I thought it was a u-joint at first but I only feel the vibration when the torque converter is unlocked. It was pretty obvious when I was pulling a trailer, nothing too bad but noticeable on the highway.

Should I take it in on extended warranty or just change the tranny fluid? Will a pan drop do the trick or does it need to be flushed? I'm at about 56k miles on an 04 4x4.

 

That does sound like the "old fluid shudder" issue, but I thought it happened more when the TC locked?

In any case, when was the last time you had a tranny service done?

An easy 'bench test' of the fluid is taking your dipstick and dripping it on a paper towel and if you have some new fluid, drip some next to it and compare..

If you've never done even a pan drop to date, then you may want to have the service done that circulates all the old fluid out while putting in new fluid..

I have an older trans that has the TC drain plug on it, so I had that done when I first bought the truck with 63,000 miles on it and I've done pan drops every year since then.

I tow a TT during the summer time and I put on about 15,000 miles a year as a whole on the truck, so it's cheap preventive maintenance IMO..:thumb:

Mitch

 

On early model units the impeller blades liked to come loose. The way to see if that is the issue is get on and off the gas at about 20mph in 2nd. They will give a chingy/changy noise as you get on and off the throttle. In the later years (03+) the fins are furnace brazed. That eliminated the problem. The next issue inside the converter that likes to cause that problem is the rivets on the turbine hub. Again in the later years ford revised these to prevent the problem. Early models were small head and hollow. The late ones have a huge head on them and are solid. Your truck should not have any of those issues but if it is a 4.6 (or 4.2) in 03 it may not have been updated yet. 5.4's got updated way before that.
Alan

The reason I say 03 is because it is possible to have an 03 trans in an 04 truck.

 

Mine is a 2004 (not heritage) with the 5.4 liter. I'm not sure if the fluid has been changed, I bought the truck used and have put about 1000 miles on it.

 

I am doubtful the problem is in the torque converter on that unit.
Alan

 

Care to elaborate on that? All I know is there is a light vibration/shuddering when the torque converter is not locked. Once it locks out everything runs smoothly.

 

I tried to explain, but basically the issues that would cause this are mostly eliminated in that unit. It may sound dumb but it could be a matter of rpm and could be something as simple as a puley or bearing in one of the components on the front of the motor. I had an alternator make a terrible vibration between 2200 and 2500 rpms. When the converter is locked the drivetrain may be absorbing it. Does it do it sitting still?
Alan

 

Nope no vibration when sitting still and revving. I can't really tell if it does it in the lower gears but on the highway its pretty noticeable. If it were rpm based then I should get vibration at high speed because I'm running the same rpm that's giving me vibration when the converter is unlocked. I had it up around 100 yesterday and it was smooth as can be.

Thanks for the help.

 

I'd have the wheels ROADFORCE balanced before I would go any farther.
Alan

 

has the codes been pulled from the pcm? any evap codes? slight vacuum leaks in the evap can cause tip in engine studder/vibrations.

 

Since I first posted this question I have lifted my truck and added larger wheels and tires. The vibration is more pronounced in first gear now when I'm accelerating hard. It goes away at higher rpms in first and is less noticeable in second gear. Tires can be eliminated as I have brand new ones now. I still notice the vibration when the torque converter unlocks at highway speeds but it's less noticeable than when it's in first gear under hard acceleration. Any more ideas? I still have not had the pcm codes checked.

 

It is possible that the balance weight came off your converter. If it was one that used a heavy weight and it came off you will get a vibration from it. The extra weight of the lockup piston applied to it instead of rotating at a different speed could make it go away. If you pull it out and get anywhere near cincinnati I will gladly spin it on the balancer for you, but I am unsure if that is your problem. Just a guess here.
Alan