Chasing a driveline vibration

TDS 854X4 · September 23, 2002

Hey all,

Well, the pickup has been giving me fits lately. No doubt rebelling, due to the neglect I have shown it over the summer.

Latest problem I have been struggling with is a wicked shake. Notice it mostly at the same speeds, regardless of RPM's. Currently at just below 40mph, and it comes back at 65mph or so. Had 2 different sets of wheels/tires on there, with no change. U-joints are good. Newer shocks that feel pretty decent given the "bounce" test. Alignment has been checked and is good. New brake drums in the rear. Newer rotors in front, but I have not checked them for warpage. Shake doesn't "FEEL" like it's coming thru the steering wheel, though. And not under braking.

Seem to get a pretty good clunk when putting truck in gear, which I have read of others that had too much slack in the transfer case. Think that would cause any vibration? I have been trying to fix this on my own, because it's expensive to have a shop do diagnostic and repairs, for how much $$ I have to spend on the truck.

Other things I have read have mentioned rear axle/differential as possibly a factor. I have thought about grabbing some of these parts from a local salvage yard, and start swapping just to see what happens. Anyone else got any ideas as to what else I could check into?

Thanks!!

September 23, 2002

Everything that you mentioned could cause a vibration. With all four wheels of the truck jacked up, spin everything looking for slack. Check the driveshafts real close to see if there is any evidence of a balancing weight missing.

I've never experienced this personally, but I think that a sloppy rear end or transfer case could definitely set up a vibration. I think it would most likely end up being a bearing in say, the output of the transfer case or the input of the diff(pinion).

How about clutch/pilot bearing or torque converter bolts?

if I think of anything else, I'll post.

Good luck and keep us informed.

Torque Junkie · September 25, 2002

My truck has a very similar vibration (at certain speeds, in 2wd or 4wd, regardless of engine rpm, and not under throttle or coasting, but in a coasting-deceleration - basicly when there's no torque one way or another on the DS & Diff) and I have traced it down to a bad pinion bearing. What it's doing is the driveshaft and pinion are slacking vertically about 1/2" each direction at certain speeds. Becuase of this, the entire rear end needs to be rebuilt: not only to replace the pinion bearings, but to replace other damaged parts caused by a vibrating pinion shaft.

I also get the "THUNK" when putting it into gear, either reverse or forward. I also get a thunk when starting after stopping, caused from the driveshaft changing position at the rear when the direction of torque changes from a deceleration to an acceleration.

Try this to diagnose it.. block all 4 tires, and put the truck in Neutral and release the Parking Brake. Crawl underneath and at the very rear of the driveshaft grab ahold and try to shake it vigorously up and down and laterally. If there's ANY play I'm willing to bet it's in the rear diff. When I do this I get about 1/2" play in each direction

I did that with my truck and thats when I started thinking it was coming from the diff., so I took it in and had it professionally diagnosed and that is for sure what it was. Now I just have to come up with the $$$ to fix it

Good luck! Driveline vibrations are no fun. Let us know what you find.

-Mike

TDS 854X4 · September 25, 2002

thanks for your replies.

I am hoping to get this straightened out within the next couple weeks, as I really want to drive the truck out of town, chance to do some off-roading.

I'll be sure to let you know what I do find out.

Shaners · September 26, 2002

I had a weight come off my G20 conversion vans' driveshaft before... that will definatly cause a vibration.

If you have a two piece drive shaft then I would put my $$$ on the carrier bearing in the middle of the shafts...

TDS 854X4 · September 26, 2002

Nope, one piece drive shaft for me.

But now I'm starting to wonder about my ball joints up front. Getting a little clunk at turns. Those heading south could be part of the shake too, I suppose.

I got a long day of chasing all this down, ahead of me.

Thanks for your replies. I'll post back w/ what I find out.

Torque Junkie · September 27, 2002

Good luck!

Please keep us posted on what you find out!

TDS 854X4 · October 14, 2002

Well, ahd a good day Saturday, and made some progress on the shake. Ruled out a few things at least.

Had the truck up on stands, so I could run it in 4wd and see what was happening. Had no shaking when in 2wd. Soon as I put it in gear, I felt the shake thru the steering wheel. Funny, because when driving it, sure felt more like it was coming from the rear.

Shake wasn't too bad with the wheels straight. But as soon as I turned a little bit one way or another It was pretty violent.

Had the wheel/tire balance checked, just to be sure, and they were on. It's almost like something is binding up, or else the rotors are so warped that they are dragging. I was working solo, so I couldn't really see the pass. side thru my checking, but right now I'm leaning towards the drive axle, because, when I had it in park even, and turned the wheels lock to lock, the front tire wanted to buck a little bit. As if the u-joint at the end of the axle needed to spin some before it would allow the wheel to turn. It's hard to describe really, other than it seemed wrong. ;) Maybe in the differential?

Well, I think I have it narrowed down enough that I can feel OK about taking it to a shop. Running short on time and patience. And the cold weather is here it seems. Going to cost me, I'm afraid. But at least I've figured out where it was coming from. No idea why it started to do that though.

Torque Junkie · October 15, 2002

I would HIGHLY suspect the front axle U-Joints on that one. I had the same problem (go figure, aNOTHER problem in that old beast ) In 2wd it would be fine, as soon as I put it in 4wd and put power down it would vibrate pretty bad. And when i turned the wheel with power it would hop, skip and make a popping/cracking noise. Then it started to hop & pop going straight. This got worse and worse until one day going up my parent's driveway (very steep w/ a hairpin curve) CRACK!!! and then I lost all power to my front end. Had my brother look underneath the truck and the front drive shaft was spinning but the power wasn't getting to the wheels. All of this occoured right after a HUGE snowstorm that dumped 3' of snow in 24 hours.

So I took the truck in and had the front axle u-joints replaced and 4wd was back again and was almost as smooth as 2wd.

That would be my first angle of approach before I started tearing into the driveshafts & differential.

-Mike

TDS 854X4 · October 15, 2002

That's kind of what I was hoping, too. I get the shake in 2wd, but had nothing when the tires were off the ground, so it had to do with the front axle turning. I had been getting some "binding" while turning in 4wd even last winter.

I just had these replaced 3 years ago I think. But the hasn't seen a lot of road time since then, I'm sure the sitting in the driveway didn't do them any good, either.

I might have to pull the manual out. See if this is a job I want to try and tackle this week, or pay a shop to just do it in a day.

Thanks for sharing your thoughts, Mike. It's been helpful through this project. And I got planty more behind this one I think, that I have found while going thru different parts of the truck chasing this down. Things do seem to pop up often with this one, too! ;)

Torque Junkie · October 15, 2002

Hey, no prob, Tom.

Let us know if it was in fact the u-joints or if it was something else. From the sounds of it and from my experience, I highly suspect the u-joints.

Good luck!

-Mike

TDS 854X4 · December 30, 2002

Well, I FINALLY got the $$$ saved up and took the old truck in for repair. Got new u-joints at the axle ends in front, they were siezed up. Interesting thing was, they were greaseable joints in there. Not common from what my mechanic told me. Probably why they didn't get greased when I would have it lubed. Anyway, he found no grease in 'em anymore. Also had one of my lockout hubs worn out, came apart in pieces on one side. Now I got a nice Warn pair on there, a definite improvement over the yucky looking old pieces. I think I like the function of these more, the old ones had to spin more than 1 revolution to engage/disengage. These are about 1/3 of a turn. And new u-joints, the truck drives nice again.

Drove the truck in to work today, it was a nice change. Next step = new inner and outer front fenders on there before the sloppy snow really gets here. Lucky so far, we don't have any. Oh, new radiator to follow soon as well. Always something.....

Torque Junkie · December 31, 2002

Glad to hear you got it fixed!

I know what you mean it's always something..... $4500 later and there's still sh*t going wrong.

My license plate is coming due next month, I think I'll spring for a personalized plate "MONYPIT"

-Mike

ClipperSkipper · January 21, 2003

Driveline vibrations are one of our specialties, in fact "Shade Tree Mechanics" hosted a show back in the fall of 1999 during which they chased down several owner complaints of vibration on a late-model K-2500 pickup. Sam and Dave replaced the universal joints in the two-piece drive shaft,

balanced the tires, but Dave found a high spot in the left front tire whilst using an on the car balancer. While checking the rim, the rim had appeared true, however there was a high still spot on the tire. Dave said that they would send it out to a tire repair shop in order to have it 'shaved". Shaved? Who can do this?

Interestingly enough I cannot find a facility in the entire Northeast Corridor of the united States who can shave a tire!

Easy to pinpoint, driveline vibrations are either "seat of your pants", rear, or in the front, steering wheel. The Other (U-joints, etc) are usually aural and 3 or more times faster than wheel roation.

Have a great one!