serious Vibration when accelerating.

[Caddy]

well with the alternator issue fixed from the last weekend out now on to the new vibration.

it is a serious pain in the rear. it only shakes when I accelerate and a due mean shake the whole truck shakes. it only does it when the transmission is in gear and I am accelerating 25%-100% of the throttle. as soon as I let off the gas it goes away.

I have check the rear drive shaft and it is solid and angles seem right. When the tranny is in neutral and I accelerate the engine is smooth. I dont think it is a driveshaft issue but I could be way off. it seems to only be really bad between 30-70 kph(kph looks wrong. I feel like it should be kmh. this may be a bad morning if I am struggling with that.)

thanks in advance. I really have no idea on this one. I have a feeling I may have to take it to a mechanic to get them to point me in the right direction. I hope not tho

[cLAY]

Is this something new? Maybe you dented the shaft on the last run or lost a balance weight.

Are you running a t-case drop or shims?

Typically in my experience a vib on acceleration is either a bad u-joing or the pinion is shimmed too far up.

[Caddy]

yah its just appeared after this last weekend up in Waiparous, it was a pretty tame weekend tho, I didnt really do anything hardcore. got high centered in a little mud pit. but other than that nothing really big. I checked the driveshaft everything seemed good no dents clean, not marks of missing weights. but I will double check that tonight.

I forgot to mention there is oil spray at the back of the transfer case on the output shaft of the rear drive shaft. this started last year and I have just been checking to make sure the oil levels are staying the same. and they have not moved in a year but there is oil marks on the bottom of the jeep, and on the driveshaft. ( i will take a pic of it tonight if need be.)

[The Machinist]

Did you pull the driveshafts to check the u-joints?  I've come accross this before where the driveshaft felt fine while installed but once I pulled it the u-joint was definitely toast.  Or maybe a unit bearing, jack up the front end and check for play in the tires. 

[Caddy]

I have double cardan joints on the drive shaft if this makes a difference.

[OffRoadNewbie]

Did you pull the driveshafts to check the u-joints?  I've come accross this before where the driveshaft felt fine while installed but once I pulled it the u-joint was definitely toast.  Or maybe a unit bearing, jack up the front end and check for play in the tires. 

i just went thru this tonight !!!    i checked all the joints and they all looked good  but i pulled the rear drive shaft anyways and sure enough the rear U joint was toast  .........i changed it and now all is good 

[Zombie]

I might have to try that when I replace the springs in the butt end of the Zombie.
that is actually sounding alot like what I have been feeling the last while and it has gotten worse.
I thought it was jus the driveline angle, but it is angled a little too low(too big of a degree difference) so it would not be the too far up thing.

thanks guys, I am gonna check that out and let you know.

ps. how do you know if the ujoint is bad? (I have never checked one before, I never had a vehicle with one, not really anyway.

steve

[specialk]

ps. how do you know if the ujoint is bad? (I have never checked one before, I never had a vehicle with one, not really anyway.

I had the same question and the answer was pretty evident once the shaft was removed.  I was able see and feel the movement once it was free from the jeep.

[Justink]

I had the same question and the answer was pretty evident once the shaft was removed.  I was able see and feel the movement once it was free from the jeep.

Should be able to feel excessive movement to missing pins.

[4Banger_madness]

sounds like a siezed or worn out u-joint

[Caddy]

Finally ended up getting time to take it apart. and it was the double cardan joint at the transfer case. the sad thing now is that the output shaft is seriously loose and leaking. so more work ahead.

may have got in over my head.... ohh well.

[jkrubi]

ps. how do you know if the ujoint is bad? (I have never checked one before, I never had a vehicle with one, not really anyway.
steve

Crawl underneith and twist te drive shaft and look for any play at the U joint.  If its seized its really hard to see movement.  As well it might make a clunking sound when letting the clutch out (std) or going frm reverse to drive (auto). In my expeence if the angles are not to steep the fwd (closer to the tranimission/ t-case) will seize and the one at the diff will show the wear.  All goes out the window on a lifted truck.

[frenchy]

Finally ended up getting time to take it apart. and it was the double cardan joint at the transfer case. the sad thing now is that the output shaft is seriously loose and leaking. so more work ahead.

may have got in over my head.... ohh well.

I'm guessing your Tcase failure was first casualty and started taking out other parts... Not sure how you maintained these parts, how old they are...could've been bad install, wear and tear, or design flaw in your setup...
You should have someone knowledgeable look at it, BUT

  I may have to take it to a mechanic to get them to point me in the right direction.

Don't waste a shops time if you have no intentions of having them fix your problems.

[Caddy]

I'm guessing your Tcase failure was first casualty and started taking out other parts... Not sure how you maintained these parts, how old they are...could've been bad install, wear and tear, or design flaw in your setup...
You should have someone knowledgeable look at it, BUT

Don't waste a shops time if you have no intentions of having them fix your problems.

yah I am thinking I will only take it to a shop if I cant fix it. and probably get charged more for working on it before them. LOL