Practice 11: best laps and breakages

The second of back-to-back Saturdays. Once again I found myself awake in the early hours, brain totally engaged thinking about the day. Having found the benefits of an early arrival (i.e. plenty of time to get ready for the first session without rushing) to my liking last week, we arrived an hour before the track opened. Unlike last week however, I hadn’t really been able to do as much of the preparation at home the night before owing to the poor weather (the garage has insufficient space to actually work in it and the lighting is awful) so the tyres (a fairly decent ‘new’ used set bought from the forums some time ago) hadn’t been inflated, I hadn’t gotten the new carb gaskets fitted, nor check everything over properly after I had stripped the back end down to dry it last week. The preparation hour was a bit of a rush; I put the new 3l fuel tank on, corrected the kind of mistakes you make when working in the dark (i.e. a front wheel with three wheel nuts but only two bolts used!) and got everything set. We were on the grid when the cadets came off at 10:10.

Our first problem of the day: the kart wouldn’t fire. I gave it a couple of aborted push start attempts but there wasn’t even the hint of it starting. I took it back to the pits and checked the ignition box wire connectors were ok and then checked the spark plug and found that we were not getting a spark. I whipped out the new plug that I had bought in the week for just this purpose and things looked more promising. Hastily, I tossed the old plug in the bin and we went for another attempt at getting on track. Once again the kart is showing no signs of starting so back to the pits again – it seemed the sparking was intermittent. I had used my only spare HT lead at a recent practice at Dunks. Good job that Clay has a shop… only the shop didn’t have one! Fortunately, I was able to borrow one (from my good friend also known as KartingDad’s Karting Dad!), swap the lead over and get the kart starting reliably on the stand and running fine (shame about the plug I threw in the bin full of wasps but never mind).

Junior was on the grid for the start of the second session but only managed three laps before coming in to complain about his brakes. I could see that one pad was rubbing the disc engine-side and there was quite a gap brake-side but assumed, as he had been running ok, that it I could just adjust it at the end of the session. He did another 15 laps but with a slow best time of 39.3s and still complaining about the brake. Back in the pits, I was surprised to see the brake-side pad was rubbing the disc and the gap was now engine-side. If you are thinking “grub screws”, you would be correct: the grub screws had abandoned ship! Pleasingly, I figured that one out straight away too. Disappointingly, this was a mechanic error – I wasn’t overly tightening the grub screws knowing grub screw damage can severely weaken an axle. I have to admit that I hadn’t checked the grub screws at the start of the day so it could well have been that I hadn’t tightened them enough (even for my liking) after refitting the axle. Everything else was still aligned and looking good so it was just the grub screws required – you’d think these would be in stock wouldn’t you? As far as shop stock went, today wasn’t my lucky day so they gave me the only one they had. Having lost a couple at home recently, I only had one spare and my Karting Dad had one also. Cue wandering around the pits trying to buy spares! I managed to get some but it wrote off the remainder of the morning with only 18 laps under our belt and a best (and faulty brake affected) time of 39.1s.

The third session was more like it: 23 laps with a best of 36.6 and lots of time still evident in Junior’s lines. The fourth was better again: running with the camera on-board for first time of the day, Junior managed a 36.5s before the camera mount snapped :S See if you can spot the moment in my YouTube video. I am not convinced this punt on the camera is working – the camera itself is fine but the case and mounts haven’t looked up to the massive vibration that karting poses. For this session we were also running with the MyTach GPS watch. I’ve still not really read up on this but the watch gives you top speed readings and we were looking to test sprocket sizes. Running a 78 sprocket (what we had always run at Clay although I know the quicker guys run a fair bit smaller), we did a fastest lap of 36.57 with a top speed of 64.6mph (ironically analysis at home showed this was not on the fastest lap, which included a top speed of 60.8mph). With our problems seemingly behind us, we switched to a 76 sprocket and ran the GPS again. This time Junior put in a 36.42, the top speed on that lap was 63.8mph and his maximum speed during the session was 64.7mph. Not much in it, I am sure you will agree – I put this down to inconsistency, particularly out of the Top Bend but there was some interesting data in there: he was 3mph quicker down the straight into The Hairpin on the smaller sprocket.

The track then seemed to cool a little and I think my not increasing the tyre pressures a fraction may have cost us a few tenths as we drifted in the 36.6/36.7s laps before we encountered our biggest problem of the day: Junior had been holding up a couple of RotaxMax’s for a few laps and ran wide at The Horseshoe, matey decided to stick his nose up on the outside and, as Junior moved wider to get a line for the bend, they hit – flicking our back end up and causing Junior to run onto the grass. He rejoined the track and ran for another 8 laps. I was very surprised when he came in and I took the chainguard off – the chain looked blackened and dry (it had been freshly lubed) and was missing a few chunks, then I noticed the teeth on the rear sprocket (a brand, spanking new one that day) were wrecked which lead me to a front sprocket with some nice sharp spurs! At this point I needed KartingDad’s Karting Dad (again) as I had no idea how to remove a front sprocket and have learnt I need to buy some new tools :S With hindsight, either of two changes I made during the day may have contributed to this: I removed the sprocket protectors after deciding to use 6 sprocket bolts instead of three (it looked like the front sprocket alignment was a little uneven as the rear sprocket was rotated so I add the extra bolts in case this was the cause and the protectors have three warped holes that no longer easily facilitate the extra bolts) and the chain was running a little looser than I normally have it (on advice!). We went back to the 78 sprocket (now my smallest), a 110  chain (also now my smallest) and fitted a spare front sprocket (thanks again, spares :)).

The track was quieter now and Junior spent the last couple of sessions racing his friends. His lines through the afternoon had really come on – a screech and a lift entering Billies always looks good, taking The Esses with a decent amount of kerb was becoming more of the norm and, although his exit from The Hairpin was still a little tight and he had acquired a new, slower line through The Horseshoe, he was carrying [a little] more speed into and out of the Top Bend. New PB!!! 36.11 🙂 Racing was obviously paying off. For the final session of the day, he spent a few laps following the South West Junior TKM champion 😉 until said champion decided he had enough and wanted to put Junior in his place. Junior didn’t mind though, he was chuffed to bits with another new PB – 36.06s.

So we got off to the worst possible start, endured a pretty expensive day, breakage wise but ended up clocking 166 laps and Junior making further progress.He is definitely quick enough to race. I have no lofty goals/dreams about exactly how competitive he will be, it would be nice to be close enough to the pack to race someone but I doubt that will be the case initially. Whether I am ready to race is another question. I am still making mistakes but I think that is just human nature – I’ll make more than most mechanics, I just need to make sure I learn from them! The troubleshooting is a worry as, if things go wrong, there is no second engine to pull out the trailer, nor is there likely to be for some time. We’re just going to have to see how we get on 🙂

Cost of day: £12 petrol, £7 fuel for the kart, £35 practice fee, £5 grub screws

Cost of replacement stuff: £10 ‘new’ chainguard from eBay, £100 new spark plug cap/spark plug/HT lead/6 grub screws/10-tooth front sprocket/Talon size 76 rear sprocket/Panther (I know I could have spent less but I am keen to see if it is stronger and longer lasting) 108 link chain (from Kart Parts UK/Spellfame)

Total spent so far: £3,396

I plan to limit outgoings to race weekends and associated running costs/repairs only for the remainder of the year so kick me if you see me post about new bits and pieces!