Monday, February 21, 2011

TCS HobbyPlex Omaha 2011

Just some notes from the first Tamiya race of the year:

I got a chance to run on the HobbyPlex Omaha track for their TCS race. The bite was very high, as they had used the same layout for a recent enduro race. Luckily, my home track is pretty high bite too, but this was even more so.

The biggest thing was being able to dial in the front end adjustments in actual competition. Some of the stuff I was doing was ok for practice or screwing around, but the need to put in consistent laps/runs more clearly defines your setup.

I found out I needed to keep the spacers under the ball studs for the upper arm in the 2-3mm range. .5mm is an adjustment step that can be felt on the track. I started with 2mm, went down to 1.5mm, and up to 2.5mm. 1.5mm was too much front grip with the amount of traction out there. 2mm was ok, but 2.5 had the best feel for a neutral, linear steering car. It started out with the same feel as it ended.

Similarly, I did try more height on the kingpin on the upper arm. I default to to the largest ride height spacer on top of the arm. I tried the medium spacer, so the upper arm has a bit more inclination/camber gain. This produced a bit more of a twitchy feeling, and I went back to the large spacer on top of the arm-less height at the kingpin.

To put it in a nutshell, the lower and flatter the upper arm, the more the car will have a linear steering feel, and will be easier to drive in higher traction conditions. This is important as you can then start varying the tire traction to gain the amount of steering you want without making the car hard to drive. I coated 1/3 of the front, but I may have been able to do more. I didn't want to experiment too much in the mains. I think that 3mm under the ball stud on the camber plate would let me run 1/2 or even more dope on the front tire. This is important as I could go faster if the car had more steering. I was able to go .1 sec faster on hot lap and also have more fast laps with my car in the second round of qualifying. However, the car was difficult to drive (this was with 1.5mm spacers on the camber plate ball stud). My average lap was better with the more neutral car, but i could feel that it was a tick slower. More steering would deliver better lap times.

The picture below will show the black groove condition of the track-->

Track Photo

Wednesday, February 9, 2011

More fun with the F104 front end

I got back to the track tonight and had a chance to play around a little with the 104 front end. I had retained the camber plate dropped down onto the lower arms, no spacer. The upper arm was spaced up 2mm at the camber plate, and the largest spacer was on top of the arm at the king pin. The track was a bit green, low to medium traction. Turn in was good with this setup but the car did wash out a bit mid corner, a symptom of the low grip.

For the second qualifier, I removed the spacer under the upper arm at the camber plate, and moved the large spacer under the upper arm at the king pin. I also doped more of the front tire to try to add a bit more steering as well. This was overkill, as the car now was great in the 180* type corners, but was too twitchy off center, and would roll the chassis too hard in the sweeper unless very little steering travel was used. This made the car look as if it was about to hike a wheel in the air, and killed corner speed.

I went back to the original dope strategy, a little less than 1/2 the front and moved the middle spacer to the top of the kingpin. I would up again with a mid corner push, but the twitchy-ness and chassis roll was much improved.

To dial into this type of track, I would have changed a few things if I had some more time. First off, I would have tried the B foam. That may have saved me from having to change anything. If that was not effective, I think that the original front end settings with more dope on the front tire would have worked a bit better. The lowered camber plate is nice due to the multiple options for setting up the upper arm. I think the most effective use is to lower the front arm and keep it relatively flat by positioning the kingpin spacers properly. That seems to produce a fairly calm and linear steering feel. Too much angle gets the car nervous and has too much mid corner bite at high speed (read:sweepers). The only other way to work with this may have been a stiffer t plate, but it may reduce the rotation too much.

So far, the lowered plate has given me a better steering feel compared to the plate with the spacers underneath. I think it is more nervous with the upper arm/camber plate raised, while not producing as much front end grip.

Overall it was not a bad night, as I was able to stay withing .3 seconds of an F103 on hot lap and average. Anytime you are within .5 of a good F103, you're close to the right pace.

Wednesday, February 2, 2011


I was going to go to the track last night, but there's 2 feet of snow here. Yikes!