Hey folks,

So I had serious vibrations in my truck and I took it in and had a new driveshaft built. That helped immensely. It used to vibrate some when driving in 5th, but when I'd let off the gas to coast, it'd get bad. Turns out I had the driveshaft shortened too much when I did my tranny swap and it allowed for some play in the slip joint.

So, $785 later I've got a new fancy driveshaft a new yoke on the rear and a new seal behind that yoke. Way more than I had hoped to spend, but whatever...done is done.

So now that that vibration is out, I've noticed something entirely different. Mainly in 5th, mainly when going over 60, I get a vibration throughout the truck and the shifter really vibrates. And it does this mainly when I'm on the gas (a little or a lot, doesn't matter). If I coast (in gear), it isn't nearly as bad.

I'm thinking there's some play in a bearing somewhere, but figured I'd throw it out there and see if you folks had any ideas.

Sorry for being long-winded.

 

Hows the tranny mounts?

 

Brand new...motor mounts, too. Well, new within a few thousand miles, at any rate.

 

HMMMM Okay hows the input shaft of the tranny? Was the new shaft balanced?

 

Last time I ran into that it was the pilot bushing bad.

 

Input shaft was never taken out of the tranny...it seemed pretty tight to me...although what do i know?

The Pilot bushing looked decent before i did the clutch, but i replaced it, and when the new pressure plate was out of balance I had to do the clutch job again, and replaced the pilot bushing again.

I'm thinking something internal to the tranny...but again...what do i know?

 

Drivetrain vibration is something I've seen over the years in Mopars. Try these items.

1. Grab the tail shaft of the transmission and push it up, down, and side to side with all of your strength. Is there a clunk or a lot of movement in the trans mount?

2. Grab the drive shaft near each u-joint and push it up, down, and side to side with all of your strength. Is there a clunk or a lot of movement in the u-joints.

3. Look at each u-joint carefully. Make sure if there are circle clips holding the u-joint in place that the clips are actually still there AND that the u-joint caps are centered.

4. Make no assumptions about your motor mounts. Put the truck in drive with the brake on, and see if the engine rocks to one side quite a bit. Do the same with the truck in reverse. Aftermarket parts can sometimes be real junk.

 

Hey thanks for that detailed reply.

I can't really get to the tranny output without pulling the transfer case, but the t case output is pretty tight (not much movement).

The driveshaft is brand new with new yokes all the way around.

I checked the tranny mounts the other day and they appear tight and right. The motor mounts are newish but I'm going to check them this afternoon.

 

What I'm getting at is that new parts can be bad right out of the box. What I'm trying to get you to do is not assume anything. That's why each item needs to be physically checked with force/movement. Not just eyeballed.

Man I've been bitten badly about assuming new parts were ok. Just trying to pass on that experience.

Mike

 

oddly enough check the t.case fluid. I had a pretty bad vibration in 4wd. topped up the tcase fuild and the problem went away completely. I had a vibration a second time a few months later in 2wd, so I topped up the tcase fluid and the problem went away again. and I only had the vibration at or close to hwy speeds.

 

Try the mount on your exhaust downpipe it mounts to one of the bell housing bolts I just remembered dads truck had that go and you could hear and feel the vibration.