Wakefield Times!

[Spunkymonkey]

This July 5th Q..........come along!

Sorry wyn. Got plans already. Going to be at the slopes skiing for the whole week.

Maybe when spring hits and the snow has melted, I might go back to wakefield sometime lol. Thanks anyway.

[Whiteline]

I though it would be a good idea to write up a conclusion to what has been discussed in this thread, as there is a lot of information spread over a lot of pages here. As well as this I will also try to answer some of the outstanding questions and doubts.

I’ll just start by saying the most effective way to reduce lap times around a circuit is to increase the cornering speeds (or lateral accelerations). As probably all our cars have negligible aero packages, mechanical grip is the only way to achieve this. With all things being equal, the way this is achieved is by having the softest possible suspension setup that will not allow the roll and pitch of the car to effect the tyre contact patch excessively (by giving to much camber change etc). The soft setup allows the wheel/tyre to track any undulations and uneven road/track profile, staying in contact with the road, and hence being able to generate grip. If a tyre is not in contact with the road then it cannot generate grip, this can arise whilst running high rates. Also when running high rates, grip cannot be generated as efficiently when the tyre is still in contact, because the uneven track conditions setup uneven loading in the tyres. Rally cars are trying to reduce this very phenomenon with hydraulically linked front and rear anti-roll bars, effectively spreading any high single wheel loads (from uneven track) to the other wheels (effectively reducing the load variations).
As an example to show that softer ride rates are advantages, the Mclaren F1 of a little while ago, still probably one of the greatest high performance road car (supercar) ever made, runs a fairly soft suspension rate. As an equivalent ride rate, a civic EK4 would need to run on approx. 2.5 kg/mm springs to attain the same rate as the Mclaren F1.

Now what circumstances will warrant higher rate springs/anti-roll bars in an application? By increasing the friction coefficients at the road (for example switching to slick tyres) more lateral acceleration can be achieved, this will increase the roll rate during cornering, and possibly upset the tyre due to excessive roll camber. Here fitting of stiffer suspension will reduce the roll, and camber effects seen at the tyre back to the original values, hence reduce any undesirable grip effects associated with the roll camber and increase the possible grip further. Now the best option here would be to fit a stiffer anti-roll bar, and this will deal with the increased chassis roll, while leaving the ride rate unaffected for the mechanical grip.

One reason for running higher rate springs would be to control chassis movement very precisely due to very large aerodynamic down force (F1). This is where the chassis needs to stay within a few “mm” of its position with load changes in the order of 1500kg. Quite simply, aerodynamics in F1 is the driving force; you can get away with a bad suspension if the aero package works well. So racecars that run huge amounts of down-force (to develop they’re grip) require stiff springs. If there is no aero then there really is no need to use springs of such a high stiffness.

It is clear that there are some differing opinions in ways of achieving roll stiffness and its advantages or disadvantages. Let me start by saying that to be absolutely correct roll stiffness not only depends on anti-roll bars and springs, but also dampers and the roll inertia of the vehicle. However to keep it simple, we can neglect damping and inertia rates, effectively assuming steady state cornering.

As it was stated earlier, one can use any combination of spring and anti-roll bar to achieve the desired roll rate. However one needs to look at what the effect will be by using different combinations. One thing to consider in this argument is that springs affect the ride rate (aka heave), where as the anti-roll bar does not effect the ride rate (that is purely vertical motion – it should be noted that one wheel bump rate is affected, although its effect is small on comfort).
The big advantage to this is that the springs can be adjusted to give the required ride rate and then the anti-roll bars can be used to adjust the roll stiffness to the desired value. This way the springs can be tuned to provide optimum mechanical grip.
On the other hand if spring were primarily relied upon, the ride rate would be much higher and ultimate grip may diminish (and increase NVH).
Additionally another advantage of using anti-roll bars is the possibility of easier adjustment. One could swap the springs on the front end (if you had the time, and spare sets of springs) or by simply adjusting the hole position on the anti-roll bar arm. Anti-roll bars are still used on the highest forms of motorsport to adjust the handling characteristics quickly (from formula ford to F1).

As stated before, I neglected the dampers for the explanation, although it should be noted some of the differing opinions about comfort said here about different types of suspension brands (even when using the same spring rate) is almost certainly due to damping coefficients. This is because for the best comfort a damping of around the 15% critical is used, and for best grip around 45% (values as a general example), and the difference between comfort and grip can really be felt. Racecars can use values approaching critical damping (100%).

I should also say that no matter what your suspension setup, weight transfer (or load transfer) during cornering is only a function of the CG height, track of the car, and cornering acceleration. It may be affected by excessive roll angle, which moves the CG sideways, although it really needs to be excessive roll to see this. Roll angle is dependant on the roll rate (spring and ARB) and suspension geometry (roll centres) as well.


Regards,

Jakub
B.E. (Mech.)

Whiteline Automotive

[Jerfield]

i think u guys should post in another thread coz it's getin very difficult to read the times that ppl have posted.
i mean this is a thread bout wakefield times after all

[tinkerbell]

sorry jer, seems the thread morphed into something it wasnt.

[dsp26]

Holy thread revival!!!!! this is a great thread...

tink... was wondering if you could outline a comparison of your previous setup to the below change.

still - the proof will be in the pudding...

i am getting a set of 6k springs for my car, to replace the 8k rears, and moving the 8k rears to the front, replacing the 12k fronts... adding a 25mm front anti-sway bar and moving the rear anti-sway bar to stiffest setting...

main reason - better street driving comfort

[tinkerbell]

ha ha!

yeah, the 8kfr 6krr wasnt good for track events,

especially at eastern creek, so i went back to the 12k fr 8krr for the whole 2007 year of supersprints.

[tinkerbell]

here are my times from 2007, i am car 62:

[Q_ball]

Dave = gangsta streetz racer hahaha

Mad times mate!!

[ONE600]

Have never been there but hoping for 1:07s this week
Times are based on the Newmann GTR which runs low 1:04s and we are 2 secs slower than them at QR and Wakefield should suit our crx much better as QR is HP track. Be interesting~

[Benson]

Have never been there but hoping for 1:07s this week
Times are based on the Newmann GTR which runs low 1:04s and we are 2 secs slower than them at QR and Wakefield should suit our crx much better as QR is HP track. Be interesting~

Good luck this thursday

[Samo]

just heard they did 1:07

[Jase EK]

HIPOWERRACING CRX 1:07 excellent for first time... see new thread from hipower