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Platinum
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Discussion Starter #1
Does your car understeer a lot when you autoX? Mine does. I have a problem steering a bit too much, so it's part of my problem, but my car understeers more than others for sure. I had B+G springs with KYB AGXs. That's the set up I had last week. I swapped rear springs to Eibach (stiffer) for today's event (so i had B+G front, Eibach rear) because My car had super heavy understeer and rear didn't rotate at all. and I still got pretty heavy understeer. I think my car needs a rear sway bar....
Are you guys having same problems? Currently, i'm running the STS class and I can't beat anybody. (maybe a few riced out Civics with newbie driver) I've been doing this for 3 years, but it's not getting any better... Is it my car? or my driving?
I always thought it was my driving, but now i think my car needs some help. What do you think??

Thanx ;)
 

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Driver
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I have a stock suspension in mines, so I don't know how it is with stiffer springs/better shocks. Anyways, since I have an automatic, I've found that by left-foot braking I can reduce understeer by inducing rotation(at the last event I was actually getting the rear to step out on a certain right hander:D). I do have to say the car isn't so good in STS, as I've usually been placing second or third to last in class standings. I know it's not the chassis or suspension because there's a 200sx with an sr20 and ground controls that's consistently 6-10 seconds quicker than me. Than again, I started autocrossing 4 months ago while that guy's been doing it for more than a year.
Have you played with tire pressures? I've found 41f/29r to be pretty good at getting the car to rotate.
 

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What tires do you have on the front of the car? If you have crap tires (Nitto 450s, for example), your car will be a push-mobile no matter what you do to it.

And yes, a ST rear sway bar will help dramatically. Leave the stock front bar alone, and add a thicker rear bar.

Both did wonders for my B13. YMMV.
 

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B14's a more difficult to get out of the understeer "hell", because of the toe-out setting on the rear multi-link beam. You definitely need a rear sway bar. ST's are a good value, but you can get a Progressive bar at ptuning.com, for $203 (maybe better than ST). You should also get a rear STB, and you can find those just about anywhere.

Also, if you're not running on Azeni's you are at a disadvantage, because you can be assured that the fast guys in STS ARE runnning Azeni's, I ga-raun-tee.

I have a ST rear sway bar, a Random Thoughts rear STB, stock springs and (exhausted) struts, and run Azeni's on my b13 and do OK in STS (top 5 usually). Car rotates BEAUTIFULLY, now.

$130 - ST sway bar
+$90 - rear STB
+$300 - Azenis
+ mods you already have
+ decent driver
= very competitive auto-xer (IMO)
 

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Discussion Starter #5
I need sway bar and practice

Thanks for your imput. I guess I am really getting the rear sway bar. I've been looking for them past a week and I can only find a set (F & R). Where can I find the rear only?

By the way, I have Kumho Ecsta Supra 712s. I had tire pressure 42 all around. Maybe I'll try to play with pressure more next time. Yeah, I was wondering about Falken Azenis times too..

Kelway, I do have the Front and Rear STBs. Should I take front one off??

I think I really need to practice too..
 

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Driver
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Taking the front STB off won't do anything to reduce understeer(all it does is stiffen the chassis, which is always good). Reduce the rear pressures man, you'll notice a difference right a way.
 

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HYDYST?
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I thought removing the front bar increased body roll but helped keep the front wheel from lifting, giving better more consistant front traction in the corners? Is this a monkey thought?

Is this progressive rear bar for a B14? Last I checked, they didn't have one for the B14.
They had Nord's design, but hadn't made any. Guess I'll just have to check.
 

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peter96 said:
I thought removing the front bar increased body roll but helped keep the front wheel from lifting, giving better more consistant front traction in the corners? Is this a monkey thought?
He asked about removing the front strut tower bar, which doesn't have a benefit if removed.
 

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peter96 said:
I thought removing the front bar increased body roll but helped keep the front wheel from lifting, giving better more consistant front traction in the corners? Is this a monkey thought?

Is this progressive rear bar for a B14? Last I checked, they didn't have one for the B14.
They had Nord's design, but hadn't made any. Guess I'll just have to check.
I could be wrong about the Progressive bars. It says 200sx, but the model years are 2000-02, so it's probably really for a b15.

Taking the front STB off won't do anything to reduce understeer(all it does is stiffen the chassis, which is always good). Reduce the rear pressures man, you'll notice a difference right a way.
Removing the front bar will reduce understeer, because it will decrease the stiffness of the front suspension compared to the rear (not the most technical explanation, I know) . No one who autocrosses any Sentra recommends using a front STB. If you're not sure, just try it. Remove it for the next event and see if you can tell the difference (I bet you will). I drove a really nice B13 around a course a few weeks ago w/ AGX's, Hypecoil springs, ST rear bar, and front STB, and it understeered much more than I expected.

There is also something called a G-load brace, available through Stillen or Nissan Motorsports, that mounts underneath the car and is supposed to work really well to stiffen the rear. I plan to get one.
 

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Kelway said:

Removing the front bar will reduce understeer, because it will decrease the stiffness of the front suspension compared to the rear (not the most technical explanation, I know) . No one who autocrosses any Sentra recommends using a front STB. If you're not sure, just try it. Remove it for the next event and see if you can tell the difference (I bet you will). I drove a really nice B13 around a course a few weeks ago w/ AGX's, Hypecoil springs, ST rear bar, and front STB, and it understeered much more than I expected.
Really...I didn't think it made a difference. I'll take it out for next weeks' event, since it's at the same lot it was today. Hopefully it does understeer less(even though I'm oversteering a little already).
 

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HYDYST?
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Doh! I was talking about the front sway bar and not the STB. :)

Doesn't the G-load brace tie the front control arm ends together? How would that stiffen the rear?

The theme seems to be,
For less understeer either loosen the front or stiffen the rear.
Stiffening the rear seems to be preferable over loosening the front. Too loose a front will have adverse effects on alignment, causing unexpected shifts in toe and camber due to flex.
Easiest way to stiffen the rear is add a sway bar or stiffer springs.
Also, Less air pressure in rear tires, more slip angle, less understeer.

Is this what everyone is essentially saying?
 

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Icy Hot Stunta
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CarbonBlack200 said:
Does your car understeer a lot when you autoX? Thanx ;)
B14's have 1/4" rear toe in and will understeer no matter what until you get rid of this. Have the axle bent for zero reat toe by an experianced frame shop.

We did this in an NPM tech article a few months ago.

Mike
 

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peter96 said:
Doh! I was talking about the front sway bar and not the STB. :)

Doesn't the G-load brace tie the front control arm ends together? How would that stiffen the rear?
You are totally right. I was under the impression that it mounted in the rear, but I researched it and it does mount ot the front. That won't do anything to decrease understeer. Shows what I know.;)

B14's have 1/4" rear toe in and will understeer no matter what until you get rid of this. Have the axle bent for zero reat toe by an experianced frame shop.
I was going to mention that as an "advanced tip", since most people would be reluctant to do something like that.
 

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Cone Dodger
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rookie need help......

just found out about this section for autoX today.....i am at a loss..just for starters, i have eibach pro-kits, upper STB, v700 kumho victoracers 195/55 r14 on '89 pulsar nx se 14x6.5 wheels, i run 35 front and 30 rear, any flaws ya'll found already, please let me know, i need help.......thanks.........
 

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Re: rookie need help......

azkicker0027 said:
just found out about this section for autoX today.....i am at a loss..just for starters, i have eibach pro-kits, upper STB, v700 kumho victoracers 195/55 r14 on '89 pulsar nx se 14x6.5 wheels, i run 35 front and 30 rear, any flaws ya'll found already, please let me know, i need help.......thanks.........
Sounds like a good start, but you are probably handicapping yourself by starting out on racing tires. IMO, it is better to start out on street tires and learn proper technique. Almost anybody can go fast on race tires, but when you see someone run really fast times on street tires, you know they are driving it.
 

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Cone Dodger
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i see......

so practice with street tires first, ie 205/55/r16 yokohama avid v4's with 16x7 white fondmetal 6700's, but won't that have enormous tire squeal?? though i do see the point of controlling it with streets, then kicking it up notch with the kumhos, thanks very much...appreciate it....
 

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Discussion Starter #17
Tire size

instead of using 205/ 55/ 16, i think your car will be more stayble with 205/ 45/ 16. I think less speed meter error on street too.
 

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I agree with Mike, get the rear beam bent. I have 325/325 GCs, AGX, F&R STB, N-tech lower brace, ES control arm bushings, and ST rear sway bar. I have 1 1/2 deg neg camber with 0 toe. Running 205-50-15 Kumhos on stock 200SX wheels, I was able to get some good rotation with the 1/4 toe in rear axle. I had to turn the rear shocks down for the first time. Try runnng less tire pressure in the rear. Do you know how to mark your tires to see if you are rolling over?
 
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