Tamiya RM01X Build and Review - Part 3 Track Test

First Outing

I took the car to my local club in Crewe for its first outing. The club has permanent carpet (primafelt GT), but the track is packed away between meetings as the room is used for other functions during the week. The car was set up as follows;

Front Tyres - Magenta

Rear Tyres - Yellow

Ride height - 3.5mm

Front camber - 1.5mm

Front castor - as per kit

Front springs - kit. 5000wt diif lube on the kingpins

Centre spring  - kit

Centre shock - 30wt oil

Side springs - kit

Side damper - Corally red syrup

Toe in/out - parallel

Motor - Dynamite 13.5 - blinky mode on 78mmpr

Bodyshell - Protoform AMR

Before running the car I set the turning circle, to ensure equal steering left and right. If you've built the car carefully regarding servo position, it should be there or thereabouts anyway. First, switch your car on and check it runs in a straight line. Trim accordingly. Then line the side of the car up against a carpet join and apply full lock in one direction. Gently push the car (no power and don't shove it so it slides) in a half circle and place your foot next to the side of the car as a marker. Pick the car up and place it back down facing the opposite way. Now apply the other lock and push the car back. It should return lined up on the carpet join. If it doesn't adjust the Tx EPA until it does. You now have equal lock each way.

Anyway, back to running the car. I decided to give the car a quick shakedown as it was its first time out. Before running I had to apply additive. This may be new to some of you running 1/12th for the first time. I use SXT3 additive which is one of the new additives on the BRCA approved list. The bottle comes with an applicator, so no need for a separate brush. I always apply the rear additive first. With the SXT applicator, I find one dip in the bottle, then squeezing the excess out in the bottle neck leaves enough for all 4 tyres. Spin the back axle up and run the applicator across the surface of the tyres. Don't drench them. Just coat evenly. For the fronts, spin the wheel up with your finger and keep spinning it whilst applying. I start on the inside edge and run the additive out across the tyre. My personal choice is to run 7/8 of the surface coated on the fronts, and set the dual rate so the car is on full lock for the tightest corner at racing speed. This gives minimal tyre scrub and less chance of grip roll. After 15/20 minutes remove the additive. I roll the tyre up in kitchen roll and squeeze they tyre to remove any excess. Then I rub the tyre surface all teh way round with the tissue to finish it off. Using this method I find the car is ready to push from the off. I quite often set my fasted lap at club from the standing start which proves it works.

The shakedown was just that. I completed 4 laps on a clean track with no grip and never hit racing speed. The car did feel well balanced and drifted evenly due to the lack of grip. Then back to sit in the pits for another 45 minutes.

First Run

What can I say. Broke the 9 second barrier from a standing start on a track where we dont normally see 8 second laps until round 2 when the grip comes up. Came up to lap 2nd place within 2 minutes and then my mistake meant I locked bodyshells with another car and lost 6 seconds. I was able to attack the track like I never have before, even with low grip levels, and the lap times were consistent. I'll admit to heavily overdriving and throwing the car around, but it was so much fun!!!!

I came back down to earth with a bump in round 2. As the grip came up the car developed a nasty bite, which is the reason for me delaying writing this review. I wanted to find a cure rather than write a negative report and leave you hanging. The car had decided it wanted to spin whenever I lifted off the throttle completely for a tight corner. Not good. I pulled the car off and checked the tyres for chunking it was that bad. Little nibbles had appeared on the sidewalls, but not a big enough chunk for the car to fall over and spin.

Time for a little work. If you remember from the previous report, I questioned the length of the front springs. As they were too long there was too much preload on them. I felt this contributed to the spin as the car would turn in too fast. So for round 3 I fitted CRC 0.50mm spring with a single washer to take up the slack. No preload now. I also raised the centre shock by fitting a 2mm shim under the front balljoint. This would reduce initial turn in on lift off. When you lift, the weight transfers to the front wheels, and part of the transfer passes through the centre shock. The more it points down the more it pushes the front in to the ground, Flattening the shock reduces this effect. A softer spring would also reduce turn in on lift off.

CRC 0.50mm spring with washer

Back on the track, the car felt a little better but still bit. I took to driving with a trailing throttle on corner entry rather than lifting off, and this helped. This also seems to be the right driving technique for 13.5 as I found out 2 weeks later.

For the final run I dropped the side damper weight to 12500 diff oil. This felt too light, but I had nothing in between to try. The car was a little easier but required full concentration not to spin.

I finished the night with a comparable time to the 10.5 powered cars (2nd fastest). The car had showed a lot of promise, but needed work to cure the spinning.

Week 2

I stripped the car and checked everything before the next meeting. First to go was the kit side springs. How hard? They were harder than any Associated side springs I had in my box. I fitted the softest Tamiya option spring. This is somewhere between an Associated black and silver. I tried an Associated spring but found it too loose on the holder, so if you want to use these, fit Associated holders too. I also changed the side damper to 17500wt diff lube after a quick delivery from MB models. I now have 15000 and 20000 in the pit box. The only other change was to pink rear tyres.

And the car behaved the same for 3 rounds. Trying a softer centre spring had no effect. I was left scratching my head.

Then I remembered when I ran pink rears on my Speedmerchant 3 weeks earlier, I parked the car it was so bad. On with the yellows for the final round and set 2nd fastest time again. The car still tried to spin but less than in the first 3 runs and less than the previous week. They yellows gave a progressive slide so I could collect the car before it fully swapped ends. On pinks in would grip then just let go suddenly, so no chance of recovery. So on to week 3.

Week 3

Another look at the car and noticed the front suspension moulding is rather flexible. I wondered if this was the cause of the spins, with the front twisting and digging in giving sudden front end bite. Hmmm. A dig in the pitbox produced a redundant Speedmerchant side link. A quick chop with hacksaw to lower the 2 rather ugly lugs on the front arms and I bolted the turnbuckle in place.

Front Brace

I now found I could adjust the camber on the single turnbuckle. So I removed the foil shims I had been using for increased camber. Now I had more ride height. There was no tweak to the chassis either as the arms were so flexible. I did change the bolts shown above for long grubscrews through the pivot ball, as the bolt heads rubbed on the body.

On the track the car was transformed. Only the slightest hint of the car trying to spin, and massive corner speed. I had some competition to aim for tonight too, as Jim Spencer, the reigning BRCA 1/12th Sportsman champion was there. I was well chuffed after the first run to be only a single lap down to his 10.5 powered car. No change to the car for round 2, and 3 seconds down. Again no changes for round 3 and finished 5 seconds down with a worse run in traffic, but equal fastest laps. I lost 3 seconds with traffic in a single lap.This is the closest I've ever been to beating Jim, and I had the slower motor which told as we hit the end of the straight and entered the sweeper. He would continue to pull away. But on the infield I could carry more speed and exited corners travelling faster than anything else.

Conclusion

So, the car only needs a brace on the front and a few different springs to be extremely competitive. Now I've proven the car with the kit front its time to fit the Associated front end on and see how it goes. Hopefully be hitting the track in Derby Wednesday night. So keep your eyes peeled for Part 4 HERE