SOLVED! Chasing a vibration

TollKeeper

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So I have had a vibration in my front end for a couple months. It seems to come on just above 70mph.

I have replaced quite a bit in my front end already, in the last 3 weeks, tie rods, ball joints upper and lower, control arms upper and lower, front brake rotors, front brake pads, and all tires (Michelin Defender LTX M/S). Also have had an alignment, and 4 wheel balance. They were all needing replacement, not just throwing parts at it.. However, the vibration continues. I cant pin-point where exactly the vibration is.

I am just looking for suggestions. There really isnt much left to replace, rear axle rebuild, driveshaft u-joints front or rear, cv axles, and I think thats about it.

I have only been using 2wd as of the last year. 4wd shifts in an out perfectly. I have visually checked the rear driveshaft, and the U-Joints look to be good, but they are factory originals, at 195k miles. Same goes for the CV Axles. Wheel bearings were replaced last year, and have maybe 2k miles on them.

The only thing I can note is that when I was working on the rear end, the drivers side half shaft had no play, in or out, up or down. The passenger side -did- have play in and out, but not up or down.
 
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Mooseman

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Wheels straight? What about the hub flanges? Rear axle flanges? No wobble when you spin the wheels? Inner tie-rods good?
 

TollKeeper

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Can't detect any bends or deformities join the flanges, no wobbles or dips, inner tie rods also new
 

Mooseman

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And new tires? I had a set of tires that despite getting balanced multiple times, they were just shaky.
 

TollKeeper

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The tires are new as of Saturday, but the vibration was there prior to the tires.
 

Eric04

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Dec 3, 2014
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Given what you've replaced I'm gonna toss this out; how old are the front brakes? I seen rotors wear strangely and essentially throw off balance without the tell tale pedal bounce.
 
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TollKeeper

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1 week old, and vibration was present before replacement
 

Mooseman

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Loose axles? Shouldn't be the front u-joints/driveshaft if you have it in 2hi. Rear u-joints are a possibility if you feel it in the seat rather than in the steering wheel.
 

Reprise

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Just a hunch here... we'll assume the wheels are in the same positions wrt old tire > new tire.

Swap the front / rear tires (like a rotation, not a remount). See if the vibration goes away / goes to the rear. If it does, you may have an issue with your wheels (you have new tires, so those s/b OK)
 

TollKeeper

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Loose axles? Shouldn't be the front u-joints/driveshaft if you have it in 2hi. Rear u-joints are a possibility if you feel it in the seat rather than in the steering wheel.
I dont get it in the seat, but I do feel it in the floor thru my feet?

Just a hunch here... we'll assume the wheels are in the same positions wrt old tire > new tire.

Swap the front / rear tires (like a rotation, not a remount). See if the vibration goes away / goes to the rear. If it does, you may have an issue with your wheels (you have new tires, so those s/b OK)
I can try that over the upcoming weekend. Im pretty sure they arent in the same position, but im not positive.
 

budwich

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Jun 16, 2013
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kanata
I haven't tried this myself but have done some work in the area. You could try an "accelerometer app" if you have an iphone (i am androided / pc / landline ... :smile: ). Most phones have accelerometers built in and hopefully the app has enough "brains" to make use of it capabilities which may be limited.
Run the app and place the phone at various locations in the vehicle to narrow down what frequencies might be seen along with amplitude at different place. Potentially, it might tell you if it is "rotational" from wheels types or drivetrain type from other areas... motor mounts, transmission, etc.... maybe. Plus if you choose your location wisely, you can perhaps narrow down which component might be the contributor.... ie... same relative "sense" on both side versus say drivers versus passenger, etc... Hopefully, you get the idea. It likely costs nothing to try and if nothing happens, you can have fun with some "science"... :smile:
 
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Reprise

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I can try that over the upcoming weekend. Im pretty sure they arent in the same position, but im not positive.
You never know. The places I've been for tires over the last few years, they tend to do one at a time, (because they only have one balancer, etc., that's available to them -- some places have multiple machines, but the tech only uses one, to keep the other machines free for other jobs).

I like to watch for a bit (does that make me a 'vehicle voyeur' ?), and although the truck may be on a lift, the tech does one at a time, at most places around here, at least. Discount Tire is a notable exception, as they often team two guys to a bay, and there are multiple mount & balancers available for them.
 

TollKeeper

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This was at discount tire LOL
 

TollKeeper

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So had it at Firestone for an alignment recheck, and once over. They said my factory U-Joints, and factory CV Axles are in good shape, with no play. But they also said with my miles that I should consider getting new shocks and struts... Uhm, they are new 2-3 weeks ago.

The alignment was off a bit. Left front was Camber, or was it Caster? The Right front was Toe. And the Steer ahead was also off.

I drove it to work this morning, but I was/am to tired to remember if there was a vibration.
 
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TollKeeper

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So still have the vibration.. I did notice something thou, the vibration is quite a bit more pronounced when coasting. Still have it under throttle, but its about 80-90% less then when coasting.
 

budwich

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Jun 16, 2013
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kanata
my guess, if it is more front the back, then cv joints but not sure why in 2w mode that would matter as they should be free wheeling without tension... so then probably something else. Maybe with brake drag (stuck caliper), under power there is more "push" versus "glide" locking up the cv joint more.
 

aaserv

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Dec 1, 2019
408
N of Baton Rouge, La.
May be a longshot but Id take a look at the rear transmission mount and also the motor mounts themselves. I caught hell using aftermarket mounts on my 6cyl some years ago. Changed probably 3 motor mounts and a couple of transmission mounts in the span of 2 years or so. Finally went to the Chevy dealer and bent over for factory mounts and never had a problem again. Problems varied from a slight vibration to feeling like the entire car was coming apart at certain speeds.... I know it would seem like coasting would eliminate it being a mount problem but I wouldnt discount it as much as theory would suggest....
 

mrrsm

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Mooseman

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We've always said on here to use either ACDelco or GM mounts. Otherwise you might as well use a block of wood as all aftermarket mounts transmit vibrations.
 

TollKeeper

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Well, sitting at 197k miles, and still on factory mounts, I would not be surprised if I have no mount left at all.. But the V8 4x4 mounts, from all the research I have done, are nightmares to replace.
 

gmcman

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Dec 12, 2011
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Sorry I missed this thread, could be related, I also just replaced my tires a couple months ago with a second set of Defender LTX's. After a few weeks, I noticed what felt like flat spots, I had to have a tire replaced under warranty for being out of round.

I've been back about 3 times for a re-balance in the 1st 2 weeks, the last set was smooth as glass, but I finally put the vehicle on 4 jack stand and found a decent amount of "hop" in one tire, a little less in a 2nd tire.

Not sure how much tolerance there should be, but it looked like a seperation but I didn't hit a thing or any type of hole, or sharp transition.

There was a review on Tire Rack not long ago about someone else having a new defender out of round also.
 

TollKeeper

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Well, before I start chasing the tire possibility, since the vibration was there before the tires were replaced...

So I thought I had replaced the wheel bearings on my Envoy last year, turns out I was thinking about the wrong car.. That was my wifes Aztek last year, and our backup car Buick Rendezvous this year. The wheel bearings in the Envoy are 5 years old now, and some 40-50k miles old.

That being said, I am beginning to wonder if its a wheel bearing... Since we all know how much these trucks love to eat wheel bearings..
 

gmcman

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Dec 12, 2011
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You stated you're using 2WD, are you using 2Hi or A4WD?

Have you checked the rear diff fluid level since it appears on coast?
 

TollKeeper

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Vibration is there all the time at speed, from 72mph up, and now its starting in the 50mph, goes away around 60, and back at 72. Dont matter if 2wd, A4WD, or 4x4.
 

TollKeeper

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So on my way to work this morning, I decided to turn off the heat, radio, and anything else that could make noise. I am hearing a grumble from the front end. So I went ahead and ordered up some wheel bearings (again), and see if this corrects my vibration.

The truck did sit from December of 2019 to November of 2020, so maybe the bearings got a flat spot in them? I dont know. Just want this vibration to go away. I cant even use my rear view mirror from the vibration.
 

Mooseman

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Dec 4, 2011
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Ottawa, ON
I had that on the Saab when I ripped out the front axles and drive shaft chasing a noise and it wound up being a hub again.
 

TollKeeper

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So go the new HUBs installed last night, I think I am getting really good at this, took 1 hour, for both sides, from placing to the jack under the truck, to putting the jack and tools away.

The drivers side sounded a bit rough, but was smooth on the spin. The passenger side was smooth with no sound. However the large O-Ring was completely smashed, and the bolts holding it in werent loose, but also werent tight. I took them off with no strain or effort with a 1/4 inch ratchet.

Anyways, I took it out for a test drive after the fact, and the vibration is still there. The 50-60 vibration is gone, and the 72 mph vibration moved to 75.

I am beginning to think its the CV axles. For the vibrations to move, after doing the repair, tells me I am in the right area, just not on the right part, but close.
 

TollKeeper

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A bit of an update, and question..

Removed the entire front drive assembly. Vibration Remains
Replaced the U-joints on the front drive shaft, and both on the rear drive shaft. Vibration Remains.
Took it to a shop to have a go at it, and one of the new U-Joints was bad. Replaced that, that got rid of the 60-65 vibration, but the 72+ vibration remains
Replaced the rear axle outer bearings and seals. Vibration remains.

I am thinking about replacing the driveshaft in an attempt to get rid of this vibration..

What are the driveshaft lengths on the GMT360?

Theres the SWB, LWB, and XUV. I know the SWB is obviously shorter than the LWB, but is the XUV different too? I cant find any info.

Hoping to find GM part #'s to go from.

Its either the drive shaft, or the rear axle pumpkin side bearings.
 
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Mooseman

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I'm pretty sure that XUV/XL/EXT are all the same. Same wheelbase. If you can confirm wheelbases, you should be good to go.

Have you tried getting the shaft balanced? Have you tried jacking it up and putting it in drive to see if it runs true?
 

TollKeeper

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Thats the issue. I cant find any measurements of the long wheel bases. Short the short at 113.
 

TollKeeper

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I didnt realize that was another variant. Its a different drive shaft 2wd to 4wd/awd.
 

Mooseman

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Dec 4, 2011
25,178
Ottawa, ON
There's also a switch from aluminum to steel at some point. My 07 is steel. My 02 was aluminum. I don't know if 06 had steel or aluminum, which was the last year for LWB 360's.
 
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TJBaker57

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There's also a switch from aluminum to steel at some point. My 07 is steel. My 02 was aluminum. I don't know if 06 had steel or aluminum, which was the last year for LWB 360's.

I did see alluminum options in there also. I was looking at an online GM parts house. The details did not show until a specific part was selected. Those details were confusing to say the least.
 

TollKeeper

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Being we are dealing with a XL LWB, and they quit making the LWB at the end of production 2006.. That just adds another problem to figuring this out..

GRR!!
 

Mooseman

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Only if you want to switch to a steel shaft. There should be a good supply in yards of the aluminum LWB ones.
 

TollKeeper

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I actually did want to switch to steel.. But frankly, I dont care, just need to get rid of this vibration..

I noticed this morning its getting worse. Now starting at about 60mph.
 

budwich

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Jun 16, 2013
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kanata
I notice in this long and "dated" thread that mention of the motor mounts kind of went by but nothing appears to have been done past ALL the other work. Not sure how to do a "full check" but perhaps there is a bit of a visual check that can be done. I recall people mentioned some form of "mirroring" to look at the mount to see if it has issues.

Beyond that, why don't you "spring" for a junk yard drive shaft... can't be hard to find or too pricey, throw it in and see what happens in terms of changes. Go from the results.... ie. more vibration , less vibration, different speeds. etc.
 
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TollKeeper

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The problem, locally, with getting a junkyard drive shaft, is that they use fork lifts to put the vehicles in the yards. I have yet to find a XL/XUV that the driveshaft wasnt dented, or completely bent.

I managed to borrow a truck from my work on Saturday, and I will have it all week. I pulled the driveshaft out on Saturday, and dropped it off at the shop this morning. Will see what they find out.

My hunch is this will not solve the issue. I do believe its the pumpkin side bearings.

But hears to hoping it is the drive shaft.
 

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