Part 7

After a rough last meeting we are back in the garage working on the car to get it ready for the August 5^th meeting. I came away with 2 major problems with the car from the June 24^th meeting. The first was the engine and the second was the general handling of the car.

The engine problem was basically a lack of power when changing gear. After some consultation with my local bike shop we decided that the problem was probably caused by excessive heat in the engine bay. The Radicals engine bay is completely enclosed apart from the airbox tunnel. Add the hot air that is being passed through both radiators we have one very hot engine bay area. Theory is that the hot air was causing the fuel to evaporate between gear changes thus causing the engine hesitate when applying the throttle after the gear change. To combat this problem we are doing a few things. The fist is to strip down the carburettors completely and give them a good service and clean to make sure there is no old fuel residue in the jets etc that could lead to fuelling problems. Joe at Hammonds Motorcycles has been given this exciting task. The next thing to do is to try and vent some of the hot air out of the engine bay. The newer Radical rear sections have vents around the air intake tunnel but my older car doesn’t have this. So out with the hole cutters and I perform some surgery on the fibreglass creating some holes directly above the engine. The faster air travelling over the bodywork should draw the warm air out of the engine bay – well that’s the theory. On the race day we did notice that the fibreglass was starting to bubble, bubbles the size of a golf ball, above the exhaust. To help with airflow around this area I have added holes above the exhaust on the back of the air intake tunnel and at the back of the car where the gurney flap used to be. Last but not least there is a water pipe that runs between the block and the carburettors, I’ve wrapped this in insulating material to try and reduce heat soak from this pipe into the carbs. Fingers crossed all these mods will work when we are next out, a lot of this is pure theory so we won’t know if it works until we are back on track. Last job on the engine is to give it a full service, oil, tappets and carbs balanced so it’ll be fighting fit.

The handling problem is a strange one as we hadn’t made any changes to the car since the last dry meeting yet the car just wasn’t working properly over the bumps. It looks like a lot of this was down to us making a mistake with tyre pressures. We’ve not tested in the type of heat that we experienced on the race day so we had to rely on past experience, which in this instance wasn’t accurate enough. I had a chat with Brian Davies from Avon it looks like we were running the tyres to hot which would have reduced grip and caused the tyres to skip rather than grip. With the car in the garage I went over the car’s suspension to see if there was anything obvious. The first thing that stood out was my old hubs had given up again so the OSF and NSR wheels had about a millimetre of play in them, this wouldn’t have helped. After a lot of hunting around for an alternative supplier for the hubs I’ve turned up blanks everywhere, so I have bought a new set from Radical. Not cheap but they needed doing and hopefully these will last a few seasons now. Another odd thing was the spring seat on the shocks had moved, I am still a bit puzzled how this has happen but I am now going to add this as a item to check for the pre-race check list. When I running the Elise I was using is everyday so problems like moving suspension, bad handling etc would have made themselves know before the even. With these race cars we have to get into the habbit of checking everything before each outing, all part of the learning curve.

At the start of the season I set a target lap time of 1:11 before I was allowed to make any aerodynamic modifications to the car. That way I know I have got the best I can from the car before I start making dramatic changes to it. Last meeting I got my time down to a 1:12.06 and that is pretty dam close to a 1:11 lap so we are going to make the changes before the next meeting. There are three major elements to increasing the aerodynamics to the car. The first is installing a rear wing, the second is installing dive plans on the front of the car and the thirds is increasing the spring rates. I’ve found a small company in Wales that supplies all sorts of carbon fibre and glass fibre parts for the Radical which has made things a bit cheaper. I purchased one of their carbon rear wings and a larger front splitter (partly because the last splitter was broken at the last meeting). The rear wing sits on a wing frame that bolts to the underside of the bodywork which inturn sits on a new rear subframe. The wing frame and subframe I had to purchase from Radical. Fitting the wing frame was a nerve racking experience as we had to take a jigsaw to the bodywork. With lots of careful measuring and a little bit of luck we got the holes in the right place and the frame was bolted to the rear bodywork. However in true handmade style we had to fettle it to get it all to fit properly. The subframe was a direct swap for the existing one so that only took a matter of minutes to fit. The rear wing had generic mounts on it so these had to be drilled to suit the Radical wing frame. Neil Cox from Corium Motorsport did this for me as the risk of cocking it up was way to high for me to do. With everything in place the wing was fitted to the car and it looks great. Of course adding downforce to the back of the car is great but what about the front? at the moment the car will wheelie everywhere, not great for cornering it has to be said. This is where the dive planes come in, these are fitted above the front splitter and increase the front surface area of the car and thus help push the front of the car into the tarmac. This are simply bolted to the front so that was a relatively simple job. The final thing is to change the spring rates. Looking at what we are currently running on the car and what Radical recommend we take a educated guess on the new springs. We bought the new springs from Merlin and they are happy for us to swap them if they don’t work, a nice touch I thought. While working out the spring rates I was reading a Radical internet forums is based in the USA, these guys are pretty handy for bouncing ideas off as most of them have been there/done that. I’ve never been a great fan of the Nik-Link suspension on the front of my car and as luck would have it one of the American guys mentioned that he removed his and upped the front spring rate to compensate. I thought this sounded like a great idea, it would hopefully remove the odd preloading feeling you get with the Nik-Link which would make me a lot happier. Of course if I am removing a ARB I need to up the springs again to compensate for the missing bar. This calculation was also thrown into the mix when selecting the springs. Until we get the car out on track we are not going to know if we have made the right decision, but with Merlin on site we can swap springs around until we find the right ones.

So now the car is ready to go, it looks quite smart with its new wings and dive planes, there is still a list of "nice to do" things but I think we have enough to keep up busy just at the moment. I have to say a special thanks to Justin again for his help over the past month, I don’t think I would have got it done with out his help. The test day is on the 3^rd August so fingers crossed the weather holds and we have a productive day.