Just to introduce this post a little, as it’s quite a divergence from the other content here… I used to race RC cars back when life was a little less busy and expensive, but sadly drifted out of the hobby when I started university about 12 years ago. With the world looking a little different in the last couple of years I really wanted to get back into the hobby with my son so the hunt started for a suitable chassis.
Choosing and building the TT02 Type-S
After much searching I settled on the Tamiya TT02 Type-S which seemed to have a good following in the drift, speed run and rallying circles in the non Type-S guise. The Type-S however appealed to me for the extra tuning options available so I hit “buy” and got a chassis each for me and my son.
Both cars initially ran a fairly modest setup of a Hobbywing Quicrun 1060 ESC, the stock Torque Tuned motor and a cheap £5 generic servo. I did however treat myself to some hop ups out of the box:
- Aluminium prop shaft (54501)
- Aluminium prop joint (54502)
- Motor mount (Fastrax FTTA020B)
- High speed gear set (54500)
- Tamiya oil diff – used in the front, with 5k oil (53792)
- Yeah Racing oil diff – used in the rear, with 10k oil (TATT-020)
- Yeah Racing aluminium steering set, more on this later (TT02-042BU)
- Team Associated servo mounts
- Some 3D printed parts, mainly the battery brace and front bumper brace
The First Run
Our first outing at the local track, an indoor carpet track in a sports hall, went very well. I was amazed how close the stock suspension, camber and toe settings were to a suitable level for racing and pretty much left the car as-is for the first few weekends.
I really enjoyed the Torque Tuned motor and when geared right it was competitive with the 13.5T brushless cars in the class out of the corners. Straight line speed however was a let down (although on its own phenomenally quick).
You’ll notice on the photo a set of 42mm aluminium universal drive shafts. These are 54515 clones from eBay which worked fine with the torque tuned motor, but I’d later find these were inadequate for more powerful motors.
Making Some Improvements
I bought a 2nd hand 13.5T motor and added my Nosram Matrix Evolution brushless ESC (which is probably a museum piece by now) after a few weeks of enjoying the more sedate pace of the torque tuned motor. Gearing was an unknown quantity so I kept it stock (but with the high speed gearing) and the performance was better than the torque tuned motor but no where near the pace of the other racers. Sadly, with the 0.4 Tamiya pitch gearing I had limited choice so had to persist with this gearing for the first evening.
The next race weekend I salvaged a 68t 48dp spur from my TC4 and this opened the door to a wider gear selection owing to the many pinions I’d kept from my earlier racing days. The pace had certainly improved but this uncovered some minor handling issues which were not an issue at the lower speeds.
I’d also encountered issues with the Tamiya screw heads. The best drivers I had were all Phillips drivers so I’d managed to damage a couple with the regular disassembly while I tweaked various settings. I imagine for the casual user these screws will be fine as the diffs and other components are likely to not be accessed as often, but for me I opted for a set of M3 screws in various sizes from www.accu.co.uk (not sponsored, I bought these and was very pleased with their pricing and service).
Lastly, I discovered the 54515 clone universal drive shafts on eBay were cheap for a reason. In total I managed to damage 3 pairs of these, all with the same failure point, so had to revert temporarily back to the dogbones. To be honest, aside from some initial issues where the dogbone popped out (remedied with a bit of foam) there wasn’t a huge difference in lap times and handling. Nevertheless I bought a set of genuine 54515’s for the front only and these are working just fine. For the rear I’ve kept with the dog bones as there’s not much articulation of the joints during normal racing and I’m doubtful I’d see an adequate return on performance for the cost of the 54515’s.
3D Printing – Rear Toe Plate
One of the bits missing from the TT02 Type-S that you’d find on a typical racing chassis is droop adjustment. I’d never really found droop a major change to handling characteristics but as another racer at the track suffered from a rapid unscheduled disassembly of the rear of his TT02 Type-S I wanted to make a part that could strengthen the rear toe plate as well as give some droop adjustment. This v1 of the part worked well but had too much flex where the droop screws sat. Screws are M3x10 grub screws.
I tried a couple of iterations of the design which worked ok, but I spotted this article from “thercracer” and he covered a part made by Fiber-Lyte (who I was familiar with from my old racing days and even have a giant Fiber-Lyte sticker on my tool box!). I bought the part but still needed a way to retain the hinge pins, so made a simpler brace on the 3D printer.
This worked well for a few weeks but I wanted to decrease rear toe from the kit 3 degrees down to 2 or 2.5 degrees. I bought Tamiya part 54967 but discovered this doesn’t quite fit nicely with the droop plate as there’s a small bit of additional material that pushes into the plate. Also, despite keeping the 3 degrees of toe with the new plate for initial testing I’d somehow introduced some serious handling issues with the rear end wanting to swap with the front when off power – akin to running a one-way diff. And with the repeated screwing and unscrewing of the toe plate screws I’d managed to foul up the threads quite a bit. With a lower confidence in the rear end integrity during a crash, and wanting to avoid the results of a crash a fellow racer encountered I created a new bracing that I thought would hold together in a crash. It didn’t.
This saw a quick swap back to a spare tub (thankfully Tamiya spare parts are quite reasonably priced…unlike the hop-ups) which had in-tact threads. I think the downfall was my use of Loctite when the threads began to show issues, which didn’t react well with the ABS plastic. As a test to cover future issues I’ve bought some brass inserts, heated them and then melted back into the correct positions on the damaged tub although I’ve not yet had chance to test how well this’ll work.
So far with the replacement tub (which is the stiffer version) I’ve not had further issues with the threads.
3D Printing – Rear Hinge Pin Ball Socket
Not really sure the exact name for this part, but after the earlier problems with the rear end and only just managing to locate all the parts strewn across the track I decided the next week would be pretty much R&D for new 3D parts including a version of the ball part.
I had no expectations this part would be any good but wanted to confirm the dimensions and ‘feel’ of the car would remain correct. This held up OK but at some point in the first round a rear wheel made contact with a track marker and snapped the part, although this was able to be ‘popped’ back in and worked just fine for the remainder of the race. This was prior to the tub being replaced, but after a more substantial brace was added, so the rear toe plate threads were still causing headaches and allowing a small amount of movement of the rear toe plate. Potentially without these threads being a problem the 3D printed ball part may be race capable. It’d 100% be fine for car park bashing.
3D Printing – Front Toe Plate Scoop
One of the difficulties at the local track is that it’s mixed with off-road classes, so the open practice hour has the jumps in situ. While this prevents a decent practice with the track layout due to slowing down for the jumps it can still be useful to get a quick idea if something that you changed during the week is actually working correctly. To avoid the front toe plate being fouled on the jump lip I created a small ‘scoop’ that allows the car to ride up over the lip easier. This isn’t a part that benefits the car during the race, as the jumps are removed, but helps prevent damage to the carbon fibre part or the threads.
3D Printing – Fan Mount
I’d not really suffered with overheating but noted the rest of the cars ran with some kind of fan or fan/heatsink combo. My motor would typically come off and be touchable for up to a second which I was told is fine, but being risk averse I chose to add a small fan salvaged from a Cisco switch I used to use in my home lab and had been destined for the WEEE pile at the council tip for a while. I needed a way to mount this and didn’t like the idea of using a heatsink that could slide over the motor terminals so I created this, which ‘clicks’ into the lip of the tub chassis and accepts (what I think is) a 20mm fan. The car has suffered some impacts yet the fan mount has held up fine. Temperature has also massively improved and I feel comfortable gearing up another tooth or two.
3D Printing – Bearing Cover
I discovered this WIP design on Thingiverse for a light weight bearing cover. This printed fine and fit nicely, removing a decent bit of weight over the gears. There’s no noticeable wobble induced on the prop shaft either.
https://www.thingiverse.com/thing:5113984
Fiber-Lyte – Bearing Cover
With my order to Fiber-Lyte I added this part in as the cost was so low it made sense. Again this is a part covered on thercracer however the author suggested to use a 5mm and 3mm spacer. Given I didn’t have these but did have the design from Thingiverse I decided to do a remix, lowering the height of the part to 5mm and removing the bearing support material. This part combo works just fine and there’s no noticeable wobble.
Yeah Racing Steering Set
I’d bought this to add immediately during the build as I’d heard that the TT02 steering had a lot of play and almost every photo of a TT02 that’s being used competitively had an aluminium steering set fitted. Just as Technology Connections says in his reviews, “through the magic of buying two” of the TT02 Type-S I could easily compare the standard setup to the ‘upgrade’ and was disappointed. The amount of slop was either equal or worse with the upgrade so after a few races I reverted to the stock setup but using the low friction step screws. I used to race the Team Associated TC3 and TC4 Factory Team versions and even these had slop, so I’m not interested in chasing a perfect zero slop configuration as I understand a certain amount is inevitable. But the amount of slop that the upgrade brought in wasn’t acceptable (albeit it didn’t seem to have a negative impact in the races) so has been removed and likely to be used on the rally bashing chassis only.
13.5T Brushless Carpet Setup
With all the above in mind, the car is closely approaching a level of handling and speed that is as competitive as I can get it. There’s gains I can make over the next few weeks in rear traction that are likely a zero cost item, and after that I’d be looking at a new ESC (as mine is ~15 years old) to extract as many amps and improve straight line speed.
In terms of electronics the car is running:
- ESC: Nosram Matrix Evolution
- Motor: Trinity Revtech 24K 13.5T
- Servo: Metal geared KO Propo
- Radio: Futaba 3VC with Spektrum module and receiver. Retrofitted a LiPo cell for the transmitter
- Battery: Voltz 5000mAh 2S 7.4V 50C Hardcase LiPo
- Charger: Overlander VSR-Mini+ 10A 100W AC Balance Charger
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