Diff or Wheel bearing noise?

[89Vette]

I've finally gotten to demo a couple of VXs during the past month. I was a little concerned after driving all three. Specifically, all of them seemed to have some drivetrain vibration.

I already posted about the first one (and how I decided to pass on it) in the VX Talk Forum. (I found out it had been put in a ditch.)

The other two have some similarity -- though there is a difference. One whines when you let off the accelerator. It's been lifted. My guess(es) on this one are either a drive-shaft alignment issue -- or -- the inner pinion bearing needs replaced. (Sound seems louder from the rear.) By inner pinion, I mean the one up at the nose. (Let me know if that's supposed to be called the outer bearing.)

The one I am most inclined to purchase also has wheel-bearing-like noise. From about 40mph, I can begin to feel vibration. By 60mph, it is fairly loud. Between 60-65, it annoyingly loud though the harmonics quiet somewhat by 70mph. I could see this being a wheel bearing or differential bearing issue. I also note it's louder when sitting in the back seat.

My search brought up a post where it sounds like this 4x4 system might be as prone to differential bearing problems as the Grand Cherokees I've previously owned. Though it doesn't have quite the same whine/growl as the JGC I'm used to, the sound seems fairly centered -- meaning it seems most likely to eminate from a differential (vs out on a wheel).

How can I figure out what's going on? Determining the extent of repairs needed, their cost, and/or the propensity for recurrence could make a difference in my decision to purchase one of these units.

Any feedback is appreciated!

Gregg

[Riff Raff]

Gregg--- My best advice is to KEEP LOOKING!!! Run away from those poor VX examples, as those irregular sounds are probably the main reasons they're up for sale. Those sounds you hear are not normal and are an expensive can-o-worms just waiting to be opened.

Be patient; the right VX is out there somewhere, and you'll immediately know it after a thorough test drive and a mechanic's inspection. Heck; it took me over 7 years to find mine, so just keep lookin'.

[89Vette]

Gregg--- My best advice is to KEEP LOOKING!!! Run away from those poor VX examples, as those irregular sounds are probably the main reasons they're up for sale. Those sounds you hear are not normal and are an expensive can-o-worms just waiting to be opened.

Be patient; the right VX is out there somewhere, and you'll immediately know it after a thorough test drive and a mechanic's inspection. Heck; it took me over 7 years to find mine, so just keep lookin'.

This isn't a thread asking advice to buy or not. (I would place that kind of thread in VX Talk.)

[wintermute]

FWIW, my recently acquired VX had a similar 'whine' when decelerating. A noticeable almost rubbing like noise when you let off the gas at low speeds, and seemed to be worse at higher speeds above 40 MPH.

I've dug around the site some and read a few posts on the topic. One of the first questions asked of me was if the tires were mismatched. My front and rear tires were not only different brands and tread patterns when I picked it up, but the wear pattern was very uneven due to severe misalignment and lack of rotation.

It was suggested to me that tires on the VX are critical to the TOD system functioning properly. If tires are severely mismatched or unevenly worn (as mine were) it can cause bad sensor readings and lead to trouble in the transfer case.

In many threads I read, users/owners tended to notice this noise more, or for the first time immediately after lifting their VXs and putting on larger tires/wheels.

I'm not sure exactly what the issue is, if there are multiple problems described here with similar symptoms but different root causes, or what the ultimate solution is, but in all cases I've read about tire condition, size, and lifts seemed to play a role in triggering or exacerbating similarly described problems.

I changed my tires out for a near stock 255/60/18 on an aftermarket 18x9 rim, and most if not all of the sound I heard when decelerating is gone. I'm not entirely convinced that there isn't a 'problem' still lurking under there somewhere, but the new wheels and tires appear to have minimized the symptom in my case.

In any event, I'm very interested to see what others have to add on this topic. When I first encountered the rubbing/whining sound there was a distinct vibration I could feel as well. I thought it could be anything from a bad CV or drive shaft to a problem in the transfer case. I guess I'm still a little skeptical that new tires and wheels have truly eliminated the problem, and wonder if the larger tires, wheels, and lifts or worn tires put more stress on an already weak component or if bad sensor readings and TOD settings are really the culprit here.

[lasturbo]

The one I am most inclined to purchase also has wheel-bearing-like noise. From about 40mph, I can begin to feel vibration. By 60mph, it is fairly loud. Between 60-65, it annoyingly loud though the harmonics quiet somewhat by 70mph. I could see this being a wheel bearing or differential bearing issue. I also note it's louder when sitting in the back seat.
Gregg

This symptom above for me and my 1999 was the differential. I was lucky to obtain a like new used one from Lisa (VX Crazy) and after installation, synthetic gear oil, and LSD additive, it was good as new.

[PK]

89Vette, as you probably know, drive train noise is very difficult to diagnose without hearing it personally. Also, some of us will tolerate higher noise levels as "normal" than others do.

Couple of suggestions -
1. There are 3 grease nipples on the rear drive shaft. If these are not lubricated it will cause a drive shaft vibration and noise that sounds centred. So your fix could be as simple as a dozen shots of grease.

2. Rear axle bearing noise is very distinct. It is a "whaa - whaa - whaa" noise and the frequency is directly linked to wheel speed. It also can sound centred if both wheel bearings are shot. Then the noise merges into the centre.

3. Diff bearings or gear noise is more of a definite whine and comes and goes at certain speeds, and depending on if the throttle is down, or you are just rolling along.

4. As previously mentioned, tyre matching and condition, and even tyre pressures, are super critical on these vehicles.

Without actually hearing the noise, that is about as much input as I can give.
Use this condition to drive the price down, or walk away and keep looking.
If you get the price down, and it ends up being an easy fix, that is your reward for taking the risk.

Good luck.

PK

[89Vette]

FWIW, my recently acquired VX had a similar 'whine' when decelerating. A noticeable almost rubbing like noise when you let off the gas at low speeds, and seemed to be worse at higher speeds above 40 MPH.

I've dug around the site some and read a few posts on the topic. One of the first questions asked of me was if the tires were mismatched. My front and rear tires were not only different brands and tread patterns when I picked it up, but the wear pattern was very uneven due to severe misalignment and lack of rotation.

It was suggested to me that tires on the VX are critical to the TOD system functioning properly. If tires are severely mismatched or unevenly worn (as mine were) it can cause bad sensor readings and lead to trouble in the transfer case.

In many threads I read, users/owners tended to notice this noise more, or for the first time immediately after lifting their VXs and putting on larger tires/wheels.

I'm not sure exactly what the issue is, if there are multiple problems described here with similar symptoms but different root causes, or what the ultimate solution is, but in all cases I've read about tire condition, size, and lifts seemed to play a role in triggering or exacerbating similarly described problems.

I changed my tires out for a near stock 255/60/18 on an aftermarket 18x9 rim, and most if not all of the sound I heard when decelerating is gone. I'm not entirely convinced that there isn't a 'problem' still lurking under there somewhere, but the new wheels and tires appear to have minimized the symptom in my case.

In any event, I'm very interested to see what others have to add on this topic. When I first encountered the rubbing/whining sound there was a distinct vibration I could feel as well. I thought it could be anything from a bad CV or drive shaft to a problem in the transfer case. I guess I'm still a little skeptical that new tires and wheels have truly eliminated the problem, and wonder if the larger tires, wheels, and lifts or worn tires put more stress on an already weak component or if bad sensor readings and TOD settings are really the culprit here.

I read that too. In your case, I think you'd be wise to mount four new, balanced tires to see what happens. But, mis-matched tires should exhibit problematic sounds under many conditions (vs just in decel). I don't think that's your "solution", but having four matched tires, will probably rid you of some road/tire noise.

FWIW, I asked a machine shop about this today. The head machinist told me how you could tell which of 1) the ring bearings, 2) outer pinion bearing, or 3) inner pinion bearings were failing.

If the sound occurs fairly evenly at all speeds, the ring bearings (aka carrier bearings) are probably going bad.

If the sound occurs under accelleration, the inner bearing (base of pinion) would be seeing the most pressure.

Otherwise, under decel, the outer bearing (nose of the pinion) would be seeing the most pressure.

[djvx]

my vx has the noise vibration upon de-accelaration since i bought it. It was bone stock, original tires, no mods, 50,000 miles. I took it back to the dealership and they did a service bulletin search and found nothing. They did nothing. I've since done an old man emu lift, torsion bar crank, bigger tires, a tranny flush, rear diff lube, greased driveshaft and put 15,000 more miles on it. Sound is there but has never gotten worse. Like I said earlier, it happens when de-accelerating and It was very concerning at first. But I now don't worry about it.

[djvx]

Otherwise, under decel, the outer bearing (nose of the pinion) would be seeing the most pressure.[/QUOTE]

What would the "fix" be for this- did the mechanic say?

[LittleBeast]

My noise at highway speeds when I let off the accelerator is getting almost unbearable. It seems to have gotten significantly worse the higher I lifted the suspension lift, greasing the grease points only seems to help for a day or so

[RamAirZ]

When I got mine it would always make a "whine" when decelerating under 40mph or so, almost like it was in low-gear and right before I would get to a stop it would just disappear, almost like something disconnected at a certain speed, would happen when you felt the transmission downshift before a complete stop. Since I put my manual hubs on I don't hear it anymore so I'm thinking it had something to do with the TOD and front axle.

[89Vette]

89Vette, as you probably know, drive train noise is very difficult to diagnose without hearing it personally. Also, some of us will tolerate higher noise levels as "normal" than others do.

Couple of suggestions -
1. There are 3 grease nipples on the rear drive shaft. If these are not lubricated it will cause a drive shaft vibration and noise that sounds centred. So your fix could be as simple as a dozen shots of grease.

2. Rear axle bearing noise is very distinct. It is a "whaa - whaa - whaa" noise and the frequency is directly linked to wheel speed. It also can sound centred if both wheel bearings are shot. Then the noise merges into the centre.

3. Diff bearings or gear noise is more of a definite whine and comes and goes at certain speeds, and depending on if the throttle is down, or you are just rolling along.

4. As previously mentioned, tyre matching and condition, and even tyre pressures, are super critical on these vehicles.

Without actually hearing the noise, that is about as much input as I can give.
Use this condition to drive the price down, or walk away and keep looking.
If you get the price down, and it ends up being an easy fix, that is your reward for taking the risk.

Good luck.

PK

New Falken tires are on the vehicle, so that's not it. Actually, you can hardly HEAR the problem sitting in the driver's seat. But you can certainly feel it. Vibration hits sensory threshold about 40mph. By 60, there's enough vibration, I could compare it to running a lawn motor. You can definitely hear it, but it's not that loud in the front. Vibration is the more relevant symptom from the driver's perspective. The vibration/sound is most prevalent under acceleration and holding speed. When the throttle is released, 20% of the vibration goes away. This is either vibration from the motor itself -- or vibration getting that power to the wheels. (It does not get louder under decel).

When I ride in the back seat, sound is considerably louder. It varies only with speed but does not oscillate. I'm not certain if this clinches the rear axle/diff as the culprit, or if harmonics of the vehicle/chassis trasmit more loudly in the rear of these cars. (Same is true for vette coupes.)

The entire drivetrain on all three I've driven have exhibited some degree of whine/vibration which makes me wonder how much is native to the TOD setup. OTOH, I'd find it hard to believe new vehicles were sold if they ALL sound/vibrate this way. The particular vehicle I'm interested in has been stored for the past two years and has less than 80k miles on it. There's enough "new" feel left, that I can sense what a new one might have driven like.

While old fluids could be contributing to the problem, it simply feels like there's harmonic vibration in the drivetrain. It doesn't oscillate, but it does vary with pitch/intensity with speed. It feels like a bearing issue.

Since it's much more pronounced in the back, I'd be inclinded to think rear diff. OTOH, I can clearly feel it in the SWheel. No fluids are leaking and the undercarriage looks very good for its age.

(What are the zerts in the rear drive shaft for? If "dry", whats the symptoms?)

On a side note: Do these have an air pump that's audible at idle/low rpms? Seems like I hear that too.

[etlsport]

doubt its the problem, but I have had problems with my rear diff building up pressure because the vent tube gets clogged, maybe check that?

for the zerk fitting, the only symptom ive noticed is a clunking during accel and decel from the driveshaft when they need to be greased.

if the bearings are going bad, you should be able to feel it by jacking up the rear wheels, holding the tires at 2/7 and pushing/pulling, then try 11/5.. then 3/9 there should be basically no play at all

[tom4bren]

Vibration with little to no noise = tire balance in my book.

Mine makes 'airbox noise' always has since I've owned it. Some gear noise has always been present too. It's hard to hear though since I'm running Wrangler MTRs.

[etlsport]

Vibration with little to no noise = tire balance in my book.

agree with that... my Falken tires have been a nightmare to get balanced properly.. ive had 3 different people try to balance them on 4 different machines, they are finally right.