Results from the PowerBox

You can see in the videos from the previous Motorkhana I had a small box mounted on the windscreen. This is a PerformanceBox, a GPS-enabled device that captures all sorts of real-time information on your driving. For example, it will record:

1. Speed
2. Direction
3. Rate of turn
4. Distance travelled
5. Radius of corner
6. ...and many more

The use is that I can objectively look at what I'm doing in the car in far more detail than my memory, or even the video, provides.

For example, in my last post, I was talking about how I needed to brake 15m before the corner, to scrub off 20kph to turn in at 80kph. But was I doing that? Not really....

From the data, I can see where I started to lose speed, where I started to turn, and the distance between the two. I can also see the speed at which I take the corners. What I can see is that I start slowing 40m before the turn instead of 15m, and I'm doing about 40kph through the turns....

Now you're probably thinking - what a clown, he doesn't even know what speed he's doing in a corner. To you I say - fair point, but there's a lot going on right then. All my limited brain power is focused on keeping it in the right direction.

Another interesting thing is I'm not braking hard enough. Looking at the rate of change in speed, I would expect to see a linear curve going upwards, which is the rate at which I can accelerate, which is a pretty straight line up to the 100kph max for the circuit. However, the brake profile is about the same pitch, just opposite. I would expect it to be much, much steeper, as I'd expect to be able to scrub off speed faster than I could pile it on. As they're the same, I might take a look into the brakes and how I'm using them.

You can also overlay results from one lap onto another, so you can see where I'm braking later, and the overall effect on speed, and where I'm coming out of corners faster. Once you get the hang of the software, it's actually quite interesting seeing what you're doing.

I get the feeling it would be a lot better on a closed loop like Barbagallo, where you cross a start finish line repeatedly, so you can get a number of contiguous laps.

March 8th Motorkhana

Ran another one of AEM's Motorkhana events last weekend. And with my best result yet - came 5th overall. About bloody time too. The car is too good to be running in the 20's. It's just a shame the driver isn't there yet.

I have to say, however, that 5th place was earnt mostly through not stuffing up, and the car basically behaving itself. All the other Birkin drivers had their dramas throughout the day. Frank's gearbox wasn't happy moving to second (leading to some interesting gearchanges), Conrad managed to go straight past a turn at full throttle in third, necessitating a rapid reverse back onto the course, and Tim had a shocking first round. He managed to hit a cone, then turn his engine off with his knee hitting the key, then overran the garage. Mind you, this was his first attempt at this event, and his final run was the 10th fastest of the round.

You also have to keep in mind that the timing is done by hand. I came ahead of Frank by 0.2 seconds, which is 0.05 seconds per run over four runs. Now you cannot tell me that someone with a stopwatch is that accurate.

Round 1 was the usual 'getting to know you' run. A bit of oversteer, which is becoming standard for my car at the moment, and needs some looking into. I also found the new tyres a bit glassy still, so the first run scrubbed them up well. The comment I got coming back in was that I was braking far too early - a few pointers of where I should be braking, a few 'you must be bloody joking' comments later, and I had a plan in mind.




Round 2 was where I implemented the plan. I think I did what I was supposed to. It all becomes a bit hard to follow, really. Unfortunately, my main evidence was going to be the video, but there's no sound this time around and therefore I'm not 100% sure of where my braking points were in reality. I know they were supposed to be around 15m before the turn, which when you're travelling at 100kph (my little Performance Box doing its thing), is half a second before the turn. In that time you have to brake, upshift to second, and begin the turn. Personally, I can't believe that's right, but I look at the video and it seems to be correct.

Mind you, I'm not stopping for the corner, so all I'm really doing is scrubbing off enough speed to make the corner. So for some of them it's probably just knocking off 20kph, as I can take some of these bends at 80kph.

The key difference was the time - I dropped 0.9 seconds from one run to the next, which is actually huge, and worth several places over four laps. Unfortunately, I forgot to set the video on this run.

Rounds 3 and 4 - well, pretty much the same, really. Just focusing in on braking points mainly.





Again, a lot of fun. Each time I get out of the car I'm shaking from the adrenaline, and I'm exhausted at the end of the day. I don't know how people do hours of racing.....

I'm going to have a look at the results from the Performance Box and see what my braking points are like - what speed to I drop to, where was I quicker etc. There may be some insights there, or perhaps just too much data for me to cope with.

Breaking stuff

It's always a good idea to go over the car the day before any sort of event, so that you can break all the things you would normally have broken when it really mattered.

Saturday was spent in the workshop, which is something I haven't done for a while. The idea originally was to just go over the car with a spanner and find anything that had worked it's way loose. It turned out to be a little more than that. Interestingly, whilst a lot got done on the car, very little of it was done by me....

First job of the day was the halfshafts - these are the bits that come out either side of the diff and go out to the wheels, and provide the drive to the rear. They weren't seated properly in the diff, which whilst wasn't a terrible thing, meant that the diff would throw a little oil out. This eventually would be a bad thing. So it was out with the tyre lever and a bit of leverage later, one was in. The other required removing the rear wheel, putting a long piece of wood against the CV joint, and whacking it as hard as possible with a hammer to get it seated in. Now both are clipped into the diff. This has also made the speedo a little more reliable - the speedo works off a hall sensor that 'reads' the number of bolt heads that go past it in a second. These are now closer to the sensor, so that it gets fewer false readings. So I no longer do 80kph sitting at a red light....

One of the characteristics of my car has always been a heavy clutch, heavy accelerator, and a sticky gearshift. I've always just taken this as part of the car, but apparently, these are bad things ;-) It got to the point where someone was testing out the accelerator pedal - and broke the pedal. Yes, you had to press hard enough to bend a 4mm ali plate. This probably indicated a problem.

It was at this point that my car became cause celibre for others for the day. I had at least three people working on it, with me sort of spectating, as the entire throttle cable was removed and replace (somehow the outer sleeve had been damaged), and the link to the throttle bodies themselves was re-engineered. I have to say the change is dramatic - the pedal throw is longer by about 30%, but there's a massive reduction in effort required. Not that it was hard work, it's just that you can't control things as well when the pedal movement isn't progressive.

The other area was the gearbox. Ever since I've had it in the car, the movement has been really, really heavy. We put a short-throw lever on it which probably just made it worse. So Frank re-worked the gear lever, making the throw a little longer, which has again made it a lot easier. It's still some way off what it should be, and perhaps the next time I have the engine out, we'll take the gearbox apart and see what's what. Perhaps a selector fork is bent, or something is causing excess friction somewhere.

There's a list of tasks for me to get on with over the coming weeks - I'm down to part time again at work, so I'll have a few days to spare to focus on the car.

The things to do are:
1. Pack the gear lever forks with grease - hopefully this will make the throw easier still
2. Redo the diff mounting plate - the mounting bolts keep working loose. These need an allen key to tighten - but the mounting plate covers the bolt head. These are coming out and are getting replaced with hex heads, but it does mean taking some of the back end out
3. Sort out the engine bay - put in the engine breather tank to take oil off the top of the engine

And, of course, what-ever else turns up, as it seems to do every time I look at it ;-)

New Tyres, New Brakes

I had the car in the workshop yesterday, and did a few small tasks.

First up was to replace the rear brake pads - not because they needed it (1200km only), but because they weren't doing much. The compound in there was too hard, so gone with a Mintex racing pad to try and get them to contribute more to the braking effort. Might help with the locking of the fronts if the rear is helping to slow the car more.

I also found a few more loose things to tighten, which to those who know me will come as no surprise. The clunk from the rear (which I thought might be the rear sway bar) turned out to (probably) be the rear sway bar, as I hadn't done up a locknut. Wouldn't have caused a serious problem, but nice to have it squared away. Also retorqued some of the diff mounts, checked over the suspension bolts, and noticed an oil leak from the diff.....

It seems that the half-shafts aren't sealing into the diff, so there some small weeping going on from where the shafts enter the diff. I've cleaned it up, and as soon as the car is down again I may look at topping the diff up.

The gearbox is also weeping oil again, probably from the top plate. I'll keep it topped up as well, then when the engine is out next I'll have to redo the seal on that. Just another step in the process of improving the car incrementally....

The wheels are off to the tyre guy today to have their new rubber fitted, so I'll have the car back on the road this Saturday. I'll be heading up to Barbagallo to see everyone else tear around the track, but I've missed out this time.

Another Green Birkin in Perth

Yup, another Birkin is on its way over from the east (something of a pattern lately), and this one is Damien Glass' car, which is where I got the idea for hothouse green.

As you can see, this one comes with the full wet-weather gear, certainly a first for the Perth market. I think it actually looks pretty good with the roof on. I'm also interested in seeing the doors, as I reckon a pair would be useful for running around the streets and freeways - might help preserve the ears from the wind a bit more.



The number of Birkin's in Perth is swelling by the month - we've had quite a few come from over east recently, and five under construction at the moment with a couple of those heading for rego either this year or early next. The Birkin grid is certainly filling up.

Perhaps a round-up of Perth Birkins is in order - would make a really good photo ;-)

Superkhana Results

The results for the weekend's run are in. I cam 14th out of 50, with that little spin knocking me out of the top 10 once more, dammit.

Lap times were:
Round 1 44.78
Round 2 56.31
Round 3 44.85
Round 4 44.4
Total 190.34

So ignoring the spin, times were getting better, and I still reckon there's a few tenths to be had just in my basic driving, let alone mechanical stuff like tyres and suspension. Lots to aim for next year.

Results etc can be found here:
http://www.classicrally.com.au/Speed%20Dome%20Day.htm

Next year's calendar is out as well, with 6 superkhana's planned, plus perhaps a fwe one-day specials as well. Should be fun ;-)

Vale Tyres

I think I need new tyres. At least, that's my latest excuse.


Anyway, this weekend was the Last Blast Superkhana, again organised by AEM and run at the Midland Speed Dome in the carpark. The circuit was the same as one of the rounds in the one-day challenge, so we could get some comparison times.


The circuit itself is pretty good - for me, it's mostly first gear still. There are only a few tricky points with this one, including a sharp left right which, as you'll see in the first video, caught me out.


So, Round 1 went fine, usual sort of testing run to make sure everything is OK. The surface was reported to be quite slippery, which it was. I think the pines were shedding a lot of needles, and these were creating a lot of dust which needed to be swept off by the front runners. Unfortunately, once more the video decided not to play ball and start, so Round 1 was missed for the cameras.


Round 2 was a different story - I got the camera working early, and I've managed to capture a small mishap for posterity, which I shall share with y'all. Coming into the left / right turn, I've somehow managed to completely understeer off the road - whether this was old and cold tyres, a bit of sand on the road where others had cut the corner, or just the car not being setup right, I somehow manage to understeer off at around 20kph, then lose it when I hit the grass. Cost around 12 seconds all up. No damage (which is one of the nice things with this circuit), just a bit annoying.





To be honest the car was pushing wide all day - you'll note from the first long left-hander I'm having trouble putting power down without the car pushing wide. As Gary and Frank pointed out afterwards, I should have backed off at that point, straightened up, then put my foot down, as going wide here cost a few tenths. The understeer at the bottom corner (sharp right-hander) occured under brakes this time - my fault. I know better than to do that now.


Round 3 was again a problem for the camera, but it was a neat run with no excitement. I think I ran around a 44.7 or thereabouts.


Round 4 was captured, which was good as it was my best run for the day. Still taking the sweeping left-hander wide, but I took the left/right a lot better this time.





I note that I'm still treating the corner with the tree with too much respect, but with the car understeering like it is, perhaps that's wise at this stage.

Ultimately, I think I do need new tyres. The ones on at the moment are three years old now, which is ancient for a soft compound. Looking at the surface of the tyre, they're shredding quite badly, even if there's some tread left. As luck would have it, Frank rang this morning, and he has some Kuhmo V70 195/50R15 in a medium compound that are looking for an owner. They're a bit of a compromise - a full soft compound would be better for most things I do, but probably won't last the year, whereas the mediums will. In addition, if I do decide to do a few hundred kays just for fun on the roads, I won't be feeling guilty for shredding race tyres. But reading the various forums, these tyres seem to be pretty popular.


So one day after deciding I need some new tyres, four new tyres turn up. Nice. Now I just need to completely shred the tyres I have now, and get the new ones on for next year's events.