Rear-end Thumping

Reply Subscribe

Thread Tools

Search this Thread

Mar 15, 2011 | 06:59 PM

dunacn1

Thread Starter

New User

Joined: Mar 2011

Posts: 1

Likes: 0

Rear-end Thumping

I have a 2004 F150 4x4 5.4. Over the last few weeks i'v noticed that when the truck has been parked for even a short time, when I start to move out I am getting a thumping noise from the rear, almost sounds and feels as though I am driving over small speed bumps, but once i get going it seems fine. Any ideas where to start?

Mar 15, 2011 | 08:25 PM

70f100longbed

Fleet Mechanic

Joined: Aug 2002

Posts: 1,899

Likes: 29

From: Raleigh USA

Sounds like the limited-slip clutches. Add 2 bottles of Ford friction modifier XL-12 to the rear end and drive in circles for a few mins. If that doesn't help then its time for new clutches.

Mar 17, 2011 | 09:59 PM

stx4x4

Junior User

Joined: Nov 2004

Posts: 97

Likes: 0

ford frixtion modifier xl-12

question im thinking im having same prob, where to we add this modifier to ?
can you explain please how it is that you did it ? thanks

Mar 18, 2011 | 08:07 PM

70f100longbed

Fleet Mechanic

Joined: Aug 2002

Posts: 1,899

Likes: 29

From: Raleigh USA

The easiest way is to pull the rear speed sensor at the top of the diff and pour it in.

Mar 18, 2011 | 08:13 PM

03r1

New User

Joined: Nov 2005

Posts: 9

Likes: 0

It is not the clutches if you are pulling out in a strait line. The clutches only break loose from each other when turning. So if you are turning slightly when this is happening i would say that is what it is. I have the same thing going on.