Making a Sentra turn

[Brettt]

As the title states, how do I make my sentra turn? I've tried a number of different things, including putting a Progress rear sway bar on the car and putting more air in the rear tires than the fronts. I know my shock settings are probably quite far off still, but the problem is that the car pushes horribly at all but the slowest speeds. I had another more experienced FWD driver take a lap in the car, and he mentioned that the steering felt numb and disconnected, not to mention turning the steering wheel 4 inches seems to translate into the same amount of steering angle as turning the wheel 10 inches in the middle of the corner. Am I driving the car way too hard and that's why it doesn't turn? Everything seems to be in order as far as the steering rack is concerned- not loose or a bunch of play that I've found.

I'm not way behind the cars in my class here, down about 3-4 seconds a lap from the podium cars at most races. The real problem is that I've been doing things that are supposed to make it turn better but as of yet it still pushes like crazy in the middle and exit of turns. Do I need an LSD? I have the factory on in there right now, I just don't want the expensive LSD to be my solution to better lap times.

Thanks for the help

[Greg Amy]

- An awesome triangulated rollcage with large plates in key areas.
- Hard suspension bushings.
- As much shocks as you can afford; I recommend Koni 8610 with custom struts as a minimum; 2817 if you're feeling flush.
- 800F/1100R springs as a start.
- This rear swaybar: http://www.kakashiracing.com/swaybar.html
- No front swaybar.
- Hoosier tires, 225F, 205R.
- Lot 'o ca-hones.
- A big engine.

http://www.kakashiracing.com/nx2000.html

[Greg Amy]

I was thinking more about this last night, and the Kumho thread got me to thinking more...I'm going to take a different tack with this. My suggestion?

Buy Toyos.

"Blasphemy!" they say. But here's the thing: all that stuff I suggested above? All of that is required primarily because of running sticky Hoosiers tires. I don't have the time or motivation to get into it, but the gist of the idea is that sticky tires cause higher lateral acceleration, which cause higher g-loads, which cause more body roll, which cause strut cars to go into wacky geometries, that cause roll centers to go underground, which causes more roll, which causes even wackier geometry, and so forth. So the whole premise of that suspension is to limit that geometry to within tighter travel, that travel being caused by those sticky tires. Don't have the sticky tires and you don't need that radical of a suspension.

Plus, if you do all that based on using sticky Hoosier tires, and you can't afford to replace them every 12 cycles or so, then you're just wasting a s**t-ton of money for no reason.

So let's try that different tack. Let's start with Toyos, which gives you an immediate advantage: you spend less money. Yes, you get a less grip than the Hoosiers, but you also get a tire that last for-freakin-ever, saving you even more money that you can spend elsewhere. But more importantly, now that you're running more-reasonable tires, you can couple that to a more-reasonable suspension. I'd suggest going with as big a rear bolt-on bar as you can find, though if you can build something like I illustrated above you're way ahead of the game. Then find the best struts you can afford; not AGX crap, but maybe something based on Koni reds? Or, if you can afford the 8610s, then you don't need to revalve them for those ricockulous rates above, you can go for something more reasonable, like 300F/400R or something like that. And, if you prefer the feel of a front bar, you can drop in the Sentra GA16/NX1600 front bar.

Attached is a photo of my NX2000 at Mosport; I think this is the exit of Moss, the tightest, slowest corner on the track. The car is running shaved Toyos (Miata 205 take-offs all around), 8611 strut inserts, 300F/200R springs, a Progress rear bar, and a GA16 front bar. And I had a BLAST! The car handled reasonably well; yeah, I didn't have the grip of the Ho-Hos but the balance wasn't bad and it was a hoot to drive!

You can't engineer your way out of this strut-suspension conundrum, all you can do is work around it. Pick your poison based on budget and optimize, then have fun!

GA

[Brettt]

Wow. That is a ton of good information right away. You rock, Greg.

I'd always wanted to try 225s up front and 205s in back, I just didn't know that it was a combination that worked. All I have to do now is get lengthened studs and spacers to make the 225s fit. I think the Progress rear bar is one of the biggest bolt-in bars, if not the biggest, that a guy can get for the sentra, so I'm thinking I'll stick with this one for a while at least.

I've never driven a car without a front sway bar, so that's definitely on the list of things to try at the next track day!

Maybe I'll have something for the miata guys next race!

-Thanks

[Charles Perry]

Brett,
we have done a bunch of work on Integras not Sentras, but Greg is right on. the guy who runs the car now, bought a front bar just recently and tried it out and immediately disconnected it, so get rid of that thing. The only thing I would say is if you run 225's all around, what we did is put the crappiest ones you can find on the rear. That way you only have to buy 2 tires at a time, rotate the worn out fronts to the rear, put new grippy ones on the front and with the springs, bar and crappy rears, it will (should) rotate. Every time we put good rubber on the rear, big push.

[EV]

I have a B14, but the same applies.. First, Greg is right on, "IF" you have the kind of money it takes to get there...

I run on a limited budget, and can't afford a Greg solution. Here is my list.

• Off the shelf Megan coilovers (ya, I heard all the rumors, and yes, they are working pretty well)
• upgrade rear springs to 550. I am running 425 fronts
• Progress rear sway bar set to full stiff
• poly bushings all around
• rear beam bent straight (applies to B14 only)
• Run 1/16th toe out on front
• remove front swaybar and use as clothes hanger
• hot tire pressures 42F/44R

Each one of the above steps have resulted in less push. This is my first season, and I run mid-pack, 2-4 seconds a lap off the leaders depending on the weekend.

When I have the cash, I will upgrade the shocks to handle the Greg Amy spring rates.

[Brettt]

A lot of people advised spring rates around 600# front and 400# rear as a good starting point for a new driver. I'm thinking that this advice is good general stuff to make sure the car is stable so a new guy doesn't loop it all day long? I run the Ksport RR system right now and they could get as close as 560#F and 420#R. I'm getting the idea from what you guys are saying that I should swap those springs front/back to make the back rate higher than the front? That is certainly another thing that would be free to do, saving me some money for the last couple races in the season here.

Is there a downside or any handling quirks to look out for when switching my springs front to back? Or do I just need to be ready to be super fast?

[quadzjr]

Swapping spring rates will make the car "typically" more unstable, however this in-stability will allow you to pitch the car around more. By swapping spring rates you are allowing the front to have more complaince, and typically more grip while reducing the movment of the rear suspension, and thusly reducing the amount of rear grip.

Though a different car and every driver and setup is different all of our FWD cars have a rear biased spring setup.

[EV]

A lot of people advised spring rates around 600# front and 400# rear as a good starting point for a new driver. I'm thinking that this advice is good general stuff to make sure the car is stable so a new guy doesn't loop it all day long? I run the Ksport RR system right now and they could get as close as 560#F and 420#R. I'm getting the idea from what you guys are saying that I should swap those springs front/back to make the back rate higher than the front? That is certainly another thing that would be free to do, saving me some money for the last couple races in the season here.

Is there a downside or any handling quirks to look out for when switching my springs front to back? Or do I just need to be ready to be super fast?

I would try it. I had someone tell me to switch my springs, and I said "really?". I decided to up the rears (because I could), and I was quite pleased...

[Brettt]

I took it to the track after only removing the front bar, hopefully to learn exactly what it did to the handling, and she finally turns! I can even make the car OVERsteer now! Now we'll just have to see if I can wrangle up the rubber and spacers in the next week... Either way, the car should be a little bit quicker and give me a better shot of holding off those miatas I pass on the start!