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post #21 of 35 (permalink) Old 03-20-2006, 03:39 PM
 
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Actually, just the opposite happens. Stiffer in front adds understeer. A stiffer front end means that, when cornering, most of the lateral load transfer is absorbed by the outside front tire, since the front end resists roll more. The extra load on the outside front tire causes it to slip more, hence the understeer. You can stiffen the front with springs, or with a larger anti-sway bar.
Uhg. I'm always doing that. I must be dyslexic. I really meant UNDERsteer. Thanks for that. You're absolutely right. I'll correct my original post.
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post #22 of 35 (permalink) Old 03-20-2006, 03:41 PM
 
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I wasn't able to edit my original post, so here's the correction...
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All things being equal, yes, stiffer front and softer rear will add a little <strike>oversteer</strike>UNDERsteer, theoretically. However, by lowering the car a bit, you get more camber. And as you mentioned, the sways can work that so it&#39;s more balanced.

I felt that overall the whole package was a huge improvement over stock.
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post #23 of 35 (permalink) Old 03-20-2006, 06:55 PM Thread Starter
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Only if you do it wrong.

Its a technique called "trail braking". You carry a bit of brakes into the corner to keep the front end loaded so you get more pressure over the front tyres. As long as you&#39;re not braking too hard to cause the fronts to exceed their grip threshold and plough understeer, it can also get the car to turn in a bit more sharply as the rear unloads and gets a little light. Of course, that also means you&#39;re liable to spin if you fail to control the brakes properly.
Yeah, in the transition from the truck to the car I definitely snapped the back end out twice when not expecting to, on dry pavement, just as I was coming back on the throttle, but with all the weight up front (off-camber decreasing radius turns).

Glad I had the full stability system on, in both times. I&#39;ve actually found that the VSD system works amazingly transparently, unless I go hard on the throttle in a low gear on corner exit to really push the rear out, and then it pulls the car back into a straight line while chiding me with the dash lights and the loss of power.

Tail braking was something I just stumbled across, trying to keep the traction up on the front-end. Actually started it with the truck (big 4x4 lumbering beast). Brake in the straight, and then as I&#39;m letting off on the brakes, start my turn, so that the weighted nose is used for turning instead of braking. But if I brake, then turn in, it plows like MAD.

Yeah, this part of the discussion is definitely better suited for the Driving Techniques forum. I was just trying to figure out which my problem was (understeer after the apex caused by suspesion tune or idiot behind the wheel).

Sounds like probably both.
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post #24 of 35 (permalink) Old 03-20-2006, 07:52 PM Thread Starter
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I wasn&#39;t able to edit my original post, so here&#39;s the correction...

All things being equal, yes, stiffer front and softer rear will add a little oversteerUNDERsteer, theoretically. However, by lowering the car a bit, you get more camber. And as you mentioned, the sways can work that so it&#39;s more balanced.

I felt that overall the whole package was a huge improvement over stock.
I find it fascinating that all of the aftermarket suspension setups seem to increase the roll stiffness to the front, which then increases understeer, if I&#39;m reading this correctly. I already feel like it understeers too much as it is. Unless they are assuming that you&#39;re pairing up the suspension with some really stiff anti-sways, and that you&#39;ll use the sways to adjust the roll stiffness back to the rear to make it more neutral...

Or, maybe they just figure if you&#39;re going the performance suspension route, you need the added "safety" of more understeer

It&#39;s not turn-in understeer that I&#39;m having a problem with, either, it&#39;s understeer from the apex to the exit, especially when uphill.

Turn-in is actually really good. Much better than the WRX that we have as well. It plows badly at turn-in, until it rolls over onto the outside wheels, and then it really hooks up and will gladly 4-wheel drift out with just a hair more in the front than the rear, a bobble of the throttle and it will step out the rear. Pretty much lots of throttle keeps it happy in the turns (unless you spool up and full boost between apex and exit, then it gets interesting in a hurry).

I wish the Z had more of the late-turn handling of the wrx, and kept the turn-in response it has, and I plan on working on the WRX to improve turn-in. It&#39;s definitely getting some new sways soon, as well.
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post #25 of 35 (permalink) Old 03-20-2006, 08:24 PM
 
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I find it fascinating that all of the aftermarket suspension setups seem to increase the roll stiffness to the front, which then increases understeer, if I&#39;m reading this correctly.
Ok, I&#39;m going to double check.....yes, stiffer front leads to understeer.....yes, UNDERsteer. Remember it&#39;s more than just the front. You can stiffen the front AND the back. If the overall effect has the back stiffer than the front, then the net result should be a decrease in UNDERsteer. But again, it&#39;s more complicated than that. There&#39;s camber, toe, driving technique, etc.


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post #26 of 35 (permalink) Old 03-20-2006, 08:49 PM
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I&#39;m getting a headache...

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post #27 of 35 (permalink) Old 03-21-2006, 12:49 AM
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Again, I have taught several SAE Vehicle Dynamics classes and have gone down this path of discussion over and over.. Over zealous drivers complaining about systems that can stop better than them. Yet, they complain that it is "messing them up".. When it&#39;s actually trying to cover up poor driving technique, 90% of the time. It&#39;s the other 10% that bugs me. So, I normally shut them off.
I swear by ABS. I think its one of the best electronic driver aids out there. It doesn&#39;t kick in until its really needed, and then it doesn&#39;t actually degrade performance. As I said before, its saved my butt more times than I can count.

TCS on the other hand, is the bane of my driving existance. Its never gotten me out of a bad situation and its actually put me into one before I started turning it off as a part of starting the car up. Even if it doesn&#39;t it still comes on too heavily and stays on for too long.


I know I&#39;m not the best driver out there, and I&#39;m getting worse in some ways. I&#39;ve lost my ability to trail brake, and left foot brake. But I know what theoretically works, and so what I&#39;ll try out when I have a safe environment to try and pick those skills up again.

I wouldn&#39;t advocate trail braking for the novice driver. I taught myself how to do it in a car with half the power of the Z, a lot more understeer and a more progressive suspension setup. And once I got out of that car into the Z, I didn&#39;t need to use those skills to keep my speed / revs up and now I can&#39;t do it even if I wanted to.



Anyway, back on topic. Try a set of swaybars first. Find a good road to test it on, put the bars on, and then drive it again. You&#39;ll find the difference to be wonderful....and you might not even feel the need to replace your dampers or springs.

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Understeer is when you hit the tree with the front wheel.
Oversteer is when you hit it with the back.
Horsepower is how hard you hit the tree...
Torque is how far you drag it...
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post #28 of 35 (permalink) Old 03-21-2006, 03:11 AM
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TCS on the other hand, is the bane of my driving existance. Its never gotten me out of a bad situation and its actually put me into one before I started turning it off as a part of starting the car up. Even if it doesn&#39;t it still comes on too heavily and stays on for too long.

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Anyway, back on topic. Try a set of swaybars first. Find a good road to test it on, put the bars on, and then drive it again. You&#39;ll find the difference to be wonderful....and you might not even feel the need to replace your dampers or springs.



100% agree


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post #29 of 35 (permalink) Old 03-28-2006, 07:55 PM
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So, I understand what you are saying 100%. I teach vehicle dynamics.
Ok what is the best way to improve handling in a turn? this is getting a little confusing? If you want to reduce understeer, and try to balance the car better do you go stiffer front sway? stiffer rear? softer front? softer rear?
I have already upgraded my tires and was wanting to add something else to improve handling but wasnt ready to shell out 1g for a coilover kit and wasnt sure if springs or sway bars would be better to go with first?

Just looking for that "riding on rails" feeling when cornering, feels like the front "floats" some times when cornering hard.

"The older I get they stay the same age"
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post #30 of 35 (permalink) Old 03-28-2006, 08:04 PM
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I recommend a set of adjustable sway bars. Regardless of if you go coilover later, money spent on sways won go to waste.

Both Hotchkis and Stillen sell for around $300 and are 3 way adjustable.
People here seem to prefer the Hotchkis bars.

Chris


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