So, after my quickest car build (phew) Matt arrived early to tow us to Bruntingthorpe, where the Dax had had its first track outing. We piled all the stuff in the car and pushed the car onto the trailer and we were off. Once there I went to the obligatory drivers' briefing (why don't they just say what they need to say and cut the woffle?). As I was standing listening I remembered something I'd forgotten, in that I had never fitted the mirrors!
Rats!
However, Matt noticed another cam7er there, in the person of Simon Parker in his Caterham. Matt blagged a loan of his passenger side mirror and we tiewrapped it to the roll cage which was at least better than nothing.
Finally, we set off on the first lap with Matt in the passenger seat. As you
can see he's rather shorter than me! He's an experienced race driver and I know from previous outings that he's
way quicker than me so it would be interesting to see what he said later.
After a couple of fairly slow laps we came in. As I was driving in there was a lot of smoke coming from the passenger side sidepod. On investigation the exhaust can was much too close to the GRP (not done that very cleverly...:-( ) and was essentially going to set it alight eventually.
I clearly needed to do something about this and so I blagged a hacksaw from
someone and made a big hole in the sidepod, as several other racers do anyway.
This had the effect of cooling things down a bit but I clearly need to do rather more later.
What's more, after a further outing the rubber mounting bobbin came to bits, but this time we just tied it up with some cable round the roll cage. Many thanks to Andy, another of Matt's grads racing mates, for his help.
I already knew that I needed to re-address the exhaust can mounting to this is just going to accelerate things. I probably ought to make it easier to take the sidepod off, as the roll cage mountings go through the top and make it rather difficult at the moment. (After my smugness about using rivnuts to make it easier!)
However, driving the car was a hoot! It seemed very quick and was limited mainly
by my inadequacies. I found that most of the time I had no idea what gear I was in and the level of grip from the
tyres seems to be such that I was nowhere near (I think) the point at which they were going to let go. Once they
do I've no idea how progressive it's going to be, or whether I'll just end up in the weeds.
I just need a lot, lot more time on the track.
I also need to finish the car. To that end I've updated the to-do list here, with some finer grained items. All the people who looked at this list and didn't tell me that "fit mirrors" was not there are to see me after class.
After the excitements of the trackday, I've had a couple of days off major fettling. However, I need to get back on top of the to-do list.
First thing, though, was to clean various bits of the car. The front wheels
had a lot of brake dust on them. No big surprise there then! I really didn't think much about the brakes on the
track (actually, there's lots of things I didn't think about). Next time, I'll have to be rather harder on them.
I did notice a largish dent in the floor of the car. Presumably something bounced up under the car at some point and whacked it. Surprising that we didn't notice it though.
I'd also had a bit of a problem at the weekend with some of the studs and nuts on the front wheels. Hence, I spent a while tidying up the threads. I actually replaced one stud entirely that had got rather unpleasantly badgered. Luckily I had some spare studs from some previous project or other.
Conversation with other people has told me that the flat spots in the engine (as detected
at the weekend) were almost certainly the consequence of not fitting the Dynojet kit yet. So, I set to to do that.
There's really three parts to it:
- A larger main jet. (Actually, the kit includes some even larger ones too.)
- A different needle and spring
- A modification that blocks up the air corrector.
Although a bit fiddly, the first two of these were pretty easy to do. I've left the final one for another day. On the right is the view inside the float chamber with the jets at the bottom. The main jet is the one in the middle.
I finished doing the Dynojet conversion. The other bit was the trickiest as you have to
drill out one of the air correctors and block it up with a tiny brass plug which I was sure I was going to lose
and send skittering about the garage.
However, eventually it was done and all back on the car. The photo here shows the blocked up corrector.
After that I started the car agani and at least it still ran. I can't really see what it's doing until I get it on a track again though.
As part of the getting ever closer to racing process, I went and picked up our trailer today. The trailer
is essentially the smallest size I could get away with and, as such, it fits in the garage. Not without, of course,
removing a lot of space. The car can mostly stay on the trailer but it's bound to want to come off at some point.
So, after larking about on the drive, I pushed everything back into the garage and got
on with things. Having done some other stuff it was time to get the left sidepod off and see what had happened
as a result of the overheating.
Actually everything looked fine apart from this which is the exhaust bobbin that failed. It looks pretty clearly to have failed as a result of overheating. One of the bolt components has completely, and clearnly, separated from the main body of the rubber component.
Still, at least I could get the sidepod off with the car still on the trailer.
It's kind of a fiddle but it is possible.
Not much time today, so I carried on with the sidepod. Firstly, I re-supported
the exhaust again. After much thought I decided to just do it the same way again, hoping that increased airflow
through the sidepod would keep things cooler. However, I remade the bracketry, taking particular care to ensure
that there was no static load on the rubber bobbin.
I cleaned up the horribly rough holes that I cut in the sidepod at the weekend. If I had the time I might clean up the holes by putting some sort of aluminium trim around them. Hoever, for now it will do.
I also cut even more ventilation holes in the sidepod itself, to the point that I sort of wonder how it can possibly all hold together. This is a bit of a problem really as the sidepod is a fundamental part of the support mechanism for the rear tub. However, only time will tell and so I re-attached it to the car properly
Also today, eeeeekkkk, I send in a race entry form for a race at Brands Hatch
at the end of this month. I'm very uncertain about everything that happens at a race meeting (on the paddock side
of things anyway) so I'm a bit in the dark really. I'm also concerned that I know nothing about the Brands Hatch
circuit. There's quite likely a test day before the race itself but I'm not sure that I've got the time/money to
spend it there. It might be that using the time to get the car ready rather than finding out loads about the circuit
is the right thing to do.
All the same, as celebration of all this I stuck the first race sticker on the car. This one tells the poor unfortunates around me that I'm novice and likely to lurch into their path at a moment's notice!
I had an email chat to Gordon Griffiin today and he reckoned that the rubber
exhaust bobbin was just guaranteed to go again. So, I resolved to do something different. I did wonder about just
hard bolting it to the chassis but eventually decided to make this device. This is basically two M8 bolts, two
penny washers and an old Rover V8 valve spring all welded together to make a bouncy support for the exhaust that
doesn't use any rubber at all.
That was very easily fitted in place of the rubber bobbin. (After taking the
side pod off again.) First impressions are that it works rather well like this, but the proof of the pudding
will come rather later.
Next thing was to look at raising the rear bodywork slightly. This was done
by rivetting some extensions to the supports at the rear of the rear tub. The version in the photo here is the
first one, I cut 20mm off it before I was happy(er) with the fit. Whether the 15mm of height increase works will
have to wait until the car's been running again.
I also want to make some slightly wider supports for the side of the rest of the tub. However, it's a real fiddle and very boring...
Well, it is indeed boring!
However, as a bit of light relief I started today by attaching the rain light. I put the wiring (and the current limiting resistor) in some time ago. So, I just made a bracket out of 1.5mm aluminium that just wraps around the roll cage.
However, after that it was back to the rear tub. I made a couple of bits of aluminium "angle" that could be bolted to the rear upright section and which would support the rear tub properly.
The intention was to put some bungy foam on them to make things creak a little less. I
bolted these onto the car using some slotted holes in the angles. This meant that I could nearly tighten things
up and then just lean on the tub until it was all snug and in the right place.
That was the theory at least, and it did seem to work out in practise.
You can see one of the supports in this photo, albeit taken before I put the foam in place.
I also decided to use some spare bonnet clips to hold the rear tub down should it decide it would prefer to fly. You can see the mounting bracket for one of these at the left of the photo.
With the tub and clips in place it looks like this. Of course, this makes the fact the
fuel tank is inaccesssible even more obviously silly. I'll have to cut some sort of big hole tomorrow.
I'll also make a couple of of the foam-asssited supports and fit them at the side of the tub. With any luck I'll declare work on the bodywork finished.
