I need some help folks. I have a 05 F150 4x4 STX with the 4.6L and 3.55LS. When driving home last night I turned left and felt this awful jerk and heard a bang like I ran over something. I passed it off for the moment like I did run over something since it was dark. However now whenever I have a turn either direction, but more to the left, that is say turning the actual tire half as far as it will go while driving I get the same felling, sometimes loud, sometimes softer, but I still fill the truck move and jerk. When driving straight the truck is fine. It also did it once from a stop when I went to go forward. Does anyone have any idea what this could be? I was thinking maybe the rear end or LS because of the turning? Or could it be suspension, which I doubt because I've never had anything like that before? Maybe a U joint? I just don't know. I can't really tell where it's coming from because it is so rash. I thought maybe the front 4x4 try to engage, but it does the same thing when I have the 4x4 engaged. Any body have any suggestions?

 

I would jack the front end up and see if your CV axles are trying to bind up.

 

How?, by turning side to side? and spinning the wheel? I didn't think CV's were turning when in 2wd?

 

When the truck is off and you have it lifted, you can spin each front tire. The CV axle will turn because there is no vacuum off the engine. It should spin freely. Watch your CV axle where it bolts on under the truck. Look for any up and down movement or signs of binding up. I had that issue and some weird tire wear on the affected side. Replaced the CV axle and no more issues.


I also meant to ask, did the jerking come from the rear or the front?

 

Difficult to tell. But I'm leaning towards front because I can really feel it from drivers seat. It does remind me of something binding. I knew about the vacuum, but I see how it can affect when driving. I sure hope so. I can fix CV's!

 

Not sure if that's what it is or not.. I might take it somewhere and let them figure it out. I'll test cv's, but it happens a lot when going straight not, and I can kinda make it happen if I let off the gas and hit it again. I might check the u joint too.

 

Anyone else have any ideas?

 

Well it found out what it is. Looks like someone threw a grenade in my rear end, spider gear tore everything all to hell. Getting a rebuilt jasper unit. I think I might break into tears now.

 

That sucks! Glad you chose jasper though. Ive bought alot of diesels from them.

 

It was highly recommended from the place I went and I've had experience with them before, we had a farm truck with one of their transmissions in it. It was actually cheaper than the people rebuilding mine for me.