Gentlemen,

I come from a long line of f150's that have always worked hard for me (at or above GCWR). I just sold my Duramax last fall to get back into an f-150 because they were always dependable for me. We have a 20 ft. lowboy gooseneck that we move a compact tractor around with about 4-5 times a year, so I thought that there was no need for another 3/4 ton for that kind of towing. Anyways, I put a gooseneck ball in my truck and when I loaded our tractor, it sat about level. When I take off at moderate acceleration, something is slipping and making clicking noises!?!? Sounds like driveline or transmission, but trans never went over 201. What the crap is this?

Specs:

2011 5.0 f150 screw 4x4 6.5 box 3.55 ls 7,500 tow rating(a bit underrated in my opinion considering they advertise 11,300 on the same chassis).
2004 Lamar 20ft. lowboy 14,000 GVWR weighs 2,900 according to registration tag.
JD 990 with 430 loader and MX6 brushhog should be around 4,500-5,000 max.

My trailer loaded shouldn't be any heavier than 8,000 (500 overweight). I understand parts may wear out faster than normal operation, but I don't think the truck should be slipping. I have hauled much much more with an old 4.6 than this. I am really upset and wondering what your thoughts are. Sorry for the long post....

 

Have you taken it in to the dealer to be looked at yet? I sure would, that's far from normal.

 

I'm glad somebody else thinks this is ridiculous. I haven't taken it to the dealer yet as this just happened today. I am afraid they will tell me "I'm overweight, that's the problem." I have heard that the screw longbox has had some drive angle issues with vibration and what not, so I'm wondering if this is a related issue. I thought maybe when I accelerate the rear of the truck squats a little below level, so it changes the drive angle quite a bit, thereby causing some part of the two piece shaft to slip???? I guess I should take it to the dealer, but they will just tell me they can"t recreate it unloaded and I don't really want to pull that unit all the way to town...

 

Check the u joints in the rear driveshaft?

 

If the U-joints were bad, wouldnt it happen all the time? But how do I check the U-joints? I got underneath and there is a little wiggle in the shaft....not sure if this is normal or not. This is the first 2 piece shaft I've ever had.

 

I've never had a 2 piece shaft, but yeah, you got it right, just wiggle it. It may not be enough play to do it all the time, just when you're towing that load that it changes enough to do it.

 

I agree with you. 8,000lbs should be slightly tougher than a walk in the park for a half ton truck. I've pulled about 9,500-10,000lbs with my 2006 5.4L a few times and it struggles some, but it can do it pretty good. It doesn't feel unsafe or like anything is going to break

 

Just a WAG but could it be Traction Control?

 

I had my brother-in-law mechanic look the truck over. We recreated it several times, and the consesus is somewhere in the drive shaft. I thought about advancetrac, but that's electronic, right? The noise is definately mechanical. I think I'm going to take the truck to ford and make them fix it. The trouble is, I'll have to take the load up there to recreate it and what are the chances they give me a rental truck to pull my gooseneck and tractor back home? Fat chance I should think...

 

If you accelerate more slowly, does it do the same thing? I wonder if it is the shudder/axle wrap phenomena? Could the clicking noise be U-joints that are at an unhappy angle? Sticky yoke if you have a 2 piece driveshaft?

 

It doesn't seem to happen when i accelerate very easy. How would i fix axle wrap?

 

uh yea i would be less than impressed myself. its kind of a kick in the pants.

 

My 2012 F350 will do that with the traction control on and hauling a load. It will do it without a load if I'm trying to take off in sand or something.

 

If it were advance trac would there be a code or does the pcm think its operating properly?

 

Try turning the trac control off and see what happens.