Shaking and Vibrating into Cab

[jaynine89]

I have a question for the mechanically-inclined out there. I'm posting it in the Urgent Help section because I plan on driving from Madison to the Twin Cities in Minnesota next week and would like to get it resolved asap. If there is a more appropriate area for me to post, let me know.

For about the last two weeks, my truck has been shaking and vibrating at highway speeds. I've really nailed it down to speeds above 63 mph that it starts to happen and only gets worse with more speed.

At first I thought there may be something vibrating from the engine that was then rattling the entire vehicle, perhaps due to filling up with lower quality gas at a station I don't usually go to. However, when I filled up two more times and still had the issue, I ruled that out.

The problem starts as sort of a low hum, which then builds up into a relatively violent vibration. Not really any shaking, but there is enough vibration permeating into the cab that the cowl and dashboard buzz and vibrate.

A coworker who has always done his own maintenance has been trying to help me trouble-shoot the problem, and so far we've done a differential fluid change (the truck has 75,000 miles on it, likely its first change in its life) and realized that the rear wheels have a little play in them. What I mean by that is that when the rear-end is in the air, and both tires are off the ground, you can shimmy each of the rear wheels toward the differential and then back away. It isn't by much, but it didn't seem right to either of us. We measured the play when we did the differential fluid change, but for some reason I seem to have misplaced our measurements. Could this be related?

His next theory is that the tires need to be rebalanced or changed. With Wisconsin winter around the corner, I will need new tires. My only hesitation comes because of the relative newness of this problem; it's only been happening for a few weeks, and seemed to happen suddenly. If the tires were out of balance or wearing improperly, shouldn't I have noticed something sooner?

My final theory is the rear wheel bearings. I'm fairly convinced this problem is stemming from the rear-end; nothing up front seems out of place.

In addition to the shaking and vibrating, the rear-end squeaks as I move away from a stop. I'm not sure if this might be related as well.

Hopefully I didn't write too much of a novel and I can get a few responses. Please let me know if you guys have any theories and fixes I can try to make this vibration go away. I'd rather not drive to St. Paul and be confined to less than 65 mph because the truck vibrates so much. That will make for a very long ride...

Thanks.

Jayson

 

[90jurassic2]

When you did your rear diff fluid change, did you pull the cover off?

 

[snake]

Most rear axles have some play so I'd rule that out, or compare it to another truck to be sure. U could have slipped a belt in a tire or slung off a wheel weight, but tires are the most common cause. If were mine id jack each wheel up and spin them slowly and look for out of round or other abnormalities. Might be a really dry u joint also and that might explain the squeak. Let us know when U figure it out.

 

[jaynine89]

Jurassic: Yes, we pulled the cover of the differential off, drained the fluid, cleaned it all up really nice, measured the play, put the cap back on, and filled her up. My coworker has never really taken his vehicles in to the shop, he's done a lot of his own maintenance and has a lot of tools, so I feel pretty comfortable in his abilities.

Snake, a really dry u-joint seems interesting. But you think that might only be for the squeak? I'll get the tires up as soon as possible and see if there's anything odd about them. Otherwise you seem to agree that it's the tires and not likely anything else mechanical?

I really appreciate these quick replies, guys. I'll definitely let you know if it gets resolved.

 

[bmerr98]

I was thinking a tire out of balance or out of round at first, but I wouldn't describe that as a hum. Tires are the most common cause of speed related vibrations though. As mentioned before u-joints are suspect (squeak on take off). A little bit of side to side play in the axles is normal, but since the vibration/shaking started before you changed the gear oil ima say it's not related to any work you've done.

 

[black_demon69]

i would focus on u joints and the tires my guess is it is one of the two..

 

[jaynine89]

I was thinking a tire out of balance or out of round at first, but I wouldn't describe that as a hum. Tires are the most common cause of speed related vibrations though. As mentioned before u-joints are suspect (squeak on take off). A little bit of side to side play in the axles is normal, but since the vibration/shaking started before you changed the gear oil ima say it's not related to any work you've done.

Yeah, we did the differential fluid partly as a trouble-shoot. We knew the axle had the play and wanted to check how much there was, just to see whether they were still in tolerance. But if that's normal, I won't worry about it. And like I said, the truck just flipped 75K, so we both felt a fluid change would be good to do anyway.

So far it seems the consensus is U-Joints or tires. Obviously tires are easy enough to replace, but out of curiosity, how involved would the u-joints be? What all would need to be done? I'm confident my coworker and I could do the work, I just don't know off-hand what it all entails.

 

[Blueox]

If you had a bad rear wheel bearing that was causing such a vibration, you would have noticed it when you had it in the air and looked for play at the wheel. As stated some in and out is normal to some extent. However, if you grab the tire at the top and bottom and push it at the top pulling out at the bottom, in other words rocking it back and forth, you should have very little to no play. If you have play, compare it to the other side. The bearing could be on it's way out. But to make that kind of vibration, unlikely.

My bet is either a u-joint, a tire or an axle Most likely u-joint. My first u-joint went out at 66,000 miles. Second was 120,000. First first time it vibrated quite a bit.

You could also have a bent axle. I was chasing a vibration and when we had it in the air in ran it in gear, you could see the tire wobble. Took the tire off and put it on the balancer and it ran straight. New axle and problem solved. But if that is the case and you need a new axle, I would replace the bearing also. I didn't and now the bearing is bad. So back to the hoist.

 

[simpler=better]

U joints are way easier and cheaper than tires. Just make sure the new u joints come with new clips (if you have that style) and be sure to clean & regrease any slip joints in the driveshaft.

I'll bet the U's are still factory and need to be changed anyway

 

[bmerr98]

You can rule out tires by rotating them front to rear. If the vibration moves to the front it's a bad tire. If it stays put the problem is with the axle somewhere. I had a bad axle shaft give me problems once. About the third set of tires I finally narrowed it down. The axle flange was off center on the shaft.

 

[jaynine89]

If you had a bad rear wheel bearing that was causing such a vibration, you would have noticed it when you had it in the air and looked for play at the wheel. As stated some in and out is normal to some extent. However, if you grab the tire at the top and bottom and push it at the top pulling out at the bottom, in other words rocking it back and forth, you should have very little to no play. If you have play, compare it to the other side. The bearing could be on it's way out. But to make that kind of vibration, unlikely.

My bet is either a u-joint, a tire or an axle Most likely u-joint. My first u-joint went out at 66,000 miles. Second was 120,000. First first time it vibrated quite a bit.

You could also have a bent axle. I was chasing a vibration and when we had it in the air in ran it in gear, you could see the tire wobble. Took the tire off and put it on the balancer and it ran straight. New axle and problem solved. But if that is the case and you need a new axle, I would replace the bearing also. I didn't and now the bearing is bad. So back to the hoist.

Good point about the rocking. Now that you mention it, every time I've checked out the play with the rear end up, it's been straight in and out, on both sides. Pushing the top in doesn't make the bottom come out. So I think the bearing can be eliminated.

As far as the axle goes, again, every time it's been up, we haven't noticed anything like that. But I'll double check it again the next time I do get it in the air.

 

[jaynine89]

You can rule out tires by rotating them front to rear. If the vibration moves to the front it's a bad tire. If it stays put the problem is with the axle somewhere. I had a bad axle shaft give me problems once. About the third set of tires I finally narrowed it down. The axle flange was off center on the shaft.

I'm surprised we didn't think of that before. Rotating the tires is a pretty simple troubleshoot. I'll definitely be doing that today. I'll also keep the axle flange in mind.

Thanks again for all the ideas, guys.

 

[jaynine89]

Well, I just conducted a quick experiment. I put the spare tire on the right rear, which seems to be where the squeaking is coming from. Something about that position has just seemed off. I was going to switch both left and both right tires with each other, but I don't have a proper jack, and doing it with the one behind the seat was going to take forever.

So, with the spare tire on (which is fully inflated-we filled it last week when we did the differential), I hit the highway for a few runs back and forth. Everything was okay up until about 63 mph again, when it started shaking and vibrating. The strange thing is that, north of 70 mph, it seemed to stop again. On the first run, the shifter was moving around quite a bit, and my watch was shaking on my wrist on the steering wheel. But that calmed down, again, north of 70, and everything seemed normal.

Except for the tracking. I didn't notice it before, but the truck seemed to pull to the left. I may need an alignment, but it wasn't this pronounced before.

Another thing I noticed is that when I had the right rear tire off, I was unable to make it stand straight up. It seems the tread is worn toward the outside, making the tire lean and fall over. I'm not sure if the rest of the tires are like that, again, I didn't really want to spend the time jacking up each individual tire and dropping it back down. Twice.

So with these developments, do you guys still think it's the u-joints, or is it more the tires/alignment?

Just for reference, the squeak has been going on for several months, while the vibrating/shaking has only occurred in the last two-three weeks.

 

[bmerr98]

That bad axle I had wouldn't show up til I got to highway speeds. Never squeaked though. It's very possible you're having a couple different problems ganging up on you. Now a u-joint would probably start as a squeak and progress to more and more violent shaking as rust takes over and needle bearings deteriorate. That being so closely linked to the transmission, the shift lever shaking would be expected. Most DIY mechanics should be able to handle replacing them, so your buddy can help there. They don't cost a lot either. Be sure to mark how the shaft is aligned where it connects at the transmission and the axle. It matters. Be sure to get u-joints that have a grease fitting too.

A broken belt in a tire can manifest itself at road speeds too, but be hardly noticed at slower speeds. And make sure your tire pressure is correct all the way around before you spend money in an alignment. A few pounds low one one side can make it pull.

 

[bmerr98]

Check your local Craigslist type sites and pick up a decent 2 ton floor jack if you get a chance. Don't need them too often, but when you do, they're worth their weight in gold! Oh! Harbor Freight has a pair of 3ton jackstands for like $18 right now I think, too. Think safety!