Engine/Transmission (1994 - 1998) Thump on takeoff

[HCanales]

I went flying on a two week trip with my job, when I came back I noticed a slight thump on takeoff from a stop. Perhaps my truck sitting for two weeks caused damage to something, I don't remember the thump before I left on this trip. It doesn't seem to be a bang like backlash, because it rolls about 5ft before I feel the thump.



I used to have a PowerStroke that did the same thing and coming to find out it was the flywheel. However, I don't have a duel mass flywheel in my Ram, but perhaps there is something in my clutch (I don't know).



My brain storming ideas were:

1. something in the limited slip

2. brakes

3. carrier bearings(Again!)

4. u-joints

5. clutch(kinda doudt it)

6. axle wrap



If any of you folks have any other ideas please share thanks!

HCanales

 

[Lsfarm]

Usually it is

Usually this thump is caused by sticky splines on the driveshaft. When you come to a stop, the rear axle is pulling back on the truck, this lengthens the splines on the driveshaft. When you start to move again, the rear axle is pushing the truck so it moves forward, trying to shorten the drive shaft. If the splines are sticky the truck has to move a few feet untill the forces are great enough to push the driveshaft forward on the splines.

I'd try lubing the splines on the driveshaft.



The other item can be the spare tire sliding fore and aft on it's cable if it isn't tight enough. Easy enough to check.

Hope this helps, Greg L

 

[HCanales]

That makes sense Greg , I didn't even consider that. My guess is that in good time it will wear into place and be back to normal again. Perhaps a little

grease will do it good also, thanks a million for the good idea !

HCanales

 

[Gary - K7GLD]

UMmmm - well, that was the SAME thing *I* told ya over in your OTHER thread on the same subject...

 

[HCanales]

Gary, I'm sorry. I also thank you for your inputs too. Now I understand

whats going on with my splines(I didn't before in your reply).

HCanales

 

[Gary - K7GLD]

Just giving you a bad time - I shoulda been more detailed in my reply, like Greg was, but was waiting for more info to surface before spending too much time running down what mighta been a false path...

 

[HCanales]

Good news ! The noise has quit when I was pulling my boat home, I drove it since and its not thumping anymore (I wish all my other problem would do the same ). I would like to give a special thanks to Gary and Greg for help . Further, I have a better understanding on whats going on and more expirience now. Thanks!

HCanales

 

[Gary - K7GLD]

IF your center support bearing assembly is not greasable, as mine is not, you might be experiencing the symptoms of wear at the splines that has formed a ridge at the area where those mating areas normally rest. Earlier center supports were greasable, and problems such as yours were far less common. I really dislike the shift away from greasable suspension and drivetrain components, and now use an injection needle to pierce the various sealed boots on those joints, and inject grease into them.



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Time will tell if it helps as I hope it will...

 

[HCanales]

Aaaahh... Bonus, I have that same tool that I found in my boat when I bought it , The previous owner had left it behind. I'm going to have to dig it out again and put it through practical use. On a different note, I couldn't agree with you more on the issue with serviceable vs. nonserviceable grease zert fittings (I think thats ridiculous). Thanks for your help!

HCanales

 

[Gary - K7GLD]

Use that needle carefully as to not tear the boot - and insert the needle as far to the OPPOSITE side of the joint as possible to get the new grease as far away from the insertion point as possible this helps assure that only trapped air and OLD grease will seep back outta the pierced point when the needle is withdrawn. ALSO, use the new grease sparingly - only enough to slightly "plump" the sealing boot, otherwise it will only make a mess as excess grease leaks back out, or worse, burst the boot or it's seal...

 

[HCanales]

Ok, the thump went away and I put on the agenda to lube the slip shaft as soon as the weather permits. So anyway, I'm driving down the road and I do a stop & go and it comes back, but only this time its a loud jolting rattle . Finally, I arrived at my work and had someone move the truck back and forth to see the center bearing only held on by one bolt. Inside the bearing housing is a fixed nut that is welded (that fixed nut is stripped). I really wish I had a digital camera to show you folks what I'm talking about . Anyhow, I'm going to tighten the one side and weld a one inch bead on the opposite end. Any suggestions before I do this tomorrow?

 

[HCanales]

I hit the "submit reply" button instead of the "preveiw post" before I had the chance to say thanks. Again, thanks for helping me isolate this problem, this could have been a real big expense if I didn't know where to look

HCanales

 

[Gary - K7GLD]

FEW things are as exciting as dropping the center-support bearing assembly, and then the front part of the driveshaft at about 70 mph on the freeway...



Be VERY glad YOU located the problem on a parking lot!