Goodwood Gearing

As you may know from most of the posts I have added this season not only here but also on the GDS Racing page, gearing and therefore pace on the track has been bothering me at pretty much every race! When I thought I was onto a good ratio the batteries wouldn't last and when they would last the car was just too slow. But thanks to some help from the team at RLR I have been able to see where I am going wrong.

The issue was simply having the gears set too high to allow the motor to rev at around 2000rpm. Over the course of 1 set of batteries at Merryfield the average rpm was under 1000 at a ratio of 3.2:1. Then with the wise words of RLR ringing in my ears, that the planned ratio of 3.7:1 for Castle Combe was still to high so a quick drop to 4:1 (the max we could drop it with the gears available) seen over the same 1 battery set the rpm rise to over 1300.

So its seems a bit counter intuitive that putting a slower gear on makes the car faster (obviously to a limit) but it works. M6 increased by about 1.5m/s even with my extra weight compared to when the team at Camborne drove it, and the batteries lasted much better. Not only that but the increased rpm also considerably lowers the amps drawn. Where I always aimed for a high speed running amps of about 20A, with this gearing its now virtually nothing, which for the hilly sectors of the tracks makes all the difference by saving energy and putting less heat into the motor. A win win situation!

Now with the final round just over a week away I have been madly working through data from the last few races and looking at countless ratios to see for myself why RLR suggest a 60 tooth and I can now see why. With the increase we should be pulling 2000rpm comfortably with no worries of high amps. For an Autumn race at Goodwood this is just what you need. As well, unlike Castle Combe, I wont have to throttle back when I hit some wind or a hill as the high speed amps will be low enough that the low speed amps wont be massive. But the main point from this I will be able to race flat out the entire lap without having to worry about what the amps are doing, how hot the motor is, if I need to throttle back etc etc, I can just go out, and if all goes to plan, just race and hopefully get that step closer to the middle of the pack where M6 just didn't quite have the pace last weekend.

Thanks again RLR and good luck at the Final!

Merryfield - The Results

Merryfield was the home of yet another thrilling race!

Superb racing all round with major weather changes and exciting battles for position set the day as a very good lead up to the final. Unfortunately however the team from Camborne didn’t fair too well.

Starting the day at 5 we reached the track a little over 3 hours later giving us plenty of time for our planned motor change. This went in hassle free so we then awaited scrutineering. With no major issues here the day was starting pretty good rising moral for the team.

We then hit the track for practice. With some higher than expected amps showing up on the dials worry started to creep in but the gearing speed was chosen specifically to achieve mileage qualification, so we had to go for it or there was no point racing.

The start of the race then loomed. We were placed at the front of the grid so had clear track ahead which was exactly what we needed. With the worry of the belt slipping a large delay was set on the controller acceleration, so we needed room to get up to speed. The flag was then dropped signalling the start.

As expected we started slow but as the car hit the downhill and out of sight back of the track we were sitting in 4^th. However by the time the car had returned to view and after hitting over 30mph we were sitting in second, only behind the eventual winner Rotary Racer.

This didn’t not however last. With the large amount of amps pulled to achieve this speed the batteries just did not have the power to see out the 80 minutes they should last. With a worrying pit stop and driver change the second set lasted just as little seeing us install our final set before the hour mark.

Disaster then struck when the car was pulled in with the motor smelling of the unforgettable fried brushes.

Despite this the team pulled together and made the choice to put in the old iffy motor. With the new use of belt drive we had to keep the ratio as moving the motor to retention the belt was not an option the team wanted to carry out, so with no heat sink, the old motor when back out.

The job of picking the highest power batteries was then a job that was carried out numerous times for the remainder of the race, but the important thing is the car finished!

Ending 22 of 24 was not the result we were hoping for considering the start and having the 5^th fastest lap but if the batteries can’t take the pull then there’s nothing to be done.

Through everything though, the fact the team pulls through no matter what the problem shows greater means far more than anything else.

With Castle Combe and the Final still to be raced in F24+ some light rebuilding will need to be sorted but next season will see a new sleeker M6. Designs are being drawn up for the rebuilding and will deem it almost unrecognisable, but hopefully help us get through our ever prominent race issues.

For the full race results see - http://www.bbk-online.net/gpt/race50.htm

Lead up to Merryfield

After a long work filled holiday, M6, the car built by my current team GDS Racing, is almost ready to run once again in the hands of Camborne School. The change from a chain driven gear hub to a single gear belt drive is finally setup but hasn’t been without its issues.

After repositioning the motor to sufficiently tension the belt, we then encountered the problem of it twisting on its mount. It however gets worse! On inspection of the motor we then discovered the shaft was moving in and out, something that should not happen. This will require a motor replacement on the morning of the race, not great, but with easy access to its mount it won’t take long to install.

If this wasn’t enough to think about, our first test run brought to light the issue of the belt slipping when under the tension of pulling away. On close inspection this was due to driving before full reassembly so easily fixed. This highlights the issue with a bolt together frame. To further help I also increasing the acceleration time on the controller, a more gradual force is now applied helping the car to pull away without the slipping.

All in all I’m quite happy with the prospects of the weekend, obviously not too happy about the morning motor replacement, but needs must. Also thinking levelled headedly, a win is not really on the cards with the teams that will be racing on Saturday, but I feel the aim of 80 miles is more than achievable, as long as we don’t encounter any issues…

If you want to follow the race see http://www.bbk-online.net/gpt/race50.htm