Increasing Lateral Grip

[BlkGTLtd]

What would it take in the form of suspension/tire mods to get about .90g lateral grip? From looking at the various car mags, our cars pull in the low .80's stock. I absolutely love the power on our cars, but compared to my previous car, a Honda Prelude SH that was lowered with Eibachs, I find the grip extremely lacking.

 

Thus my question is would just changing the tires to high performance drastically improve cornering grip? Or do I need at least a combo of springs and high performance tires to reach the upper .8g's?

 

I realize that the combo of coil-overs plus good tires probably would reach the .90g goal,but they're beyond my budget. Ideally, my goal is to emulate the handling of the E36 gen M3's.

 

Thanks in advance for the feedback.

[SBT]

Would recommend HP Summer tires as the first order of business, then sways, endlinks and struts/springs, in that order. After the addition of some really good HP Summers, think the 20mm RSB/adjustable endlinks and STI Pinks on stock struts will get you 95% of the way to where you want to be.

 

SBT

[Sands]

don't forget an alignment

[05LegacyGT330Ci]

Changing tires will drastically change the grip, one of the most under rated and overlooked change to the vehicle.

 

 

Song of Post- Pink Floyd- Money

[SFGR415]

I remember they stuffed a 350z with some 285's in the back and i belive either 245 or 255's in the front and it went from low .9's to 1 lateral g. I assume putting some good 255's all around would help out alot.

[Xenonk]

Coilovers will make the job easier first of all. These are the major components that will increase lateral grip:

 

-Tires (DOT-approved race tires are the only thing that will get you near .9s)

-Lower center of gravity

-Significantly stiffer springs

-Sway bars are a big "?" since it depends on the rest of the active suspension.

-Camber alignment

-Weight Reduction (for less mass and more acceleration, but same amount of force)

 

Dont forget that the suspension geometry is the key to get the most of the grip. There's really no point to run 265 wide tires when the car is leaning too much and the camber doesnt make all use of all 265.

 

245 is probably the best you can make of it while running all 4 tires flat on the ground. The springs will be a major help to keep the outside tire in contact of the ground. Remember, 4 tires on the ground can produce more grip than 2 tires..

 

 

Keefe

[BlkGTLtd]

Thanks for the replies guys. Reason why I really want to increase grip is because I'm using the basic rule that more grip = quicker lap times, and as a amateur auto-xer I'm always looking for ways to trim seconds. My question for you all is that is this assumption really true,especially for our cars? To better re-word my question, is the quickest way to drive our cars through avoiding as much tire slippage as possible?

 

I say this because I've heard people say that in certain cases having a little tire drift is ideal to maximizing lap times, and therefore I don't necessarily need to aim to have an extremley high grip set-up since it would be beneficial to slide a bit. I'm hoping those of you with road-course/autoxing experience can provide input.

[apexjapan]

Mmmm... From my experience, balance is just as important as grip. Too much grip in the wrong areas can slow you down more than speed you up, as you may increase understeer to the point where you have to slow down too much to get through tight corners. I've seen some tuner cars lose the tsukuba time attack trials due to this, they had the car so slammed down that they simply couldn't get any rotation in slower corners, slowing them down out of contention.

 

Tyres will certainly make the most difference in times, but close behind that is the suspension setup. Don't disregard the stock setup too much - Subaru has a fairly good idea of what they are doing. Well, except for the addition of that dinky rear stabilizer bar on the USDM version. But the rest isn't too bad, and can be utilized for fairly quick times. I'd balance out the car with stabilizer bars (if it's allowed in your class), get some better summer rubber, and then experiment with the limits to see what you need beyond that.

 

Cheers,

 

Paul Hansen

http://www.avoturboworld.com

http://www.e-bacs.com

[racerdave]

As Paul hinted, your allowed mods will depend on what class you will enter.

 

So what class in autocrossing are you planning to be in?

[Xenonk]

Thanks for the replies guys. Reason why I really want to increase grip is because I'm using the basic rule that more grip = quicker lap times, and as a amateur auto-xer I'm always looking for ways to trim seconds. My question for you all is that is this assumption really true,especially for our cars? To better re-word my question, is the quickest way to drive our cars through avoiding as much tire slippage as possible?

 

I say this because I've heard people say that in certain cases having a little tire drift is ideal to maximizing lap times, and therefore I don't necessarily need to aim to have an extremley high grip set-up since it would be beneficial to slide a bit. I'm hoping those of you with road-course/autoxing experience can provide input.

 

Neutral steering is more ideal than full on grip driving. That is the truth that a little rear end slide is faster when the two speeds are the same. You ALWAYS want your car pointing towards the direction you are PLANNING on going while holding the same speed as if you were to do the grip line.

 

There's one way to really drive fast: achieving top average speed. But there are different ways to approach turns to gain the highest speed around a turn. You can rely on the tire's lateral grip, exiting speeds entry speeds either use the classic line or the parabolic line for turns to achieve the fastest top average speed. That's the driver in you that have to know what is the best way to handle the car to gain the best top average speed per lap.

 

If you think about it, if you were to aim for the fastest lap time, then it must mean that you are aiming to have the lowest time (simple right?). Since speed is based on time and distance, you want to keep the time low (since it's the "divider" of the problem and the distance is fixed). When entering in a turn at the same speed as your previous lap, but your exiting speeds are different, that's where you make up the time.. the reason is that you will make up the time in the straight as you are traveling x-mph more than your previous lap. This applies as well in autocross as it applies more to braking or entry speeds more so than exiting speeds (because it takes even a longer time to gain back speed on a car than it is to lose it by braking or scrubbing).

 

You should pick up the book "GOING FASTER" by SBR. Here is the link:

http://www.amazon.com/gp/reader/0837602262/ref=sib_rdr_fc/002-7186287-8592021?%5Fencoding=UTF8&p=S001#reader-page

http://www.amazon.com/exec/obidos/tg/detail/-/0837602262/qid=1109004542/sr=8-1/ref=pd_csp_1/002-7186287-8592021?v=glance&s=books&n=507846

 

You'll learn all the basics you need about how to drive the car at a higher level (or the "standard" level as I call it). Just get use to driving the car smoothly. That is the biggest thing you'll learn about driving faster is to be SMOOTH. All that jerking around, hard and heavy braking and acceleration which disrupts the car's balance and adding uneccessary opposing g-forces to the tires only slow you down.

 

 

Keefe