Hey guys I know this is f150 but not getting much help from expedition forum. 99 expedition xlt 4wd 5.4l, Started a vibration a couple of days ago, feels like rumble strips. Feels like it is behind me when driving,. put on jacks not getting same vibration. Bearings feel ok, u joints ok, no noticeable wobble in drive shaft, Does it od but not on jacks. Rear making more noise than I think it should. Fluid first knuckle low and all kinds of stuff on plug. anything I should look for or expect to see?

 

Never heard of a rumble strip sound, but if it occurs at lower to mid range highway speeds and feels more like a wobble, bad wheel balance or the trans is about to fall out, then it's good guess it's the rear gear oil. This can occur anytime after 145,000 miles IF the rear gear oil has never been serviced...the formulation/modifiers break down enough to notice. It will get worse much quicker now, until serviced anyway if this is what's going on.

 

you all have been great with help on my 97 f150,spot on as matter of fact! was thinking you might be able to give me insight 0n wife expy. Has a vibration just after torque converter lockup. have no codes other than cat related as po removed.Have read could be misfire, torque converter, rear end. Does it 45/50 mph under light acceleration. Does mot do it with o/d off. Also T/C does not appear to unlock when tap on brakes ( don't see increase in rpm's when tap brake).Any help in direction/ where to start is greatly appreciated. Thanks

 

Thanks Jbrew, It has about 170,000 No idea when./if rear has ever been serviced! Could be more like washboard road at speed.

 

Changed rear gear oil, all looked/ felt ok. Gear oil was a caramel color. Still have same issues. Going to change tranny filter and fluid next. Don't know if this is related to problem but in overdrive and converter locked up, when I tap the brake the rpm does not change and does not feel like converter unlocks?

 

That's good, rear gear fluid needed to be done and don't rule that out yet. It can take 80 miles or so before the new fluid works in and only if you used the correct fluid/modifier.

Washboard, yea haven't heard of it, as I said before. Service the slip yoke, check the joints again and look for missing weights from the shaft (noticeable on steel shafts). Doubt it's the trans, but check the T-case fluid....it doesn't last long lol.

Drive line vibs aren't usually a trans issue, but it's always good to change it if needed.

 

used the 75/140 synthetic and motorcraft friction modifier.I'll have to put some miles on it.thanks

 

I changed the gear oil with modifier, have about 100 miles since same results, changed the tranny fluid last night 13 quarts came out 15.5 quarts went in. drove last night had brief vibration/ shudder told wife all fixed, she drove today said acted the same. I checked the transfer case fluid kinda smells like tranny fluid and brownish red in color. I can't remember if I changed it when picked it up. I usually change fluids so I know where I am with it. Also not so sure the torque converter is locking up as I only see 3 rpm drops when shifting?

 

It's something out of the norm (the rumble strip description) , just going to have to be plugging away at it. Could be a bearing or joint going bad.

 

pull the driveshaft out to really inspect the u-joints, this cant be done when the truck is parked