Shudder symptom. Is it what I think it is ??

[Desotocrazy]

Hello everyone. I'm new here and couldn't find a thread relating to this, so maybe I'm asking an OLD thread question here, sorry.

Ok, I have an 04 KJ, automatic 4wd with 95k on it. I have a shudder problem that used to be barely noticeable and is getting increasingly worse and through a wider range of speeds. Originally, the problem occurred only between 51&54 mph and only under light and steady acceleration. Now, I'm noticing the shudder between 40-44 mph then it stops...then re-appears again at the 51-54mph range. It's the age old "driving over rumble strip" symptom; however, I thought that if this was the case a code would be stored due to the torque converter slipping up. I have ZERO codes stored in the computer.

I've also noticed that if I have the cruise set at 53 mph the shudder eventually evens out BUT there's a set of railroad tracks that will launch me pretty high off the ground. When this happens, the shudder instantly comes back....and no, it's not the railroad tracks I'm feeling. I can feel the shudder increase when the car leaps over the tracks and the wheel are at the bottom of their strut travel; however, when the KJ's weight comes to bear again on the suspension, the shudder again goes away.

So, here's the thing. I know there's a big issue in newer KJ's with the torque converter having to be replaced and the PCM re-flashed to correct this problem BUT with this whole attack angle thing causing a shudder going on when I go over a nice sized hill at speed......well, I guess I'm confused. Does this still sound like a torque converter issue or does it sound like a drive shaft joint issue ? I'm leaning towards the driveshaft issue BUT there is no "thunking" sound when going from reverse to forward or de-acceleration. Just too many thoughts on this issue. It's starting to hurt my brain !!!

Sorry, I also forgot to mention that this problem happens in 2wd at around 1400 rpm and when I have overdrive on. If I have the problem in the ranges I described above and turn OD off, the shudder goes away instantly.

Thoughts please !

Thank you in advance.

Desotocrazy

 

[AZKJ]

Just a guess... wheel balance, damaged drive shaft??

 

[HoosierJeeper]

I'm leaning more toward the TC....the tires would still shimmy with OD off....

 

[Desotocrazy]

No, I don't think it's wheel balance as it DEF feels as if it's coming through the drivetrain.

 

[moparman]

Engine miss and soft ****** mount.

 

[Desotocrazy]

I also replaced all of the plugs with iridiums in the past 2k miles; however, the ****** mount MAY be something to look at. I didn't think of looking there.

 

[HoosierJeeper]

Has it ever been wrecked???

 

[Desotocrazy]

nope, never been wrecked, flipped, etc. Just driven....a lot.

 

[HoosierJeeper]

So that rules out a mount being damaged from a wreck....

 

[Desotocrazy]

Well it may not have been wrecked, but that doesn't mean the mount isn't faulty either. I've seen dozens of mounts fail over the years for lots of reasons. I remember the Grand Wagoneers used to pop their mounts religiously if you gunned the engine in 4wd low. My uncle used to get a new GW every 2 years and as soon as his son would get hold of it to do some hill climbing in 4wd low, sure enough there'd be a new air cleaner impression in the middle of the hood. HA HA HA.

I'm going to crawl under the KJ in about an hour to double check the mount. Like I said, I never thought about that one.

 

[Desotocrazy]

Well, I crawled under the Libby and the rear mount seems fine. The rear drive shaft has zero slop in it. The front drive shaft though is another story. The joints themselves seem fine, BUT I can twist the front driveshaft about 20 degrees clockwise and then counter-clockwise. Is that normal ?

 

[smcbride11]

Is it a shudder only upon gear shift or quick throttle changes? I've got a manual '04 and there a very pronounced shudder/steer when i come off the gas to shift.

I'm blaming my suspension, so if you're still on your stock shocks that may be something to look at also.

 

[Desotocrazy]

Yep, it only shudders on UPshifts. Normal downshifts through the gears. If I jump on the gas from dead stop through 60, no shudder.....it's only when I do "normal driving" acceleration that the shudder occurs.

I am still on the oem struts and your query has me wondering too.....maybe if the struts are too badly worn than maybe I'm stressing the front driveshaft. I dunno.

 

[JeepJeepster]

The joints themselves seem fine, BUT I can twist the front driveshaft about 20 degrees clockwise and then counter-clockwise. Is that normal ?

Yes