I have a 2005 Ford F-250 Power Stroke with the 5r110 auto tranny 4x4. My scenario is that I was pulling a long trailer in the desert and drove through alternating whoops which caused the chassis to twist and led to a sound from where the torque converter bolts to the flex plate that could only be described as metal grinding against metal in a spinning motion. I thought it may be the turbo, but I had my turbo replaced later that month and the sound still occurs. Now I notice the sound when I am pulling a trailer while locked in OD on a hill and the rpm's drop to around 16-1700. The truck/tranny starts to 'buck' and I have to kick the truck out of OD. When the rpm's jump up, the sound and feel is gone. It's loud enough that passengers can hear it. I was first suspicious that one of the U-joints might be out in the driveline, but they seem to be okay. I had my local mechanic look at it, but he couldn't find anything wrong with it upon inspection, but he didn't tear into the tranny and he couldn't replicate the sound because he didn't hook a trailer to the truck. The only other thing I noticed is that my truck now leans to the driver's side (I measured from the ground to the wheel wells and the driver's side is 3/4" lower on the whole side) and I don't know if that would have anything to do with it? I'll be taking it to a local body shop to have that inspected. All this being said, do you have any idea as to what it could be? Also, the only modifications to the tranny is a Precision Industries triple disc torque converter that was added 5 years ago and a deep tranny pan. The truck has 120k true miles on it. Any help in diagnosing this problem would be greatly appreciated!

 

Just my 2cs here and will bump this post back to the top,
Bad shock or spring when the truck was twisting it may have over extended and pressing the other side to far down, same thing for the springs, Now Mark the Tranny guy needs to answer the Over drive question , I was told to never pull in over drive. I guess that was more than 2 cents, headed for the top of the list

 

Mine would do that and it sounded to me like one of the plastic straws being pulled up through the plastic lid. Would do that on hills if I had a big load (fifth wheel with full tanks) and/or headwind and I didn't get it to downshift. It also bucked when doing that.

After I figured out how to prevent it I never worried about it again.

 

I can't address the frame flex or aftermarket torque converter but many times on these trucks engine issues "feel" like tranny problems.

 

How would you know that they are okay? Did you take the driveshaft out of the truck and check them? If not, then you don't know if they are good or not. There is NO WAY to determine if they are good with the driveshaft in the truck.
Then you were told that you can never tow with one of these trucks. There is NO WAY to turn off the overdrive. Someone gave you some really, really bad advice.
I've seen bucking problems in overdrive just like you're talking about. It's always been an engine miss. As for the scraping noise my guess is the sheet metal cover at the bellhousing.

 

Thanks Mark ,that's what I thought too, being there's no od on the shifter, Like on my 92 chevy there is a od on the shifter and I still never pulled with that eather.

 

Doesn't turning it on tow/haul mode essentially turn off the overdrive and also cause it to downshift when braking. Once you turn off the tow/haul it shifts up a gear as it did in the past when you hit the overdrive button enabling it.

 

No, the tow/haul does NOT turn off the overdrive. It keeps it from shifting to overdrive until a higher speed, but it still will use overdrive.

 

Where the he[[ is this "overdrive" button???? My '05 doesn't have one!!?????

 

IIRC the older trucks had the overdrive button. We have tow/haul and a 5r110

 

They are referring to the tow/haul button which on other trucks like my 03 F150 canceled the OD