wtcc5's TT-02 race development and race reports

[ThunderDragonCy 7882]

Fantastic as always Kevin. I am interested in the long arm design. If the top and bottom arms are the same length, how do you get camber gain? 

[wtcc5 4896]

My upper arms are shorter by the same amount the Xray T4 had it, but of course I run a little more camber and caster and it suits the car very well.

[ThunderDragonCy 7882]

Ah, OK. Sounds good! 

[wtcc5 4896]

In a discussion the topic of the Inline KingPin angle popped up. Here my response to that: Our 1/10 have the kingpin inline in front, so I don't see (and recognized) a problem in my design there. In the rear 1/10 touring cars have the angled "kingpin" and/or the shorter upper link. My design does not have this, but favors a simple hub design and long arms.
Regarding the balance, this design is the best so far. Steering and response was superior since the v2. The rear was ok, but outdoors it had a tendency to be snappy and needed to be calmed down, especially if I favored steering and rotation. With the v4 design this nervousness is gone.
The long arms on the car make a difference regarding the amount of caster and camber. Camber of 1° or 1.5° never worked for me on any (standard) tc. For the v4 I use 0.5° more camber than before and the car loves it. Also anti-roll-bars and springs need a different approach. Overall a much softer setup than before. For example: The soft 7.0 and 6.5 range of Mugen springs work great here.

Yesterday, I spend 3/4 of the day to find out what exactly caused my rear suspension angles to be off. I suspected the droop plate being not correctly manufactured. I printed one and found that nothing had changed. Measuring the arms also showed no manufacturing fault. I then checked the tub chassis and the droop plate is not sitting centered. The mounting holes are off by 0.4mm . Uncool! I paid 6€ for it, I want it to be perfect... Just kidding  But still a not welcome surprise. I used excenter Awesomatix ballnuts for now to compensate.

I also made some more pictures with tires on. I really like how low the car looks on some pics:
























 

[ThunderDragonCy 7882]

Bravo

[wtcc5 4896]

For the article in the magazine I had the idea for a new livery for the Bwoah! body. Unfortunately it wasn’t possible to get it in time, but I ordered it anyway. This is it:

 

 

 

 

 

[svenb 3778]

wow

that sir is excellent

[wtcc5 4896]

After the last practice at my indoor track, I came home with some homework. Mainly the rear damper mount needs a stronger redesign, but also the rear hubs will get a design update to keep the active toe arms better in position.

While this is going on, I will also make my own anti-roll-bars and design a proper spool. Goal is to use the TRF420 spoolcups together with the gear half of the standard TT02 diff. All parts to work with arrived today:



The rear bones are a little short with their 44mm and will be replaced with the 46mm variant.

[wtcc5 4896]

The new parts are added.

 

 

I also bend the anti-roll-bars. I have sets in 0.8mm/1.0mm/1.2mm/1.5mm. Unfortunately there were no 1.3mm and 1.4mm wires available...

 

[Collin 1956]

Who signed that shell?

Ah, and ... great job... you know...

 

 

 

[wtcc5 4896]

@Collin: That was Peter Lindner who painted it.

[Sweatpants 101]

sadly none of your pics are loading for me?  anyone else have this trouble?

[wtcc5 4896]

On 11/23/2021 at 7:05 PM, Sweatpants said:

sadly none of your pics are loading for me?  anyone else have this trouble?

Strange it works in Safari and Chrome for me…

 

 

The upgrades for the rear axles finally arrived and got installed:



Firstly, I beefed up the lower damper mounts:



The hubs and toe arms got changes to make them sturdier regarding impacts and keeping the angle setting:





So that is how it looks now.

The next race was pushed to February, so there is no hurry from my side.
In fact I will focus on one race of the Tamiya Euro Cup in the coming days 

[ryback 61]

On 11/6/2021 at 9:49 AM, wtcc5 said:

I really like how low the car looks on some pics:



 

Loving the thread.

The car looks almost low enough that it could drive upside down, if you took the body posts off!

[wtcc5 4896]

The time before last time, I wasn't happy with the balance as I found the rear not predictable. Yesterday then the car was on rails. I discovered a lot of dirt on the outside of the tires, that was really hard to remove. It was as black as the rubber, so I must have missed it and thought my setup was at fault. Luckily it was my fault. I drove a 10.0s fastest lap, about a tenth faster. Overall the car was very good on the front axle. Balancewise it is ok, but the rear is not still there. What I still look for, is the smooth rotation of the rear to allow for faster direction changes. Right now it depends a little too much on the front. It is the off throttle rotation I am still missing.
The overall grip is impressive. Touching or riding the curbs doesn't bother the car at all, grip roll is no topic.



Unfortunately I miss practice, as if some of my skill vanished in the Corona time. I somehow seem to have my old habit back: Having one larger hiccup/stupid move per run. I was also easily disturbed by others yesterday. Not cool. In the afternoon then, it was one hiccup too much, I banged the car into the board and broke the rear left shockmount... just stupid...



Of course it wasn't repairable and my day was over. That killed the fun I had until then.


Every run is a test drive with the car and the parts are sturdier than they look. One guest driver yesterday saw the car and was wondering if these thin carbon arm will widthstand a crash. They do. The rear shockmount was on my list already. It was flexing too much for my liking and maybe causes the rear indoor to behave like it does (outdoor it was nice). With the broken part, I was now forced to do something. As I also had a friend of mine testing a new touring car prototype for a large R/C manufacturer, we could "talk shop", which strengthened some of my ideas for improvement.
In the end, I changed a lot parts on the v4.1. In fact so much, that I should call it v5 right away 

So, that is how it looks now:


I changed the bumper, the lower and upper arms, the upper plates, the droop plates, the front lower shock mounts and the rear upper shock mounts.


The bumper wants to break at the same place and got more "branches" to direct the forces into the chassis.



Quite obvious are also the solid, closed lower arms. Even though, I moved the shock much closer to the centerline, it still flexed the arm more than I liked. With so much surface on the arm, it invited me to move the droop screw in the droop plate rearward, to reduce scrubbing and have it more protected. I also changed the lower shock mount. The idea for the 4.1 was to have the possiblity to move the shock even closer to the axle if I use the standard front hub. But I never do, so I removed that freedom and have now more strength in the lower mount.

This also had an influence on the upper arm. The front strut now can be more straight. At the rear of the upper arm I also had overlooked a collision with the rear mounting point. The steering turnbuckle could touch it at full throw. You can see on the first picture, that I had to take material away.  The rear mount was moved 2.5mm to the front to prevent that. You can also see the spool:





I did the same changes for the rear regarding the lower arms and droopplate:




And finally the rear shockmount got a new design. My dream would be to have it made of aluminum. It is now separated from the rest of the plastic part underneath the upper plate:



Another thing I am never happy with, are the rear body posts. Horizontal or vertical, I cannot decide. So they change with every version. It is now the third revision and the best in my opinion so far. It also sports a brace to reduce the flex for indoor use.


With the race coming up in several weeks and my bad driving, I want to have the car rtr at all time. So I made a version of the rear shockmount for my old fdm printer and installed it. The upper carbon plate needed a little modification and I cut off the old mounts of the plastic part underneath:











This design just needs comparatively short body posts 

The location fits very good to the Zooracing BWOH body:




I printed two more mounts just in case I have my stupid hiccups again. This is how the car looks now:

[wtcc5 4896]

I am back from a very nice practice (satur-) day.
With now really old tires I could improve by two tenth and now have the car right where I want it to be setup-wise. It turns and rotates with ease and the rear end is planted, but knows when to help with rotation. The balance is now exactly like I want it.
Some good drivers were there too and so I got a good comparison how my car performs in comparison to the ETS 13.5t class. Good drivers with Awesomatix were running their best laps around 9.5s. The world champion Dominik Greiner drove 9.2s - 9.3s. I ended up with 9.8s as fastest lap right before my tire set died (I hope to have the 9.7s in the bag with a fresh set).

So that was an awesome day. The car so good to drive also brought back a little confidence regarding my skills. The printed damper stays held up well. The stupid "hiccups" also nearly disappeared. Well, with this setup they aren't so easy to make...



I still destroyed a part when I had a coming together on track after a misunderstanding:



Without a bearing inside (I ran without anti-roll-bars in the end) this part is of course not strong enough to withstand an impact...

My setup:




And a short video of the car and a run:

https://youtu.be/EH1zKIyjZJk


If you haven't already, I would like to invite you to check out my youtube channel 

https://www.youtube.com/user/KR1ae/videos

[wtcc5 4896]

I spent another saturday at Senden for practice.
I put on new tires and was surprised how long it took to groove them in. Nearly 200 laps until they were good.
Then I managed a miracle lap (fresh charged battery and sauced tires) of 9.795s. Just six or seven hundreds improvement with new tires… Somehow I thought I would be faster…



Oh well, the car was good, but showed too much roll in some high load situations (looked like it collapsed). I put on slightly harder springs all around and since then it was on rails. The car last time out was great already, but now it got better in all areas. It got even easier to drive and allowed very similar laptimes. The shown run was with two slower guys on track. This couldn’t harm my rhythm. Sometimes I had to wait for a couple of corners until they let me through and the lap still became good. Also driving the fastest time of this run on lap 22 shows the potential.



This run was also the fastest so far. I improved by over four seconds on 5 minutes. If I find another 3.3 seconds, I could break into the 31L. The 20s laps shown came when the transponder signal wasn’t caught by the timing line. With the car so good on curbs, I took maybe a little too much 

[lukej 319]

This car always blows me away!

Would love to get your opinion on a club rule book that I think is far too open.

Luke

[wtcc5 4896]

There will be a last production run of the TT02 KR soon, before I am going to close this chapter.

If one of you is seriously interested in buying the custom parts for the 4.1 final edition, please let me know in the coming days if you want one (or more) 

[lukej 319]

31 minutes ago, wtcc5 said:

There will be a last production run of the TT02 KR soon, before I am going to close this chapter.

If one of you is seriously interested in buying the custom parts for the 4.1 final edition, please let me know in the coming days if you want one (or more) 

You know I am in for one!

[wtcc5 4896]

With the help of two friends I was able to get two cool upgrades on the car.

 

I disassemble my car first:


 

Here now a picture of both driveshafts:


 

Weight comparison:






The new shaft ready for installation:




In the car:










And now the spool. A beautiful part:


 

Explosion view:


 

The standard diff-bevel-gear-part needs a little treatment. I widened the center hole to 9mm and the four screw holes to 3mm for stronger screws (with extra flat heads, taken from the TB-03):









Assembled:




Weight comparison:






In the car:






Especially because of the driveshaft the slop in the drivetrain is reduced drastically. The spool is not only light, but allows the use of blades and Tamiya TRF420 outdrives.
 




 

[lukej 319]

3 minutes ago, wtcc5 said:

With the help of two friends I was able to get two cool upgrades on the car.

 

I disassemble my car first:


 

Here now a picture of both driveshafts:


 

Weight comparison:






The new shaft ready for installation:




In the car:










And now the spool. A beautiful part:


 

Explosion view:


 

The standard diff-bevel-gear-part needs a little treatment. I widened the center hole to 9mm and the four screw holes to 3mm for stronger screws (with extra flat heads, taken from the TB-03):









Assembled:




Weight comparison:






In the car:






Especially because of the driveshaft the slop in the drivetrain is reduced drastically. The spool is not only light, but allows the use of blades and Tamiya TRF420 outdrives.
 




 

I cannot wait to get my hands on one. How close to the final version is this?

Luke

[wtcc5 4896]

9 minutes ago, lukej said:

I cannot wait to get my hands on one. How close to the final version is this?

Luke

I hope you are not disappointed, but the set will not include the drive shaft and spool. Especially the spool won't be easy to get into production for an affordable price (below 100€). For the drive shaft I need to ask if the friend who made it, can/wants to offer more.

The car in CAD looks a bit different, but is ready for production. I am just waiting of the offer for the cfk parts.

[wtcc5 4896]

I am back from a practice day. In different forums many wondered how the one-piece driveshaft would cope with a flexing chassis... and I can tell now, that there is no negative effect, neither in handling/feeling, nor in laptimes or bevel gear wear or sound. The car was a blast to drive yesterday and all parts held up without noticeable wear. And I involuntarily tested the strength of a lot of parts unfortunately:



Ouuff! That was quite a shock! I had a lot of good runs until then, no mistakes, consecutive times within two tenths, then I was a bit wide on exit to a short straight. That happened before, so I expected a small parallel tap on the board, instead the car got stopped instantly  The left front axle hooked into the edge of a protruding board... I really thought the day was over. Luckily it wasn't. Inspecting the damage, the upper arm sacrificed itself to save every other loaded part, except for the aluminum steering turnbuckle (it got bend). The lower hub ballstud got pulled out of its cup. So the impact energy was reduced step by step and saved hub, lower arm, titanium ballstuds and steering assembly.
I just changed the upper arms (wanted to use another geometry anyway) and straightened the turnbuckle. I checked the car for possible damage, but didn't find more. Back on track the car ran as great as before. I am really a lucky kid!



I continued testing. The Volante 28 tires ran great also. They don't feel so grippy, but seem to not scrub so much speed into the corner. In the end they were as fast as the Sorex 28. I also did a install the TRF420 front hubs to have a comparison with my hubs and to see how the different Ackermann amount would work. I expected them to be more aggressive, but they weren't. They provided less steering and the feeling was less connected to the car. In the end I lost about 2 tenth every lap. That was a little surprise, but a welcome one for sure.

Right now, the pre-production KRv4.1 is laying on the bench in parts for a full check, cleaning and race preparation (for sunday).




Both spool and shaft made a good job. I am very happy that they did, because they look fabulous on the car 

 

[Pylon80 2630]

On 2/11/2022 at 10:16 AM, wtcc5 said:

With the help of two friends I was able to get two cool upgrades on the car.

 

I disassemble my car first:


 

Here now a picture of both driveshafts:


 

Weight comparison:






The new shaft ready for installation:




In the car:










And now the spool. A beautiful part:


 

Explosion view:


 

The standard diff-bevel-gear-part needs a little treatment. I widened the center hole to 9mm and the four screw holes to 3mm for stronger screws (with extra flat heads, taken from the TB-03):









Assembled:




Weight comparison:






In the car:






Especially because of the driveshaft the slop in the drivetrain is reduced drastically. The spool is not only light, but allows the use of blades and Tamiya TRF420 outdrives.
 




 

I really like the one piece shaft 👌

The TT-02 bathtub just doesn't flex enough to *require* a separate prop shaft and adapters. Good job as usual!