Vibration only on take off when turning

[TomzBoss302]

I've read a couple of different posts here that appear somewhat close to what I'm experiencing, but none show resolution yet. I have a 2003 Lincoln Navigator and a 2005 Ford Expedition. In the Lincoln I had a sensation of running over rumble strips at highway speeds when shifting into overdrive. I fixed that with shudder fix so fairly sure it was the torque converter.

So a little history on the Expedition:
1. I purchased the Expedition with 123,000 miles
2. It needed a timing chain, plugs, a coil, and cam solenoids. I replaced all with Ford parts.
3. The truck runs great, we've driven it about 1 year since.

The oil looks great after oil change. New tires all around. I've checked brakes all around and the suspension is tight. I have spun the front wheels to check the bearings and don't feel anything unusual, but not ruling out a wheel bearing as my issue. I was a mechanic for 20 years and work on all my own and family's vehicles.

We've noticed that on acceleration from stop if the wheels are turned either left or right there is a short shudder only once or twice. At first I thought a tire was rubbing the wheel well, but inspection confirms no evidence of rubbing. If I keep the wheel straight, no shudder. If I continue to turn at low speed no shudder after 1 or 2 times. Doesn't seem to matter if it is a very slight turn or full lock, vibration feels the same. Never any strange sound or shudder at higher speeds even in hard turns left or right. No cyclical rumbling like a wheel bearing at any time. After the truck is driven for a period and is warmed up, the shudder/vibration is not felt on take off. So I'm thinking front wheel bearing or differential. I feel confident it is not engine or transmission or drive shaft. It is a 2 wheel drive with H6 (3.73 Limited Slip) axle.

 

[00XTL]

I’m willing to bet that its the clutch pack in the LSD. Not sure how long this has been going on but after a few months that shutter will get significantly worse. If it in fact it is the clutch pack

 

[TomzBoss302]

Planning to change the fluid this weekend and take a closer look. It's been doing over 6 months, no change at all. The truck did set for over a year waiting on me to install the timing chain. If it doesn't fix it, I guess I'll buy a clutch pack. Might check and see if the one I have will fit, I know it fits the 8.8.

 

[SRQ Bill]

My 2003 with 190,000 miles does the same. Same with my buddies 2003 excursion with similar mileage. Love to know what it is. It doesn’t seem to get any worse

 

[Vincent Vega]

You might try different dosages of friction modifier in the rear end before replacing the clutch pack. When I replaced the gear oil in the rear end, I started out with Mobil 1 gear oil only, which has some amount of the modifier in it. But after that I noticed a shudder from the rear end, so I added Motorcraft friction modifier incrementally (about half the bottle) until it went away. Good luck

 

[TomzBoss302]

Yeah, I've always been of the mind that if the clutches are worn they won't grab/shudder and your rear end will act like an normal rear end traction wise. I've repaired one or two like that many years ago. I'm figuring new fluid and friction modifier will fix it. Thanks for the advice of adding more modifier, hadn't considered that the off the shelf may not have enough. Ford calls for 4 ounces. Mobil 1 states addition may not be needed. Wish they would state how much is in it by ounces or %.