First I must say neat site guys! everyone seems to get along great.

Ok I have a mystery "bump" in the drive line. A little backround I just aquired a 2006 150 work truck model 5.4 automatic with 90 thousand miles by the looks of the cab and bed it has to be alot of hiway miles. It does appear to have hauled some sort of service equipment in the bed. there is paint missing on the back part of the bed and some wear marks like it hauled a welder or maybe a pest control tank etc Im guessing fairly heavy.. enough to squat the back of the truck Now the mystery problem when taking off from a dead stop it has a bump like theres a bad u-joint. It wont do it taking off going down hill or slope, I can ease the gas and it wont "bump" 90% of the time. It doesnt do it in reverse. I had a mechanic look at it and they said the drive line seemed fine no slack in the 3rd member or u-joints and suggested it might be the motor mounts. this made sense so I replaced them at a cost of $208 (OEM part only) and still have same problem. I thought maybe the rear gear had wear but the truck moves forward for 5 to 10 feet before the 'bump"....any suggestions?? TIA

 

Maybe pull your rear differential cover off and inspect. If there is something on the gears you will see it.. Plus you never know if they replaced that oil or not, and if they were hauling alot it should be done asap. Also make sure you use 75w145 gear oil. Just my .02 Also this bump, does it feel like you hooked up a chain to the back of your truck and you come to the end and BAM?

 

Oh and i forgot Welcome to the sight. Alot of good knowledge on this site. And one more thing WE NEED PICS of the truck lol

 

Not taking the time to go out and look under mine (too darn cold), If these trucks have a two piece drive shaft, I remember reading an article in Trailer Life mag. that said to lube the drive shaft splines where the two pieces enter the center bearing. They were refering to a clunking noise the writers truck was having.

 

I would grease the slip yoke at the back of the transmission, some trucks were have a bump at take off and that was the problem.

 

Greasing the yoke at the transmission and the center peice of the drive shaft did the Trick!!!! 25 cents worth of grease fixed the problem! Thanks guys! my transmisson guy couldnt belive it either ( and wouldnt have if he hadnt performed the work himself) sorry for the slow response in thanking you guys!

 

Could this be the same problem when coming to a stop? When I slow down to say like 20 mph and then get on the gas I have the same issue. Like a clunk or thump. I think it's worth a try.

 

sounds like a winner to me. i hear that noise on my truck all the time so im gonna have to try it.


thanks

 

I had the same exact problem. pulled the slip yoke and regreased.....problem 100% gone. Here are some links with pictures showing how to do this on HD trucks. The 2004+ F-150 is basically the same.
2004 F250 Slip Yoke Service
Slip joint regreasing

 

Rangers have this problem too; my last one was a 2000. Grease the slip yoke- problem solved!

 

I had the same exact problem. pulled the slip yoke and re greased problem gone.