XRAY - Model racing cars

The two main effects that I know of are weight distribution over the rear axle and turning radius.

A shorter wheelbase will place more weight over the rear end. I've found that it works well to give more consistent rear grip for my FK05 as its weight is biased towards the front. I didn't suffer stability in the straights, but I also run 4.5d of overall front caster. The longer wheelbase worked better for my original FK. I suspect this is the same for older T1's as well since they all have more of a rearward weight bias if you have both sides of the saddlepack mounted in the rear slots. When I tried the shorter wheelbase on the original FK with 3d caster, I did notice less stability down the straights.

A shorter wheelbase will decrease the cars turning radius around corners (i.e. more steering) at low speeds and off power as well. But it may provide less steering on power due to more weight being shifted to the rear. Again, this works well for my FK05 since it already has a ton of on power steering.

The gives a little more insight, but bear in mind that this was written before the FK05 was available with its new forward biased weight distribution.

I reduced the wheelbase by 1mm last weekend and found the car to be more aggressive on high speed corners, no problem on straights and slow corners such as hairpins. It definitley gave the car more consistent rear grip. I wouldn't attempt to reduce the wheelbase by more than 1mm from the standard setup because the car will be very inconsistent on high speed corners , unless you drive like a demon.

TeamGP....the shorter wheelbase could work well actually. I've just finished taking my car apart to clean etc. and upon checking I found the front shocks had different rebound lengths as well as the back.

This is quite frustrating because it took me ages to get these right and they were all fine when I put them on......4 races later and they go pear-shaped.

So the bad handling on the car must have been the shocks and not the wheelbase. Let us know how it goes.

The shortest wheel base, with all spacers behind the arm, worked great this weekend for the I was able to dial in on the FK05. The cars speed was on A main pace with the fourth fastest lap time per driver (10.138) of the day.

However, my driving was rusty from 5 weeks of not touching the M8 and I mistakenly swapped the right front (plaid) and rear (magenta) tires in the last qualifier. The car worked decent for three laps until the tires warmed up fully. Then after six laps of trying to "lightly" turn left and avoid oversteer, I pulled over and dialed down the left EPA 30 points. Surprisingly, I went on to post a few 10.3's and 10.4's before deciding to take the car off the track early to find and fix the problem before the main.

In the B main, the old worn chassis I had cracked and CA'd previously during asphalt season didn't hold in the end. I started from pole, made a mistake on the 6th lap that cost me 3 seconds and allowed the #2 car to catch up. We had a great battle for 1st for awhile, but I believe the front bumper must have started to separate from the chassis and nullify the effect of the 2mm front anti-roll bar I was using. With each lap, the front end became more and more inconsistent with intermittent and very quick initial oversteer that would cause me to clip the apex or even run directly into the slappers. The bumper finally came off on the 23rd lap and used the anti-roll bar to compress the springs and push both front wheels up into the wheel wells.

However, things look very positive for this setup seeing as I used a lot of old worn parts and only tried a few setup tweeks during an afternoon of practice on Friday. I'll be rebuilding the car with a few new parts in the next two weeks and there's a few more carpet spec parts and setup tweeks to test. I believe I should be able to reduce the lap times by half a second with more testing and practice time.