I'm currently at the dealer having my transmission checked again (as the truck has the following symtoms):

1. When driving from a stop, the truck seems to hesitate a little before the transmission engages (has a minor clunk feel/sound when accelerating).

2. When merging onto a highway from a speed of 40mph, when pressing the gas the truck seems to hestitate before finally picking up speed. However, once it engages the transmission clunks and then has a little whiplash.

3. When gearing from 1-2, it is not a smooth gear change and kind of "clunks". I've driven 15 year old courier vans that have a smooth transmission.

Truck is an 09 XLT with 5.4L and 3.55 gears.

I had the truck in before to hagve the transmission TSB performed. This really didn't help out but the truck was still usable. Here is the summary from today's visit:

1. Tech couldn't find an issue and all seems to be fine. The service manager then drove the vehicle and found a slight issue described by me. They are now going to "grease" the axle as it was told these trucks came from the factory with "not enough" grease.

Does this sound right or are they just hosing me?

Thanks

 

They're refering to greasing the slip yoke on the drive shaft.....on some trucks this has caused a clunking sound on take offs or shift changes.....they can try this BUT it wont might help any of the other issues you described OR you can grease it yourself.....

If they're going to do it for nothing than have them grease it....

 

A dry slip joint in the driveshaft ... (either in the rear shaft of a two piece shaft behind the center carrier bearing ... or at the rear of the transfer case {4wd} or transmission {2wd} if a one piece driveshaft) ... can bind under power as the rear axle twist slightly forward because the shaft must shorten, and a dry slip joint (splined joint) will sometimes suddenly "pop" as it releases pressure and you will feel it.

It may be that it's burred from use with no grease for long time in which case there may be a ridge at the edge of heaviest wear where the two parts (male / female halves) have to get over each other. Like an "earth quake" .... but in the drive train.

If grease helps it, likely it will reoccurr and you'll need to keep it well greased.

If it's worn bad enough, you'l either learn to live with it or replace it.

If that's the cause, likely no hesitation in transmission / engine ..... rather more likely just the sudden clunk drawing your attention.