High speed vibration issue.

[Davus]

Hi all. 

Thought I would post here first, before diving any deeper into a problem I have. 

The car is a 2000 pathfinder with a touch over 300,000 km on the clock. 

 

We’ve only owned the car for a month or so and are workin through that various bits and pieces for road worthy. My son (17) bought it as his first car. It is otherwise a great car, and has been looked after well by its one owner since new. 

It has a notable high speed vibration that comes in at around 80 km/h, and then goes away at about 95 km/h. It’s not a front end vibration, and cannot be felt through the steering at all. This presents as a low frequency “humming” vibration felt through the seat / floor of the car. 

Wheels (stock pathfinder wheels) have been balanced, and both uni joints on the main driveshaft have been replaced. 

 

I have removed the front driveshaft to eliminate anything front end…..and can confirm that there was no change in behavior. 

 

I also fitted up a second hand driveshaft I got from a wrecker, which didn’t change the behavior at all either. 

 

Before I start digging deeper (diff / bent axles etc), I thought I would just post a query to ask if there’s anything specific to these vehicles that I might want to look for. Do they have a tendency to fail in any particular area that might be causing this issue?

 

Also open to any other ideas. 

 

Thanks all.

[gypsy_time_travelr]

I'm at 261000 miles and have replaced my entire front end almost. I'm convinced it's the control arm bushings, they are basically gone in mine and besides the rotors that is all that's left to replace. Also rear strut bushings fell apart and have to replace also. UJoints on drive shaft were also warn which caused some vibes. It's so many things once they get this old unless you know the parts are good

[Davus]

True - Its very difficult to narrow down without using the "process of elimination" approach and just replacing things until the vibration goes away. 

 

I did come across an iphone app called NVH wich is a vibration diagnosis app, and claims to be outstanding for diagnosing this type of thing. It also has a few solid reviews on YouTube, however its $150,and for an app that seems like a lot to pay. 

 

 

[Davus]

Hi All,

 

SO ive been continuing to work through this issue, and wanted to post a summary with a little extra info, and get as many ideas as i can. 

 

Here is what i know so far. 

 

1) The vibration occurs around 75km/h, and is very evident through to about 95km/h. After that it is still there, but it reduces significantly, almost to the point a "regular"passenger wouldnt realise. 

2) The vibration is a very fine type vibration that comes through the floor / seat. It is not through the steering wheel. 

3) If i roll downhill at the speed in question and click the car into neutral, it still vibrates. In addition to this, the vibration does not align at all with engine revs. This eliminates engine. 

4) There is no difference when i apply the brakes, therefore i have eliminated brakes / rotors.

5) I removed the front driveshaft from the transfer case to the front diff, and had no change in behaviour. Vibration still there. Therefore I have eliminated front drivetrain.

6) I have changed to a second set of wheels, and even rotated them (and had them balanced). This made zero change to the vibration. Therefore I have eliminated it being wheels / tyres.

7) I removed the rear tailshaft, effectively turning the car into a Front Wheel Drive, and went for a very careful drive up to the speed in question. I was extremely on edge (given i didnt want to put too much strain on the front (thin) shaft, but couldnt feel any vibration in this configuration, leading me to think it must be something to do with the driveline from the transmission back. 

I changed both uni joints in the rear tailshaft (its a one piece), and have had the tailshaft professionally balanced. Unfortunately didnt make any difference. Therefore, I have elliminated the tailshaft.

9) I purchased and installed an app called NVH (at the handsome price of $150 AUD), on my iphone which pointed the finger at an engine vibration. Clearly wrong given i have already eliminated it being an engine vibration.

10) I jacked up the rear of the car, places it in gear and slowly accelerated up to 75km/h. Vibration clearly there. (really just confirming other tests). While the car was up in the air i checked for wheel trueness, which all looked fine. For reference at the moment the car has standard wheels and tyres on it. 

 

So that's where i'm up to. 

 

I am now at a bit of a loss, and really starting to think outside the box The car does have a 2 inch lift kit in it. Some research seems to indicate that the uni joint working angles in the main rear tailshaft may be an issue because of the lift kit. Ive taken some angel measurements, and calculated that the front Uni joint at running at around 5.2degrees, while the rear uni joint is running at around 4.5 degrees. Google seems to indicate that 2 degrees is much more acceptable, and that the angles I have are a high potential for causing the vibration. The suggested fix is adjustable rear trailing arms. 

 

Outside of that, i would have to assume its something in the rear diff. I would not suspect the axles in the rear diff housing at this stage for two reasons.

1) They ran true when i had the car up in the air. 

2) When i ttok the tailshaft off and drive it, if it were the axles, the vibration still would have been there. 

 

So - What do folks think?. Im depserate here, so hoping to hear any and all ideas. 

 

EDIT: Sorry i should also add that the vibration itself is more of a "cyclic" / "harmonic oscillation" type vibration. SOme online reading seems to support the uni joint working angles with this type of vibration. 

 

Thankyou!

 

Edited June 20 by Davus

[adamzan]

When you had the rear tailshaft off, did the pinion bearing feel okay in the rear differential?

 

Was the tailshaft "phased" correctly? 

[hawairish]

Have you checked the motor mounts and transmission mount?  They tend to look intact when they’re really split apart, and metal-on-metal contact is possible if the rubber has worn down enough. 

 

Just curious…when you drove around without the rear driveshaft, did you have something to plug the output on the t-case?

 

As far as the rear driveshaft angles go…it takes a bit of lifting to cause the noise, like beyond 4”/100mm of lift.  I suppose it’s plausible, though, depending on what the pinion angle is, but looks like you’ve checked that.  How is the 2” lift being achieved in the rear?

 

You’ve mentioned the u-joints were replaced and the shaft balanced. I’m presuming the run-out is good then, but have you confirmed it while on the truck?

 

Every now and then, I see vehicles with bad shocks that allow for a tire to rhythmically bounce while at speed. I’ve always wondered how that manifests inside the vehicle…like, how do people drive like that and not notice??  To that point, possible to have someone pace with you in another vehicle or someone hold a camera out the window and observe something like that is not occurring?  That’s something that would be speed-dependent, but I suppose I’d have also expected it when the rear driveshaft was removed. 

[Davus]

20 hours ago, adamzan said:

When you had the rear tailshaft off, did the pinion bearing feel okay in the rear differential?

 

Was the tailshaft "phased" correctly? 

Good question - I did not check the pinion bearing in the diff. To be honest im learning more about this as i go, so id have to remove the rear driveshaft to check that again. As luck would have it, it's up on a mates hoist at the moment, so ill do that tomorrow. 

 

I believe the "phasing" of the shaft is good. Again, I don't fully understand it, but i believe it's the same correct orientation as your picture. 

 

Here is a pic of my tailshaft before installation. To be honest, i dont really understand how it would ever be incorrect. I wouldnt be able to phase it incorrectly if i wanted to????

 

 

[Davus]

1 hour ago, hawairish said:

Have you checked the motor mounts and transmission mount?  They tend to look intact when they’re really split apart, and metal-on-metal contact is possible if the rubber has worn down enough. 

 

Just curious…when you drove around without the rear driveshaft, did you have something to plug the output on the t-case?

 

As far as the rear driveshaft angles go…it takes a bit of lifting to cause the noise, like beyond 4”/100mm of lift.  I suppose it’s plausible, though, depending on what the pinion angle is, but looks like you’ve checked that.  How is the 2” lift being achieved in the rear?

 

You’ve mentioned the u-joints were replaced and the shaft balanced. I’m presuming the run-out is good then, but have you confirmed it while on the truck?

 

Every now and then, I see vehicles with bad shocks that allow for a tire to rhythmically bounce while at speed. I’ve always wondered how that manifests inside the vehicle…like, how do people drive like that and not notice??  To that point, possible to have someone pace with you in another vehicle or someone hold a camera out the window and observe something like that is not occurring?  That’s something that would be speed-dependent, but I suppose I’d have also expected it when the rear driveshaft was removed. 

 

Hi Mate,

 

Thanks for replying. Clearly you're a troubleshooter

 

So, a couple of questions and comments. 

 

1) I haven't specifically checked the mounts for either the gearbox or the engine. TO be honest, given i took it for a spin without the rear tailshaft in (with no vibration), i didn't really consider them. Do you disagree?.

 

2) Excellent question! - I was wondering if someone would pick up on that, and it intrigues me that you have. You have clearly taken the time to read through all the testing and troubleshooting i have dine, which i thank you for.

Please treat this as innovative, rather than bad practice :). I removed the shaft, and placed a double layered thick plastic cover over the end of the transfer case. I knew that this would still mean fluid exited from the rear seal, but given it couldn't really go anywhere, and i was only driving for around 5-8 minutes, figured it would be fine. When i got home, i cut the plastic, and collected the fluid that had been caught. I discarded it in-case it had contaminants in it and refilled the transfer case as required. Innovative ...... yes?

 

3) Im not sure what you mean by runout. Can you explain a little more? Sorry - As i said, I'm still a little new to tailshaft physics / mathematics. I assumed that given the shop had balanced it and checked it over fully, it should be OK to simply re-install. Am i wrong in that assumption?

 

4) Thats a good idea. I will get my wife to drive the car, while i observe her from behind. :P

[hawairish]

 

Haha, I'm definitely a troubleshooter...and in this case, I've had my fair share of vibrations and some really wonky stuff on my own truck.

 

9 hours ago, Davus said:

1) I haven't specifically checked the mounts for either the gearbox or the engine. TO be honest, given i took it for a spin without the rear tailshaft in (with no vibration), i didn't really consider them. Do you disagree?.

 

The motor mounts are just deceiving.  I'm not fully convinced it's your problem, but it's definitely one thing on the drivetrain that tends to get overlooked and worth ruling out.

 

I randomly decided to replace mine a few years back after getting a good deal on a new set.  I figured my current ones were just "worn", but wasn't having any problems with them.  Well, they were beyond worn...they were split in half and rusting from the inside, and came off the truck in 4 pieces:

 

I've not had a transmission mount split on my R50, but have had it happen on my D22 Frontier (Navara) where all 3 mounts were split in half like this.  I'm surprised the motor and transmission didn't just flop over.

 

Bad mounts also manifest into other odd things.  My buddy's R50 had this thump at all speeds that he couldn't figure out.  His driver's mount had split and the engine was basically lifting and falling onto the mount with every gear shift.  I swapped in a new mounts for him and the issue was gone.

 

9 hours ago, Davus said:

2) Excellent question! - I was wondering if someone would pick up on that, and it intrigues me that you have. You have clearly taken the time to read through all the testing and troubleshooting i have dine, which i thank you for.

Please treat this as innovative, rather than bad practice :). I removed the shaft, and placed a double layered thick plastic cover over the end of the transfer case. I knew that this would still mean fluid exited from the rear seal, but given it couldn't really go anywhere, and i was only driving for around 5-8 minutes, figured it would be fine. When i got home, i cut the plastic, and collected the fluid that had been caught. I discarded it in-case it had contaminants in it and refilled the transfer case as required. Innovative ...... yes?

 

That's actually very clever!  Did you pull the dust shield off to do it, too?

 

I tend to have a lot of spare parts around so any time I've thought about how I'd do it if I needed to, I figure I'd try to put a spare slip yoke in, but never figured out what would be a good way to keep it in...considering it'd be spinning like a blender.

 

I actually now have that option, though, since the output shaft on my transfer case has been tapped to support a "slip yoke eliminator" that installs how the slip yoke would, except it's bolted to the output shaft and can't fall out.  Allows for using a driveshaft that has a slip joint on it, instead of relying on slip at the transfer case.  For now I still have my OE driveshaft, but will switch to a slip-shaft eventually.

 

9 hours ago, Davus said:

3) Im not sure what you mean by runout. Can you explain a little more? Sorry - As i said, I'm still a little new to tailshaft physics / mathematics. I assumed that given the shop had balanced it and checked it over fully, it should be OK to simply re-install. Am i wrong in that assumption?

 

Run-out is the amount of axial deviation something has...it's "wobble", so to speak.  Imagine a circle spinning around a "center" axis, except that center is slightly off-center, so that the distances from any point on the perimeter to that center aren't all equal.  Runout is a measurement of those differences.

 

It can also be used to detect axle shaft warpage by measuring it at the face of the wheel hub, and also on the outside perimeter of the wheel hub.  These axle shafts aren't puny like that craptastic ones found in Jeeps and 05+ Nissan trucks that magically bend, so I'm not convinced it's the problem either...but again, things to rule out.

 

Specifically for the driveshaft, I would expect runout to be checked during the balancing process.  Sources of runout include a bent shaft, but also the u-joints not being centered in the yokes when installed.  Most replacement u-joints only come with one set of snap rings, but in reality, many applications call for using snap rings of specific thicknesses to ensure they stay centered.  That ultimately means there may be some play that allows the joint to be slightly off-center, thus introducing runout.  I have experienced this first-hand on my truck after having a shop build an extended driveshaft for my R50 (which they screwed up multiple times, the shifted joint just being one of the problems)...and each time that shop gave me my driveshaft back (3 times!) it was supposedly "balanced".  The amount of runout observed was appalling.  I always check for it when I replace my own joints, too.

 

Now, you've tried two driveshaft, and literally no driveshaft, so again, I'm reluctant to think it's the problem.  However, the sanity check here is just confirming that there's no runout observed when it's actually on the truck, vs. when it's on a machine in the shop.  

 

Specifically for a 2000 R50 (and likely the same for all R50s), the runout limit is 0.6mm/0.024", and it's measured at 3 locations on the driveshaft.  If you don't have it already, you can download the chapters of Nissan Factory Service Manual (FSM) here: https://www.nicoclub.com/nissan-service-manuals.  When you dial down to Pathfinder > 2000, you'll have a list of chapters.  View the "Propeller Shaft and Differential Carrier" (PD) chapter and jump to page PD-8.  That has the specific distances where run-out should be checked.  Note that you'll need a dial indicator and magnetic base to measure it, but sometimes it can be eyeballed.  One option is to lift one rear tire up (other on the ground), transmission in neutral, and have someone steadily rotate the up-tire, while you watch the driveshaft or feel for runout with your hand on it.  Can also hold some sort of stationary object, like a screwdriver, piece of chalk, etc., to see if there are little anomalies.  Riskier option is to get the rear axle off the ground, and let the truck idle and spin the shaft (be super mindful of spinning things, especially the tires!).

 

Also, you're correct in that your driveshaft cannot be phased incorrectly.  It only applies on shafts that can be split apart, such as the front driveshaft, or two-piece shafts that use carrier bearings, presuming the splines aren't keyed.

 

One thing about having a suspension lift is that it will pull the driveshaft out of t-case a little.  The driveshaft should be fairly recessed into the t-case shield, maybe 50mm/2" from the outer lip of the shield.  You may want to confirm it's not out too far (unlikely), but at the same time, you don't want it to be all the way in either.  It has to slip with suspension travel.

 

9 hours ago, Davus said:

4) Thats a good idea. I will get my wife to drive the car, while i observe her from behind.

 

I take every opportunity I can to observe my wife's behind wife from behind.

Edited June 21 by hawairish

[Davus]

3 hours ago, hawairish said:

 

Haha, I'm definitely a troubleshooter...and in this case, I've had my fair share of vibrations and some really wonky stuff on my own truck.

 

 

The motor mounts are just deceiving.  I'm not fully convinced it's your problem, but it's definitely one thing on the drivetrain that tends to get overlooked and worth ruling out.

 

I randomly decided to replace mine a few years back after getting a good deal on a new set.  I figured my current ones were just "worn", but wasn't having any problems with them.  Well, they were beyond worn...they were split in half and rusting from the inside, and came off the truck in 4 pieces:

 

I've not had a transmission mount split on my R50, but have had it happen on my D22 Frontier (Navara) where all 3 mounts were split in half like this.  I'm surprised the motor and transmission didn't just flop over.

 

Bad mounts also manifest into other odd things.  My buddy's R50 had this thump at all speeds that he couldn't figure out.  His driver's mount had split and the engine was basically lifting and falling onto the mount with every gear shift.  I swapped in a new mounts for him and the issue was gone.

 

 

That's actually very clever!  Did you pull the dust shield off to do it, too?

 

I tend to have a lot of spare parts around so any time I've thought about how I'd do it if I needed to, I figure I'd try to put a spare slip yoke in, but never figured out what would be a good way to keep it in...considering it'd be spinning like a blender.

 

I actually now have that option, though, since the output shaft on my transfer case has been tapped to support a "slip yoke eliminator" that installs how the slip yoke would, except it's bolted to the output shaft and can't fall out.  Allows for using a driveshaft that has a slip joint on it, instead of relying on slip at the transfer case.  For now I still have my OE driveshaft, but will switch to a slip-shaft eventually.

 

 

Run-out is the amount of axial deviation something has...it's "wobble", so to speak.  Imagine a circle spinning around a "center" axis, except that center is slightly off-center, so that the distances from any point on the perimeter to that center aren't all equal.  Runout is a measurement of those differences.

 

It can also be used to detect axle shaft warpage by measuring it at the face of the wheel hub, and also on the outside perimeter of the wheel hub.  These axle shafts aren't puny like that craptastic ones found in Jeeps and 05+ Nissan trucks that magically bend, so I'm not convinced it's the problem either...but again, things to rule out.

 

Specifically for the driveshaft, I would expect runout to be checked during the balancing process.  Sources of runout include a bent shaft, but also the u-joints not being centered in the yokes when installed.  Most replacement u-joints only come with one set of snap rings, but in reality, many applications call for using snap rings of specific thicknesses to ensure they stay centered.  That ultimately means there may be some play that allows the joint to be slightly off-center, thus introducing runout.  I have experienced this first-hand on my truck after having a shop build an extended driveshaft for my R50 (which they screwed up multiple times, the shifted joint just being one of the problems)...and each time that shop gave me my driveshaft back (3 times!) it was supposedly "balanced".  The amount of runout observed was appalling.  I always check for it when I replace my own joints, too.

 

Now, you've tried two driveshaft, and literally no driveshaft, so again, I'm reluctant to think it's the problem.  However, the sanity check here is just confirming that there's no runout observed when it's actually on the truck, vs. when it's on a machine in the shop.  

 

Specifically for a 2000 R50 (and likely the same for all R50s), the runout limit is 0.6mm/0.024", and it's measured at 3 locations on the driveshaft.  If you don't have it already, you can download the chapters of Nissan Factory Service Manual (FSM) here: https://www.nicoclub.com/nissan-service-manuals.  When you dial down to Pathfinder > 2000, you'll have a list of chapters.  View the "Propeller Shaft and Differential Carrier" (PD) chapter and jump to page PD-8.  That has the specific distances where run-out should be checked.  Note that you'll need a dial indicator and magnetic base to measure it, but sometimes it can be eyeballed.  One option is to lift one rear tire up (other on the ground), transmission in neutral, and have someone steadily rotate the up-tire, while you watch the driveshaft or feel for runout with your hand on it.  Can also hold some sort of stationary object, like a screwdriver, piece of chalk, etc., to see if there are little anomalies.  Riskier option is to get the rear axle off the ground, and let the truck idle and spin the shaft (be super mindful of spinning things, especially the tires!).

 

Also, you're correct in that your driveshaft cannot be phased incorrectly.  It only applies on shafts that can be split apart, such as the front driveshaft, or two-piece shafts that use carrier bearings, presuming the splines aren't keyed.

 

One thing about having a suspension lift is that it will pull the driveshaft out of t-case a little.  The driveshaft should be fairly recessed into the t-case shield, maybe 50mm/2" from the outer lip of the shield.  You may want to confirm it's not out too far (unlikely), but at the same time, you don't want it to be all the way in either.  It has to slip with suspension travel.

 

 

I take every opportunity I can to observe my wife's behind wife from behind.

Thanks for the in depth reply mate. Much appreciated. I actually did the sump gasket on the car yesterday, and as part of that i needed to lift the engine slightly, which gave me a chance to look at the mounts. Whilst they clearly arent new, they not looking too bad really. But in reality, given that ive removed the shaft and been able to eliminate the vibration, i think im leaning very heavily towards something in the rear of the drivetrain. 

 

Transmission mount is obviously very easy to change, so i might order one and just do that anyway. 

 

I've also noticed a bit of a "squeak" when i go over a speed bump coming from the rear, which almost speaks to trailing arms. I might have a look at those bushes. 

 

The guy who balanced the driveshaft did say it had a mild warp to it, which he fixed. Im making an assumption he also checked the runout (thanks for explaining that). Ill test it thought with my dial indicator, but im now suspecting anything out of the ordinary there. 

 

Logically in my mind im having trouble not suspecting the rear diff. By process of elimination, it seems to be the next logical place to target. 

 

The driveshaft is recessed well into the transmission housing. It sits in most of the way. 

[hawairish]

This is a tough one.

 

Agreed that the rear differential or axle is the next target.  May come down to being a driving load vs. a coasting load, if that makes sense.  Force is being applied differently.

 

I mentioned previously noise induced by having bad pinion angles.  In my case, where I have 6" lift in the rear, I would regularly have a buzzing sensation whenever the truck transitioned from a drive load to a coast load.  Notably, the noise comes from the u-joints, even if they're good. 
In your case, when the driveshaft was off, there's was no drive load; it would've been 100% coast load all the time.

 

So if you suspect it's a drive load, that might suggest either the pinion angle is bad (not likely), a/the pinion bearing(s) are worn, or the gearing backlash is a little off (though this could have also produced whining on coast).