Honza

Tamiya used to make #54372. It was included in XV-01TC pro kits, with some luck, you could probably still find one.

No, XV-01 uses narrow XJ/XM mounts. FF-03 has XD/A mounts. The modern equivalent are these: https://www.tamiya.com/english/products/54881/index.html https://www.tamiya.com/english/products/54880/index.html There could be a problem with front-rear mount, which is mounted upside down on FF03R. I'm not sure if the adjustable mount allows that.

I am, but I've been running 3D printed gears in my rally car as a long term test. So far, they wear slower than the original gears that they engage. PETG seems to be surprisingly wear resistant, as long as it's kept from heating too much. It would be probably an issue on a high speed model, but that's not a case on a rally car. Unfortunately the belt was routed through the spur axis, so XV-01 slipper was out of question. I probably could modify an TD4 slipper, but it would provide only basic functions. I'm more interested in torque splitting solutions, and there are quite interesting options in that area. Exactly, after an asphalt race with my MF-01X, it's clear that getting all heavy components as low as possible has to be priority.

@Wheel_Nut there are two benefits: The motor is now separate from the gearbox, so it can be anywhere on the chassis. That gives some space for experimenting with weight distribution. The second benefit is option for center diff or slipper, shaft drive has much more options, including some exotic ones, like true LSD or one way slipper. Also, I never liked belt drive cars and shaft drive is easier to cover. My idea is something like XV-02/XM-01, but without things I don't like a out that layout - I don't like the upright battery and shape of the bathtub that doesn't leave much space for wheels.

First sketch of the gearbox layout. I tried to make it as compact as possible. Maybe I was too successful, diff now only fits in this orientation, if I flip it, it'll crash with the large bevel gear. And that's assuming I drew it correctly. I'll use MF-01X diff outdrive as an input - it's just long enough to fit two 3mm thick bearings alongside the gear. Because of how XV01 gears work, I need to make custom bevel gears with 1.6 ratio. While I tried to draw bevel gears before, this it's the first time I actually design them from scratch, so let's see how it turns out. Next step will be the gear case.

Wow, it's been a while since I made any progress with this project... The original idea was to get XV-01 to continue. But I couldn't find any second hand one and getting a new one, just to throw 90% of parts away doesn't make sense. And getting just parts I need is not economical either. So, here's new plan: Merge This^, this and this project into one. Each has its strengths and weaknesses. I'd like to combine all strengths, while getting rid of weaknesses. I'd like to built an M1:10 version first, then upscale it to full size TC - the opposite would be more complicated - so it's natural to start in this thread. The XV-01 gearbox internals and M-07+XM-01 suspension will stay. But the rest will be replaced. I already started putting some ideas on "paper" and looks like it will be possible. So stay tuned.

That's different, if the molds are designed for FRP, they account for shrinkage of that plastic. But if you put FRP into mold designed for polycarbonate, it'll come out with different dimensions because of different shrinkage. Different polymer will make even more difference. That being said, Tamiya did make FRP variants of polycarbonate parts on rare iccasions - non-reinforced chassis for TT-02 is polycarbonate, if I'm not mistaken, while reinforced chassis is ABS-CF. There was also reinforced variant of TL-01 B parts.

There's so much weight transfer that it's not hard to let the inner wheel slip. You just need enough power to overcome grip - which usually is the case with spec class. With that power, the outer front wheel just pulls the car into corner.

I've never used anything but the basic paper spacer 😃 Heat has nowhere to go in TT-02 anyway, so I think it wouldn't hurt. Regarding cooling, what about one of those ring shaped fan mounts used in TC racing? I'm not sure which solution would be more effective, but small fan can remove surprising amount of heat even without heatsink

XV-02 ball diffs are simpler and maybe lighter? I wonder how oil filled gear diffs compare.. If there are aluminium out drives available, it could shave additional few grams. Staying at drivetrain, aluminium swingshafts at rear could save another few grams. Unfortunately they wouldn't last long in front. Edit: at first look, i thought it's an S-variant with steel out drives and swing shafts. Plastic drivetrain of the stock is likely lighter, so disregard this part. TB03 had nice, lightweight servo mounts. I wonder if they (or similar ones) could fit in TT-02. More expensive upgrades would be probably carbon damper stays and titanium screws.

It was just design philosophy starting around 2000. TL-01, WT-01 WR-01/2, M-03/4... This design consists of fewer large molds that are easier to produce, which is great for entry level chassis. M-05 was a bit more complex variant of this design, M-06 returned to more standard bathtub design, which continued with subsequent chassis.. so M-chassis aren't weird, it was just that the more known Tamiya M-chassis came from the "backbone chassis" era. MF-01 is the only current M-chassis that follows this design for a simple reason, it's just TL-01 and M-05 mashed together, with minimum new parts - those again being relatively simple chassis molds.

Thank you Looking back now, the design is quite primitive with many mistakes.. but that was the purpose I can now use what I learned for future projects. As soon as I have something to show, I'll make a new thread

That turned out great! Looks like an actuall autocross buggy, unlike the monstrosities that are running on tracks nowadays.. I wonder, if the opposite could be done by stacking the inserts to reach 280mm WB of standard buggies. It would be quite nose heavy, but that could make interesting handling.

You're missing a lot here... TB series is basically dead, unfortunately... TB-05R re-release is likely the last thing We'll see. TA-series is quite interesting - Tamiya often experiments here, so it was first Tamiya to feature new suspension style. TC-01 - another interesting chassis, unfortunately Formula-E body is disproportional and Tamiya took its time to release it with another body that would take advantage of its build.. M-series - This is where Tamiya shines, IMO. The nicest bodies, decent chassis in the form of M-07, M-08 and XM-01. Even MF-01 can be fun. But there's also MB-01/BT-01 - TT-02 with the few good things removed... According to reviews, TRF421 isn't bad at all. There's no need for yearly upgrades, like other "high-tech luxury" manufacturers do, just to fix mistakes they did a year earlier due to rushed development.. what hurts TRF is lack of factory team, which is why they stopped with buggies.

1) that's a big one. Weight transfer during acceleration/braking has huge effect on available grip on front/rear axle. So which axle is driven is going to change handling quite considerably. Generally, under power/braking FWD is more likely to understeer, RWD to oversteer, 4wd depends on other circumstances, it has some characteristics of both. What hurts RWD the most, is lack of front brakes. Braking by rear wheels just causes loss of traction and directional stability. There's reason why real cars limit rear braking power. 2) center diff allows front and rear to spin at different speed, which can help in certain situations, since front follows longer path in corner. The disadvantage is, that, depending on settings, it moves handling towards FWD characteristics under acceleration and RWD under braking, because torque is usually split 50/50, but weight on wheels isn't, so lighter axle is more likely to break traction. One way diff also allows front to spin faster, but the tradoff is loss of front brakes. No diff - since the wheels are locked, power is transferred proportionally to weight transfer. The disadvantage is, that in tight, slow corner, front and rear wheels will "fight" for traction - similar to spool on an axle. 3) that's more to do with overall packaging that's usually determined by drivetrain. Belt driven cars have transverse motor, which creates minor front/rear interta, while shaft is left/right. Also, shaft can twist the chassis a little, which may have an effect. Belts can somwhat dampen vibrations in the drivetrain. More complicated drivetrains are more about energy loss. GF01 and similar is very inefficient and take up a lot of space. 4) I definitely felt difference between ball and oil filled gear diff on a low grip. Ball diff was better. My theory is, that ball diff transmits more or less constant force to the more loaded wheel, when the other spins, while oil filled diff is more dependent on speed difference. Open diff will just spin the inner wheel, outer wheel loses all the power when that happens. That moment is quite noticeable and it's not desirable.