I mean with the handling on the limit being a bit sketchy or "bumpsteer" if thats what it is I never found it to be unpredictable
You just get to know when it might let go for what seems very little reason

 

Dan uk

The reason I asked about the Spring rates and heights is that the stiffer the springs and the less travel you have in your coilovers the less of a problem bump steer will be. but the less compliant your suspension will be as well.

Thats because at different points in the range of travel of the rear suspension you will have varying toe measurements. On an AP1 this variation in toe can be significant.

This makes the car unpredictable and a poor platform for tuning the suspension.
Why, because if you make an alignment, sway bar setting or damper adjustment you can't isolate what difference your adjustment made because the toe in the rear is changing all the time as you are driving through different turns. Going form toe in to toe out under different conditions and turns is not a good thing.

Its the same reason you want a stiff chassis. If the chassis is flexy then its hard to tell what you suspension tuning is doing because your alignment is constantly changing as the chassis is flexing.

Can you drive around it? Sure, but why would you want to.

And we have not even taken into account that as you go through a turn, especially one with a lot of weight transfer, the right rear is going to be at a completely different place in the suspension travel range than the left rear. Now the toe on the right is constantly changing and its always different with no correlation to the constantly changing toe on the left. This not my idea of a fun car to drive. challenging yes. Fun, predictable, confidence inspiring, no.

There is a reason why they make bumpsteer guages and why racing teams use them to adjust all or as much of the bump steer out of the car as they can. Same reason why they changes the suspension in the AP2 to correct it.

 

I understand the theory of the toe-change I just think its realy a non-issue at least on my car. As I understand the BSK doesn't realy 100% address the issue and haven't a few broken?

The way I would address it would be a rear subframe swap

 

I have 340lb rates all around, 1" drop, Saner front bar on full stiff (EDIT - full SOFT), stock rear bar on my MY00. 245s all around. Rear is silent. Makes my C5 seem like a barrel of monkeys (which it isn't).

I have no clue what all this talk about a twitchy rear end is. I find the car very easy to drive fast (way more forgiving than C5), just pay attention if trail braking, as in any car.

 

[QUOTE=Bikey,Sep 2 2010, 06:35 PM] I have 340lb rates all around, 1" drop, Saner front bar on full still, stock rear bar on my MY00.

 

Thanks for pointing that out, that brings me to my next point:

The only difference vs current my setup and stock (which for me was crappy 205/225 all seasons) = more grip. The car is slightly more balanced and has less body roll but it still took some effort to make the rear lively in stock form.

My point is that I think driving styles play a large role and are easier to address than a bsk.

Also - thanks for the link for spring rate calc.

Is your position that a stiff enough front will negate the rear toe effects that you suggested? Does anyone have any measurements of exactly what toe changes occur at what ride height/compression and what causes them? Or is it a combination of toe and ?

 

After reading more, I have decided to keep my current setup (CR front and MY02 rear). I feel a lot more confident going quicker around corners without the rear kicking out.

My current suspension setup is Koni yellow with Swift street springs which are too weak. Planning to upgrade to either Ground Control or save up more for a set of coilover.

 

Here's a good link for info on BSK and Camber kits. Good reading.

https://www.s2ki.com/forums/index.ph...ic=793517&st=0

There is a link to a 10 page thread that has more detail in this thread.

The majority of serious tracked cars, S2K challenge and all the W2W cars have a BSK.

And as I said before;
All the pro racing teams I can think of do all thats required to get as close to zero BS as they can. Every purpose built race car is designed to eliminate it.

A happy driver is a guy with a predictable, tunable car.

Everyone has fun differently, some golf some fish. If you are happy with what you've got and it puts a smile on your face

 

I think with those springs and the saner on stiff it would understeer a lot.
I ran mine on soft mostly it was still understeery... I think being limited to -2 ish camber up front doesn't help that either

 

Had a look, Saner bar ended up getting installed on full soft which explains the lack of understeer.