So this past weekend was the Queensland state titles... to say it was, at times, a perplexing weekend would be an understatement!
The main issue was that the track was super sensitive to temperature, with a only a few degrees of temperature difference causing a large change in balance and laptimes...
Anyway, made some progress during the weekend, and did manage to make progress forward to a more consistent balance.
Friday was practise, and the I basically started out with the car as the weekend before. Admitaly, I wasn't very happy with how it had been but needed to start somewhere, and also provide a reference for the changes I wan't to work through on my list!
As expected the car was the same as it had been in the previous week, being ok on entry, struggling to rotate mid-corner, and then pushing on exit. The worst bit was that if adding in a little more steering to overcome the exit push, it would step out.
Anyway, having had some discussions with Ryan Maker during the week, and looking at a lot of other cars, realised that the standard rear link setup on the car is quite short, as the inner hub position is well inside the wheel rim. This would have a big effect on the camber change on the car. Doing some bench testing and comparing the two link positions, it became pretty apparent that with the short link, there was a pretty non-linear camber gain, with a lot of change happening at the top of the suspension travel. With the long link, there wasn't as much change, but it was also a lot more linear change.
In theory, that should make the car a bit less sensitive in roll, and not 'dumping' the grip when at full travel.
So, the first change was to go with that. It was a definite improvement, the car becoming a lot more driveable off the corner. However, the exit push was still there, and the lack of rotation in the middle was hurting times a lot. With a couple of changes to the rear roll bar and rear shocks, this improved matters a lot. It did make me wonder that a lot of the settings I had been using were simply a compromise to try and rectify the issue with the link.
Next up, to try and help the rotation some more, I went back to the BD7 style motor mount with raised top-deck... and this is where I think my weekend fell apart a bit! For whatever reason, in that run it worked really well, freeing up the car on power again, so I decided to keep it on the car, which with the benefit of hindsight was a mistake... but I'll come back to that!
For the rest of Friday, I made some fairly sweeping changes to the car, but couldn't really get it how I wanted, so ended up back almost where I started, bar the above changes.
On the saturday, the car was good in the first two rounds of practise, on old tyres it worked well and I achieved my first sub 20s laps, getting down to a 19.88...and having droped to a 2.5 block on the rear. Again with hingsight, this was track morning happy hour, having had a number of runs, but without the heat having built up...
First round of qualy, car was sliding all over the place on new boots, the 2.5 block just not bitting enough. Managed to put in a consistent run (removing the two worst laps, was down at .19 split of fastest to average!), which was good enough for 8th overall, but had dropped a lot speed compared to practise. Car also felt like it was a bit soft, not really carrying too much corner speed.
For the second round, I put the 3.0 block back on, and switched to Ride Blues. An improvement for sure, as ducked back under the 20s laps, but it did feel like the car lost steering as well, compared to practise. Another 8th in round though
Third round, after much bugging, I switched full bore to Ryan's latest settings, with the single exception of keeping the Ride Blues (as they were faster than HPI silvers when backed to backed on a previous occasions, because of the bumps). This was a big change, including dropping the front blocks, changing the camber link height's, and switching to less rear toe as well.
Car did feel nice to drive on track, with a good balance... but looking at the times, I'd dropped 0.2's a lap, losing 4second over the run. Thanks to the joys of round by round, actually ended up couting it as a 6th though
Fourth round, I put a combination of settings on, going back to raised blocks, and a 3.0 rear block again, and it was also time for new tyres... and they were crap, sliding all over the track, and only coming in after about 3minutes of running. Still managed my 9th, but with lost over 12seconds compared to my best run of the day. Had effectively locked myself into the A, so could try a few more things with the settings now.
In the fifth qualifier, only changes I made was to lower the outer rear link 0.5mm, and also changing additive to CS from Tweak, trying to get it a little more stable... Additive for sure worked, but wasn't so convinced on the link change... But that was the day done, and mission accomplished (A-final), albeit with needing to find more speed if I wanted to move up the rankings.
Overnight, I sat down (in between drinking lots of rum and coke, and having a pizza box throwing contest) and had a contemplating/fiddling moment with the shocks, as for a little while I've been wanting to give the four hole pistons a crack, as they in theory should reduce the pack (initial resistance) in the shock, making them faster to react to bumps. On the bench, 4-450 felt similar in action to the 3-400 I had been running, but with much less initial friction to the movement. So I built up all the shocks with 4holes, and switched to 500f/450r oils to keep the spilt.
First run on sunday morning, and the car did feel good with that setup, riding over the bumps nicely, although also maybe feeling a little underdamped. Unfortunately an un-glued tyre resulted in me ending up in the wall, with a broken rear hub... only run I failed to finish all weekend
Laps times seemed ok, but really difficult to tell with the tyre the way it was.
So, onto the finals..I went out on four run old boots for the first final, figuring if they were that crap in the first run, might as well use the old ones first! First final was a bit of a crap fight, having a lot of slow early laps as battling close with people. Times were off where I wanted to be, so (with more hindsight!) new tyres would have been the better option, maybe...
Second final, new tyres it was... along with going back to the standard V2 motor mount setup, in anticipation of the being loose... which didn't happen! Went from doing 20.6's to 20.3's, even with a half broken wing following a 'incident' that made the car very loose in the high speed sweepers. 9th in that one, but with a genuine feeling of taking a step forward with the settings.
Last final, given how the car had been initially in the second, I wanted to give it a bit more steering and mid-corner, so lengthened the front wheelbase (2mm shim from 2.5), adjusted the ackerman to suit (1.5mm), and also dropped the front shocks back to 450. Car was more positive into the corner, and hugging better lines on the sweepers. Promptly put in my best run of the day, and was battling with guys I had consistently been 0.2's a lap off all day, also posting my fastest times of the day in a run where everyone else fell off. Felt very happy with that, and scored a 7th in the leg.
So overall, ended up 9th... but the big picture of the nationals in November at the same track is the target, and I now have a much clearer idea of where to go on settings, and some thing to avoid.
Some further thoughts....
V1/V2 combo mount - This does make the car looser on-power. For high traction tracks, this probably isn't too bad, and even low traction in stock classes I reckon it'll work well... but for mod, low traction, nah. Just makes the car too nervous on the throttle, and need to be very smooth.
Shocks - For me, 4hole pistons are a good option if it's bumpy. Only minor flaw I've seen is that one of the plastic pistons was catching the damper wall slightly. A bit of light sanding solved that, but the machined pistons are on their way already. Heavier oils I am going to try as well.
Chassis flex - Talking to some of the other racers after the meet, appears that the guy who dominated with an Xray, was running a 2.5mm chassis, and getting much heavier springs to work (pink/silver). When I've tried them before, the car has been slower, and not steered as much... however, that's with the 2.25mm and flexi top deck. I've got a 2.0mm top-deck, and a 2.5mm chassis here to try... so one of my cars is going to be re-built in this combo, along with a top deck "tweak" that I need to do.
Other wise, still very happy with the car. It had been a pretty painful few weeks, struggling with the car, and the track, but progress is being made... and the durability is still very good
As a side note, had the second fastest car down the straight, clocked at 91kmh on the speed gun.
Ed