Vibration Under Acceleration

Still putting the Six Mil Dollar Jeep back together after the devastating trip to Red Creek.

Bout fixed everything and have it running and idling good now but I've got a pretty good vibration in the drive train under acceleration. Wish I could describe it better but not sure how to other than to say it's kinda like driving over a washboard. It doesn't do it when coasting so I'm sure it's not the tires, and it's not there when just sitting in neutral revving the engine so I'd rule out an engine problem. It only happens under acceleration. Hard to tell if it's tranny or axles or t-case...just seem to feel it and hear it as if I were sitting on top of the noise.

FWIW, I've replaced a starter, starter solenoid, clutch slave cylinder and re-filled an empty power steering reservoir since the trip.

You might remember that the jeep was under water...up to the top of the fender for quite a while...probably 30 minutes. Never stopped running but my brother was nervous that the hot engine running under water may be just too hot for it. I have no leaks in anything so I figured that no water would have gotten inside anything but you never know.

Any help or ideas as to where to look would be greatly appreciated.

 

Just a thought, have you checked the universals? I had a bad one that sounded just like what you described. On acceleration, the torque would cause a vibration, but when I let up the vibration would go away. (Rear drive line at the t-case.) HTH

 

Haven't checked them but definitely will as soon as I get home...assuming Mitzi hasn't got me lined out doing something else. Thanks.

 

Another vote for U-joints...and I happen to have a couple extra lying around too...

 

doesn't take but a second to jump under and shake the drive safts around... i'll vote for it...

 

My $.02 as well I had the same problem with my u-joints. All six of them

 

Yepper, u-joints are my vote too.

 

Well, I thought of a plan to test to determine if it was the front joints or the rear joints. Figured with the Atlas I'd be able to shift it into Front Wheel drive High Range and see if I had the vibration then. Hopped in and grabbed the shift lever only to find that it was just flopping around. Climbed under it to find that the rod connecting the lever had become disconnected. I reconnected it and went for my test drive. Unfortunately I can't seem to get it into to Front Wheel Drive only. I can get it to shift into all ranges except Front Wheel Drive High.

But...I don't seem to have the vibration. Only thing I can think of is that the t-case was kinda sorta in and out of gear. Or maybe not fully engaged.

I played with my CB a bit instead. Got on channel 20 and keyed up and got a response from a guy who was only about a mile from me. He was a CB radio repair man so I drove over to his house. I bought a new antenae for it and dropped it off at his house to have it tuned up a bit for better reception and signal strength. Should pick it up tomorrow. Not really sure what he does to them, but he says that he can open it up and adjust the settings and I'll have a much better radio.

 

Good news. Cheaper to fix the CB than the Jeep

 

one thing seems to lead to another

 

I submerged my Jeep a couple of years ago and I can say without question that you can get water into a gearbox or diff that doesn't have any apparent oil leaks. It would be cheap insurance to dump the fluid out of the diff's, tranny and T case and you might be surprised how much water you have in them. I had water in all of them. I even have the front diff breather on a hose up into the engine compartment and it still sucked water in from somewhere.

 

This may fit in with your noise issue. A few years back I had a bad vibration also, and after checking my u-joints and everthing else I could test, I laid under the Jeep puzzled. After a few minutes I noticed that my rear drive shaft yokes were not aligned together. So I popped the shaft out pulled it apart and realigned it. I never realized my drivetrain was so quiet...just something else you could check out.

 

Well, here's some more poop on the vibration. First....I had a chirp chirp chirp sound that I had diagnosed as an idler pulley on the belt that turns the OBA. My brother took a test drive with me to help me diagnose the vibration and the first thing he said was "you've got a bad u-joint"...he said that chirp chirp chirp was the u-joint not the idler pulley. We climed under it and sure enough the u-joint on the rear shaft @ the t-case is very sloppy. I'll fix that.

Then we checked the front shaft and those joints seem fine, however I've got alot of play in the yoke where it enters the differential housing. Martin said that this was just a pinion bearing, but I've had another fella tell me that I probably have a worn out R&P that'll have to be replaced. He mentioned something about a crush collar that would hold it steady if it had been installed properly.

Thing is...these gears are pretty new and I think they were professionally installed.

Opinions on the slop in the front yoke?

 

There is supposed to be some play at the pinion (rotational). It usually seems like a lot, but it really isn't. When the R&P heats up during use, some of that is taken up. My opinion, don't worry. That bad U Joint is probably the source of your vibration.

 

Just got off the phone with Nick Miller (Nickmil as if y'all didn't know) and he made me feel much better. 1st...the play I'm describing is not necessarily rotational as I didn't even check that. I just grabbed the shaft and shook it up and down and the play I've got is in the pinion yoke whereas it just kinda wobbles in dif housing. Nick said that it could be as simple as the pinion nut not being tight enough or it could be the pinion bearing but either way it's fixable and not too complicated.

Nick says to tell everyone hello. He's been out of touch most of the summer because he doesn't have a computer @ home....he usually checks in from work like me and he's been off work most of the summer. He said he'd probably be back on-line tomorrow to check in.

Nick also said that the u-joins were probably my vibration as my vibration starts around 45 MPH and he said most of the time that's about the speed you'll pick up u-joint vibs. Prior to that speed you'll hear the chirp chirp chirp sound I've been hearing and blaming on the fan belt / idler pulley.