wisem1

Hello All,
I have a 2006 F150. Recently, I noticed that when I take off from a start that and am making a right or left turn, there is a noticeable rumble. Once I get up to speed and/or straighten out, the rumbling goes away. The problem only occurs during slow turns from take off. I am not in 4 wheel drive and I'm not taking off too fast (tires not slipping). The rumbling appears to be worse after the truck has warmed up.

A friend of mine says that he believes that the limited slip differential may be the problem. On an early Ford, he added some type of chemical (recommended by the dealership) to the rear end and the problem went away.

Questions...does this sound like a rear end issue? If not, what is the problem? Also, my factory warranty just expired and did not get the extended warranty. I have 39,500 miles on the truck. Do you think the dealership may cover this despite all the company's financial difficulties?

Any feedback is appreciated,
Maikel

rplatt56

My 07 did the same thing. It was the clutches in the limited slip rear end. It was fixed under warranty for me.

Jasonsfx4

I have an 04 f150 fx4 and my truck does the same thing and its getting worse. If I give it a little gas when I take off i get a clunk , almost feels like rear end is engauging. And then when i turn I get the rumble. When I tow my boat its worse. And to top it all off I have a manifold leak. The truck only has 34k miles so my warrenty is up. Im fighting with my ford dealer to fix the manifold leak but having no luck. Ive had bad luck with fords. My 99 f 250 with 60k had the manifolds rot right off and brake lines. Anyway just wondering whats up with the rear end?

shawng111

The stuff your friend is reffering to is called friction modifier. I changed my rear diff fluid with royal purple 75/140 synthetic which already has the modifier in it, plus I added a bottle of the modifier as well, my problem went away after that. hope this helps a little

wisem1

Thanks for the feedback. I'm taking the truck in next weekend and we'll see what happens.

Cheers,
Maikel

plucroy

I have an 05 FX4 and it does the same thing and it's even worst when it's warmed up. Mine is doing it on turning but even on leaving a stop in straight line. I've talk to a transmission expert last week and he told me it can be possible that you feel a little vibration when turniing because of the limited slip, it's a turning radius thing, but if it's still doing it wen you got straight it's not normal. I've got an appointment tomorrow to have it fix. The place where I deal with only does transmission and differential so they probably got the solution and they said it was common in the newer F-150 04 to 08. I'll let you know what they found.

dustybottoms39

I have a 99 f150 and it is doing the same rumble when going from a stop and turning... but then just recently it started making a loud noise when im going straight down the road. when i slow down below 10 mph it goes away but then comes back when i go faster. It doesnt happen all the time, maybe a 1/4 of the time i drive

Is the limited slip shot? will it hurt anything the way it is if i drive it? what would be the recommended fix?
thanks

wisem1

Yep...the problem was the rear end in the truck. The clutches in the differential rear end wore out. Cost about $1300. The dealership added a friction reducer chemical to extend the life of the new clutches. I asked the dealer if he could installed heavier duty clutches but none were available. The dealership won't budge either on the warranty. As an engineer myself, I can say that this is either a design flaw or manufacturing defect.

I only had 39,000 miles on the truck with around 8,000 miles of easy towing a trailer (< 4,000 lbs). This really makes me concerned what will happen in another 39,000 miles. I know you Ford guys will harass me for this comment but I am wondering if I should have bought another brand.

Cheers,
Maikel

dustybottoms39

so the loud grinding noise is just the clutches? didnt hurt anything else?

plucroy

Got it fixed 2 days ago, they changed clutch pack and rear end bearing. 1200$ job...