XRAY - Model racing cars

Here we go...

I had the opportunity to attend a very well run and attended "unofficial" large race in Rosewood, NC this past weekend. Although we were way back in the woods the indoor carpet track and nearby accomodations were more than adequate.

In preperation for the all day Friday practice session, I decided to take some advice from KT and add .75d of pro-dive for a tad more steering on corner entry and exit (from the increased caster). It would also help to absorb the bumps I'd heard of on the straight and a small sweeper leading into the straight.

During Friday's practice, I was pleasantly surprised to be able to get a good rhythm going on only my fourth pack. And seeing that I was properly prepared and had the privelege of being first onto the track, it was certainly good for the confidence. It was good enough for me to put in the freak of nature C2 19 turn I had worked on the dyno earlier in the week, just in case I had enough courage to run two classes. Boy was that a good idea.

Race day is here and I'm runnin two classes (stock & 19t) with the big boys!!! First up in qualifying was stock. As per my MO, I took it easy and worked more on consistently not hitting anything to get a decent qualifier under my belt. However, I quickly realized that I was undergeared and only a hair above average in lap times. But I finished without incident and slotted into the top fifteen after the first round. 19t was much of the same, except the gearing was good, the rear end was a little sloppy in the chicane and I needed more high speed corner entry steering.

During the intermission, I decided to slightly change my setup for 19t to add .5mm of rear droop and close one more hole on the rear shocks. For stock, I switched from the Brood Monster to a Brood P2K2 to test the torque waters on the tighter than I'd been used to track.

With two decent qualifiers, I pushed harder in the second qualifiers, only to realize afterwards that my times hadn't improved. I could attribute too tall of gearing to the stock run, but the 19t run left me clueless.

After taking a few moments to reflect on my laps during the second break, I realized that the car was transitioning perfectly, but that it seemed to drift on all fours at the each mid corner apex ever so slightly (six to eight inches or so). A few moments later I decided to go down in spring rate all the way around from Lt red to purple on the front and from red to Lt red on the rear (I know what you're thinking, but keep in mind that they're laid down two extra holes in the rear ). Of course I had to bounce my issue and solution off of one of the top drivers in attendance (Mr. B. Spence) and it held up to his scrutiny. I made the changes and put on a new set of trued 2 stage tires, while going over my aggressive strategy for the last qualifiers.

During the last stock qualifier, I quickly realized that the car was finally dialed at each apex and was certainly faster. However, I found an issue that had not been bothersome to me personally until now. The increased chassis roll had allowed the new front tires to eat into the shock ball ends and spring collars which took a large chunk of tire AND rim, the size and shape of a large sharks tooth, from the inside half of my left front. Obviously, turning right became a problem, especially in the right sweeper that ends in a very tight right hander. However, after realizing that the car still handled fairly well, I set off to change my lines into the right handers and actually was able to match the lap times of the previous two qualifiers where I had been over/under geared and missing every apex by half a foot (can you say "+.2/lap"?). Not good for the qualifying position, but it did give me even more confidence knowing that the setup and DRIVER were adaptable to adversity in the audience of so many skilled drivers. Now here is the kicker! After pulling the car off the track and checking the suspension, I found that the shark's tooth must have helped to split the left c-hub along the hinge pin. For whatever reason, the c-hub must have decided to stay put and just tease me with movement in those right handers.

Originally I had decided to save all of my new IB3800 packs for the stock class, but with the pack I had used in the first qualy being nice and cool, I couldn't resist charging it for the last 19t run. After replacing the left c-hub with my last spare (I had to replace one in practice on Friday after literally putting a hole in the wall on the outside of the sweeper) and using a file to shave off 1mm and round off the inside inner lips of the front tires, I went out on my final qualifier with the C2 strapped in. After getting up on the drivers stand, I realized that I hadn't increased the rear droop or closed one hole on the rear shocks either, as I had before the previous 19t qualifiers. Boy were those spring changes the ticket for me though. The car no longer needed the extra droop for turn-in or an over damped rear end for the chicane. The lap times improved by at least .3s/lap and I qualified 3rd for the B main only a few seconds behind the 10th place A main drivers time. The confidence was high and I was now locked in on obtaining a first place finish!

Now comes the fun part...

I'm lined up in 8th place for the stock B main start, with my historically fast Monster freshly cut, strapped in and geared much better. My strategy was to use my past experience as a scale drag racer and kick a field goal out of the box on the tone and split #6 & #7 right up the center. It worked to perfection as I passed them about midway up the straight. #5 was heading in wide, the usual line, and I knew my car could turn on a dime now at any speed so it was only natural that I pass him on the inside without ever letting off the gas in the beginning of the sweeper (thanks to the one-way ). The car held the line and I had perfect position to come alongside #4 right before the tighty righty. Now wouldn't you know that #4 wasn't going to give up that easily and decided to rub fenders side by side. Unfortunately we both scrubbed speed just enough for the guys behind us to punt twice on the same down. Both of our cars were quickly taken off the track as I gingerly moved off the drivers stand and sprinted around the track to get my car. The 19t B main happened to be next with a 3m break after the one I had so quickly exited.

Back in the pits, I realized that a right 6d c-hub just wouldn't work on the left side, nor would the car work right without a replacement one-way outdrive that must have a great view, somewhere in the sweeper, of the race that was still going on. I frantically ran through the pits bumming parts. Thanks to two other XRAY drivers, my pit mate and a very gracious extra 3 minutes from the race director, my car was grided up in 3rd with freshly sauced and unscrubbed tires.

With no time to think, my plan was the same for the start and it almost worked to perfection again. The wheel spin out of the hole must have scrubbed the tires in well by the end of the straight and I made it into second, but only for a brief moment. I was quickly re-passed as I made a few mistakes, but I was able to settle into third. For the next 8 laps, I could see that #2 couldn't pull away and I preceeded to overdrive the car while trying to catch him. It didn't pay off as I made too many mistakes until finally settling down for the second half of the race with a clear track in front and no one close behind for another ten laps or so. Other than being lapped by #1, it was pretty much smooth sailing the rest of the way.

I came away happy with the results and handling of the car using a final setup that worked well at a large event without any changes between stock and 19t.

This past Monday I confirmed that the I had dialed in at Rosewood worked very well at my local track and the gearing was nearly spot on for both stock and 19t as well, while being ever so slightly on the tall side.

I wanted to make sure of some things with the T2 before I gave the update. I'll write it up hopefully later today.

First up, the FK05...

Before Christmas I took a good look at Paul Lemiux's interesting setup from Cleveland and analyzed the differences between his setup and Mike D & Peter's. What stuck out the most was the use of the 2mm chassis instead of the usual 3mm. At first glance, I thought well maybe it was all that was available on such short notice. But after thinking long and hard, I believe I found the reason why he made this move. Almost the entire cars center of gravity would be lowered by 1mm. Not to mention, that there is a 40g difference in weight between the two, which would allow him to place the additional weight needed to pass tech wherever it was needed to balance the car out.

Needless to say, I had just received my latest batch of FK05 parts, including a 2mm chassis, and I just had to try it. In the name of low CG and weight reduction, I also ditched my motor fan & mount and relocated my PT from the top of the servo to inside the pre-cut bumper. The results were crazy

On the 17th of December, with the 3mm chassis, I had pulled out a half a lap lead on everyone in the pro stock main, before a corner worker placed a crashed car right in front of me at the apex. I ended up 2nd, but I recorded a fast lap of 10.009 which was pretty close to the record of 10.007. At the time, a few guys had run some unofficial 9.9s but not in an official race.

When I tested the car on the 20th, after switching chassis's, I used my #3 motor and #3 battery pack in order to get a close comparison of lap times. After figuring out the gearing and knocking off the rust during the first two packs, I was able to record a 9.75 on the third lap of the third pack, several 9.9's on laps 14 & 16 and 10.1's & 10.2's well after the 5 minute mark. Needless to say, the 2mm chassis knocked off .3s/lap average from my times in the race the previous Saturday which were equal to everyone else's best. And the kicker is that I was not pushing the car and driving as tight as possible to the corners either. Since we had the weekend off, I was unable to run the car in an actual race. However, the next Tuesday (27th) in testing I ran another six packs with it and came away **unofficially** with a fast lap of 9.44, a 9.9 on lap 26 and just barely missed a 31 lap run (never been done before and the current record was 30@5:06) with a best time of 30@5:03.

I used the slightly heavier, but stiffer, adjustable top deck with all 3 braces and 4 posts. I hand tested the flex after switching to the 2mm chassis, and the entire structure is more than rigid enough. However, Paul used the standard wide top deck.



Now for the T2...

I first opened the kit after coming home from church on the 28th of December (thanks Mario & RC America ) and finding a FedEx package on the stairs for little 'ol me. Of course I flew upstairs to the bat cave and ripped it open with controlled fury (didn't even take off my tie). But after looking into all the parts bags and drooling a little I regained control, changed clothes and prepared my workshop for some major building.

Build Day (night) 1:

I decided to spend only a few hours that night to carefully prepare the CF chassis, front top deck and shock towers. First up was filing the slots for the battery packs. This took all of 15 to 20 minutes after I realized that all of my top four packs were bent and subsequently flattened them back out again. Then I lightly sanded off the sharp outer edges of the chassis, front top deck and shock towers. The same treatment was applied to the battery tape slots, the spur gear slot and the bottom sharp edges of the cell slots. Finally I applied the CA to all of the sanded edges and the coned screw holes (using a Q-tip for all of the slots and the screw holes).

Build Day 2:

After arriving at work somewhat early, I talked my boss into letting me take some vacation time for half the day on Thursday and all day Friday. As we had a New Year's Eve race scheduled, I had to make sure I could get at least a few hours of practice in before the store closed on Friday night. I was more fortunate in the build process than most of the team drivers, in that I had a copy of the new T2 manual and Hudy Setup Book to work from. Following the manual was easy and although I really took my time, the build process seemed to go by quickly. Before I knew it the clock reported the time as 12 hours later with dawn about to break in a few hours. Yet I was excited and not at all sleepy. I simply had to put the car through my full alignment process before going to sleep. My goal was to shoot for a setup as close to the FK05 as possible. Following the Hudy Setup Book, I took a guess at the correct shim sizes to increase the track width and implement 2d of front in-board toe-out and 1d of rear in-board toe-in. The toe came out correct, but during the alignment process, I realized that my front track width was 4mm too narrow and the rear also came up a little skinny by 2mm. But oh well, I didn't feel like changing the suspension holder shims and kept things the same. Here is a list of notes for setup items that I had to work out some things in order to closely match them to the FK05 setup:

* Caster - The team kit only came with 4.0 degrees caster c-hubs (used 6d c-hubs in the FK05), so I decided to increase the overall caster to 5.5 degrees through implementing 1.5 degree's of front pro-dive (kick-up)
* Lower arms - I was able to implement the 1.5d of front pro-dive and rear anti-squat through using the +.75 holders on the forward pin positions and the -.75 holders on the rearward pin positions on both the front and rear arms.
* Upper camber links - I used the inner mount points on the rear hubs and the low outer positions on the front & rear Quick Roll Center mounts in order to implement the shortest links possible for maximum camber gain and quicker suspension reaction. I used the low outer positions for the inside links and shims underneath the outside links to add about 2 degrees of angle front & rear for even more camber gain.
* Springs - Although I had a second pair of light red springs for the rear, I did not have another pair of purple springs for the front of the T2. And since I had decided to run the FK05 (which had my only purple pair mounted) in the 19t class that weekend, I mounted light purple springs up front on the T2 instead.
* Shock angles - It made more sense to me to use the lower inner mount positions with the wider foam rims. In reality, this proved to be the best in order to keep those pesky ball ends from getting eaten by the rims. With the front shocks using the outermost upper slots on the shock towers, the front shocks were now standing slightly more vertical than those on the FK05. I thought this was a good thing, seeing as I had slightly softer front springs and an extra .75 degrees of front pro-dive than what was on the FK05. With the fronts mounted, I had to figure out the difference in angles of the front and rear shocks on the FK05 and then choose the correct position on the T2 for the rear upper shock mounts to match the angle difference. It really wasn't that hard though.
* Ackerman - I moved the servo saver forward and used the rearward mount points on the steering blocks in order to produce minimum ackerman effect.
* Multi-Flex settings - Too easy. All top deck and chassis mount screws and the aluminum brace were used for the stiffest setting.
* Track Width and in-board toe. Now the tricky part was trying to match the front & rear track widths (190mm), the wheelbase (252mm) and the front & rear in-board toe (+2d & -1d respectively) from the FK05. I had to take a guess at how to use the shims for the suspension holders and the rear arm pins. This first time I opted to leave a 1mm shim on the forward side of the rear arms for the wheelbase. For the front track width and in-board toe-out I could only use a 3mm shim on the forward holder and a 1.5mm shim on the rearward holder, due to the length of the forward holder mounting screws not allowing for more than 3mm shims (unless I wanted them to strip out the bulkheads in a hard crash ). After putting the car, with tires mounted, on the setup board I found this resulted in a front track width of 185mm and 1.5d of in-board toe-out. For the rear track width and in-board toe-in I used a 2mm shim on the forward holder and a 3mm shim on the rearward holder. This resulted in a rear track width of 188mm and 1d of in-board rear toe-in. Of course I corrected the front toe-out to +0.5d using the steering rods and the overall rear toe-in equaled 2.0d. The wheelbase ended up being 254mm, due to the sweeping inward geometry of both the front and rear arms.

Note: The Jaco 2 stage foams fit a little too snug on the steering blocks and I had to lightly skim off the inside edge of the rims. I came up with a fix for this that is noted below.

Race #1 (12/31/05) - post initial build:

I posted the track results previously in the . However, I'd add that I only had time to run about four packs with it on the Friday before the New Years Eve race. During this time, the only changes I felt necessary were to stand the rear shocks up one notch and open one more hole in the rear shock pistons.

Mid week adjustments:

During the middle of last week, I fought the urge to keep the car the same and eventually altered the suspension holder & rear arm pin shims to almost an exact match of the FK05 setup. At one of our LHS's I was able to find some longer M3 button head steel screws for the suspension holders that would accommodate more shims. While there, I also acquired some .5mm fiber shims that fit in between the outer steering block bearings and the holding pin. These allowed me to space the hex nuts for the front wheels out .5mm from the bearing, without added slop or friction. FYI, anything more than .5mm will not fit behind the holding pin without causing it to bind the bearings. In order to increase the front track width and in-board toe-out I switched to a 4mm shim on the forward holder and a 2mm shim on the rearward holder. After putting the car on the setup board the results were a front track width of 188mm and 2d of in-board toe-out. To increase the rear track width and keep the in-board toe-in the same I switched to a 3mm shim on the forward holder and a 4mm shim on the rearward holder. This resulted in a rear track width of 190mm and 1d of in-board rear toe-in. Last, I moved the remaining 1mm shim from the forward side of the rear arms to the rearward side in order to shorten the wheelbase even more. The front toe-out was corrected to +0.5d using the steering rods and the overall rear toe-in stayed the same at 2.0d. The wheelbase was now shortened to 253mm. With the only differences now being -2mm on the front track width and +1mm for the wheelbase, I was satisfied. I then got rid of the excess wiring and re-balanced the chassis left to right and front to rear (lightly dremelled two holes on each side of the underbelly after carefully measuring the midpoint from the new front and rear axle points). Last, I decided to retire the FK05 and move the purple springs to the front of the T2. My hope is that all of these changes will allow the car to run consistently in both stock and 19t, without any setup modifications, as the FK05's setup did. At the time of writing this essay, I haven't been able to test the car with a 19t motor yet. But I plan on testing this by the end of the week.

Race #2 (01/07/06):

In the previous week’s race, although the speed was evident, most of the top pro stock drivers were running 19t. So I knew I had my work cut out for me with all of them returning to run stock in the continuation of our local point’s series. Before the first qualifier, I decided to re-check the alignment and to my surprise, the camber was off by +.5d on both fronts and -.5d on the left rear. After re-adjusting the alignment I ran the first two qualifiers with mixed results. The car was still fast, but not as easy to drive as the previous week. At first I chalked it up to the track width and wheelbase changes, but a quick check on the setup board proved that to be untrue. Apparently the camber was now off by -.5d on both fronts and +.5d on the left rear. I couldn't figure out how the previous readings were incorrect, but this made sense as the steering was a little inconsistent in transitions and the rear seemed to step out slightly if I wasn't smooth entering into tight right handers. I adjusted them back to setup specs and the results were great. The car was a dream to drive again and I was able to match my fastest lap from the previous week and set a TQ time only 3 seconds off my unofficial fastest run previously with the 2mm chassis FK05. After starting from pole and going wide into the first turn, in order to avoid being punted, I was able to successfully escape the wreck that everyone knew was going to happen. The local favorite to win was also able to avoid the mess and move up a few spots from his qualifying position and into second. I was able to pull out around a two to three second lead from him and had found a decent rhythm. Then it almost fell apart. A few cars had wrecked and as they were trying to recover, I was also trying to come around them wide. Didn't happen. But that's racing. I lost just enough time for the second place driver to pass and pull out a small lead which I couldn't recover from as we both tried to slice through lapped traffic. I thought it was better to preserve second than push and lose it all. However, I couldn't help but feel that the car was somewhat slower though and certainly off the qualifying pace. A quick check on the dyno later that night indeed showed that my decision before the main, to increase the spring tension on the motor, was not a good one. Lesson learned again...unless your slow, leave it alone before the main!

The T2 setup, in jpeg format, can be found on

Being this is the one way/foam thread can I assume you ran the T2 with the one way ? If so how did you fight the urge to run the ball diff just to compare it to the 05 ? This past summer I ran a guys 05 with a one way/foam on carpet. I found the car extremely sensitive around center while going down the straight. Any little input and I was going board to board trying to recover. He was a new racer and loved it. I'm an old racer and thought it had possiblities.
If I get another Xray I'll try a one way with your set up.
Thanks.

Hi there!

I recently finished building my first Xray, the T2. A phenomenal kit!

Here in Norway we have been racing on rubber tires using one-ways. But this fall the wheel rules liberated in the stock and 19t classes and we all run foams now. Still with one-ways.

One of the setup issues I am trying to understand in more detail is the ackerman effect. My first evening with the T2 I chose to go with teamgp's advice and use minimum ackerman effect. The car showed excellent corner speed, but it felt slightly docile going into the turn. (I got the -0,75 mm rearward hingepin holders on the front arms to gain some caster) I chose minimum ackerman effect as I figure foams on carpet is a high grip situation.

Both you (teamgp) and the setup book recomend using less ackerman effect in high grip conditions. I then wonder why the base setups suggest to use the rearward inner ackerman position on foams (more ackerman) and the opposite for rubber tires

This thursday I plan on testing with more ackerman and will report back my findings.


Sigmund Overeng
Oslo/Norway

I had the opportunity to test the T2 one-way setup in a high bite large event this past weekend. The venue, "The Track" (a.k.a. Mimi's) in Gaithersburg MD, was a new one for me. It is notorious for having very unforgiving boards and extremely high levels of competition from pro drivers. I absolutely concur in both cases

The car had already been prepped with a setup from practice the day before at our local carpet track, but this quickly proved to be insufficient as the grip was higher and the layout proved to be faster in spots AND more technical in others. I had to pull off the track with a broken steering block without even putting in a full run. Back to the virtual bat cave I went, where I found another T2 driver needed assistance in order to continue running. I handed over my last steering block and left c-hub, but not without a tug of war going on inside my head. From this point on, my game was altered and priority #1 became dialing in the car with as little track time as possible, in order to minimize the possibility of breaking anything else. Priority #2 became making the car easy to keep away from the boards and just fast enough to make consistent above average lap times. First up was figuring out how to stabilize the rear end which seemed to be too stuck in some spots abrupt loss of traction in others. After replacing the steering block, I put the car through two more packs while trying slightly different combinations of rear spring rates, angles and dampening. The rear finally came into line, but was still a little erratic if I didn't hit the lines just right.

In the first qualifier, I played it safe and came in with a respectable, however somewhat slow, time somewhere in the high 22 lap range. For comparison, the top pro drivers ended up in the low 24 lap range after the first round. Upon reflection, I realized that the front, although stable, was just too stuck for the rear end to keep up if I made quick steering changes. I could also tell that the front end stick was causing me to scrub too much speed and loose time in a fast and technical chicane that seemed to be very important for a quick lap time. Stiffer front springs (light purple to purple), softer rear springs (red to light red) stood up another notch...ORDER UP! The gearing seemed a little low as well and I added a tooth to the pinion.

In the second qualifier, the results were much better as I came in with a high 23 lap time only four seconds below what was needed to qualify for the A at the time. Although the leaders had moved into the low 25 lap range by then. I didn't change a thing between rounds as the cars handling had met my goals and funny enough, all four tires were wearing almost exactly even with only a slight (.05mm) bit more wear on the left side due to the high speed sweeper at the end of the long straight. But alas, the traffic was more difficult to overcome in the last qualifier and I had to settle for qualifying for 7th place in the B main. Ordinarily I would be disappointed with this result. However, considering the high level of competition, lack of much needed practice time and lingering thoughts of breaking something I couldn't replace, I was on cloud nine. Plus, the challenge of coming through the pack to earn a place on the podium always makes me focus more and I love it! Underdogs R Us (me and the Pittsburgh Steelers)!!!

Before the mains, a mistake was corrected with the A main roster, which I believe bumped up the first two B main drivers. But somehow I was fortunate to start in 5th place instead of 7th. To make a long story short, I was able to slot into third quickly, pass for 2nd on the 8th lap and almost run down the leader. However, he made Swiss cheese of the lapped traffic, and I really didn't want to risk a forced pass on anyone and possibly miss out on a podium finish and a better reputation with some of the drivers that think I'm a crazy hack.

Funny thing is the setup I ended up with is almost exactly the same setup that I ended up with the previous race day at our local track (which I had tinkered with and changed between the two race days ). The only differences between the two setups are with the rear shock dampening. For the rear shocks only, during the week I had changed from XRAY 35wt oil to 30wt. Correspondingly, I ended up also going from all piston holes open to three holes closed which must have been needed for the much thinner oil. I was able to test the car with the exact same setup from The Track, gearing excluded, during lunch time today at our local track and it worked perfectly again. I still think the car will be a good bit faster with 6d c-hubs and less front kickup though. Gotta wait on those c-hubs...

The traction was definitely something new for me and I'm looking forward to what I've heard about the Snowbirds unlimited traction. See y'all there. It should be easy to find me. Just ask around as I'm sure I'll be the only one running a one-way!!!

Although there isn't much difference from the previous setup sheet, the updated T2 setup, in jpeg format, can be found on