Honza

Tamiyausa already lists spares for BT-01 - chassis extension (you can compare it to MB-01) and transmission parts for FMR layout https://www.tamiyausa.com/shop/spare-parts/rc-bt-01-fl-parts/ https://www.tamiyausa.com/shop/spare-parts/rc-bt-01-e-parts/

Not true. The motor itself works in short bursts and electronics limit the current around the target position - that's the humming/hiss when you put a load on the servo. It's not meant to be stalled with full battery voltage on it for long periods of time. What happens if you put too fast gearing on a motor? Now imagine it stalls. The servo tester - or a microcontroller - are the best solutions.

That would likely lead to the motor burning out, if there's no current limiter.

An old analog servo might move a little after connecting the battery to the red and black wires. But for controlled movement, you need to generate proper signal to the white wire. What do you want to do?

Make it 3D 😁 You can design one part that mounts into original shock tower mounting points, then a new tower that goes in front of the shocks and connect them. There appears to be enough space to do that. It will look like it would cause more load around the chassis mounting points, but since the shock forces will act into the same point, it will be more or less same as the stock tower, as long as the new part won't flex too much. You may use the body post hole for additional reinforcement.

Some parts arrived, so I had to add them to the car, although it's not big a progress in the build. Unfortunately Tamico sold out some items before I managed to order them, but the most important bits are there. First, the suspension mounts. Although I like the modern solution with exchangeable blocks, they cannot be used on TB-03 due to reinforcement that runs under the inner blocks. Tamiyas idea was to put 3mm shims under a block flipped upside down, which cannot be really done on the newer type of block. Rear. I'm using 1XA setting, inspired by stock setting of TB-05R. The plan is to use the adjustable mount on the rear for easy toe-in settings - the mount will be in the next order. Front - 1A blocks front/rear. Don't mind the arms, they are just placeholders. I also replaced the scuffed propshaft. I missed opportunity to get the option part, but I kinda like the look of the silver shaft. So this is the current state. Still a bunch of the car is missing and I'm not even putting in all screws, since I expect to disassemble the whole thing again, as the new parts will arrive. But it's slowly going together. And back to hibernation...

I think that Himoto/HSP/Maverick onroad cars use dogbones that fit Tamiya, the length is around 50mm

RWD M-05? These older M-chassis have split arms that can be shimmed to move the axle a few milimeters.

DB-01 or TD-4. Even those might experience some drive line issues on the carpet due to high grip, I'd definitely run them with a slipper. TRF buggy would be the best, but probably unobtainable.

The inner mounts are XM, that means that you can get up to 3,5deg. Thinking about it, the XV-01 suspension has quite low roll center, which can also contribute to Slow side-to-side weight transfer. You can try to shim the arm mounts and inner pivot on the tie rod to compensate.

Do you run stock rear toe-in? Iirc, it's 1,5° on XV-01, while M-06 and M08 have around 3°. That might be the root cause.

There was a buggy with a similar layout in the early 00's - ttech predator.

Bearings are the biggest must have, as well as metal pinion. Those are required if you want to run on a regular basis. V2 chassis, if you're running a square lipo. Front CVDs won't wear out as quickly as the stock dogbones. Metal hex adapters will clamp on the driveshaft instead of being stuck inside the wheel and losing your cross pin Others are more like "nice to haves" to improve drivability, oil shocks to make it less bouncy, high torque servo saver to reduce play on the servo arm, ball or oil filled differential to reduce wheelspin, adjustable top links to reduce play, V2 arms to add downstops(only works with V2 chassis)..

It does, but then there's the "S" version with proper suspension, metal hinges and option of adjustable outer mounts. MB-01/BT-01 has even the outer mounts integrated, so there's no way to replace it with more capable suspension design - unless someone design one from scratch.

They did this with TA and TB series. With TB-04/TA-06, Tamiya introduced PRO variant. Apparently the non-pro didn't sell well enough to continue selling the cheaper mid-range models, TC-01 and TD-2/4 currently being the only exceptions.

I didn't expect them to make an evolution. But they could at least keep the quality. I don't hate MB-01 concept, although it's a bit weird.. but I hate ABS plastic being used on everything, plastic hinges, integrated suspension mounts, limited gearing.. it's a step back even compared to TT-02. I'd be happy to see TB-03 with TRF420 suspension. I don't think they'll ever do TB06, TB05 have been discontinued for years and replaced by kits I mentioned.

(Edit: I know, it's not official Tamiya.. but it could be. And the mini rally block tires suck, so if the shell can be fitted with 1.9 wheels without looking too ridiculous, people will want to do it.) It's not issue only in S wheelbase, it appears that there won't be much place for front wheels either. But I might be wrong. At the same time, Tamiya reintroduced them for buggies and it's option for XV-02 from it's introduction. I personally prefer ball diffs and open gear diffs for rally. XV-02 uses the separate suspension blocks in a way that doesn't allow to get to standard TC block width. That's why the "asphalt spec" RS pro comes with the off-road suspension.

I know, I meant that XM isn't replacement of MF-01X. Meanwhile MB-01 replaces M-05/6 and it's definitely inferior quality wise. In similar fashion, TB-series were split into TC, XV and TT-02SRX, neither of which can fully replace it.

Battery position - I don't like it on XV-02, I like it even less on XM-01. They've done it to put the spur to the center of the car... Which is not necessary either. I'd like to se a bathtub closer to TT-02, with possibility to swap ends to choose between front and rear motor position. Something like MB-01, just better. Rear wheels are very close to the bathtub in S wheelbase. It might not be possible to mount 1.9 wheels. Same with front. 1280 bearings on differentials. I understand they wanted to make it compatible without th TT-02, but it unnecessarily complicates design of ball differential. Suspension mounts - that's not really an issue on XM-01, but I don't really like the solution on the XV-02, it doesn't allow to fit standard TC suspension properly. All they had to do is using "E" adjustable suspension blocks and their plastic equivalent instead of "A"...

Unfortunately Tamiya seems to be doing the exact opposite. Replacing cheap plastic (PC/PA in M-05/6 and MF-01X) with even cheaper plastic (ABS in TT and MB/BT). I mean, XM-01 is nice, but it also costs twice as much and still has many design compromises so typical for Tamiya...

Careful what you wish for, Tamiya still could make a 4WD version of MB-01 to replace the MF 😁

That's exactly what I'm trying to make. The overall layout will be similar to my MF-01X conversion, but with bathtub-style chassis, which would provide some cover for battery/motor/electronics.

They have more in common than it seems. BT-01 comes with same 70T spur as TT-02, and its pinion gear count is shown in the MB-01 manual, because it uses the same gearbox. Notice that the 29T position also shows "24" on the bottom. So it can be easily compared to TT-02 motor positions. If there's any difference, it's only because of poor quality and it would lead to excessive wear of stock gears - so your modification solved another issue I guess that with 0.6 gears, you could easily fit a 30T pinion, if anything like that exists.

The alternative would be belt with 2 extra pulleys to get over the motor and hoping that it won't crash into itself Overall it's less complicated than MF-01 or TA02.

With the XV-02 diff, it should be also possible to fit the 39T ring gear for 2,43 internal ratio. But if it is possible to fit 48p and 64p gears with proper mesh, it's much easier solution with more flexibility. I'm just curious why @qatmix and @ChrisRx718 's findings are so different.