Upgrade questions for the gurus

[yellowkyd278]

I've never been a big suspension guy but I"m getting into the game so I'm still picking things up.

Here's a little background: I attend full on track days when I have the opportunity which ends up being maybe once or twice every few months. I rarely autocross. In the future, I do see myself going to the track more often but do not see myself becoming a more serious autocrosser. The drag strip is fun too but big whoop.

Here's the suspension mods I currently have installed:
1. Evo8 Wheels + Evo8 Stock Advans

Here are parts I have in my garage going in this week:
1. Front/Rear Struts (think they're Megan but even I know brand hardly matters on these)
2. Front/Rear RMDSM sways

Here's what I plan on getting within the next 3 months:
1. Koni Yellow + GC
2. Polyeurathan Bushings
3. ???? Camber Plates ????

What do you all think? Will this set up suit my needs and how drastic an improvement will I see with the parts installed?

Also, can someone please explain the idea of camber to me and whether are not camber plates will be necessary with the KY+GC. What is it? What do the plates do? Which ones are recommended if needed?

I'm not going to lie I've spend 90% of my time on this forum in the bolt-on tech and tuning section so please don't flame.

Thanks

 

[wret]

Assuming you are coming from a basically stock suspension, you will see a dramatic improvement. Your list of upgrades is pretty good though I should clarify: the Megan "struts" you mention are actually strut tower braces, right? If so, then you are correct. Even the cheapest ones work.

The Konis and Ground Control combo is (debatably) about the best choice for your purposes, but you still need to put some thought into spring rates. Stay with Energy Suspension brand bushings if you drive on the street.

"Camber plates" are not used on 2g DSM's. These are typically used on McPherson strut based suspensions. When you lower your car, the camber will become more negative. Some negative camber is desirable for best cornering performance but to balance it, you will want to increase the rear camber somewhat (less negative). This is easy to do with washers and longer mounting bolts. If you need to alter the front camber, you will need a kit that consists of either adjustable ball joints or mounting bushings. The adjustable ball joints allow you to adjust caster as well. For your style of racing, you will not need to be as aggressive with the negative camber but we do not have optimum road racing alignment settings posted here.

You may want to add some brake upgrades to your list.

Here is some material for you to read if you haven't already.
http://www.dsmtuners.com/forums/showthread.php?t=169955
http://www.dsmtuners.com/forums/showthread.php?t=169559

 

[yellowkyd278]

Thanks guys, I love quality responses. Does setup for a autocross car vs. a tracked car differ by much? High speed wide turns are fun as hell but it'd also be nice to be somewhat agile (e.g. mountain passes, occasional auto-x)

I have 1300 - 1500 budged for the shocks/springs/coils. I know the GC+KC falls a tad bit under that amount but is it still the most optimal choice?

Secondly, what spring rates are recommended and what are their cost? I know that's a very "what turbo is best for me and how much" kind of question, so suggestions with reasons are all I'm really looking for in an answer.

Thanks again for the advice, I'll keep reading to actually learn about the parts. My goal for this thread is to leave with a solid setup plan granted what I already have and what still needs to be purchased along with a ballpark estimate price.

andrew

 

[DG-FNR]

For those that are interested in "advice for the masses", check out http://farnorthracing.com/autocross_secrets.html

I've come to the conclusion that my racing days are finished (too much to do at the Regiment) so there's no reason to sit on my secrets any more. So I'm publishing them for everyone.

It's a work in progress, but the intent is to publish *EVERYTHING*.

Want to learn how to win Solo/ProSolo at the National level? It'll all be there, eventually.

I'm also revamping some other websites I control too, bringing them up to date.

Enjoy!

DG

 

[jtmcinder]

Does setup for a autocross car vs. a tracked car differ by much?

Oh, my, yes. Most autocrossers like a car that's at least a little bit loose (i.e., prone to oversteer). Combine this with the typical tendency for cars to become more loose as speed increases, all else being equal, and you get a car (set up for autocross) that is downright terrifying on a road course (or even at the top end of a drag-strip). This is often a combination of the choice of springs and swaybars, plus the alignment.

If you are planning to do both, I would serious put some time and effort into getting an adjustable rear swaybar. The stiffest setting would be for autocross; the softest would be for the track. The beauty of using an adjustable swaybar to do the switching back and forth is that it has no effect on anything else, so you don't have to play with alignment.

- Jtoby

 

[DG-FNR]

Does setup for a autocross car vs. a tracked car differ by much?

On my racing engineering course, this was expressed as follows:

"As maximum vehicle speed increases, the optimum handling balance moves increasingly towards understeer"

As the extreme example, an IndyCar at IRP (where you are flat out all the way around the track at over 200 MPH) the aim is to start out with understeer and then slowly dial out as much as can be done without scaring the driver to the point where he is unable to keep the throttle down all the time.

A full-on autocross setup has to be entry-oversteer biased so the car will "dance" through transitions - watch the top drivers at National level autocross events as they go through slaloms (Danny Popp is a good example) and you'll see that the back end never looks planted; it looks like it is sliding or wiggling around (even though it isn't) That's the goal of an autocross setup; get the car dancing.

Driving a DSM means you never have to worry about exit oversteer, but that much entry oversteer on a track car means that every once and a while it'll throw you - and with the higher speeds and the closer proximity to Hard Things, you really don't want that to happen. So you back down on the total natural frequency a bit (set the front at ~ 2.0 Hz) and use a lot less rearward bias on the bars.

Something I always meant to toy with was to use a really aggressive multi-element rear wing as a speed-sensitive balance tuning device. Set the car up with a lot of mechanical oversteer, (for slow-speed agility) then let aero downforce tame the rear on higher speed stuff - the idea here not to try and get increased TOTAL grip from the aero, but to let me have my oversteer cake and eat it too.

A wing aggressive enough to pull this off would murder top speed, but it might make it up everywhere else on the track - there is more time to be had by making the slow parts faster than by making the fast parts faster.

I never got around to trying this out, but it'd be worth a test.

Anyway, never let your balls get in the way of your brain: yes, a touch of oversteer is faster, all else being equal. Yes, a better driver can deal with more oversteer than a lesser driver. But don't let that lead you down the path of "I'm a great driver so I'll run more oversteer than anybody else". You'll go faster with less oversteer if that gives you the confidence to really lean on the car.

Here's a Happy Fun Fact: I ran a multi-channel data logger on my car for every single run I ever made in the car, starting mid 1999. I have data on hundreds of autocross runs. Every single fastest run on a given course on a given day has something in common with every other fastest run - the total throttle percentage is higher.

More gas makes you go faster - go figure, right?

But that's an important point from an engineering perspective. Where, given a "perfect" driver, there is a particular setup that maximizes total grip that *should* be the ideal setup for that car, the ideal setup for that car plus the real-world driver is the one that maximizes driver confidence and lets him hold the gas down longer. This shows up ALL THE TIME at Indy, and it applies to us every bit as much.

DG

 

[jtmcinder]

Your idea of setting the car up for oversteer and then slapping on a large rear wing has already been implemented by the top BMWs in SM. Although it's kind of like closing the barn door after the animals have already left, there is a very good chance that new limits on wings will be in place by 2008.

One disagreement, however, on DSM's and power-on oversteer: ACM had serious issues with this after switching to a 35/65 center diff. In the end, he had to put a half-dead VC back in, to act as a safety net. Yes, this is more of a drivetrain issue than a suspension issue, but it helps to remind everyone that the two must work in conjunction. That is why, if you read my Read Me First thread, I suggest that you decide on your driveline before you plan your suspension. Kind of a bummer to do all the work to get the car set up for a 50/50 center and then have to redo it when you switch to a planetary center.

Note, however, to bring this back to the original question: the interaction between driveline and suspension is more pronounced for autocrossers, due to the speeds involved and the attraction of oversteer.

- Jtoby