# B14 Understeer prob? (SCCA)



## CarbonBlack200 (Apr 30, 2002)

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


----------



## barnoun (May 7, 2002)

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). 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.


----------



## SERprise In WV (May 15, 2002)

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.


----------



## Kelway (Jun 19, 2002)

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)


----------



## CarbonBlack200 (Apr 30, 2002)

*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..


----------



## barnoun (May 7, 2002)

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.


----------



## peter96 (May 4, 2002)

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.


----------



## barnoun (May 7, 2002)

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.


----------



## Kelway (Jun 19, 2002)

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.


----------



## barnoun (May 7, 2002)

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).


----------



## peter96 (May 4, 2002)

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?


----------



## morepower2 (Apr 19, 2002)

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


----------



## Kelway (Jun 19, 2002)

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.


----------



## azkicker0027 (May 31, 2002)

*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.........


----------



## Kelway (Jun 19, 2002)

*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.


----------



## azkicker0027 (May 31, 2002)

*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....


----------



## CarbonBlack200 (Apr 30, 2002)

*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.


----------



## azkicker0027 (May 31, 2002)

*oh i see......*

lower profile tire, interesting, just trying to avoid risking a bent wheel on the streets, good idea though, thanks........


----------



## eric96ser (Apr 30, 2002)

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?


----------



## azkicker0027 (May 31, 2002)

*okay.....*

yeah, i rolled them off so bad one time, i erased the mark, and i guess iam looking for a compromise, an effective everyday driver and weekend auto-x car......


----------



## CarbonBlack200 (Apr 30, 2002)

eric96ser said:


> *I agree with Mike, get the rear beam bent. *


When I first saw the NPM article about benting the rear beam axle, I thought these guys were crazy and i was never gonna get interested. But now i kindda wanna do that to fix this understeer problem. The thing is, I don't trust "ANY" bodyshops around here. If I ever decide to do this, only place I am taking will be that shop did that to the Project car. It's 13 hours away from where I live though...


----------



## azkicker0027 (May 31, 2002)

*okay.........*

how much do they bend the back?? is it too mcuh that it's obvious the the rear is bent??


----------



## myoung (Apr 15, 2002)

Here's the article Mike is referring too.... We did this to Project 200SX last November..... You'd amazed at what you can find in the back issues...

http://www.nissanperformancemag.com/november01/westend.shtml


----------



## CarbonBlack200 (Apr 30, 2002)

*Springs*

We had a big discussion about how aftermarket lowering springs could give understeer problem. If you are experiencing this problem, you might want to take a look at this thread.

http://www.nissanforums.com/showthread.php?s=&threadid=4384


----------



## Guest (Aug 28, 2002)

CarbonBlack200 said:


> *
> 
> When I first saw the NPM article about benting the rear beam axle, I thought these guys were crazy and i was never gonna get interested. But now i kindda wanna do that to fix this understeer problem. The thing is, I don't trust "ANY" bodyshops around here. If I ever decide to do this, only place I am taking will be that shop did that to the Project car. It's 13 hours away from where I live though... *


I had heard a *WHILE* back someone was looking into bending the axle (like two years or so ago) I hadn't heard anyone had done it. Like yourself though, I really wouldn't trust a local shop to do what we need done  I don't think my driving ability justifies it just yet... soon though I'm sure


----------



## CarbonBlack200 (Apr 30, 2002)

02 ALMERA said:


> *
> 
> I had heard a *WHILE* back someone was looking into bending the axle (like two years or so ago) I hadn't heard anyone had done it. Like yourself though, I really wouldn't trust a local shop to do what we need done  I don't think my driving ability justifies it just yet... soon though I'm sure *


I don't trust local shop period! I bet they are going to brake my rear axle beam in half. I am really interested to get this thing done though. I will do it only if I have a chance to drive down to southern California. (that shop did on project car is located down there).


----------



## johnnykomac (Jan 30, 2003)

CarbonBlack200

I also race a b14 se-r in sts. My current set up is ST f/r sway bars, strut tower bars, Progress springs, kyb gr2, and progress camber bolts @ 2.2 deg. Stock 15x6.5's with 205/50 Falken Azenis.

Ok. First, Dont take any thing off the car! (except setteling on a set of springs) I've learned that the se-r is made to STICK. Trying to augment your suspension to drift the rear in order to get more rotation will ultimately frustrate you! TRUST ME! I used to think the same thing. Now, I lower my tire pressures and just let the suspension work! The multlink rear beam suspension is AWESOME! its not supposed to lose traction....so why make it?

As for the rear axle bending.....its too far away...plus theres a more important lesson here.

drive the way the car wants you too, dont change the car to the way you think you drive....


----------



## CarbonBlack200 (Apr 30, 2002)

Very good point johnnykomac. Nissan designed the Multilink beam suspension to keep the rear end stick on road. I remember when B14 first came out, everybody (car magazines, other road tests) liked the way B14 handled because it was very stayble. I believe this Multilink beam technology had won numbers of awards as well. People says it is cheap, because it isn't the independent suspension, but not only bad things about this multilink beam suspension.
But the Multilink Beam suspension can be evil when you change the suspension set up. At stock height, there's barely enough room for suspension travel, but most of us with lowered springs, there's not enough suspension travel at all. When you AutoX, you'll just end up bottoming out all over the course. I believe that was one of the problem I was having.

Front suspension was the same way. I am running 2.0" F 1.7" R drop B+G springs. Those springs are waaaaay too soft (like just a bit stiffer than stock) So i get serious body roll. And since I lowered that much, front suspension bottoms out like crazy. Same time, I am a crappy driver so I steer too much too. I think that was exactly why my car was understeering so much.

It is an old thread, and I was reading my old posts and lookes like I knew what I was saying, but oh man, i really don't know shit about this. haha Good thing you posted, cuz my 2003 AutoX season just starts in one week!


----------



## bahearn (Jul 15, 2002)

You can get some large handling changes by playing with tire pressure. Lower pressure to get the rear tires to roll over or raise pressure to induce bowing of tread to reduce contact patch. Either way will reduce rear traction if that's what you want.


----------



## eric96ser (Apr 30, 2002)

I agree with Bruce, tire pressures can make all the difference. If you are using GCs, or any other adjustable coil over suspension, high rear spring rates can help. Just going from 200 to 325 in the rear made a difference. I'm hoping to get my rear beam bent sometime soon also.


----------



## CarbonBlack200 (Apr 30, 2002)

*Tire pressure*

Thanks for the tip Bruce and Eric. I am definitely playing with tire pressure for this Sunday's SCCA event. I was running 40~44 psi front, 35~40psi rear in my Kumho Ecsta Supra 712s (205-40-17) for AutoX. If you have same tires, how much air pressure should I go?


----------



## barnoun (May 7, 2002)

Adjust the fronts first so you're not getting any rolling onto the sidewalls, then play with the rears(higher than the front, or way lower than the front to induce some rotation).


----------



## bahearn (Jul 15, 2002)

I ran 45 psig up front no matter what tire I used, they all rolled over unless I used that much air; 185/60-14, 205/55-14, 205/45-16 it didn't matte. Rear pressure varied, as low as 25, as high as 35.

Nice thing about playing with pressure is you can set up the suspension for good street duty yet still get the rotation you need for autocross.


----------



## johnnykomac (Jan 30, 2003)

I use 40psi up front and 36psi in the rear with 205/50/15 falken azenis but they have a stiff sidewall......

carefull, tire pressure is a black art.....


----------



## 98sr20ve (Oct 6, 2002)

My B14 Likes much lower rear pressure then the fronts 8psi seems about right. Get the Stillen Adj, rear bar or the New Progress adj bar. I am bending my beam soon to fix my understeer issues with the car. If you are bottoming the front then it will understeer even more. Just for a referrence I have spun my B14 with R-compound tires. You will be amazed at how fast it can go in the faster stuff. Try to slow down a bit in the slow stuff and speed up in the fast stuff. I thought it would spin but I just kept going faster in the fast stuff and was amazed.


----------



## CarbonBlack200 (Apr 30, 2002)

I just went AutoXing yesterday. This time, i tried to play with tire pressure. At 41psi front, 34psi rear, car handled a lot better. I was trying to drive a lot slower, use more brake and tried to steer less and they worked very well. Car was still very slow, but i felt more confortable controling my car that way. I think there's still a lot more to improve, but I just learned small things like adjusting tire pressure helps this much. 
As for driving, I was pushing my car way too hard. Flooring the gas pedal didn't help to go my car fast at all.


----------



## SE-RMadness (Apr 30, 2002)

*Re: I need sway bar and practice*



CarbonBlack200 said:


> *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?
> *












Right here

Just click on Nissan your car and year - Suspention and you will see it. it's going for $131


----------



## tkvtec (Apr 20, 2003)

hey, if you have a coilover setup or aftermarket springs, try using much stiffer rear springs. I have 325 up front and 650!!! rear. I have no troubles getting the car to turn. Using Ground Control with KYB AGX. No front or rear bars added. As a matter of fact, I was on the highway today and had to get into a tight spot in another lane and I swerved over there and the rear moved a lot more than I'm used to. It rotated and snapped right into place. I bought the setup from someone else who used it mostly for dragging, but the stiffer rear springs work well for getting the car to rotate. You just have to be careful on uneven or bumpy roads.


----------



## morepower2 (Apr 19, 2002)

tkvtec said:


> *hey, if you have a coilover setup or aftermarket springs, try using much stiffer rear springs. I have 325 up front and 650!!! rear. I have no troubles getting the car to turn. Using Ground Control with KYB AGX. No front or rear bars added. As a matter of fact, I was on the highway today and had to get into a tight spot in another lane and I swerved over there and the rear moved a lot more than I'm used to. It rotated and snapped right into place. I bought the setup from someone else who used it mostly for dragging, but the stiffer rear springs work well for getting the car to rotate. You just have to be careful on uneven or bumpy roads. *


Your car is probably dangerous. If you are not an experianced driver, you could get into a bad oversteer condition. Those are drag race only spring rates.

Mike


----------



## B11sleeper (Oct 15, 2003)

A thought on tire roll... I drive a 83 B11 and I used to think I needed Low profile tires to minimise tire roll, then one day I was driving on a canyon road behind someone driving slow and I realized that the tire roll can be caused by insufficent tire pressure and other problems, but in my case i was making the tire take up too much energy and that was deforming the side wall, so I cleaned up my cornering by trying to put out energy from the sidewall. So it really has to do with coming into corners with a good line and staying on the gas (unless you like the back end coming around fast...) Having an auto trans will make it difficult to keep the wheel from absorbing energy from the road. this worked for me, it's atleast worth a look at technique... I also took out the powersteering rack and use a manual. --i like to feel the road


----------

