Hello Jim,

I am in the market for suspension bits for my 05 STi, and I'm considering Whiteline products for the job. I have a few questions about some of them-

First is a question about your ALK. I've read through your white paper as well as whatever else I can find on the internet about front suspension "anti dive/lift" geometry. I feel I have a pretty firm grasp of the concept, but one thing escapes me- when you show the diagram on how to calculate the SVIC, the bottom line goes straight through what appears to be the front and rear inside pickup points on the A arm, as well as the outside point where the ball joint is. They all appear to be line up perfectly. It also shows lines for accelerating and braking which move above and below the static line. What confuses me is this- what two points are used to figure out the slope of the lower line? If it is the front and the rear inner points then it wouldn't move (unless the chassis did). I assume the rear most point (that the ALK lowers) and the ball joint are what is used for the calculation?

Second, if the ball joint is used as a point, then the amount of anti lift/dive changes when the car is lowered, and if I understand the diagram lowering would reduce swing arm length and SVIC height and reduce the "anti" geometry too. Which makes me ask if the changed geometry is necessary for a lowered car, or if it could even be detrimental. I myself won't be lowered much as I explained in the RCA thread I started here (14" F and 13.5"R hub center to fender), but I'm just curious so I cna better understand the forces at work here.

FInally, I am curious about your polyurethane suspension bushings. I brought this topic up recently in a thread titled something like "hardened bushings vs pillowballs" in the other suspension forum here. As I said there, I've had some bad experiences with poly bushings in a similarly designed rear suspension (the mk2 mr2 to be specific) with binding and I've been a bit wary of their use in off axis movement. Your bushings were said to be higher tech and of better build than a typical bushing there. So my questions are then, is binding a potential issue if I replace all of my bushings (lateral links, trailing links) with your products and what makes your bushings better (and perhaps less susceptible to binding) than say, the energy bushings that I had an issue with?

Thanks for any info. I greatly appreciate a company like yours that not only understands their products, but also innovates with new ones.

<!--[if gte mso 9]> < G'day everyone,

Iron giant, thanks so much for your positive comments and question but as a simple answer to the first part, I'm not really sure.

I realise that's not really terribly useful but though I think I understand your question its the first time anyone has asked. Frankly I'm not sure I completely understand your point as the white paper says that the lower line runs from the lower arm rear pickup centre (ALK centre) to the tyre contact patch, ball joint isn’t mentioned.     

Regardless, you're correct in implying that there are other variables that impact here and the most obvious one is the angle of the strut as a consequence of any significant changes to caster at the strut mount. But, I remember when the engineer put this together the affects on the anti equation were minimal and so was lowering within a reasonable range found in this application.

On the second part, poly bush design has come a long way in the last decade and Australian manufacturers have done a great job in developing new materials and technologies to overcome any issues. Your question touches on kinematics and the importance of programmed distortion to allow for dynamic alignment change.

I'm not entirely familiar with the specific bush application on the MR2 but the rear end is multi-link which means there is a lot of designed dynamic change that relies on "distortion" to make the system work properly. This is pretty standard tech for us nowadays so I'm confident that you'd have less or a problem with binding from a Whiteline bush than any other design.

Hope that helps.   

Cheers

Whiteline Jim

www.whiteline.com.au

 

Here is the image that has me so confused, the diagram for calculating the SVIC (with some color added to illustrate my question)-

Figuring out the upper line for calculating the SVIC seems easy, it's just 90 degrees from the angle of the strut. It's the lower line that has me confused, which I highlighted in red. I understand that the rear control arm mount (where the ALK is) is one point for calculating the angle of this line (the green point in the diagram from what I understand). So what is the other reference for the lower line? At first I thought that it was the purple point, which appears to be the front control arm bushing, but neither of those points move under acceleration or braking (which is shown in the dotted lines). I guess I'm under the assumption that the red line becomes (or moves to) either of the dotted lines under accel/braking. So if the line moves, then one of the points used for calculating this line must move relative to the chassis, which is how I concluded that the line must be calculated using the outer balljoint (at the knuckle and illustrated by the yellow circle), which happens to be in line with the line between the front and the rear bushings of the control arm in the pic.

Hopefully that makes sense, it's hard to explain what is tripping me up. Hopefully you can provide insight.

Thanks

 

G'day Iron giant,

Thanks for the extra info, I wil refer this to our engineer to provide an answer.

Cheers
Whiteline Jim
www.whiteline.com.au