What causes a rapid thud when taking off. It kind of feels like slack in the driveline. Some times there's two or three. I came across a thread here that described that as a slipping tranny, especially in only 1 gear. That's my case, in first gear. There's also a bit of a shudder when taking off, also. I was hoping it might be in the torque converter, as I'm planning on upgrading it in the future, anyway.
If that were the case, what does it mean in real terms.

Waye

 

I don't know all the correct terminology but it could be the driveshaft where it slides into the rear of the transmission. That may need some grease. Make sure you chock the wheels before pulling the driveshaft.

 

Seems like every 40k miles my slip joint starts sticking. I end up having to re-grease it and everything is good for a while more. Sometimes if I tow a heavy load, it loosens up or something because the 'thud' goes away. Eventually it comes back though.

Could be your slip joint. Does it happen when you first start moving after each dead stop?

 

That's exactly what it does. I sure hope that's all it is!

 

How does the driveshaft u-joints or whatever their called, brain fart now. I've seen some pretty bad ones on here that were wasted, had slack in them, just beat.

 

Here's a LINK to drive shaft slip joint lube.

 

Not shure what year your truck is ive got a 2001 f350 and mine started somethang like you are explaning. And found out that the bolts to the full float axle were finger tight. Dont no how it happen but it was just the driver rear axle that was doing it tighen it up and retorqe to specications and good as new . Good luck

 

Thanks for all the input. I'll check it out and hope it's a fairly simple fix.

Wayne

 

If it is the slip joint I've had better luck using the teflon based lube from the dealer. Like $10 bucks a tube.

PTFE Lubricant

p/n: XG-8

 

theres not a bowling ball in the bed is there? i had that happened one time...............looooong night!!

 

I'll double check to make sure. I was sure I eliminated that, though.LOL

 

That's funny. Sounds like me yesterday. First drive after installing new tie rods and springs and I hear this weird rumbling... It was the old springs rolling around in the back of the truck!

 

it was a wild one, my truck wes only a few months old. was pretty funny til i saw the damage to the bed the next morning.

 

I tried to order the XG-8 PTFE lubricant at my local ford dealership. He looked it up and sure enough that's what it's used for. Motorcraft doesn't stock it and one other source he uses doesn't either. What's a reasonable alternative. Give me specifec brands if you can please and where there sold.

Thanks,
Wayne

 

I used Schaeffer's on mine.

Schaeffer Mfg. | Moly EP Multi Purpose Grease

I also installed two zerk fittings 180 degrees apart on the short section of the slip yolk. No more pulling the drive shaft to grease it, a few pumps every 6 months or so keeps it pretty quiet.