It's starting on mine!!!
 

9,000 miles and today I got the big bump bump from the rear end slipping on slow take off. I guess I'll do some searching and find out if others have found the problem so I can go to Ford about it. Any one want to comment?

Sorry to hear you’re beginning to have issues at 9,000 miles. I hope that you will be able to get them squared away fast without a hassle. :thumbsup:

I don't get it. The rear end is slipping? How does that = bump bump bump? Does the truck jerk forward, produce noise, etc? Please describe! :confused:

Is it a consistant or intermittant issue?

I have $100 on the clutch packs.

Is it worse when the engine is cold? Worse when turning and giving it gas?

I was at a light and taking off slowly.
Felt and heard 2 big bumps along with the feeling of I guess the trans missing. Right at that point I could feel the truck stop moving forward just for those moments. It was as hard as if someone kicked the back of my seat.
Engine was warm and I was going straight. This is the 1st time I really felt it hard. Other times I was not sure if it was this or I ran over something small, but now I know it was the same issue just not as bad before.

I'm guessing as to what it is. Just seems like the loud deep bump or thump noise is coming from the mid to back of the truck.

Driveline slop? I still have issues with my 99 Cobra with this, guess I've learned to live with it. I've also detected the vibe around 85mph but it's very mild.. once again, driveline vibration is not new to me because of my Cobra.. it's a PITA to do a runout on the driveshaft also...

This is on level ground.

your clutch packs in the rear end there is a T S B on this . Mine still doing it at allmost 6000 miles started about 3000. One member said his did go away after awhile its up to you i'm trying the go away before i have them tear down the rear end.Also you dont feel it under a harder acceleration right

That's right!! Only on soft take offs. Thanks for the info.

Hello,
I would assume it's your slip yoke going into transfer case.I had this slight slip or bump bump upon take off. I marked the driveshaft and took it out and put synthectic grease on the splines and it took care of my problem.:smoke: Hope this helps.
Wes.

You did this or the service department did this under warranty?

hello,
I did the grease on the drive shaft myself. I just made sure i marked it first.
Wes.

I assume the road was NOT wet?

Ford greased up the slip yoke on mine, then replaced the entire drive shaft, then did the clutch packs.

After all that, it still does it every once in a blue moon. I would say it corrected about 90% of it.

weird huh?