Ok so firstly Im not new to the forums i just forgot my login info.
that said here's the thread...
My z is up to 107,011 miles on the odometer. Recently i noticed alot more vibration on the steering wheel as well as the entire car when i get to cruising speed on the HOV lane (usually 95-115mph is my HOV/express lane cruising speed when trying to get to work in the morning). I knew i needed to replace bushings as well as a few othwr things since they are still the original bushings from the factory. Can anyone tell me what i can realistically expect after installing the new bushings i ordered? Also any feedback on your experience with said bushings would be greatly appreciated.
the bushings i ordered are listed as:

1.) Whiteline Plus 03+ Nissan 350z / Infinity G35 Front Shock Absorber - Control Arm (Lower Shock Bush) (w52992)

2.) SPL PRO Front Lower Arm Bushings - Inner Front Multilink

3.)SPL FKS Front Compression Rod Bushings Front Multilink
Also if anyone knows the diff between SPL FKS and SPL Pro id love to know

 

have you tried the obvious and simple solution of balancing the wheels and or getting new tires? how old are you current ones?

 

Exactly what I was thinking

 

My curent tires are a couple weeks old. I work at a wheel and tire shop so i rarely ride on bad tires

 

The other solution for reducing vibration are the shocks. At 107K, have you replaced the entire set already?

 

No its on the list of things im replacing soon. I just didnt think they were in to bad of shape. Any shocks you'd recommend?

 

Seems like the Koni Yellow is very popular for the 350Z.

 

If the shocks haven't been replaced, they will play a much bigger role in controlling vibrations than the bushings. Personally, I use the Koni 8241 SA yellow sport shocks, but there is a lot of sentiment for Bilstein here as well. Both are fine products and you should do a simple search to see what the comments are on both.

Personally, I'd replace the shocks (or dampers, as the Brits call them) FIRST, before worrying about replacing the bushings.

 

i had tokico s-specs, but good luck trying to find them now

 

Have fun. Bushings are a PITA to remove and installs. Hope you got a press handy.

Also solid mounts probably won't help as much as new soft ones.

 

SPL FKS front lower arm bushings feature Teflon lined FK spherical bearings that are self-cleaning and self-lubricating.
http://www.splparts.com/spl-fks-fron...ings-350z-g35/

SPL PRO solid aluminum subframe bushings replace the stock mushy rubber bushings on your Nissan 350Z to eliminate free play of the subframe relative to the chassis.
http://www.splparts.com/products/spl...-350z-g35.html

 

You ordered the wrong bushings for a daily driver car imho.

 

Yep!

 

yeah solid bushings are pretty hardcore for daily street cars.

also while you are doing this you may want to look into the diff bushing and make sure you replace the gasket on top of the shocks. i just redid my suspension with poly bushings a few months ago and i do notice a huge difference.

 

Vibration usually starts with the tires then upwards to and through the suspension; and finally to the driver, the terminating point.

To track and eliminate, you start with the tires - new or not - and work your way up and back to the steering wheel/driver compartment. Lots of questions to answer first:

- Did the vibration start before or after new tires?
- Are the new tires OEM size or did you also uprate wheels or tire size? If so, what type and size are now on the car?
- Did you align the car following the new tire install?
- Can you isolate the vibration to front or rear?

Next thing is to try and isolate what type of vibration it is. Is the vibration in the steering wheel or an overall vibration resonating thoughout the entire car?

- Is the vibration constant or does tit increase/decrease with speed?
- Is the vibration noisy or just a "felt" type vibration?

Based on your saying in your original post that its related to the speed of the vehicle, I'd seriously start by re-checking the balance and inflation of the tires.

Vibration from the suspension - unless it's something sudden and obvious like loose lug nuts, or the wheels are missing weights from falling off, or maybe a bushing has actually broken - doesn't usually come on suddenly. Degraded bearings start to show minor vibrations or clunkiness slowly and you'll start to notice it gradually, not just one day, all of a sudden it's vibrating.

And by the way, if NVH is a problem now, wait until you drop in those solid bushings. As dboyzalter and others have mentioned, the "bushings" you chose are far too severe for street duty. Trust me, I've run solid bushings on my early Z cars and ended up changing them back out. Even on my race cars, the delrin/aluminum ball/socket joints I've used were really excruciating, even on the track. If it turns out to be the bushings, I'd recommend returning the ones you got in favor of bushings that have at least some isolation to them if running them on streets and highways.

Start there and report back what you find. Hopefully, it'll be something simple like your rear wheel weights fell off or something.

 

Also, going 115mph on the street is never going to be smooth. I have only been to Austin, but those highways were far from perfect. Although, 1,000,000 times better than what we have here in NY.

 

Tires
front: toyo extensa hp 225 45 18
rear: nitto nt05 255 35 18
The vibration was there before new tires. Alignment done after.
It feels like the front is vibrating from the bottom then a bit at the pedal with small vibration in the steering wheel.
The wheels are the stock 08 wheels.
There is also squeaking when going over bumps . my bushings look the all be mushrooming though i havent lifted it to see if there is tearing. I assume since they have never been replaced there is alot of wear on them.
My tires are kept at 34-36psi rear and 36-40 front cold. Didnt spl change their solid bushings to include a white o-ring to help with the noise?
the vibration isnt really noisy and is mainly felt, but i do have a kinda loud exhaust with alot of drone at 80+ speeds.
The only noise i notice is the creaking when my car bounces be it fast or slow.

Within the last 2 years i was on a flat straight road going over 150 ( no cars within my line of site in any direction) and i have by FAR less vivration than i do at 100 now. Im looking into konis and billsteins now and possibly tein shocks depending on what i find.

 

Thank you for the info!

 

have you checked the run out on the wheels to make sure they are true?

 

If run out is the same as tire wear which it sounds like it. The backs i can tell are very well aligned i can tell because after a standing burnout i look at them and only a cm or so is left unmelted on te outside. Im not so sure about the wear on the fronts.. They are pretty new so i cant tell were they are wearing at much. But it doesnt feel like the wheel itself is wobbling if that helps at all