You are either going as fast as you possibly can, or trying to stop as quickly as you can. There is no "cruise" mode in a race car. Because of this, everything in the car gets subjected to the outermost limits of their tolerance pretty much all the time.
It is said that if you ever want to find the weakness in your road car, stick it on the track for a couple of laps. Very soon the weakness will become known. This, I have witnessed first hand on many a track day, when seemingly robust and well conditioned cars end up disgorging their innards onto pit lane.
That said, we build our race cars to withstand the tortures of the life to which they are destined.
Although, recently I have been wondering about this. You will recall that I have been having a few issues with cracked front disks. This has now become a regular one-per-race scenario, with the last one presenting a fairly catastrophic failure that stopped just short of a piece actually breaking off the disk. You might be thinking at this stage that, surely, this is rather dangerous and just a little foolish. You would be correct on one account. Racing is a slightly foolish endeavour, especially for us amateurs. As to the danger, interestingly, all these disks have cracked after being abused. I actually heard one crack a couple of race days back while we were sitting in the holding area after our race. Granted, this scenario might well be different were we doing a three hour enduro, but for our sub-15 minute sprint, the disks actually hold up, until they start cooling down.
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| New extreme sport. How badly can you break stuff? |
Ok, so in defence of the disks, these are not exactly high performance racing components. More like off the shelf, cheapies that we slot ourselves. The reason is two fold. Firstly, I can buy ten of these for the price of a high performance race item, but, more importantly, these disks are from the Toyota Rav4, and not a whole lot of race equipment manufacturers make high performance parts for this particular run of the mill shopping trolly.
Anyway, we are going to be adding some brake cooling ducts soon to see if that helps. If not, we might have to look at changing the fronts for something that has a little more support in the performance market.
All of this is, naturally, due to the upgrades we did on the car a while back. Remember, we took a perfectly functional and reliable car and bolted on some go faster goodies. The knock on effect has been quite educational to say the least.
Another casualty of the increased power and torque was one of my rear half shafts. The half shaft is a particularly important part of the car in that it connects the output of the gear box to the rear wheels. Break one of these and you are effectively in walk-home mode. Which is precisely what happened on a Sunday drive some time back. Thankfully we were near home and a quick tow avoided embarrassment. The shafts I use need to be lengthened, which necessitates a sleeve being welded onto the shaft to join the two parts. Unfortunately, the act of welding on the shaft creates a point of high stress in the metal and this is where the shaft had sheared off.
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| Another entry in the Extreme Sport of Breaking Stuff |
Craig did a fine job of welding up the broken shaft, but I had this niggling feeling, driving to race day the following weekend, that I might be in for some more breakage.
And so it was. On lap three of the qualifying session, as I speared into turn one and snatched third gear, there was a thump-clatter-clatter sound that I had heard before. Sure enough, as I exited the corner and come on the power, nothing happened. I coasted to a stop on the inside of the corner and suffered the ignominy of being towed off the track for the first time ever.
Closer inspection confirmed my fears. I was fully expecting the same shaft to have broken again, but it was the other side one this time. The failure, however, was exactly the same, a clean break at the weld point.
This provided me with a bit of a dilemma. I would need to get the shaft repaired so that I could drive the car home again, but should I fix it and race on it? The chance of another weld giving up was pretty high, going on the current experience. However, it was a race day and we were there to race, so I decided to give it a go. The shaft was duly stripped off and handed over to Steve at Harp Motorsport, who set about making a new sleeve to join the two bits of shaft. While we were inspecting the damage we noticed a spiderweb of fine cracks in the remaining intact weld. It was only a matter of time before the shaft broke there too. Clearly they were being pushed way outside their comfort zone.
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| Track side repairs, a necessity in this game of racing |
The shaft repair took a little longer than anticipated and I ended up getting the car finished an running again just as the leaders of my race crossed the finish line. In retrospect it was probably just as well. Later inspection would show that the remaining weld on the shaft that had previously broken was also mimicking a spider web.
I slunk off home, smarting from the three most expensive laps of racing I had ever done.
Thankfully there are all manner of clever engineering folks around town, and within a week Craig had organised me a set of custom made drive shafts. The chap who made them would not tell us what he made them of, but assured us that we could enter the car in a drag race without any problem. Judging by the beefiness of these things, I tend to agree with him.
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| The old versus the new |
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| New beefy shaft ready to be fitted |
The new shafts were duly fitted, and not a moment too soon, as the next race day was looming awfully close on the horizon.
We had been treated to some of the best weather Cape Town had to offer over the week leading up to race day, so it was no surprise that rain was forecast for the actual race day. I arrived good an early, cleared documentation and managed to qualify well, but as we sat in the holding area before the race, the rain began to fall. A couple of slick shod cars pulled out and headed back to their pits. By the time we were waved onto the track it was well and truly wet. The race, if one could call it that, proceeded without major incident and was won by a Porsche followed by a string of other Porsches. I wonder if they have some kind of driver aids to deploy in these conditions....
As it usually happens, the weather cleared up straight after our race and everything dried out nicely. By the time our second race rolled around, everybody was back on slicks and ready to do proper battle.
I had drawn fourth on the grid and had a Lotus 7 and a pair of Porsche GT3's up front in class D. Behind me were a few more GT3's and Steve who was piloting the Harp Mazda MX5 Turbo for the day.
By the start of turn 4, on the first lap, I had been overtaken by a Porsche and Steve in the MX5. Now, the Porsche I could understand - it was an RS after all, but the MX5 was a little more difficult to stomach. That said, Steve is an old campaigner and can probably lap Killarney faster in a wheelbarrow than most of us in our race cars. Either way, I was not particularly happy with this position and decided to try for a bit of a comeback. This, while also keeping the remaining GT3 firmly behind me.
I quickly realised that I was much quicker on the straights than both the MX5 and the Lotus, and, it turned out, the GT3 behind me. This provided a bit of wiggle room, so the usual plan was hatched. Catch up on the back and front straight, hang on through the twisties and then pass coming out of turn 4 onto the back straight again. This would give me the front straight to make some headway and hopefully stave off an return challenges. Steve is, of course, a wily old bugger and made his MX pretty wide, but in the end there was no substitute for grunt and I watched him rapidly shrink in my mirror going down the back straight. Hennie in the Lotus suffered the same fate a lap or two later, and then it was all about staying ahead of the GT3. We had a great battle, as the GT3 was better under braking than me, but I was faster on the straights than him. In the end I managed to hold on to my position and finished the day with a fourth place in class D. I was the Harper fly in an otherwise all Porsche bottle of class D ointment.
I would like to say that everything had gone smoothly for the day, but sadly I have cracked yet another disk. Those cooling vents are now absolute top priority! Other than that, the car is going exceptionally well and is regularly clocking 22's.
With a new set of tyres and a bit more practice that ever elusive 21 should be making its eventual appearance.
The only problem I can foresee with achieving this goal, is that the next will be to crack a 20. Doing 20's around Killarney is pretty serious business and the air starts getting quite rarified up at that end. Knocking a second off a lap time when you are doing 27's is not that hard, but as the number shrinks, the effort required to knock time off exponentially increases.
But then, in the last 18 months we have managed to slice close on 4 seconds off the Type 6 lap times. All we need is another one. Just one.
I mean, really, how hard can it be?
