These both sound like the same issue I'm experiencing.

I don't think there is anything wrong with the ACD. It doesn't know if the rear diff is locked or not. Considering the way the rear diff is supposed to behave, the ACD should be able to send torque to it when needed.

Time to order a X????

 

This is basically the only A Stock mod I haven't done. For one, it's a ***** to swap out. And two, nobody makes a good adjustable one because they're a ***** to swap out. I put a deposit down on the one WORKS was developing, but they never finshed it. To compensate I'm running some pretty harsh low speed compression dampening up front, but the inside rear still finds it way off the ground.

 

You should consider the 26mm Whiteline fixed FSB GTWorx.com sells ... might as well prep the car to the max and see what she does, imho.

 

I certainly can respect that and so will your competition

If you don't want to get more lock-up at the rear diff then obviously you will have to dial in your driving style to make the stock stuff work....still lots of tricks you can do within limits but honestly, if you want the car to rotate send me a PM.

Jon@TRE

 

Iam in the same boat as Boder, autox class, and similar mods.
The hanging rear wheel hasnt really been a problem before yesterday. The course we ran had a LOT of big sweepers. I spent more time on 3 wheels than on four (its the talk of the day ). I feel like I just cant put any power down till that wheel is back on the ground, which obviously really hurts corner exit speed.
Before yesterday I had not experienced the problem Boder describes of the wheel off the ground "breaking loose" on touch down. I was told by another competitor this weekend that in fact they did see a bit of tire smoke on touch down a few times.
I havent replaced the front sway bar but i have drilled a second set of holes on the stock bar, which seemed to work fairly well. Yesterday, besides the "stiffer" holes, I tried out a homemade adjustable mount on the control arm allowing a "stiffer" adjustment of the sway bar. My observations say that I went to far. It was really hard to keep the car from pushing in these long sweepers. My datalogs (maxQdata) back up my observations, I never hit a lateral g higher than my previous 2 autoxs, I just didnt have as much grip. (the Kumho 710's are on their second event).
In a world where push is overcome by corner entry speed (slow in) and exit speed is limited by not having a wheel on the ground (slow out) it makes for REALLY slow times. Before this weekend I have been a consistent second in PAX, this past weekend I was 8th with the same car (DS VW R32) in first PAX as there has been at the previous events (meaning it shouldnt be course dependent).

I feel the same as Boder, I would rather not cheat. Maybe I just have overstepped the limitations of the AS evo, and would just be happier in BSP.
Or the AS evo prefers courses with tight "get the turn done quickly and get the wheels back on the ground" type courses.

Any comments, suggestions would be appreciated.

 

To be honest, because I got sick of seeing my car 3 wheeling and the unusual amount of outter tire tread wear, therefore I ending up moving to STU where suspension mods are allowed. Plus I hate changing tires for events ...

Gears: Stop recommending cheating to all the SCCA competitors

 

No one answered my original question -- I always thought that front sway bars and replacement shocks were legal in Stock? If so, upgrade to a 26mm front bar (I just installed the WORKS front bar on my Evo IX). It will do two things -- first, it will keep the front tires flatter and so let them grip better on turn-in, as well as eliminate some of the dive on the outside front tire and theoretically keep the inside rear tire on the ground through more corners. You can also swap over to the MR Bilsteins in order to stiffen up the car across the board (stock shocks are way underdamped).

One other thing you can do here is try to lessen how much torque is transferred to the rear wheels, and simply drive it like a front wheel drive car through the courses where the rear is coming up. If you have ACD, switch it to the Snow setting to keep power going through the front wheels longer.

Before you start going crazy and modding the sh*t out of your car to jump to Street Prepared, work on maximizing the car for stock.

 

The MR Bilsteins are actually softer than the stock EVO KYB shocks and would make body roll worse (unless they have been revalved to become stiffer). Also the stock EVO KYB are over damped (not under) for the spring rates that come with the EVO. The front swaybar would probably be a benefit to help combat some of the front body roll the car experiences through corners.

And yes front sway bar and shocks are allowed in A-Stock.

 

I thought that the MR Bilsteins were slightly softer in the front and stiffer in the rear, but I could be wrong.

There are a couple of things you can do here. If the KYBs are a bad choice, there are now Ohlins shocks as well. You can also have the Bilsteins re-valved to match what you're looking for (place a call to Bilstein USA in SoCal).

For autocross, slightly too stiff for the spring isn't necessarily that bad as it basically will make the shock act like a slightly stiffer spring. This is a very bad thing on a bumpy surface, but most autocross surfaces are pretty darn good.

 

Good advice Peter. As I stated, I set up the front bar to act like a stiffer bar and I just got way to much steady state understeer on long sweepers.
I am currently running a set of MR Bilsteins revalved. The fronts are set at twice as much compression over stock and a little more rebound, rears are twice as much rebound and a little more compression than stock. Boder I know is running the Ohlins with stock springs, and from what I understand has even added more compression to the fronts than they come with.
The front shocks would need an astronomical amount of compression (read: its no longer a shock) in order to keep that rear tire on the ground. I may have to bite the bullet and try the new front bar, but Iam having my doubts wether it will make enough of a difference to counter the increased understeer.

Also interesting comment about the "snow" setting. My experience with it says that the car feels like it understeers MORE on "gravel" or "snow". I find it interesting that you suggest using it to "keep power going through the front wheels longer", and Jon (GEARS) suggests MORE REAR lockup, two different schools of thought here or am I misunderstanding? I would think more rear lock would make the car push worse, no? Or is the thought that more rear lock would break the rears traction and give the yaw angle that we dont have otherwise?

Explain, discuss.....

 

Dealing with steady-state understeer is a front-end problem. In the case of my Evo, it was basically too much weight and body roll, with the outside tire taking too much abuse. A stiffer front rollbar makes both wheels work better in concert, and limits that outside tire from rolling over and loading up too much.

My opinion is that most people tell you to increase rear rollbar to induce the rear to slide. While that theoretically fixes understeer, it does so by inducing oversteer. Not really a fantastic response to the problem. The converse of that (decrease front rollbar) is NOT true, even though many will tell you that that's an answer. Yes, at some point too much rollbar becomes a serious problem (this is true for front and rear), but there is a right time and place for using them as a tuning aid. I don't think you'll see a massive imbalance created by increasing front bar, but will rather see an increase in front traction which will ultimately make the car faster.

A great example of this was the set-up on my old M3. Most fast guys for years swore by gigantic rear bars and stock front sway bars in order to get the rear loose on the car to make it rotate. Ultimately that killed lap times as it killed your tires, and never really resolved the front-end understeer issue. At one point I went dramatically the other way -- giant front bar and no rear bar, in order to get the front tires flatter during corner entry, and let the rear tires have maximum traction for power-on in the corner exit. It transformed the car, and I found 2 seconds, not the least of which was from better driveability!

Take all of the with a grain of salt, as YMMV. Changing only the front bar will have to be tested to see what impact it has on the overall balance. I've got upgraded bars front/rear from WORKS, and increasing front bar diameter (not conventional wisdom) helped the steady state understeer.

 

First off, talk to 10 different guys and you'll likely get 10 different answers!

The guy from Gears is recommending a differential solution? *SHOCKING* Kidding of course, but there is something to be said for focusing on getting the chassis right first and changing diffs later. The driveline will only mask the underlying problem.

What I'm recommending is not in conflict with what was proposed, only offering a different path. I'm basically telling you to drive it more like a FWD car if the rear wheels are getting off the ground (a common sight with FWD racers -- my old VW used to get like 8" under the inside rear tire, and that was on canyon drives!). Easiest way to do that is to tell the diff to not transfer torque to the rear wheels as soon or as aggressively. This definitely requires that you change your driving style a bit, but I think it's a viable option.

IMO, increasing the rear lock-up will help. It will make the one wheel on the ground work harder and take away some of the spin on the other wheels. It will also help push the rear around.

The more I drive my own Evo, the more I wish I had a locked center and rear diffs so that the diff behavior was more consistent. It certainly would make turn-in a little more difficult, but I don't think it's anything you can't drive around. That said, I'd never trade even the most magical diff set-up for a well sorted chassis.

 

peter*g,
I have the Ohlins dampers and have already had them revalved as brian94ht said. The fronts cannot produce any more damping force without the danger of blowing the gas out of them. I have the capability of running 350 lbs/in @ 1 in/sec on the compression side. That's about 7x that of the stock KYBs.

I think you are right about the sway bar, I just don't want to get to the point where the sway bar is too stiff, like brian94ht's last experiment. This is why I want to do something like a 3-way adjustable sway bar so I could go back to stock if need be. The problem is, nobody makes one. If you know otherwise, I'd be the first to try it out.

I also agree with the GEARS statement about more lockup in the rear. I think I would be happy with the car if the rear diff would work as it was designed(even with R compounds). The car sprint out of the corners and the inside rear would touch down that much sooner because of the rear weight transfer. It seems that everything I try to do to keep the inside rear down on the ground just causes understeer (with the Stock allowances). The only Evos I've seen that don't do the 3 wheel motion are ones with coilovers that have been lowered a little.

I think another solution is more rear toe out. My car felt great last year when I added the toe out(only 1/16th"), but this year I think my front tires my have lost a little grip since last year and has overcome my toe setting. I might have to try 1/8th" for the next event. I am also going to experiment with the "Snow" setting.

Thanks for all of the opinions and comments.

 

I do buy still a PITA to change

 

More preload on the clutch pack really has the greatest effect in mid-corner, and more generally equates to more push. What really needs to be altered are the ramp angles. If the car turns in fine and is ok mid-corner, but pushes on corner exit, then the ramp angles need to be altered to produce less exit locking.
Cheers,