Thump, thump, thump, my tires?

[TexasTruck]

Hello all,

First I like what you've done to the site! I've been away, mainly because I was at risk of loosing my job because of it (I'm kidding).

Anyway, I didn't have much luck with my 2007 F250 HD and have moved on to a 2008 FX4. When I accelerate through 35/40 MPH I hear a thump, thump, thump, not a fast sound, like a tire thumping, that speeds up as I accelerate, then it goes away past 40MPH. When I decelerate, I don't notice anything. I haven't tried to accelerate real hard because the truck is still so new.

I checked the tires and the tire pressure, they were at 75psi. According to the door sticker, they should be 65 front and rear, so I lowered the pressure, but noticed no change.

I'm not able to tell which tire, but if was to guess it would be the right rear. I was thinking about swapping it with the spare to test.

Any ideas?

TIA!
Scott

[JD69X]

Hmmm....not sure what this could be.

Are your nuts loose?

Might just want to double check all of them.......

[TexasTruck]

Thx... yes my nuts are tight and torqued properly... no missing or moved wheel balance weights either.

Scott

Originally Posted by JD69X

Hmmm....not sure what this could be.

Are your nuts loose?

Might just want to double check all of them.......

[HighwayPrisoner]

Could be a drive line shudder, does it get worse under hard acceleration, or pulling a trailer? There is a TSB for driveline shudder. The carrier bearing in the driveline is shimmed using 1/4 inch shimms, using up to 3 shims. I think 1 shim is what most trucks need. Have your dealer check it out.

[TexasTruck]

Thx for the reply. My first thought was DLS too, but I thought that symptom was under hard acceleration or pulling a trailer, not just driving "normally", I could be wrong... I still have some large washers and flat stock I made for my 4" lift kit days when I had DLS on my '04, maybe I need to try that next...

I swapped the RR tire to the FR and visa-versa. The first test drive didn't reveal any change, but I need to drive it on my common path to and from work to see.

[TexasTruck]

Well, I shimmed the carrier bearing 1/4" without any change. I noticed F??d changed the carrier bearing bracket too. I indexed the diff end of the drive shaft 180 degrees and notice no change. What is going on?

One other bit of information is whenever I make left hand turns, there is a growling, grinding sound, like the tires are fighting against the pavement,. Turning to the right I do not hear this sound.


Could this be the limited slip diff chattering and causing the thumping sounds?