Front Drive Shaft Movement??????

[nosferatu49426]

Im not sure if this is a dumb question or not but while I was under my truck the other day looking around, I happened to grab the front drive shaft and noticed there was a significant about of movement (up, down, side to side). Im assuming there shouldnt be any movement but not sure. This being said I have a distinct vibration from about 2300 rpm to 2600 rpm. could this be the cause? But at the same time the front hubs arent locked in so It shouldnt really be spinning I wouldnt think. any thoughts would be appreciated. Oh the trucks a 98 with a 4.0 auto trans.

 

[adsm08]

That joint should not have much play, won't be zero, but it shouldn't be much. That being said, a vibration from that would require the front hubs be locked in, and would be related to ground speed, not RPM.

A vibration that is solely related to RPM is an engine issue.

 

[nosferatu49426]

Kind of what I thought for the vibration. Any suggestions as to what could cause the movement in the drive shaft? Should I start another thread in the 4.0 section for the vibration?

 

[adsm08]

The drive shaft probably has a worn out CV joint.

The engine may be a misfire, a bad harmonic balancer, damaged piston, lots of things. Hard to know where to start.

 

[nosferatu49426]

Ok. I'll check the cv joint. Thanks for the info. Im slowly trying to learn/ teach myself all this stuff. It's a lot of fun. Is there any way to check the harmonic balancer? I'm pretty sure the pistons should be ok, just replaced both heads and the tops looked good. But I guess I can't say for sure about the bottoms.

 

[nosferatu49426]

Also can the cv joint be rebuilt?

 

[nosferatu49426]

Just for the fun of it I checked the price of a balancer on rock auto and there was a section attached with a tech article and it listed some diagnosing things to check. Im kind of leaning towards that being the issue. I took a screen shot of it just for reference. Not sure if it will show up.

 

[adsm08]

That would be my first instinct as well. It is the only part that should be able to cause an engine vibration that would be considered a "wear item" as the rubber in it will dry-rot, crack, and generally give out after so many years.

I know when I rebuilt the 4.0 for my 87 the balancer was shot. I replaced that bad boy because it was cheap insurance.

If you go that route buy a cheap steering-wheel puller too. The one with the screw through a forked bar, easiest way to get the balancer off.

 

[nosferatu49426]

Not sure why I didn't think about the balancer in the first place. Seems like it should've been the first thing to think of.

I think I have a puller from a long time a go.


The engine does have 160,000 plus on it. Thanks. I really do love this forum.