Improving Handling - Nissan 350Z Forum, Nissan 370Z Tech Forums
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post #1 of 35 (permalink) Old 03-18-2006, 04:16 PM Thread Starter
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My main complaint with my Z (2005 Touring) is that it seems to bee really fussy about how it wants to go around a turn. When I'm driving hard, I can plant the nose with the brakes, roll into the turn, and it sticks like mad. Wonderfull in the twisties on summer days.

However, when I'm just commuting to work, over the same twisties, it REALLY likes to push the nose out in turns, especially when going uphill. I figure this is partly my driving technique, and partly the suspension setup on the car (bone stock).

It just seems like the front wants to wash out in the turns unless I'm driving really hard, and have put a ton of weight on the front-end to keep in planted in place. It doesn't help that when driving lazily, I often coast into a turn, and lightly accelerate through it. Which transfers the weight back, lifts the nose, and it starts to push to the outside of the turn. If I let off on the throttle, the nose comes down, grips more, and turns in nicely, but I don't want to decelerate my way through the turns.

I'd really like something that carved in more on the turns. Both my wife and I have noticed this with the car (we split the driving time 50/50). The other car (2004 WRX) is much easier to toss through a turn at low speeds, although it rolls like mad).

My thoughts are that for problems that show up during spirited driving, I should try to fix me first, and then the car, but this shows up mainly when driving much further back from the edge.

Anyway. I've thought that what I needed to do was swap out the sways for a set like the Hotchkis that stiffen the rear up more than the front, to induce more oversteer. Also, I know that the staggered tire size setup also increases the understeer. I'm not looking to change up wheels/tires right now, though (running stock wheels, and KDW2's).

However, it looks like all the coil-over setups shift the roll stiffness to the front, which seems to me that they'll make it understeer more?

Also, how much of this can be tuned out with a different alignment. I'm going to realign the front to ensure that the toe isn't eating up my tires (starting to feather a touch at 25K miles on the car, 8K on the tires), and was thinking I could bump up the rear camber at the time, if that will help.

Thoughts?
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post #2 of 35 (permalink) Old 03-18-2006, 05:45 PM
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My basic drivers' ed class taught me that you should start to accelerate halfway through the curve (I assume long curve). It helps carry the car through better. If one brakes into a turn, doesn't that lose control? I would think so. I think a driver has to find the medium or point of balance between throttling and slowing down to take corners well.

I have been told that the Hotchkis setup does improve handling. That's why I bought the kit. I haven't installed it yet (damn winters), but I can't wait until I do get them on and start driving like it was meant to be driven.

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post #3 of 35 (permalink) Old 03-18-2006, 05:53 PM Thread Starter
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If one brakes into a turn, doesn't that lose control?
No, or at least not in anything I've driven. I do my breaking in the straight, or as part of the transition of an S, and then try to smoothly go from the brakes into the steering (go from full braking and no steering to no braking and full steering), and hold that to the apex and start rolling on the throttle. On a longer turn, especially if off-camber at the start, I roll more on the throttle early, which seems to "plant" the outside rear tire, and it just rips through the turn. But on an uphill turn, that will push the front-end out.

It's just so wierd feeling the front-end pushing out like that.
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post #4 of 35 (permalink) Old 03-18-2006, 05:59 PM
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It's been so 'long' since I drove my Z that I've forgotten what it's like. I do feel like the front end gets a little squirrely when taking a long sweeping curve too fast or not correctly. Maybe an upgrade in wheels and tires would also help.

I hear you about braking early and then applying the throttle going into the long turn/curve. At least that's how I do it (if I even brake).

Anyhow, people with the Hotchkis setup say that it feels like they are riding on rails. Might be something to think about.

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post #5 of 35 (permalink) Old 03-18-2006, 07:12 PM Thread Starter
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It's been so 'long' since I drove my Z that I've forgotten what it's like.
Nice thing about Cali, I can drive it year round without too much worry. Although I've had to drive twice on ice. Not fun at all with a Max Summer type tire...

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Anyhow, people with the Hotchkis setup say that it feels like they are riding on rails. Might be something to think about.
I'd been leaning towards the Hotchkis sways... But figured I'd rule out other stuff before making modifications.
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post #6 of 35 (permalink) Old 03-18-2006, 09:08 PM
 
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Thoughts?
  1. Better Tires. This will make the biggest difference in overall grip. The OEM tires suck with re to dry grip.
  2. Hotchkis TVS Stage 1. This is where you can really dial out the understeer since the Hotchkis bars are adjustable. I set my front sway bar to the softest setting and the rear to the stiffest. I LOVE the way the car handles now.
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post #7 of 35 (permalink) Old 03-19-2006, 02:07 AM Thread Starter
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  1. Better Tires. This will make the biggest difference in overall grip. The OEM tires suck with re to dry grip.
  2. Hotchkis TVS Stage 1. This is where you can really dial out the understeer since the Hotchkis bars are adjustable. I set my front sway bar to the softest setting and the rear to the stiffest. I LOVE the way the car handles now.
Well, I'm already on the better tires. The KDW2s blow the stockers out of the water. Is the TVS just the sways or the whole spring/strut/sways combo? Lowering the car is not an option (hit enough stuff with the underside of the nose as it is).
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post #8 of 35 (permalink) Old 03-19-2006, 09:44 AM
 
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Well, I'm already on the better tires. The KDW2s blow the stockers out of the water. Is the TVS just the sways or the whole spring/strut/sways combo? Lowering the car is not an option (hit enough stuff with the underside of the nose as it is).
The TVS kit is springs and sways. It does lower the car, but very little -- less than an inch. I believe it's advertised as dropping 15 mm in the front and 19 mm in the rear. I don't currently have any issues hitting stuff with the OEM chin spoiler, however I can see it happening if you have some aftermarket bumper or spoiler.

While the hotchkis springs give a net increase in spring rate, it's pretty small so you don't notice it. However, what you do notice is an improved overall ride since they change the balance by increasing the rate up front and decreasing it in the back. It got rid of that annoying highway bounce. Of course, they also helped increase the overall handling, too.
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post #9 of 35 (permalink) Old 03-19-2006, 01:23 PM
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Hotchkis back springs are stiffer than 2003/4 Zs and lighter than stock 2004.5-on Zs. Most aftermarket springs follow the rates of the 03 springs (the ones with the bounce) and when the new 04.5s came out nobody went back to the drawing board to see if there were improvements to be made.

It seems as if most will drop the car but finding springs that are also of an increased rate is difficult. Nismo, Eibach KG/mm and Espelir have higher rates out back, RSR is similar to stock. Other than that it's coilovers.

Chris



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post #10 of 35 (permalink) Old 03-19-2006, 01:58 PM
 
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Sport Coil Springs
Item#: 19413
2003+ Nissan 350Z

Hotchkis Tuning Sport coils [....]
Front 9/16" (15mm) Drop
340 lbs/in
Stock 310lbs/in

Rear 3/4" (19mm) Drop
330 lbs/in
Stock 350 lbs/in
stiffer in front, softer in rear
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