Recently, I have been hearing a lot of rumbling noise in my front tires when I'm braking to a stop (<25-20mph).

No vibrations, just a low, rumbling noise from the front tires.

At first, I thought it was my cheap NanKang tires, but after browsing around the web, I was made aware of this feathering issue with our G35s.

Only problem is, couldn't really find a definitive fix to this problem.

I have a 2005 coupe - so rotating the tires would be out of the question...

Just wondering if anyone has had this issue, and a permanent, legitimate fix to it? Any side effects from the fix?

FYI - I don't do much spirited driving, just my daily commute of about 16 miles.

Thanks guys.
SubtleSkeptic is online now Report Post Edit/Delete Message

 

Well, there really is no permanent and definite fix but there are quite a few guesses as to why this is happening. Many are quick to point the finger at bad alignment, but the frequency of this issue popping up and the dozens (hundreds?) of alignments performed due to it would point at a more serious root cause. I personally think the geometry of the oem setup and especially the 350z which uses a slightly lower ride height than the G coupe and even more so lower than the G sedan is prone to some sort of side to side resonance/wobble that then manifests itself in the inner tire feathering. My coupe didn't really present this issue much at all until I switched to OEM 350z springs. The car dropped about a half inch all around but with it came tire feathering which became pronounced every 8k miles or so usually accompanied by pretty heavy tire roar up front. At the time my best solution was to switch to unidirectional tires (Vredestine Sessentas) so that i can run the tires forwards and backwards and thus at least equalize the tire feathering and minimize the noise. This has helped and allowed me to stretch out how long I can last on one set before succumbing to the road noise, but it still doesn't address the core issue.

What makes me even more confident that this is either a geometry or actual hardware issue and not just alignment is that some ppl have reported getting rid of the feathering issue after swapping to coils, which assuming they have used them to lower the cars would mean that the geometry problem causing the feathering must disappear at certain ride heights.

Also the feathering issue has been much more prevalent on the earlier Z cars (03-05) and one relatively important suspension change that I know was made sometime around then were new front compression arms with tougher inner rubber bushings around 05 -06 (?? correct me if im wrong on the exact year). Here comes the interesting bit, as my car has been gaining millage and age I've noticed that the feathering comes on sooner than before after tire rotations and with (for a pretty long time) no real suspension mods the only thing that could have been causing this were deteriorating bushings. My car has also recently showed signs of worn bushings with significantly increased tram lining/tracking of groves in the road. If you aren't familiar with it, best way to describe it is your car going in and out of alignment on the run and basically having to correct the steering even when going straight. So I got to work and replaced the lower control arm bushing with whiteline units and will be doing the compression rod inner bushing soon as well, replacing them with SPL pieces. Personally I don't think the lower control arm bushings are to blame, but I am leaning towards the compression rod being the root cause of the feathering.

Im relatively confident in this deduction due to a few reasons. First only the early Zs and Gs have this problem to any significant degree and only the early Zs and Gs have the weaker compression rod bushings allowing for more play and possibly slop/vibration and minute fluctuations out of alignment. Second my right side has shown significantly worse signs of feathering than my driver side, which was also in line with the state of my compression rod bushings. Passenger side being in worse shape and having to be temporarily replaced with an updated nissan bushing until I bite the bullet and go with SPL. Third feathering is fundamentally an issue with alignment and deteriorating bushings that allow for too much play, which would explain why stronger compression rod bushings would minimize the prevalence of feathering in the newer Zs and Gs. Fourth and lastly the road noise associated with feathering is particularly heavy during braking and Im fairly confident that most of the braking work performed by the tires and then on the uni body is done via compression of the ....well compression rod (btw i hated statics in college so i might b way off here, but it only seems logical) and thus only reaffirming the potential root cause being a weak compression rod inner bushing.

So I apologize for the extremely long post, but it basically sums up my thinking on the issue over the past 3-4 years. Hope this helps.

Cliff notes: My $0.02 is that the compression rod inner bushings are too weak and are the root cause of feathering in early Zs and Gs.

 

Have noticed this recently as well and thought it was an alignment problem as you said... interesting.

Curious on the bushings point... I plan to get some mods in the near future. What mods would wind up replacing the bushings by default? I'm not sure where exactly these would come into play as I've not gotten completely to the point outside of just wheels/tires replacement just yet.

Am looking at BBK way down the line but coil-overs in the near future. Would the best time to replace the bushings be then?

 

Replacing bushings is really unnecessary unless your over ~50k and are seeing signs of deterioration or unless your are looking to sharpen up your steering. In my case both facts were true as well as the whole feathering issue. Installing urethane or SPL solid bushing will SIGNIFICANTLY improve the steering feel, and nearly eliminate the lag from when you turn and when the car actually responds. Your best bet is to do some searching on my350z and driver and see if this is the path you want to go down as there are quite a few options for bushings and links so you should first make yourself familiar with the general suspension geometry. You should also keep in mind that you will see the best results from your new coilovers if you do stiffen up the rest of the suspension links and bushing at the same time and if my lil theory turns out to be true you might just also get rid of the feathering.

 

yes this is a problem I am having also and would love to find a fix for it. My tires only have 4k miles on them and the road noise is horrible more so at highway speeds. anyone know where or the part # of the bushings that was mentioned?

 

vp-g , you can pick up updated compression rod bushings at mynismo.com
http://mynismo.com/products/?id=7780 , but bear in mind that I am not certain that this will solve your feathering issues. Of course if these are already blow, which if you have an 03 or 04 they probably are, then you need to replace them regardless (as I did). If you do choose to go with this, you might however also consider just going for broke and getting SPL compression rod bushings http://splparts.com/store/product-info.php?pid24.html . These will probably last longer than the car and if the feathering is in any way associated with the compression rod then it should be eliminated. Just keep in mind that I haven't been able to confirm the feathering to be absolutely caused by the stock sloppy compression rod bushings and this is merely an educated guess by me, one which I have yet to confirm to be 100% correct as mentioned in my post higher up.

 

^^thanks yes mine is an 03 I wonder if warranty will cover it?

 

my bushings were shot dealer replacing them both..

 

So has anyone seen results on the feathering issue from replacing this bushing?

 

Well its been a month and I can honestly say that my tire feathering has disappeared. The inside edges of my tires looks to be wearing very evenly and the tire roar has just about disappeared...so yea I'm satisfied. Just to recap I replaced my lower control arm bushings with whitelines and my passenger side compression rod bushing with a new nissan one.