The Scythe returns…

Put some electrics in the scythe again after almost a year on the shelf, ran it in the finals after problems ruined qualifying with the ARC (motor overheating and stopping the lrp esc, solution was to turn the protection off). First run in blinky (55t spur!), car drove sweet-as and went from 10th to 3rd in both finals (with the shell squashed like a pancake in the second!). Result – 2nd in the B at the WLRC BTCC. Very happy!

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Post-soaking rebuild

A belated update on my post-WLRC maintenance…

I put the car on the workbench just two days after the race meeting, and already the bearings were completely knackered, and every metal part had surface corrosion on it.

A complete stripdown was essential, with liberal doses of WD40 clearing the corrosion of the parts. The bearings were past saving though, so a full set of rubber-sealed replacements were ordered…

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I also tried to improve the waterproofing… it wasn’t entirely successful.

I used Liquid Electrical Tape to coat the circuit board of the receiver, and this worked brilliantly… at first. I could submerge the whole board under water and it would work perfectly (although submerging the exposed servo pins caused glitching). A day later, I powered up the car again – and nothing worked. Drying the receiver out didn’t work either. Seems like the water had managed to creep under the LET at the antenna wire (which probably made a break in the seal when it was aligned in the case). I could see the discolouration as I peeled the LET away. So I’m back to trying a more generous amount of blu-tack – the fact that I need to change crystals and unplug the ESC lead for programming means a totally bagged and sealed receiver is out of the question.

I also placed a little Liquid Electrical Tape on the sensor board of the motor – but again, most if it had to be scraped off because of the tolerances within.

The other problem that I couldn’t quite resolve was the tyres. I hoped that a little superglue would be enough to repair the cut in the damaged tread, but it wasn’t, and the glued tyre still balloons up under power. The set is basically useless for competitive running now – not that I am very keen on running in the wet unless I absolutely have to. Bad tyres, unreliable electrics, and a bill for new parts is not my idea of a fun day out!

Dave

BTCC West London Racing Centre – 3rd June 2012

It rained.

All day.

Well, I say all day but that is not entirely true. It stopped for a while after round 2 and the organisers decided to sweep and vacuum the puddles away.

Then after two minutes of the first heat, it rained again.

My car-share buddy for the day was James Alexander, and his “gazebo” turned out to be the Khyam tent of my dreams – so we were very comfortable in the rain with shelter on all sides and a good spot right next to the track.

Round 1 was a race of many firsts – my first run on wets, my first run at WLRC, and my first run with my newly waterproofed electrics – and it went pretty well. Within a few laps I had found a rhythm, and managed a 15/307-ish, which wasn’t blindingly fast, but was good enough for 7th in the round (from a field of 30-something). I was pleased that the electrics survived the full 5 minutes – something a lot of cars were failing to manage.

Round 2 was not so good. As I drove to the line, the car came to a complete standstill. No steering, no throttle, no nothing. Turns out the receiver had got wet despite the blu-tack around the openings. My theory is that since the blu-tack is not a perfect seal, small amounts of water trickled down into the receiver as the car was sitting in the pits between rounds, and all it took was one corner to shift a droplet of water into the wrong place on the circuit board. After a good warm through in the car (soundtracked by a Motown Chartbusters compilation), the receiver was working again.

By round 3, the rain had eased off and the track had dried a little. I wrapped the receiver in a balloon kindly donated by Michael Warren – it was even a “factory” red to suit the TOP Scythe. I put a tie-wrap around the neck of the balloon and filled it with Mugen Super Grease as a quick water seal. The electrics worked perfectly for the whole race – sadly the car had chronic understeer because of the lack of standing water – there is nothing like a puddle to get a car slowed down for a corner! I only manged a 15/304, 13th in round.

Round 4 was almost a carbon copy of round 2 – except this time I didn’t even get the car onto the track. It simply refused to switch on. Another damp receiver, which I assumed was caused by condensation gathering in the well-sealed balloon. My setup change of laying the front shocks down by a hole didn’t get tested.

The meeting format was a little different, four rounds and one final instead of the usual three and two, with the best two from four round-by-round results determing the grid. I was 13th overall.

Before the B-final got underway, I dried the receiver (again) and wrapped it in a balloon (again). This time I chose not to seal the neck with grease, hoping that the airflow would stop the condensation forming. Sadly, the tie-wrap alone wasn’t enough to keep the water out, and within 3 laps the car was going crazy in the middle of the track. Yep, a soaked receiver again…

Next idea is to either put the receiver in a sealed box, or coat the circuit board with Liquid Electrical Tape.

Despite being another disappointing day on the track, we had a laugh in the pits which made up for it!

Dave

PS Not very impressed with the durability of the BRCA wet tyre… cracked a wheel in my first run on the new set, and one of the rears is already on the verge of ballooning up and tearing through the tread. The Schumacher wheels get rather wonky too…

Another Cotswold practice…

…and sometimes I wonder why I bother.  I set off with the intention of answering some questions, and came back with even more!

Sensor issues didn’t flare up after I put the Speed Passion V3 motor timing back to the middle of the slot. Car’s pace still felt OK, balance was OK with a shade of oversteer, but the laptimes weren’t what I was hoping for, mid-19’s to quick 20’s. Made a couple of gearing and setup tweaks which didn’t make much difference. With nobody on the track to compare with, it’s hard to work out where the time has gone. Is it the conditions? The car? Me?

I still haven’t got my head around warming the tyres to get the most out of them in cool conditions. At 50C with the Nosram Asphalt additive baked in for 30mins, the balance went from good in the first minute, to understeer in the second minute, and a lively back end for remainder of the run. A toilet break for my son meant I had to leave the car in the middle of one run, and I ran a few more laps on cool tyres to get five minutes out of the battery. And the car was the best it had been all day! So perhaps 50C is too hot and you lose balance as the tyres cool on the track.

I’ve ordered a laser thermometer and will have to try taking more measurements to try to find the answers. 5C over the track temp should be a fair starting point with the warmers, but they need to be quite warm to get the oily additive baked in. So maybe I should be running the watery additive again. Hmmmm.

Running these Sorex 32s in conditions that are just too cold for them is not that much fun. No wonder so many people are getting frustrated with touring cars and going to buggies…

Dave

First attempt at waterproofing the touring car…

After a little thought, this is what I’ve come up with…

The case and cables on the ESC and receiver have been sealed with “Starbrite Liquid Electrical Tape”. Other similar products are available, they all seem to be variations on the theme of a solvent-based rubber adhesive. Exposed wires on the servo plugs and capacitor bank have also been dabbed with Liquid Electrical Tape. The switch has been sealed inside the finger of a latex glove, then closed off with a cable tie and more LET. Bigger holes have been filled with sticky-tack. I’ve taken the fan off the ESC to stop it sucking water in, but I’m not worried about the holes in the motor can, the motor is a very effective fan and spits everything out.

It all works in the dry. Fingers crossed it will work in the wet!

Practising again…

Today’s practice session reminded me of one thing.

Tyres.

If the tyre prep is wrong the car won’t perform.

I was happy with the ESC and motor setup I got last week. This week’s target was to get the chassis working.

The weather at Cotswold was a little cooler today (around 10C ambient when I arrived, mid-teens when I left), and the skies were overcast. Grip was lower, which meant that the problems I had with a flighty back end were even more apparent than last time.

Before I came to the track I had decided to rebuild the front of the car with a more kit-like setup (0.5mm shims under the suspension blocks and 2.5 degrees sweep). Initial impressions were that the car had only slightly more steering (I preferred 90% rates instead of 95%), but the balance on late corner entry was still too tail-happy.

I tried a softer bar on the rear (which seemed to have a more dramatic breakaway), a stiffer spring on the rear (more consistent) and a stiffer spring on the front (more consistent again).

And then I tried a different additive on the tyres. Nosram Carpet instead of Nosram Asphalt.

What a huge difference!

Suddenly the car had grip and I could attack the track.

My theory is that the asphalt additive simply wasn’t interacting with the tyre in these low temperatures (bear in mind I don’t have tyre warmers), and it wasn’t softening the rubber. The carpet additive is much more volatile and gave a nice tacky tyre within five minutes.

I crudely timed myself over a 5-minute run and would have posted a slow 16-lapper, not bad considering my best in very good racing conditions is a middling 16-lapper. Even better considering the left front tyre had worn through to the insert by the end of the session (which may have explained the loss of rear stability after about 2 minutes)! This was probably their 30th run so I’m not complaining.