I was told by someone a few months ago that the front sway bar is stiffer for the 2004 Z, so here's what I found out when installing my Cusco front bar last night:

2003 Front bar - 34mm hollow, 10.5lbs

2004 Front bar - 34mm solid, 14.5lbs

Cusco Front Bar - 35mm solid, 13.0lbs

The softest setting on the Cusco bar has the link in the exact same position as stock. The stiff setting (there are only 2) is just in front of that, less than 1/2".

My conclusions are that if you have a 2003, you can just use a 2004 front. If you have a 2004, you're screwed or will get minimal gains. Any opinions?

 

Humm, Interesting I posted that I didn't feel any difference with my hotchkis bar up front (in the middle setting) when I first did my install. Not many agreed with my opinion.. I wish someone could (independently) measure the rates of the different bars in some sort of comparo. I know BJ posted actual ft/lb number with his bars a while ago to back up his % rate changes. I actually spoke with the hotchkis engineers at a local track event and they said that they come up with their published numbers by calculation based off of the thickness of the bars and its wall thickness.
My take on it is that the stock front sway bar up front is sufficient right from the factory. The aftermarket bars are great for the fine tuning and adjustablilty. You won't get that instant "my car is so much flatter" response that you get when replacing sways on other cars.

ps. what do you think of the cusco's. Can you feel a difference up front?

 

I didn't feel a difference, but I haven't been on a track yet. I will have a better idea this weekend after autocrossing. Considering it's only 1mm bigger than stock with just one firm setting, I'm not expecting any miracles.

According to this thread, it's 120% or 137%, which i'm assuming means 20% or 37% stiffer than stock (120% or 137% total stiffness).

https://my350z.com/forum/showthread....Cusco+sway+bar

It seems like the hardcore autocross and track guys are using ~34mm solid front bars, like the EVO bar. All that I've seen are using 2003 model year cars as well, hence the noticeable difference.

I think the important point here is that the 2003 front bar is not the same as the 2004. I see a lot of companies selling bars that are "X% Stiffer than stock - 2003-2004 350Z", which isn't true because the 03 and 04 bars are different. Is there anyone with a 2004 running a different front bar?

 

I have 350 evo front and rear bars. I've been running medium front and full stiff rear but the car tends to spin up the inside rear. I'll be trying soft front and medium rear for my next HPDE.

I've never run with only the front bar so I'm not sure the difference that bar alone would make. The two bars toghether are excellent! No more understeer!

 

Two bars, both the same diameter, one hollow the other solid, will only see a fractional difference in torsional rigidity providing the lever arm distance is the same. The 1mm thicker Cusco bar will definately be stiffer, not to mention being able to offer even greater stiffness via shortning the lever arm distance.


This if all very suspicious, jumping ship from hollow core bar design to solid for just a fractional increase in stiffness doesn't make sense and goes away from the weight saving rational. And take a look at previously posted bar weights, notice how even the same brand differs depending on whom did the weighing.

Cusco rear: 10LBs
OEM rear: 2LBs

Cusco front: 14LBs
OEM front: 12LBs

Nismo Rear Sway 6lbs
Cusco RearSway 8lbs

Nismo Front Sway 10lbs
Cusco Front Sway 15lbs

And then their are the Nismo sway bars, truely going stiffer in the front is exactly what the Nismo bar set does. Look at this,
Nismo Sway Bar:
F: 36mm, hollow, 23.2 kg
R: 22.2mm, hollow, 6.7 kg

Front 1299lbs
Rear 375lbs

Oem
Front 1100lbs
Rear 380lbs

Nismo front bar is 18% stiffer then oem.


Now, what we do know for a fact is that the 2005 G35 coupe and sedan with sport suspensions are getting thicker sway bars. Up until this point all Z's and G's used the same sway bars. Will be very interesting to climb under one of those cars with a dial caliper and measure these new bars. Never the less, liability nannies won't let the bars be near the stiffness that the aftermart ones can do and most important of all, they can't be tuned.

 

I don't know what that will tell you though. I measured mine vs. a 2003 bar and they were the same, even though there's almost 5lbs difference between the two. I weighed all three on the same scale, so even if my scale was off, the difference is still there.

The #s Cusco and others list are probably the percentage increase over a 2003 bar (front), those published numbers can't be the same for a 2004 model. I'm thinking someone would have to make an even bigger bar to make a significant difference on an 04 model.

 

Your forgeting the fact that the 2004 bar, if the greater weight is the result of greater bar wall thickness, will NOT be a benefit in a meaningfull manner stiffness wise. The most it will gain is +5% at best. That is why hollow bars exist, they give up next to nothing for being hollow and they weigh less.

A bar doesn't have to be made bigger to be stiffer, they can just use the same principle behind how adjustable bars can adjust to be stiffer, move the mounting holes for the end links holes closer to the bar centerline. Thats the only way the 2004 bar is factually stiffer beyond +5%.

In any event. Sway bars should be used to tune, you CANNOT do that if you run fixed bars. Equip your car with adjustable bars so you can fine tune behavior to suit your given talent level.