Originally Posted by mmoranda

Originally Posted by Smogrunner

Of course Paul will tell me that it won't be worth my money since I haven't raced my car around a corner since getting my suspension done and my motor built.

Originally Posted by chronohunter

for everyone but you Tom it's absolutely worth it

I do echo Joe's concern for the strength of the product, we need a track hoe Ginnie Pig to do some track days on 305 R compounds to be sure (now where did Tom go with his car!?!).

Originally Posted by jcnel_evo8

Where's the freekin' whiteboard when you need one? Doesn't evom have everything??? j/k.

Paul, are you willing to talk a little (more) about roll center on the EVO?

The way Joe described this was a "bar" extending from CG to another point(s) RC. I've never seen this relationship officially pointed out to me. Is there a good picture or even animation you know about that would help me visualize this relationship?

Cheers,

~j.

Originally Posted by chronohunter

for everyone but you Tom it's absolutely worth it

I do echo Joe's concern for the strength of the product, we need a track hoe Ginnie Pig to do some track days on 305 R compounds to be sure (now where did Tom go with his car!?!).

Originally Posted by Whiteline

G'day everyone,

Looks like we have an apology to make to our WRX supporters

We targeted the EVO first because quite frankly, it has a bigger problem in this area. And by "this area", we mean front roll centre, not "ball joint extenders", "camber curve correctors" nor any other issue that may be addressed by other products currently in the market. That is, the copy of the bulletin for KCA395 at the beginning of the thread refers to a solution specific to the front roll centre problem we perceive on the EVO but we don't want to get involved in interpreting other manufacturers products and claims.

All strut based systems are prone to migrating roll centre issues due to the nature of the underlying geometry. In the EVO, front roll compounds and accentuates front roll forcing people to adopt all sorts of "band-aid" solutions to what is fundamentally a geometry problem. Our race testing on Project EVO showed the classic symptoms that was backed up by some measurements so we went to the drawing board (no experience with ball joints etc) and worked out a possible solution. Made some prototypes and everyone seemed happy (Project EVO had best times in slalom and technical sections in Dutton 2006 national tarmac rally series :banana: ). Next job was to do some durability testing before pushing the production button.

So I guess that's the good news, in our minds the WRX is not drastically affected by the roll centre problem. The other good news is that we are working on a product for the WRX but the bad news is that we're a few months away from being able to release details of the products contents and configuration.

Sorry its not more positive news but that's where we are at.

Best regards and Merry Xmas to all.

Jim
Whiteline Automotive

Originally Posted by Whiteline

G'day everyone and happy new year.

Robbi suggested that I might like to jump in and answer some of the questions on this thread. Unfortunately our office has been closed until today so I apologies for the delay.

I'd like to go through some of the issues raised in point form;

- We don't like to refer to these products as a "ball joint extender" or "spacer" kit as that implies that we've simply added some bits to a kit of standard parts which is not true. The replacement hardware has been designed specifically for the job by well established tier 1 ball joint suppliers that use FEA during the production engineering process. To my knowledge they are not OE suppliers but we have test fitted many sets here before release and are comfortable with the longevity and integrity of the interference fit between alloy arm and housing. We also clocked many months of trouble free road and competition kilometres before approving production.

- Joe Henry is correct in saying that this is a very sensitive area and that's why the amount of RC change we deliver is less than 10 mm. That's right, not 38 mm or 25 mm but LESS than 10 mm. This is not "rocket science" but it is our own proprietary recipe and we would prefer not to disclose the exact numbers. What I can confirm is that the design process did include mapping the roll centres, centre of gravity and roll axis meaning it was done front and rear. This was then modelled via simulation software to ascertain the level of migration relative to various static ride heights and roll angles. The critical thing here is that the front to rear relationship and resultant roll axis first needs to be properly understood before one can work out a sensible solution at the front.

- Continuing on that theme, the problem with simply lowering ride height on this and most other strut based cars is that the RC plunges exponentially with compression. That is, the further you compress the outside strut the more it lengthens the roll couple (referred to as "torque arm for roll" by Joe Henry) which serves to magnify the trait in a continuing loop. Hence, lowering the static ride height without adjusting the RC puts the car further in to the danger zone requiring larger and larger springs and or bars to try to hold up the nose. Fitting the KCA395 allowed us to use softer spring rates to promote wheel articulation and maximise the contact patch.

- Roll centres, roll couple, roll axis and all these related themes are one of the real brain-teasers of suspension setup and geometry change but they are fundamental to the basic design and behaviour of the chassis. To a degree, the innate chassis balance of a vehicle is determined by this relationship. AYC however is about torque distribution or power delivery and its effect on balance under power or acceleration. That is, a poor roll centre outcome will affect the chassis, balance and driver at all stages of the corner from entry to exit. AYC however is designed to maximise power delivery to the road with a resultant affect on chassis balance. As quoted by Mitsubishi itself, "Super AYC 6 traction control" with the word "traction" being the key. Changes to roll centre will therefore be felt irrespective of AYC but AYC can mask roll centre, balance and geometry problems... enough said there I think .

- The KCA395 is designed to work with stock wheels and brakes. That is, it does not impinge on either or on sensible upgrades to either.

Like all active torque distribution or traction systems, AYC has a bearing on how the car drives. The Impreza STi uses DCCD with the current generation also incorporating a yaw sensor. We had to purchase one to keep ourselves current with the dynamic behaviour as it does have an impact however it does not change the basic geometry of the car. Needless to say we have conducted many race tests with Project EVO on various settings using various components before signing off on the parts. However, thinking about this logically, the lack of a stock AYC system on US cars would suggest that fixing stuff like the roll centre would become even more important.

Hope that explains the points raised.

Best regards
Jim Gurieff

Whiteline Automotive.

Originally Posted by malevlnt2

i don't know much about suspension and that just made me feel like i know even less.

these pieces don't cost much but i don't want to purchase/install 'em if it hurts the setup.

can anyone put all of that into layman's terms and come to a conclusion on whether or not this compliments shiv's vishnu spec'd ohlins?

thanks.

Originally Posted by Whiteline

John, as previously mentioned, the KCA395 kit was designed for stock wheels, tyres and brakes (JDM) which are 17" with Brembo's. Therefore they should clear anything larger than that and I would imagine, even wheels with aggressive offsets. We're not wheel experts so can't comment on exact offset measurement off the top of my head but suffice to say we try to do things right . We support 2 cars, MRT Performance Project EVO 9 (another JDM car) which uses the factory 17's with Yokohama ADVAN 225 mm intermediates (semi-slicks) and the Whiteline EVO 8 which uses white Enkei 17's with Dunlop D02 intermediates in 235 mm. Both are used to test the products and this includes fitment with larger wheels purely for car shows.

Not sure what you mean about the power levels used for testing, both cars run around 240kw at the wheels measured with a hub dyno but we find that the biggest stress factors are actually braking and high load corners with "ripple" or bump strips impact at high frequency. To illustrate, I have attached a copy of a standard G circle plot we use when testing that shows a typical run with our EVO 8 on the Dunlop's at our preferred test circuit. Its a technical track with relatively poor surface which suits us fine as we're trying to bridge road and time attack type use as our main target. As you can see from the plots, acceleration G's peak at just over 0.5 where as braking loads are more than double with peaks of 1.2. On the lateral G side, being a clockwise circuit, the left hand corner (right side of image) max G's peak at 1.35 with solid sampling still at around 1.2. Hitting a kerb strip at these loads is equivalent to over 4x shock load with a large part of that borne by the ball joint.

We do not know what limits the ball joint manufacturers use in their testing, we could probably find out but frankly that's why we chose a good supplier. However, we still prefer to do some real world testing as you can see. The interesting thing here is that one of the weakest links in this whole chain we've found is the stock proximity of the ball joint to the brake rotor. Our testing has shown that stock ball joint dust boots start to burn as rotor temperatures reach 600+ deg C and careless treatment of the car with out sufficient cool-down dramatically shortens the ball joint life for obvious reasons.

For the record, I'd like to better clarify the quoted post before re "no experience with ball joints etc". What we were trying to say (quite poorly really) was that we've had little experience in designing ball joints though we've had quite a bit of experience with geometry change products. The modified ball joint is simply a means to an end for achieving a particular target outcome in the roll centre and bump steer area. But knowing the sensitivity of the part we got some help from the experts once we had established the precise desired dimensional change.

nothere, again I think we could have made our point clearer. What we were trying to explain is that we actually strive to use the softest spring possible when setting up. This is consistent with the whole Whiteline philosophy and for anyone interested, we explain why here. http://www.suspensionparts.info/showthread.php?t=272 . The upshot of all those words is that to maximise the quality and regularity of the tyre contact patch, you need to use as soft a spring as you can get away with to maximise wheel articulation. Using a heavier than necessary spring rate that helps to resist body roll will mean that you're likely to have too much rate for mid corner surface changes resulting in a reaction by the body AWAY from the road taking the wheel/tyre with it.

Needless to say these are very general goals and are affected by many parameters but we can use our EVO 8 as an example. This is arguably the fastest time attack and tarmac rally EVO in Australia with 3 straight years at 1st place in the Dutton Rally national series. As already mentioned, it runs Dunlop semi-slicks but the spring rates are 7kg front and rear (approx 392lb). To be fair, this car is fully caged and weighs less than 1300kg's but a road going EVO with out cage would only use 8-8.5kg springs in our setup which is comparatively very low (the top 5 fastest EVO's use our setup). We actually aim for the lightest spring rate but this is only possible once you've up-rated swaybar sizes and dealt with a lot of other small geometry change issues both front and rear.

So, getting back to your question, I'm not sure what springs, tyres, swaybars you're running but the changes delivered by the KCA395 are meant to be universal positives irrespective of other band-aid mods or changes as it deals with the fundamental chassis balance of the car. That is, whatever your performance EVO does now, in our view it will be able to do it better with the roll centre change.

Hope we're clearer with the answers this time. :smiley6600:

Best
Jim

Whiteline Automotive