Race Day 05-08-2012

Its been a while since I've done "serious" racing. I've done most of my racing at a club that's very new and while we get a far bit of track time, it's all pretty laid back and no overly serious. I decided it was time to gauge where I was with my car setup etc.

WCMRC are the other outdoor club in Perth racing F1 so I decided to make the 45km trip. Its a track that's been around a fair while, starting as a nitro track before houses started to encroach on it. The electric club took it over in 2010 and have been getting it back up to a top quality facility, hosting the Australian Titles in 2011. The club offers most current electric classes but on the day it was F1, VTA, Mini, Modified and 1/8 Electric. I had intended to run only F1 but due to lack of numbers I offered to run Mini as well. This stretched my battery supply to the limit because I had decided in advance to not take my charging gear with me.

The Track

Built in the late 80's, it doesn't appear the surface has ever changed much. The electric club appears to have resorted to using "tennis court" paint to revitalise the surface and increase the grip level. This is quite common around tracks in Australia that have the money to do so. The only real downside I've observed is that, if it rains, it can take quite a while to dry. The track also has quite a bit of elevation change.

Practice

After setting up I quickly hit the track for some practice. Now we have to remember I've done most of my recent running on a fairly low grip track, so it was almost a shock to feel the amount of grip available. Thankfully the base setup I have been working on proved workable from the start and I could focus on learning the track for the first run. 2nd run was more learning but I was playing with radio settings to increase my steering rate and reduce brakes. I didn't feel there was much point in changing any car settings until I had a comparison against other cars.

Heat 1

The club uses staggered start qualifying so its all against the clock. I made a dreadful start and ended up off the track. The grip level and my diff settings weren't quite in sync (this carried on all day to be honest) but once back on the track I was able to run competitive laps times, working myself back to 3rd qualifier for that heat. Compared to the regular runners I could see a couple of places I was losing time to them. Most obvious was the S section after the banked first corner around until the entry to the back straight. Through this section the car was slow to change direction through the S section and then it under-steered through the next section onto the back straight. I realised watching other races that the under-steer was, in part, due to the line I was taking, but the rest was all car set-up.

Heat 2

I tend to find running more than one car drastically affects the amount of time I can devote to car set up. I tend to resort to simple and obvious changes, which can sometimes make too drastic a change. In this case the simplest and most obvious change to the car which was a change of front tyre compound. I changed from Shizimu F1 to F3, however this totally destroyed the balance at low speed. Reducing the steering rate made a slight improvement but I decided after a half dozen laps to pull in and make sure I didn't cause an incident by spinning out in front of someone else. Annoyingly I set my fastest single lap of the day with this set up but it wasn't drivable over a race distance.

Final 1

I qualified 4th overall despite dropping out of 2nd heat. Finals were normal grid starts. For the first final I had returned to the original tyre combination but made a castor change. Wrongly as it turned out. This was also the first time I had a really good indication of just how much my diff was slipping, as I was barely able to hold onto 4th as the race started. The race was pretty uneventful which wasn't really surprising as I was still learning the best lines around the track. The car was still slow to transition but was a little improved as far as under-steer was concerned though I think this was more because of my cranking up of the dual rate on the steering again.

Final 2

The only change I made was to tighten the diff a little but at the start it still slipped far to much. This race was a little slower over all but I couldn't pinpoint any one reason. I hadn't made any significant changes so I wasn't expecting much, but I did manage a 3rd place.

Final 3

A quick inspection turned up a very gritty diff so any other changes were forgotten to do a diff rebuild. One thing about racing in WA is the sand. Everything is built on sand and it tends to get into everything. I'm using a 3Racing out-tuned diff and this uses a similar thrust bearing combination as the F104 "Pro" diff, except it uses an alloy spacer instead of thrust washers. In practice I am suspecting this reduces bearing life and I think in this occurrence this was the problem. I didn't have a replacement so rebuilding the rest of the diff made little improvement.

I had a good first lap but that was followed by 2 dreadful laps and that put pay to any decent result. Luckily everyone seemed to be having an off race so I came back to 4th by race end. It was interesting to note that even the cars that didn't have any real problems were a lap slower than early in the day. I think the track was getting slicker as the track became more shaded. 

Overall I think it was a pretty good day considering it was my first racing visit. The biggest surprise or realistation was how little grip my "home" track has in comparison and also how much better race days etc could be organised. I am not sure if I will get the chance to race there again as my partner has accepted a job which will mean moving back to the east coast, but if I do get a chance I definitely have some setup directions to try.

Front Suspension

The good ol' f103 front end definitely has its fans and its worked pretty well for many years. There are a few variations on the theme, such as the one that comes with the F109, but not everyone considers them improvements.

The main disadvantage with the original F103 front suspension is lack of adjustment. While this ensures strength (which is obviously a good thing), serious racers tend to want a bit more of all the technical bits in search of that last 10th of a second. The F109 achieves some of this with the supplied front end allowing castor and camber adjustments, but the downside is the original plastics are soft or prone to easy breakage. There are some alloy hop-ups but these have their own issues and also seem to be getting harder to get.

Doing some reading online, I came across and American F1 blogger who makes up his own version of an Exotec F104 front end but wider to suit the 200mm width. It's actually VERY simple to make and most bits are probably in a serious racers spares box already. 

Minimum you will need - 

* F104 front suspension mount (plastic or alloy)

* 5mm ball ends

* 5mm ball studs

* 45mm turnbuckles (I used 42mm because I had them but longer would be better)

* original 3Racing upper ball mounts 

* Xpress Alloy upper arm joint set - part of their 1/10 4WD Mini. The plastic versions seem to be almost non-existent, but the alloy ones are still around in online shops etc, and they are cheap enough.

Ignore the big orange thing - its just a bumper

 I still use the original version though the the "creator" has since switched to a slightly different version which he says offers some advantages in ease of set-up. I didn't have any turnbuckles long enough but I also wanted to just test the concept. It takes a bit of fiddling to get it exactly right, as well as a bit of modifying. For example the original writer says that the F104 suspension mount fits straight on top of the F109 lower suspension, but I found that it needed about 3mm ground off one end to allow it to fit as the lower mount is "stepped" around the mounting holes.

Its surprisingly slop-free for a suspension with so many ball ends, but it seems to have less movement that the original 3Racing front end. It is totally different to adjust though as the rear turnbuckle affects camber and the front affects castor, but they also both affect each other so adjusting one changes the other (this is one area the newer version is supposed to be better). It is a little frustrating at first until you work out in which direction each one affects the other, but once that issue is sorted it comes together quite well.

I fitted this to my F109 that I use with a Le Mans body so its not directly comparable to my straight F1, but as both chassis did have a similar basic setup (castor, camber, springs) when I first started with them, I feel I can use the feedback with a fair bit of confidence. So far the LM hasn't seen as much track time as the F1, but this setup does seem to induce a little more high speed under-steer in the car but at the same time the car feels more stable throwing it into corners. Given that I use a 10T brushless set-up in the LM compared to a 17.5 in the F1, this is a actually good change, but since I use a higher down-force LM style body the induced under-steer is a bit puzzling, but I am sure with a bit more track time I can get on top of it

The original version of this suspension is here

Its all in the springs

The single largest area that needs work on a standard F109 is the side springs. It is also the area that seems to be the most contradictory when reading online information. Some seem to get the car to handle fine using the standard kit or option springs and others need to make serious modifications. The only pattern I can find to this is that most of the people making the standard springs work appear to run foams on carpet.

My view (and I've discussed this with others and they agree) is that the original side springs are simply too soft to support the pod when turning under power. The springs "collapse" for want of a better word. They are also too soft to make the pod return to center when rolling from side to side. This makes the car react as if it is tweaked and causes the car to spin out far to easily. I was able to use the hardest option spring and a bunch of shims to put a lot of tension on the springs when I started looking for a solution but in the end I knew I had to find different springs.

Most seem to do the CRC spring mod.

However, CRC parts are not the easiest to source for me as ordering from the U.S tends to be quite expensive if you want any form of express freight, and not ordering express can lead to waiting for months for an order to arrive. I was able to source Associated springs more easily, though this meant I had to devise my own mounting system. Unfortunately I didn't take any pictures at the time but its turned out to be quite simple involving 2 5mm ball studs and small amount of cutting to the original spring seats. This allows me to also adjust pre-tension and therefore tweak. It also doesn't require any modifications to items such as the upper chassis pivots.

I decided to go straight for the 6.25lbs springs which is the hardest spring Associated make for their 12R cars. This may have been a bit over over-kill as even the 5lbs spring is considerable harder than even the hardest of the 3Racing springs. However on-track performance is what counted and the hardest springs had worked thus far.