Dan's NC track toy

[Dan]

I put my APR GTC-200 Wing with risers onto the car tonight. It's a model specific wing so it sits right on the edges of the boot. It was pretty easy to install, taking only took a couple of hours to assemble, drill and put on.

The height of the wing with the risers from the front appears to be about right being just under the roof level and inside silhouette of the car but from the side it looks like something from Boeing which makes the car look pretty racecar.

The risers will need to be off for the CAMS Supersprints but since the wing takes less than 5 minutes to come on and off that isn't really a problem.

I'm planning to use the wing at SMSP GP/North/Brabham and do some testing at Wakefield to see if it's beneficial. I think at SMSP this wing should be very effective as there are a few of high speed corners that I'm lifting on so I'm really looking forward to testing it out

[Guran]

Nice work Dan. Russ and Phil will need to watch their backs.

[Dan]

I've been looking for a new steering wheel for a while since my stock one was starting to show some wear and tear. A couple of weeks ago a Guardian Designs steering wheel showed up for sale on the forum second hand so I picked it up.

I've got to say the build quality of this steering wheel is excellent, the feel is much better than stock with the thicker wheel and I just think it makes the interior look more modern.

Definitely happy with the purchase

[Regie]

haha was wondering who bought that. i would have taken it if i didn't have my AutoExe wheel currently

[cwto24]

That wing! :O

[david_syd_au]

With that wing, you will have to do the club drift day in March, although you should remove the front bar and re-attach it with cable ties first to get the authentic look :-)
Just make sure you carry spare cable ties

[Dan]

Haha, I thought it looked big for an NA car - Then I saw Lightyear and Beavis' cars and felt like it might not be big enough..

Proof will be in the times

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[Dan]

Thought I'd do a quick update since I've been playing around with suspension height and have got the car down to where I think it should be, I lowered the car around 20mm on both ends to the point where now it's got approx 10mm between the top of the tyre and the guards at the front and a little more on the rear. this is about as low as I want to go since the front lip is only about 80mm above the ground.



The thing I'm debating right now is the amount of rake I should be running. At the moment it's around 10mm which seems like a lot but I've got a rear wing on the car now without increasing the rear spring rate (I'm getting some stiffer springs soon) and the car still feels like it has much more understeer than the old suspension so I think I'm going to test it out like this and maybe make a change at the track to see how it feels.

The droop travel seems ok since MCA say that you need to check for at least 50mm of droop travel on each end and to only adjust the shock length using the bottom adjustors if it has less than 50mm of droop. At my current ride height and no changes to their shock length settings I have:
Front - 63mm droop travel
Rear - 68mm droop travel

This week I'm heading out to pick up some fresh Z221's from Gary's Motorsport tyres, I'm moving up to 245/40 from my current 235/45's since I'll get a slightly smaller rolling diameter and I have some parts sitting around for some engine mods which I'll be doing soon

I have a track day coming on the weekend at SMSP South Circuit (RTDC day) too which will be a good chance to test out the car and maybe beat some Evo's as long as the wet weather holds off..

[Magpie]

On the weekend I got the following changes in ride height between no weight and drivers weight (measured at the pinch welds):
FL - 0 mm
FR - <2> mm
RL - <3> mm
RR - <5> mm

I ended up with leaving about 1mm of rake (with drivers weight) and a 50.2% cross weight.

Hopefully I will get this right. Lower the end of the car you want to grip. Too much understeer lower the front, too much oversteer lower the rear. However increasing rake moves the CG forward, this increases oversteer. Also, increasing rake can impact brake balance as the rears will grip less.

The wing should increase rear grip. Not knowing your spring rates (or drivers weight) of the 10mm rake a few mm for drivers weight and then the balance needs to come from the aero. Assuming 6kg springs and 7mm of travel you would need approx. 80kg of downforce to get the car level (assuming no front downforce).

Since the wing does not give large amounts of downforce at low/med speed then you may have too much rake and this is causing understeer.

Another thing to consider is having the car that low may have increased bump steer. That is as the wheel moves up the wheel turns without any input from the steering wheel. This will also have an effect on your toe/camber and caster.

I have raised my car 15mm on the weekend, but maintained the same splitter height of approx. 95mm so will see what this is like on the track soon. Since I have a starting point I can make height adjustments at the track to maintain the 50/50 cross weight or height adjustments and move the cross weight.

[Dan]

Yeh, your understanding is pretty much the same as mine except saying that because you don't get a lot of downforce from the wing at lower speed the rake will cause understeer -(it should do the opposite so I assume you probably meant to say oversteer).

My aim with the wing was to be able to have a car that can be balanced around different corners, so for low speed corners it turns in and runs towards the oversteer end of the spectrum and in high speed corners the wing pushes the car more towards understeer.

I understand the wing isn't huge but at 10 degrees AOA it is supposed to produce just over 80kg of downforce at 100mph which a bit under the speed of T1 of Sydney Motorsport Park and according to your calculation should get the car level (I run 6kg springs which you based your calculation on).

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[Magpie]

10° AOC will cause drag that will impact top speed, interesting to hear if this is correct. What are you getting down the main straight?

Yes it should have been oversteer as the weight is transferred to the front

You could try and take out some of the rear rake and see what happens. Another thought is to use a gurney flap, this will allow a smaller AOC whilst producing the same downforce for less drag (more top speed).

[Dan]

My car only gets up to 180km on the straight and my vmin in the corner is about 165. With the resurfacing of T1 since the last time I drove it and a wing hopefully I can take it flat, I probably could have taken it flat anyway but my old setup was pretty unforgiving and I'm a bit of a wuss

I do plan to add a gurney flap since it's more efficient like you say (L/D @ 100mph - 10 degrees = 8.85 vs 0 degrees with Gurney flap = 10.14) but there is still less drag with 10AOA without a gurney flap than 0AOA with a gurney flap according to the data on APR's website (Drag in lbf @ 100mph - 10 degrees = 20.3 vs 0 degrees with Gurney flap = 21.9).

I could go to neg2 AOA with a gurney flap to get slightly less drag with a bit more downforce than 10AOA but I think if I was going to put a gurney flap on I'd probably just chuck it at 0AOA and enjoy the extra downforce

[Magpie]

I was getting (in October) 199 down the main straight and 165 at the apex of T1 with the wing at about 3° and a gurney flap. T1 is about have grip, the wing and tires will help. It was surprising how fast clubsprint cars with AD08's were going through T1.

My speeds are no real indication of what a better driver could do with my car. If I get there in October this year I reckon I will be a bit faster as well as get over 200k down the main straight.

Watching (stalking) your performance

[Dan]

Yeh, it's a lot of things. I was talking to John Boston a few weeks back at a track day and he had a Japanese professional driver do the GP Circuit in his rental NC while doing some tyre testing for Yokohama with similar mods (Stock engine, suspension etc..) but with a wing and I asked how he takes T1 and he replied "flat" in a 'how else would you take that corner' tone

I'll let you know how it goes, next supersprint at the GP circuit is the 15th of may.

[Magpie]

My 'balls' are not big enough to take T1 at flat out, rather they shrink and go into the safety of the body.

Good luck on 15/05.