I have read abit about the slip yoke, is there any real way to for sure see if this is the problem? My 97 has the same ol clunk in it, and to me it seems like when I pulled the rear end cover off, it seemed like it was loose in there, although I am not exactly sure. My truck is a 97 4x4 extended cab shortbox with a 4.6 litre and an auto, shifter on the floor for the transfer case too, if that makes any difference.

 

The slip yoke noise usually shows up just when you first take off from a stop. It usually sounds almost like a honk rather than a clunk.
It's easy to remove the driveshaft and lube the slpines inside the yoke to see if that's the problem.

 

Cool thanks man, I will have to give er a try!

 

what kind of lube are you suppossed to use? Bearing grease? lithium? wd-40?

 

Ford sells a Teflon grease made for lubing these splines.
I've seen other people just use good quality grease, such as wheel bearing grease, though and it seems to work ok.

 

I dont know if this helps but I had the annoying clunk when taking off and I also noticed it a bit when stopping, it seemed like excessive axle wrap to me, the grease was a temporary fix lasting a few weeks (frustrating) this weekend I dropped add a leafs under her for the 33's and lo and behold that clunk is now gone and the truck behaves. I have driven it a pretty hard 40 miles now taking off pretty harshly and there is not even a hint of clunk smooooothhhh

 

I wonder if, now that the truck is sitting a bit higher, and the driveshaft will be pulled a bit further out of the transfer case, if the splines are now riding on a different area on the output shaft and that's making the difference.

 

I lubed my slip yoke, but still "shudders" from a stop into a turn, especially on an incline. Clutchpacks? is my t-case toast?

 

I honestly think mine was due to excessive axle wrap, upon take off there was this hesitation clearly felt followed by the clunk. I am sure my leafs were getting weak as I pulled my boat for the last 3 years that weighed in at 7000# not sure on tongue weight but it was heavy.

 

Stephen, It sounds like you need some friction modifier added to the rearend if it is limited slip. Hopes this helps you. NorminN.B......

 

Thanks, I'll try that... It was last refilled by the dealer after replacing the axle seals. Probably didn't add any modifier. Will adding the modifier fix the problem, or is the damage done?

 

Stephen.osbourne1 you need friction modifier....I almost garantee it.Let me know....and Fordxcab4x4 you are definetly riding on a diffrent spot on your slip yoke ,and that's why it's gone. The tolerances between the slip yoke and transfercase or tranny splines are very tight ...too tight and you wear a certain spot on the slip yoke then when you accelerate the diff moves upwards a bit making your slip yoke go in ,but keep in mind your drivshaft isn't turning very fast and slip yoke binds a bit...that's why you don't feel it going down a bumpy road.The shaft is spinning very fast and the yoke slips past the rough spot easier.That's my experience. This is a very common problem.Early 90s chev 's had the same problem.

 

HOLY CRAP!!! I changed out my diff. fluid with some royal purple. What a difference! no more vibration! I just hope that no, or little damage was done to the rear... From now on, I'm bringing my OWN fluids whenever I have someone else work on my truck, which isn't often, especially since my warranty just expired. Thanks guys

 

The problem wasn't a slip from the driveshaft twisting it was more of a slide back and forth which was making the clunk. I am not sure how changing the angle would cause less axle wrap seems to me only by stiffening up the leafs would you eliminate axle wrap, I am no expert just a DIY. 105 miles now since the leafs were added and not a sign of a clunk. :-)

 

No your not reading this right.When the diff is under exceleration the driveshaft must move inside the tranny farther or transfercase farther. the driveshaft is getting stuck on the slip yoke splines.Not alowing it to slid properly.When you get going your splines are not riding on the same exact spot on the splines because the diff isn't torqued up as high.The clunk is the shaft breaking past the rough spot on the splines that was under a little force to get by that spot...then bang,it pops past the spot giving you your clunk and feeling of something wrong back there.Then everything is smooth until you stop and re accellerate torquing up the diff again and getting stuck in that bad spot.If you don't beleive me call ford.It's a nown problem and it needs to be greased up.Stop thinking complicated.Kepp it simple..cause it usually is.