wtcc5's TT-02 race development and race reports: Race report from the RCKleinSerie @ the IRS

[wtcc5 5758]

I have to apologize for letting you guys hanging without new infos for so long. I had to finish another urgent project first. Since then I used most of my free time for the v5.1. Never underestimate the time it takes to make all the little details perfect, to draw all the setup arms and prepare the parts for production. Today, I finished the parts list and made the new setup sheet. I still owe you pictures of the rear design.

Overview:





Most recognizable is the new shape of the droop plate. Mostly influenced by the changed anti-roll-bar layout. I am very happy how close the lower damper end sits to the arm centerline and that the damper slips in between arm and the active-toe-link. The anti-roll-bar-mount is attached by one screw and is guided by the slot in the droop plate. To avoid possible collisions the arm has 0,5mm layer removed just above the rod stopper:





With the upper shock mounts moved closer to the center of the chassis, I had to come up with new rear body post mounts. The plastic was replaced by carbon and I added several height adjustments (as requested by my patron and friend Michael Koos):





Also attached with one screw, it will interlock with the rear of the top plate.

So this is the new version. What cannot be seen here are changes I made to the droop plates and top plates to make live easier and the build more enjoyable. Up to now you had to glue 0.5mm plates underneath the top plates to fill the space between the central drive shaft ball bearings. Now these are integrated. Also the chamfering by hand of the droop plates to avoid a collision the lower diff housing of the tub won't be necessary anymore.

In the last step, I contacted my part producers and now wait for the invoices for the prices.

[wtcc5 5758]

Here the previously mentioned files of the partslist and the setup sheet:

KRv5_1_partslist.pdf tt02_krv5__1_setup_sheet.pdf

[wtcc5 5758]

Got an answer from my manufacturers: I can offer the set of carbon and 3d-print parts for 189€ (plus shipping) if anyone is interested 

[wtcc5 5758]

In other news: All parts are ordered and the waiting time can begin. I also made the setup sheet interactive. See attached file.

tt02_krv5_1_setup_sheet_interaktiv.pdf

[wtcc5 5758]

Made more updates I don’t want to keep a secret:



Most significant is the updated bumper design. It got a bit slimmer and strengthens towards the bumper posts:



And then I made adapter plates for the RCmaker pro mount. This way my customers and I can skip making holes in the body for the horizontal body posts, use shorter and lower body posts and have a better force load from wing to chassis. You can also set the body height in finer steps:
 

[wtcc5 5758]

My manufacturer is busy:




I am too. A good friend is king of the bumper game and I asked him to print the new v5.1 design. It became perfect:




Since I am doing practice runs today, I immediately installed it:

[wtcc5 5758]

The practice yesterday was for the upcoming RCK-Challenge race. I will join the GT-Challenge class, like I did mid November last year. 
Changing back to the much weaker RCK-17.5t motor was a mild shock. At first I didn't hit one apex and later on I thought I had bearing failure, because it doesn't accelerate much after the chicane leading on the straight  Compared to the Hobbywing G4 this RCK motor is a "bicycle tyre inflator". After checking, the car was alright and I could adapt. In the early afternoon I had the car in the sweet spot. Very easy to drive and predictable, while not scrubbing speed (everything I tried later was slower). 



My times in the last race felt not bad: fastest lap 9.852s, fastest qualifyer 30L 5:02.214, fastest final 42L 7:05.111
With the track development throughout the last months and my setup improvements, I could easily beat all these times: fastest lap 9.578s, fastest five-minute-run 31L 5:07.820, fastest seven-minute-run 43L 7:07.841






Saved all changes in a Setup Sheet:



 

[wtcc5 5758]

Early this week the carbon parts arrived:



With the next race this Sunday, I thought about if I should build the v5.1 (taking a risk) or use the v5 and build the v5.1 later... Well, I think I am pretty much easy to fathom: I started the build!

As always, preparing the 3d-printed parts. Removing them from the frame:


Painting the white spots black:


Drilling the bore holes. First with a 2.5mm drill, then drilling the 3mm holes:


Then making the M3-threads:


I moved all ballstuds from the v5 upper brace to the v5.1 brace:


New anti roll bars are needed. I made a drawing and then bend the front bar:




The front arb is integrated in the bumper:






The next steps were a bit tougher. To make a very compact arb-arm-mount happen, I use Tamiyas 54869 Open Face Adjusters and optimize them. In the first step, I took the 2.5mm drill and completly drill through the shaft until it comes out in the ball opening. Then I make the M3 thread. In a last step, these need to be cut down to 10mm length:


I also shortened the thread of the 5mm ballstud from 5 to 3mm. This then results in this assembly:



 

[wtcc5 5758]

Unfortunately, the weekend race has to happen without me. I got ill  At least I could finish the build before getting knocked out by influenza.


Still at the front of the car, the droop plate received the arm mounts. I raised the bar of the v5.1 build by having all chamfers made by my manufacturer now. So no extra work needed:




Front arm installation:





Installing the droop plate to the tub:




And then one of my build highlights, installing the shocks:


The last steps for the front.

Front bumper assembly:


Before the bumper can be installed, the droop plate support comes first:


With the new arb-mount design, it is now much easier to install the bumper plate:




Only upper arms and hubs left. For now I stayed with the Xray steering arms (because I thought I would race this car this weekend...):







 

[wtcc5 5758]

Now to the changes in the middle. With my new weights layout, I moved the battery close to the prop shaft. This made a relocation of the upper mounts necessary . I also added claws to the ends, so I don’t need to glue a piece of foam to the chassis wall:




And while at it I exchanged the aluminum prop shaft as well, as it was ligthly bend.

For the rear upper plate it was pretty much the same work as in front. Exchanging the ballstuds, checking the proper shimming of the ball bearings, adding the thumbscrews for the shocks:


New is the mounting concept of the rear body post plates via one screw and a pin from the topplate. Unfortunately this pin didn’t fit in the hole as planned. I removed a bit of material from the upper side until it fit:


The rear droopplate has compared to the front, two different features. One are the split arb mounts:


...and two are the active-toe-link ballnuts:


In this picture I have already added the arm mounts and droop screws.

Putting in the arms is generally no problem. It can occur though, that they sit tight on new ball cups. If so take a round file and remove a whee bit of material step by step until it is perfect. On my old and worn ballcups I experienced both tight and loose situations. For the latter you can put on a film of crazy glue into the ring, let it fully dry and then check again 



In the picture the distance for the toe-links for 2.5 degree toe-in.

It was time to complete the arm assembly with the arb-damper-mounts. Again preparing four ballcups as described above and shorten two ballstud-threads to 3mm:


Then put the parts together like shown and attach the ballstud to the mount:






Rear anti-roll-bar bend and added:






The whole unit attached to the tub and dampers installed:





And then I realized, that I cannot install the droop plate support with the arb installed  Luckily it is just two screws to remove the arb-mount:


... to be continued.




 

[ruebiracer 1181]

Crazy cool Kevin, it look´s so compact now with the short dampers behind an d in front of the wishbones. Cool, that you still found the place for steering links etc.. Really stunning, and countless ideas still in your head! Hats off!

[wtcc5 5758]

Last step’s before completion.
The rear hubs got the new toe-plates:



These are generously chamfered for more suspension angle.


Only the upper arms left to add:




And that’s it. The new v5.1:

[ThunderDragonCy 8380]

This is amazing 

[chen chun hsiung 0]

Where can I buy this tt02 conversion kit?

[wtcc5 5758]

@chen chun hsiung: Hi! Sorry, I missed your inquiry. If this is still on your mind, please send a PM.

 

The same happened as last year. After the indoor season (2023/2024) I was a bit fed up with Onroad and development of this car. The summer break was much needed. I gained a lot of motivation to work with the v5.1 again. The car will have its first race for the RCKleinSerie in two weeks from now.

So where did I left? Last winter I ran one battery indoors with this version. It already felt promising on track, but very soft on the spring. Until some days ago, I thought, I made a mistake with the damper mount geometry.

The first run after the summer on our indoor track was ok. Not great, but it never is after summer. The track misses grip and the line has to be used several days to gain back its traction. The car behaved ok, but was beyond the sweet spot. It lacked steering and asked for a wake driver in fast sections. The rear had a tendency to step out of line. Well, on the first day the focus is to not crash the car and relearn the rhythm. I did that and setup wise just made sure the ride height and tire loads were correct.

As homework, I noted to make anti-roll-bars in two more wire thicknesses (1.2mm & 1.5mm, with 0.9mm already on the car):

 

The second practice day (a week ago), I focused on an easy-to-drive-setup and worked with the bars and droop. The day started with laptimes beyond 10s. The car felt much too soft, so I tried harder springs, which felt good on the table, but terrible on track. The front was unwilling to turn-in and the rear tried to overtake the front in the fast corners. So, I stayed with the proven 2.5-2.8 in front and 2.6 in the rear. Limiting the droop was very effective. Even though the car feels very soft, it hardly rolls with increased droop. The rear was still too nervous. I tried a 1.2mm bar in the rear and voilá, the rear was planted from then on. Overall my best time got down to 9.9s/lap.

Again, after that day, I noted different setup changes and tasks on my Todo-list:

 

1. I shimmed the lower inner arm mounts upwards

The rear got 2.5mm all around.

 

2. The front was totally shimmed wrong with too much anti-dive. The FR-mounts now are shimmed 2mm and the FF-mounts 1.5mm:

 

3. While at it, the rear diff received 2000cst oil for more rotation and

4. I replaced the 44mm drive shafts, which are slightly too short with the new TRF421 45mm versions.

 

Chassis overview:

 

Today then, I tried the new setup and was instantly convinced. During the day, I could further improve balance and rotation while making the car super easy to drive. I made more changes to the roll-center by shimming the inner upper arm mounts, increased the droop a bit more in the rear and tried harder oil in the rear differential. And while the tires were getting close to falling apart, I managed to improve my times by 3 tenths/lap to a 9.6s and 31L in 5:08,0 minutes:

 

That was a satisfying day with an important step for my race setup. Next time, I will use new tires, confirm my setup and see if I can squeeze out a bit more rotation for that last tenth 

 

[Carmine A 2455]

Wow, Kevin.... WOW!!! 

I've admired your work on the FF chassis cars for years. But I never realized you also took the lowly, ambiguous, entry-level TT-02.... and made it into a total track weapon!! Impressed doesn't even begin. 

[wtcc5 5758]

Race Report from the RCKleinSerie event at Indoor Racing Senden

The old body was beaten up from last years action pretty much. I felt the urge to make a new one last week. Same livery, but optimized and combined with a MCIracing Toyota GT One sticker sheet:

 

On Saturday I went to the track for practice. It became a productive day for me, thanks to European- and World-Champion Dominic Greiner. He was looking for company on track and I wanted to practice race rhythm. So we found each other on the same pace with different cars. Dominic tested a new FWD prototype for Serpent and is as fast with it as I am with my KRv5.1 4wd 

Still our runs together made this day satisfying. I haven't driven under pressure for the whole year and wanted to practice this. Dominic tested my focus, by staying close when I was in front. We switched positions often and tried to hunt us. For me it was a revelation to see how much time I loose when missing the apex by some centimeters, also how much speed you need to carry through the corner every time. I learned a lot and gained a lot of confidence in our last run when not cracking under pressure for a long time.

You seldom get a chance to run with this level of driver this close and I was afraid to screw up, damaging both of our cars. In the end our runs really made my day and gave me a good feeling for the upcoming race day.

Sunday came and I was still pretty nervous again. The typical: "I have done that a hundred times, but not if someone watches." -thing. On the first qualifying run I really got a shot of adrenaline which interfered with my motoric capabilities. It hindered my fine precise movements and made the fast chicane difficult to drive. Luckily my adrenaline seemed to be drained for the rest of the day as I calmed down more with each run.

The outcome for the GT-Sport (my class) was very low. We had four entries and one guy didn't show. The other two drivers were relaxed. One just wanted to attend a race, took all the stuff he had at home and put together a (TT-02) car. He drove slow but clean pace, not crashing and with a good situational awareness. The second driver drove this class at the Augsburg RCKleinSerie World Championship Warm-Up just one week earlier. Tim Gehrling finished second behind my great rival from 2019: Chris Funke there. He used the Xpress XQ2S and I expected him to be a lot closer than the other guy.

Qualifying then showed that I had found a very good setup and overall pace. I won each heat with two laps advantage, which was definitely more comfortable than thought. The finals over eight minutes resembled the qualifying. With my gained confidence, I blasted away in the first one and fast built a lead... to roll the car three laps in  Tim then asked jokingly, if I try to make it more thrilling for us  The track marshal was fast and I continued on, this time without more mistakes. In the second final, I make a small mistake again, again without consequences. I am very proud of the third final:

To conserve the tires, I switched rears and fronts. You shouldn't do that normally, but I could risk it. Surprisingly the car loved that bit more steering and rotation, while staying planted. This time I made no mistakes during the never ending eight minutes. The car was great through our fast sweepers, where I could run through full throttle.

This was an easy win. I am extremely happy that the v5.1 is a step forward regarding driveability and control on the limit. The v4.1 and v5 had a tendency to loose the rear suddenly, especially with thick diff oil. This version translates diff oil into safe rotation. Good for drivers with limited abilities like me.

And the body looks like new also  Win-Win! Look at the cool prize the winners got instead of cups or medals:

[Carmine A 2455]

Wow again, Kevin!!! 🏆 V5.1 is an enormous leap. Beyond anything Tamiya ever envisioned when they came out with the TT-02, 11,000 years ago! 🤪🤣

So..... is this enough of, YOUR car to market it as a premium racer? Or is it too much still a Tamiya product, risking copyright issues? 

You got to practice with Dominic Greiner!?!? Another WOW! An honour.... but also a rare opportunity to really hone your skills. It seems you didn't need the help.... but it was sure nice to have.     I had a similar experience, WAY back in the early 80's. Racing semi-Pro, under Team Associated, with the old A-Stamp RC-10 Gold Pan (STILL my favorite buggy to this day, despite improvements). There was a bratty young kid there (I was ALSO a bratty young kid!), named Gil Losi, Jr. He was from the other side of the US then, working on a prototype buggy - Not Quite  the JRX-2 yet, but close.  My car was faster, but his was quicker, more precise in the corners. And we still raced buggies on hard packed dirt or clay (1982-89), not the carefully prepared surfaces today. So the degree of inconsistencies were always there.

I still don't really like flat plate chassis buggies, but can't deny their performance advantages. IMO, molded alumininium pans and plastic pans or the other plastic/composite complex chassis's, seem more scale, to me. Hence why I've always been more of a Tamiya fan...... despite numerous "quirks"!

But I digress.... as usual! Brilliant job on an exceptional machine! 👏🏆👌

[ThunderDragonCy 8380]

@wtcc5 Fantastic writing. I can imagine how great it was running with that top driver on the Saturday. 

[Old_Corny 315]

Congratulations, what a fabulous car and a great write-up - thanks for sharing