Feathering
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This page is dedicated to the troubles and tribulations with my 350Z.

Unusual Tire Wear.

    An issue that is being found by new 350Z owners after about 4000 miles is a type of abnormal wear on their front tires.  Although this wear has received the popular terminology of "feathering" and sometimes even "scalloping", it is neither.  Classical Feathering is a term to describe a raised heel and lowered toe tread block wear across the tire and is due to incorrect Toe alignment.

    Feathering:

Other reference: http://www.kimmeltire.com/html/tire2.html

    What I have experienced is a raised heel and lowered toe pattern in the direction of the tread (circumferentially around the tire, on the inside tread block ring only) which is caused by excessive castor.  It was also suggested that this issue is found on BMWs and Audis that have large camber alignments.  There is no official terminology for this abnormal wear that I am aware of.  And although some call this "Cupping" it is not.

    My Tire Wear:

Other reference: http://www.discounttire.com/dtc/brochure/info/helpDeskAlignment.jsp

http://www.discounttiredirect.com/direct/brochure/info/tmpInfoAlignment.jsp

    I had the dealer do an alignment check, as many others have done.  Here is the alignment data sheet from the dealer:

    Here are the alignment specifications from the service manual:

    The dealer found nothing wore or bent in the suspension.  This could imply the alignment was off from the factory or at least from the time I drove it off the lot.  There have been rumors about carrier straps bending control arms in shipment and factory processes failing to perform alignment.  However, Nissan has not officially stated either is the cause.  

    Additionally, others have reported pulling to one side or the other.  These are hard to diagnose because of road crown.  In my case, there was no pull in either direction.  Most reports along the lines of pulling are due to being on one side of the road crown.  In other words if you drive in the right lane the car will pull to the right because the road is slanted to the right.  If you drive in the left lane, the car will pull to the left because the road is slanted to the left.  If you straddle the crown, there is no pull either left or right.  However, incorrect alignment can cause a pull depending on the alignment problem but not always.  So it is possible that your alignment is off without a pull and it possible if you have a pull.  But if you have a pull to one side or the other, accounting for road crown, then it is a pretty good sign that your alignment is off.  Just don't expect to have a pull.  In my case, there was no pull and it cornered very well before and after the alignment.

    Let's talk about the root of the problem.  The concern I have is that this unusual wear may not be caused by improper toe alignment and may actually be caused by excessive castor alignment which is fixed/non-adjustable.  Or a complex combination of Camber, Caster, Toe or the tire itself.  If that is the case, then this might imply the front end suspension has a design flaw.  It could be that the alignment parameters are such that very small amounts of Toe adjustment are enough to compensate and avoid this unusual tire wear problem.  But if that is the case, then one could also view this as a critical sensitivity to Toe which causes this unusual tire wear.  And that begets questions of normal suspension wear sensitivity and the respective continual problems as the vehicle ages.  Keep in mind, we are talking about Toe adjustments that are less than tenths of a degree even hundredths.  That is not a lot of design margin.  I would be willing to bet the suspension flex in normal driving is more than the alignment parameters.  And a design that requires tire rotation and alignment every few thousand miles is bad.  I have also talked to other people that claim this issue can be caused by the tire itself.  There is a lot to a tire design.  Many people will never know how many sets some have to go through just to get four that are actually round!  In this particular case, I don't think it is a roundness issue (although I do have one that is out of round on the rear, I can barely hear it, and the tire is balanced and the rim is not bent but no big deal).  It's also not tire pressure since the 4 tire pressure sensors and alarm pretty much keep me busy airing up and deflating as the temperature changes (you basically never have a chance to run incorrect pressure).  Instead, I think the primary contributors to this issue from the tire aspect is belt design and compound composition.  These tires are designated summer tires.  It could be that a stickier tire (wears faster) is more susceptible to the alignment conditions.  It has also been noted that some Z owners have this same tread wear but on the outer tread blocks.  That could be accounted for by camber.  How can that be?  Well, camber is not adjustable but as you add weight to the car, or take weight away, camber is sure to change.  How much is the question.  The dealer never offered to measure alignment with me sitting in the car but even if they did or knew to ask, the only thing they can adjust is Toe.  So the point is moot at the moment.  However, there are aftermarket camber adjustment blocks available for the Z.  But this is a Nissan stock issue, not an aftermarket issue.

    Now before I get too critical, realize that I DON'T KNOW.  These are just worries/fears/concerns/theories.  It is probably just improper Toe alignment and this sensitivity is not as severe as I have described.  I say this because of factors other than technical that I will talk about at the end.  And of course it could always just be a tire issue and braking may also play a part.  It is hard to visualize this wear with just cornering and driving.  But add braking into the forces and I can see where the toes of the tread pads might get a lot more force if the tire design is weak.

    How do you know if you have this problem?  In my case, I noticed very loud road noise at low speeds, somewhere between 20 and 30 mph.  This noise started some time ago but it gradual got worse to the point that I decided it was time to investigate.  By this time, I had 5000 miles on the vehicle.  The road noise sounds like a grinding roar and is predominant at low speeds.  By the time you reach 50 mph, it is inaudible.  There was no pull to one side or the other.  There was no thumping, just a cyclic roar.  At first I thought it was a wheel bearing going out.  As I inspected the tire, I ran my hand over the tread and felt the abnormal tire wear as described above.

    I once heard a theory about a frog in hot water.  If you place a frog in a pot of boiling water, it will jump out.  However, if you put the frog in a pot of tepid water and gradually raise the temperature to boiling, the frog will not jump out  (please be kind to frogs, do not attempt this at home...etc.).  That is exactly the issue with this problem.  As the tires wear, the road noise increases very gradually.  The effect is subtle over time making it difficult to notice.  At some point, you will notice it and it will be too late.  The damage will already be done to the tires.  So, now that you are aware of the existence of this problem, perhaps you will catch yours in time.  Spread the word.

    Nissan has a technical bulletin out on this issue, but your dealer may not be aware of it.  My dealer did not know to swap the tires from left to right on the front.  So be aware of the procedures in the technical bulletin and ensure your dealer knows.  The technical bulletin instructs the dealer to do an alignment and balance and swap the front tires right to left (tires not rims).  This requires the front tires to be dismounted from the rims.

    In calling Nissan North America (NNA) Customer Affairs (1-800-647-7261, Option 0) to file a complaint, I found out that I am to drive the vehicle for 2000 miles and see if the noise goes away.  If it does not, they will replace the tires.  So, if you have this problem and want your tires replaced, go to the dealer have them perform the procedure then call NNA and file a complaint.  Regardless, I recommend you have your alignment checked.  This problem can creep up on you.

    I should mention that the dealer and the consumer affairs representative at NNA were very nice and appreciative of my concerns and in the case of the NNA rep, have gone out of their way to help.  But they are not engineers so realize their limitations.  They have to go with the procedures that have been provided to them.  And those procedures may actually work.  At no time did anyone try the abuse routine, like you hit a pothole or some such.  That is a very good sign.  Speaking of engineers.  I do believe that the Nissan engineers will get to the bottom of this and fix it, if they haven't already.  The problem is, I personally won't be convinced for another 4000-6000 miles or until Nissan officially states what the problem is.

    With that said, the first time I took the Z in, the dealer did not read the TSB, even though I told them it was available, so they didn't swap the tires.  But, the NNA rep caught it, called the dealer on my behalf, and I took it in a second time where the dealer was embarrassed and apologetic.  So that's fine, no big deal.  They learned, and I got a second opportunity to test drive the Murano!  I can deal with it when they admit it.  What I can't stand is when they try to BS me, but they never did so everything is cool.  I respect that, very much.  Also, the way the NNA rep caught the issue was because he called me back after the alignment and asked if the road noise went away.  I told him it didn't.  Now, after they swapped tires, the road noise did go away, immediately.

    I view the TSB procedure this way.  By swapping the tires, the tread will now wear in the opposite direction (scuff off the high points that are now oriented where the low points were originally scuffed off.  The problem is, we are dealing with an abnormal ...change that to read... "premature" tire abrasion.  Now I'm not so worried about the life lost in the tires of my brand new car that I paid good money for.  But I am worried that the premature abrasion will continue.  So if it took 4000 miles to get to this point, and NNA wants me to drive it for a couple thousand more till it wears back to even, then may it continue to wear back to the original problem in another 4000 miles?  I should interrupt this thought line to state that while NNA wants me to drive it for 2000 miles they have offered to replace the tires outright.  Back to the train of thought, I'm convinced that the Nissan engineers know the answer to this question.  The micro-tolerance of the Toe alignment is a huge indicator as well as the large 8-9 degrees of Castor and some people have it on the outside and the tires are summer tires.  So unless Nissan says something, I might not know for sure until another 6000 miles.  But I think I know.  The castor is so excessive that a minor change in camber (dependent on weight of driver and vehicle contents) coupled with soft composition tires is what is causing this problem.  Harder composition tires may solve the problem or significantly delay it.  But just a couple degrees less camber might also solve the problem.  But I won't know for sure until another 6000 miles.  And a lot can happen in that 6000 miles.  Due to this abnormal, premature tire wear, it may be time for new tires anyways.  Or the alignment could be off again.  What I really don't want to do, is go buy the tires I really want, only to have them destroyed because of a design flaw in the suspension.  But that is a worst case scenario whose likelihood is probably small and is born strictly from fear.  I do hope that the Nissan engineers read this page as I have eluded to the NNA rep.  And I am willing to run the tires for a while as a test.  There is at least one person that had this problem and has bought the tires I ultimately want (Michelins) and has not had this problem yet.  Unfortunately he doesn't have enough miles on yet to tell.  I have also heard Bridgestone has signed letters saying the tires are not the problem.

    In conclusion, do not let this deter you from buying a Z.  Just have it aligned as soon as you get it.  The selfish side wants to embargo all Z sales until they fix the problem for those of us that already have them and those whose are on the way and those that are yet to be produced.  But keep in mind that the alignment may have actually already fixed it.   And you should know that I still drive my Z every single day.  I find excuses to drive it.  My other vehicles are getting jealous with the neglect!  It handles the same now as it ever did.  It eats corners like they are not even there.  I love this Z.  So while this may be a potentially serious problem, I am sure Nissan will correct it for all of us, and it's still an absolute blast to own and drive.  At this point, I have no regrets and recommend to all that want a Z as I did, go get one now.  I can't imagine missing out on the last 5 months of enjoyment because of a fear that may be unwarranted.  If it is a design flaw and Nissan fails to take care of the issue, then all of us will have regrets and a warranted fear.  But the resulting legal battle and bad press may be too much for Nissan.  Look at some of the demographics of peoples that own these.  Doctors, lawyers, engineers, and celebrities.  Nissan needs to handle this forthright and directly.  There may not be a recall due to the associated bad press and they may have decided to handle them on a case by case basis.  I think that is the case as NNA is aware of the issue and they have a technical bulletin on the issue and they are willing to replace the tires if the customer is dissatisfied.  However, if there is a design flaw with supercritical toe requirements and if they err on the side of cost, it will hurt them and the name of the Z and future sales.  If next years model suddenly has a different castor alignment, different tires, or adjustable camber, the world will know at the speed of Internet.  It is getting increasingly difficult to hide things with the advent of the Internet.  Nissan should know this as they participate in the Z forums.  I believe they will fix it, if they haven't already with this Toe alignment or tire replacement.

This page was started in February of 2003 and updated 3 Mar 2003.  Here are the updates as of 29 Mar 2003:

With almost 8000 miles, the abnormal feathering is continuing.  Only now, the noise is audible over the entire speed band, not just low speed or braking.

The TSB states:

Vehicles built before: JN1AZ34E93T004958 JN1AZ34D63T104023, Sept 19, 2002.  Since the TSB requires an alignment and tire swap, I believe that Nissan found a quality issue on the production line.  I believe that issue was the Z's were not being aligned properly.  However, I am now living proof that the alignment and this TSB isn't fixing the problem.

There is a theory making it's rounds in the forums that the problem is caused by the camber setting or springs and shocks.  The spring and shock/strut theory took interest because a number of owners are complaining about "bouncy" rides possibly caused by insufficient shock/strut dampening.  Unknown if bounce and feather are related but adds to the argument of those that want Nissan to fix their perceived bounce problem.  I don't think the ride is bouncy and believe this just confuses the issue.  However, the theory has merit as I can visualize every other normal wear mechanism except this one.  This one is difficult to explain.  I have talked to my Mechanical Engineer friends (I am EE) and this is a real head-scratcher.  If we had to design a system to cause this effect, we couldn't.  However, the spring/shock theory does have some merit.  A technical explanation along the lines of the suspension system (to include tires and rims) that results in a high frequency vibration (many times the wheel rpm) could cause alternating or even every (depending on frequency) tread block to wear unevenly.  Combine that with the camber theory and now we know why most of the tread wear is on one side of the tire.  One member in the forum is working with their dealer to do a test case by changing camber as the dealer service manager has seen this before personally on the Mitsubishi 3000GT.

So again, all of this combined together supports my original thought that this is a complex integration issue and no one parameter is the cause and therefore no one parameter will be the ultimate fix.  But it also suggests that changing one parameter can change the natural oscillation frequency of the spring/mass/dampening system which could alter the abnormal wear problem.  Changing the camber to me will result in spreading the load more evenly across the tire, so this abnormal feathering effect will take longer to occur, but not eliminate it.  Same with harder composition tires although that will also change the oscillation frequency.  Changing the springs or shocks/struts may fix the "bounce" that some people are experiencing but will also change the natural oscillation frequency of the system.  Same with changing rims.  Stiffer rims may prevent the high frequency vibration from affecting the tires sos harshly.  The trick is to alter something such that it does not make the problem worse or create a whole new one.  Hence why complex integration issues are so tough.  At any rate, this information on spring part number changes was provided in the forum:

Front Springs
June 2002 - December 2002 = 54010-CD002
Decemeber 2002 - Present = 54010-CD003

Rear Springs
June 2002 - May 2003 = 55020-CD010
As of May 2003 = 55020-AM810

I cautioned the forum that these part number changes could be something or nothing at all, perhaps a supplier issue.  But, I resolved to find out.

Some owners have started a petition for Nissan to fix the feathering issue and some have filed with the NHTSA as a Safety problem.  I support the petition and added my info to it, but I do not see this as a safety issue, nor performance in terms of cornering.  But it does chew tires and provide excessive road noise unnecessarily.

The problem is gaining momentum.  A guy at work that I never met before saw me pull up and said to me, "I heard the new Z has a tire eating problem.  Is this true?".   Also, people in the forums are emailing the car review magazines about this issue. Nissan better fix this or sales will be affected and the name of the new Z will be tarnished.

Some people in the forum are getting really outraged.  This is getting out of hand, they are fighting amongst themselves and are starting to blame the NNA service rep.  I posted this lengthy discussion to help quell that:

quote:

---

Originally posted by Vincey2kr1
Enforcer I spoke with STeven about the same time on the different part numbers, he wasn't aware of it or knew little about it. I really don't think STeven has any type of authority, I've dealt with him the last 2 weeks about these issue's and he has yet to find any type of solution. I Believe he's just a puppet, a speed bump, we need to get someone involved who is over Steven. He explains he has to get back to his manager, who the hell is his manager? Ian how big is the list?

---

In other words, bashing the poor little support rep at NNA who has an IT degree isn't going to help the situation.  What I need to do is get the engineers and Nissan corporate to understand the TSB isn't a fix that works through him.  Also, others were complaining that he wasn't calling them back.  He has always called me back, faithfully.

So, I called NNA again (twice and he called me back both times-very quickly I might add and that was no small feet as I gave him three numbers to try and find me at), Steve Lam at 1 (800) 647-7261 ext 3866, told him everything above.  He checked with engineering and confirmed that the springs aren't the problem and the part number changes are most likely a supply issue.  He confirmed Engineers know the TSB isn't working and are looking into it.  Success from my point of view.  He wants me to go back to the dealer and have the alignment re-checked and corrected if necessary.  Seems prudent since engineering doesn't have a solution yet.  Well post that info when that happens.

Now I think I have a better understanding of the problem and believe I can fix it.  The force acting on this system that provides the energy required to sustain the oscillation and a wear mechanism are the keys.  There are two energy source possibilities.  First, it is the rotational energy of the wheel and tire.  But if you assume that the tire construction is uniform across the tread block and the wheel and tire are balanced, then the leading and trailing edges of the tread block or any point in between should wear the same amount or show evidence of scalloping.  That disqualifies that source.   Second, the side to side "wiggling" energy caused by the castor and forward momentum (grocery cart wheel).  To create more wear on the leading edge of a tread block than the trailing edge (assuming the tire is uniform across the tread block and therefore force distribution), the tire would have to scrub back and forth when the leading edge makes contact and the energy of the side to side energy is at a peak.  Then as the tread block is in road surface contact recession, the wiggling energy is at mid oscillation (no movement).  It also explains why this happens at a broad wheel rpm range (any speed).  The oscillation is a natural response, increased speed means more energy in the wiggling not a significantly different frequency.  This is over simplified but it is all about energy and force distribution as tread blocks make contact with the road and the resulting friction and oscillation.  So, the first web site I found early on that states this abnormal feathering wear is caused by castor is now substantiated and I have a visualization of the problem.  The ultimate fix is to reduce the castor setting.   That would require changing the expensive aluminum multi-links and a design change.  But, a wheel that has less flex (hub to rim) might mitigate the problem, as well as camber to distribute the force across the tire evenly and a strut or spring change to alter the frequency and a stiffer tire composition to change the frequency and wear longer.  However, all these mitigation solutions will be quickly overcome as there will be more play in suspension pivot points than either of these can mitigate as time goes on.  There is no way around it.  The castor is the key and must be changed.  With that said, this is just a theory.  One that happens to fit.  It does not mean it is correct or the only theory.

This picture shows the driver side tire.

A close up of the outside block.

Inside.

Middle.

Abrasion.

Not cupped.

Tread Pattern.

Here are the results of the second alignment before it was realigned to nominal values:

As you can see, holding alignment to hundredths of a degree is impossible.  Since I know the roads I traveled between the two alignments and that I did not hit any anything, this represents best case driving conditions IE no pot-holes, railroad tracks etc.  I maintain that Toe is not the cause of this problem and we'll be lucky to hold it to a quarter of a degree or .25 degrees on normal road conditions.  This is not abnormal.

Finally, while I believe the problem is caused by castor, the control arms and tie rods can allow enough range of movement in the side to side oscillation caused by the castor.  While I do not know this is the case, let us suppose for a moment that the control arms and/or tie-rod ends are potted in rubber.  I was told this was the case with the RX-7 and Mazda quickly fixed it (got rid of the rubber).  This design would allow enough wobble to cause the side to side scrubbing motion required to cause this unusual tire abrasion.  However, if the control arm/tie-rod ends are already metal on metal and no rubber is used, then tolerance limitations would indicate the only possible fix would be to change the castor.

Lastly, a word about obfuscation.  A popular response from dealers (and others as the rumor spreads) about the cause of this problem is the "transporter tie-down" theory.  The fabled but flawed theory is that the control arms are damaged from vehicle carriers tightening down tie-down straps and chains connected to the control arms.  Let me thoroughly debunk this "excuse".   First off, if true then the control arms would be damaged.  After thorough inspection, my control arms are not damaged.  Secondly, if they were damaged then they would be replaced and the carrier charged for the damage.  Lastly, this is not new, far from it.  This is as old as the "your breaking up" ruse used by radio operators that don't want to acknowledge a transmission.  Let us presuppose for a moment that this is true, then all dealers and automobile manufacturers as well as the carriers would have solved this problem decades ago.  The solution would come in many forms.  The least of which would include arrival inspections, tie-down procedures, and legal action.  Now, while this may indeed still happen on occasion, it is an old issue that is highly protected against and is quickly determined by inspection of the suspension components as part of the PDI or the TSB.  So, I'm not sure what the best reaction is to have when you hear this from the dealer or elsewhere, but mine involves laughter and head shaking.

Here is the first page of the TSB:

Today, 25 April 2003, I had the dealer install a new set of tires.  The tires are Michelin Pilot Sport.  The dealer also performed a four wheel alignment for a third time under warranty.

An old theory that comes up from time to time is insufficient tire inflation pressure.  Let's debunk this once and for all.  First, the tire pressure requirements for the OE Bridgestone Potenza RE 040s is stated on the manufacturers website.  Second, the tire pressure is labeled on the inside of the center console.  Third, the tire pressure monitoring system prevents you from running the tires under inflated.  Lastly, the tires are not cupped or scalloped nor feathered in the traditional sense.  The tires have an unusual heel to toe pattern circumferentially around the tire on the inside tread block.  When the tires are swapped from left to right and vice versa per the TSB, the inside tread block wore in this unusual fashion resulting in now both sides being wore in this unusual pattern.  For tire inflation pressure to be the culprit, both inside, outside and middle would have to be wore in this unusual pattern.  Also the tires would be cupped.  My tires are not cupped.  So, debunk this immediately.  It is not the tire pressure.  Also, do not inflate the tires to the maximum pressure rating.  This will result in cupped tires and is potentially dangerous.  Maximum tire pressure ratings of tires are required by law to prevent people from doing what some have recommended, that is dangerously over inflating tires.  Bottom line, don't be stupid.  Run the manufacturers recommended tire inflation pressure.  The tire recommended tire pressure for the 350Z is listed on the underside of the center console cover and is 35 psi for front and rear.

Don't believe just me on these issues.  Check the links provided above.  Here is another good one:

http://www.babcox.com/editorial/tr/tr129622.htm

May 23 2003 with 1200 miles on the new Michelins, the front tires are beginning to "feather" on the inside tread blocks.

I took the car into the dealer and we put it on the lift and I took pictures of the front suspension members.  If my castor theory is correct.  Then I now know the culprit component.  This is illustrated on the Front Suspension page.

On 12 December 2003, with 13,041 on the odometer, engineers from Japan were coming to look at my Z.  I had taken the original Bridgestone tires down to the dealership for them to look at.  They took my front tires back with them.  While they were there, they performed the alignment again:

I was not available to meet with them as I was out of town on business.  But I wrote them a letter and left it with the service manager.  So when I picked up my car I asked what they found and was told the Nissan engineers from Japan did not say what the problem was.

June 09, 2006 with 20,616 miles on the odometer.  I just got the Z back from the dealership on the 7th.  I was without my Murano from November 2005 to April 2006 and had been driving the Z during that timeframe.  Basically from December 03 to November 05 I only drove the Z occasionally, maybe once a month on a weekend.  In November the Z had about 16,000 miles on it.

When I got my Murano replaced in April 06, I started thinking about taking the Z into the dealership to have several nuisance TSBs and a couple recalls done all at once now that it had about 20,000 miles on it.  I made a list of what I wanted done and went to talk to the dealer.  While there I learned Nissan had a new tire that would, as the technician stated, "would not fix the issue but would allow you to get 10,000 miles out of the tire...these are 10,000 mile tires anyways."  He showed me the tire and I noticed a reinforcement rib had been added circumferentially around the tire on the inside of the inside and outside tread blocks.  There are also other changes see the pic below..

The rear tires look unchanged so I added this pic for completeness

So I decided to look into this issue when I got home and found out that there are people pursuing a class action lawsuit, there is a webpage for it, and the tire feathering thread on the 350Z forum is the longest running I have ever seen in a car forum.  I also downloaded the new tire feathering TSB.  The road noise had been steadily increasing even on the Michelins and once again was sounding like a dump truck.  So I decided to replace my Michelins with all Bridgestones and get back on the Nissan tire trail.  It is to note that the above tread pattern on the front tire does not look like any of the tread patterns shown on the Bridgestone website or on tirerack.  I can only presume that this is a special tire available only through Nissan.  Here are the alignment specs from this last alignment:

As you can see only the left front and right rear toe was out.  Keep in mind these are very small numbers.  The toe was only out by several hundredths of a degree.  Most vehicles have toe alignments in degrees, not tenths.  This does not explain why both front tires have the problem.  Just more proof the issue is not alignment and not classical feathering.

Here is the list of the TSBs and recalls that I had performed for completeness:

So, as of now the road noise is gone as it should be with new tires.  I believe it will come back but will take longer to do so.  These new Bridgestone Potenza tires are soft composition meant for summer.  I am keeping my Michelins, they have a lot of tread left on them, only about 10,000 miles on them so far.  These tires do have the heel toe wear but they can be "trued".  There is one local shop that can still "true" tires.  They basically put on a machine that has rotating blades that cut or grind the lateral face of the tire flat.

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