MB-01 - How bad can it be?

[ChrisRx718]

Starting this thread now and I'm bumping my build up the list because the XM-01 has recently been announced and I want one of those too.

The MB-01, what is it?
Is it to replace the M-07 / 08? Definitely not, those are far more accomplished. Is it to replace the M-05 / 06, since the 07/08 took a different (and more expensive) path? Likely, I reckon.

It's essentially an M-chassis sized TT02. You can orientate the motor and diff housing to either the front or rear to drive either axle. I think the announcement of the XM-01 rather puts to bed any rumour that there would eventually be a 4WD MB chassis variant. It would be doable, but would require a few new parts and leave no space for a battery. 

It's not been very well received, the MB-01. That's putting it politely. Poor turning circle, issue with friction ball suspension tolerances (popping out on light impacts) and lacklustre performance.

So I bought one. I have no justification here, I'm not really sure why I did. I had a feeble excuse that I needed a home for my MK2 VW Golf bodyshell, but I ended up just building a 2nd M-05 out of my leftovers.

If the XM-01 had been announced before January 12th, rest assured I would not have bought this 

But, every dog has his day. So let's dive in (I'm not even sure this unloved chassis has a build thread on TC yet?)

So this is a "Kit in a Bag" from L&L Models, and it only felt appropriate to use a bodyshell I haven't found a home for yet (but bought on impulse...because Gran Turismo)

The bronze TE37s are wrong I know - do not panic - I since found the correct black ones in my stash.

You'll notice straight away that I've already "invested" in some blue gold. But not of the OEM Tamiya kind - it seems even Tamiya hates this little M-chassis ginger stepchild...

Sport Tuned motor (Kit in a Bag doesn't have a motor / electronics). I couldn't find a 29T Steel 06 Mod pinion, if anyone has a source? So I'm rocking the alu-cheesium one which comes with the kit for the time being.

Step 6 sees you install a big old max-pad of foam:

 

Its purpose became obvious later.

And by the end of the first couple of pages we're already ticking boxes:

• Excess of Blue Gold
• Motor Installed
• Bathtub Chassis has entered the chat

What's this? More blue gold already?!

I bought this piece on a whim. I'm going to guess this is where the servo goes, which seems like a pretty safe guess 

Not one to pass up a bargain, I nabbed this from Japan for cheap. I figure if it doesn't fit / work, I can put it in my TT02 Budget Rally Car build (another stillborn project)

I've never assembled an oil-filled gear diff before, and this experience was not enlightening! Getting this cross-pin to behave is an absolute pig of a job. As is keeping the cross-pin and bevel gears (with teeny-tiny shims) all together as you drop them into the diff housing. Much, much swearing happened.

Finally getting it together was a relief. The tiny 1.5mm hex-head screws are way too soft, Tamiya. Being black in colour I thought they would be strong steel, but I managed to round one easily. The fact they package a spare is telling...

Rear upper arms in-situ, you simply insert the diff housing assembly at the end of the chassis where you want driven wheels. This tiny cross-connector transfers power from the spur shaft output to the diff casing. And it rattles like a child's toy 

I'm not dismantling it myself now, but I suspect you could shim this ~ 0.5mm of movement out of the shaft if you were inclined. Frustrating though, I do wonder how much noise that will produce when running...?

Rear diff casing assembled and lower arms installed at the same time. I was surprised that the shock tower fixed to the bulkhead with just a single 3x10mm screw.

I've ran out of image space and need to wait for this thread to be moderator approved. More in part 2...

[Alex97]

3 hours ago, ChrisRx718 said:

it seems even Tamiya hates this little M-chassis ginger stepchild...

That's one way to sum this chassis up 🤣

 

I agree that the M05/6 needed an update for their budget m chassis and this ticks many boxes however I haven't heard a single good review for this model, it's a shame as the principle is great. 

[Pylon80]

I love that shell and livery! And the chassis is probably going to look good with these blue bits 😀

 

[ThunderDragonCy]

29t hardened alu pinion

https://smddirect.co.uk/collections/pinion-gears/products/29-tooth-0-6-module-pinion-gear

[Kowalski86]

On some websites you can find a bundle of no-name, coated aluminum 0.6 pinion gears, that's what I ended up going with. It comes with a few bigger pinion gears if you want to experiment with smaller spur gears.

One thing to be mindful with blue bits on the MB01, it's a bit of a "pig" for an M chassis in terms of it's weight.

[ChrisRx718]

I will check out the pinion links thanks guys.

When you say pig, do you mean it's relatively heavy? 

Interestingly I'll have an M06 on the bench next with the same 210mm wheelbase, I'll weigh both of them to see how they compare once laden with electronics.

[svenb]

Not good to be ginger on this forum is it!

[Kowalski86]

56 minutes ago, ChrisRx718 said:

When you say pig, do you mean it's relatively heavy? 

I compared mine to a fairly hopped up M05 and the MB01 weighed a bit more, it was almost as heavy as a TT02.

I might be similar to an M06 though, I remember those being a bit heavy too.

[Andreas W]

Following this with interrest - mostly out of curiousity. I got myself a Carten M210 FWD not long ago (also in need of a competent chassis to put a Golf MK2 body on), but as you said things would probably have been different, if I knew about the coming XM-01. 

 

Kowalski86 did astonishingly well in the racing by post with his. Not bad for a heavy, sloppy body-holder at all, but his expectations were probably almost on point zero .  From there things can only get better. 

[Verskis]

17 hours ago, ChrisRx718 said:

I couldn't find a 29T Steel 06 Mod pinion, if anyone has a source?

Here you are: Team Corally - M0.6 Pinion - Short - Hardened Steel - 3.17mm | EuroRC.com

[Kowalski86]

4 hours ago, Andreas W said:

Kowalski86 did astonishingly well in the racing by post with his. Not bad for a heavy, sloppy body-holder at all, but his expectations were probably almost on point zero .  From there things can only get better. 

Thank you, yes my MB01 did okay as a postal racer despite it's wider turn radius. The extra weight and near even weight distribution means that you can power out of turns predictably.

I reccomend buying low friction suspension balls if you really want smooth suspension movement. There's Tamiyas aluminum set, and a stainless steel set "Xtra Speed I think? Via RCmart", Also keeps it from falling apart over minor bumps in the road.

[ChrisRx718]

I have got some low-friction balls (oo-er) but only on the front end. The pukka Tamiya TT02 ones were OOS so I too have Xtra Speed (who bizarrely sell them in a quantity of 5?!)

But this lunchtime, when I really should be cooking my egg and soldiers, I think I may have 'solved' my pinion gear conundrum...

 

Take a bunch of parts I had put to one side for my TT02, following a read-up on @qatmix RC Racer's website (I'm not even a Racer, what am I doing with my life?! )

Voila!

I've done the math and this combo gives me a 5.2 FDR (vs. 5.83 originally)

3Racing 96T spur with 48T pinion. Even I can do those maths  

Will it be any good? Have I chronically over-geared it? Will it get hotter than the surface of the sun?

This answer and more in the next update 

 

[JimBear]

How bad can it be?

Mucho Bad? (or Better, given the Egg and Soldiers cooking upgrade?)

 

[Kowalski86]

..

[alvinlwh]

.

[Honza]

21 hours ago, ChrisRx718 said:

3Racing 96T spur with 48T pinion. Even I can do those maths  

Will it be any good? Have I chronically over-geared it? Will it get hotter than the surface of the sun?

This answer and more in the next update 

Isn't this combination a bit too tight? 29T/65T position on MB-01 should be equivalent of "J" position on TT-02 mount (26T/68T), for which the article you refer to, suggests 46T/96T combination. 

It's quite weird that the metal mount doesn't come with slots to mount the motor. That would make the gearing selection much easier.

I'll be watching this build. Isn't it fun working around limitations of Tamiya's design? 😁

[ChrisRx718]

9 hours ago, Honza said:

Isn't this combination a bit too tight? 29T/65T position on MB-01 should be equivalent of "J" position on TT-02 mount (26T/68T), for which the article you refer to, suggests 46T/96T combination. 

It's quite weird that the metal mount doesn't come with slots to mount the motor. That would make the gearing selection much easier.

I'll be watching this build. Isn't it fun working around limitations of Tamiya's design? 😁

I think it's all out of the window really - the slots on the MB-01 are very different to the standard slot positions on the TT02 - the High Speed gear set isn't listed (at least to my knowledge) as an "official" MB-01 Hop-Up, it just happens to fit because they share a similar design (albeit you don't need the spacer sleeve, just 2x 0.5mm shims to take out the slack).

I tested with a 45T thru to 50T. 46T wouldn't reach the spur at all, a good 2-3mm gap. 50 wouldn't quite squeeze past, 49 felt too tight (but still span) and so I ended up on 48T. I'm also surprised that Yeah Racing didn't just do an elongated slot - but the Hop-Up motor mount came out so quickly following the MB-01 release that they can't really be faulted!

Just waiting (impatiently) on some 1050 bearings in order to finish this now. I have some en-route from Plaza Japan, they can't come soon enough (I can't bring myself to assemble it with bushings, only to have to dismantle it straight away...)

[Honza]

@ChrisRx718 This is weird, I tried to do some math and arrived to similar numbers as the article. 2-3mm gap doesn't sound right, since the two teeth difference does 0.4mm difference in gear radius.

BTW, when I checked MB-01 manual, I noticed that the stock mount is marked "20/22/24" on the bottom - I guess that's for the 70T spur that'll be used in BT-01 - and also aligns with E/G/J positions on TT-02.

[Kowalski86]

The only way that I know of to really alter the FDR, is to run a TT-01 spur gear and hunt down a 31t or such spur gear. They're out there if you go with no name stuff.

BTW, I'm pretty sure that these no name pinions are re-labled and sold under Ruddog.

[Honza]

9 hours ago, Kowalski86 said:

The only way that I know of to really alter the FDR, is to run a TT-01 spur gear and hunt down a 31t or such spur gear. They're out there if you go with no name stuff.

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.

[ChrisRx718]

9 hours ago, Honza said:

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.

I should point out that the TT02 and MB-01 share no resemblance in terms of motor mount, hole positions or even stock gearing. The MB-01 uses a unique spur gear (65T) vs. TT02 (70T). TT02 I think comes with a 22T pinion, MB-01 is 29T, all 0.6 mod. 

I quoted The RC Racer as I had used @qatmix's guide to plan ahead and buy some parts for my TT02 build, but by sheer coincidence they fit the MB-01 chassis and the spur I purchased fit inside the gearbox cover too.

 

[Honza]

2 hours ago, ChrisRx718 said:

I should point out that the TT02 and MB-01 share no resemblance in terms of motor mount, hole positions or even stock gearing. The MB-01 uses a unique spur gear (65T) vs. TT02 (70T). TT02 I think comes with a 22T pinion, MB-01 is 29T, all 0.6 mod. 

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.

 

[ChrisRx718]

Update time...

For the drivetrain I'm using Yeah Racing M-chassis universals. I understand these used to have a bad name in the racing community, but I'm not planning on racing and these are much nicer and easier to obtain than metal dogbones - and much, much nicer than the kit standard plastic drivetrain parts!

Aluminium clamp hexes - of course. We spared no expense (though we probably should have)

Starting to look like a car now. A big plastic brick of a car, but hey...

Instead of the kit-standard "Big Plastic Washer and Screw" assembly for the king pins, I've used cone washers on the top side and countersunk washers on the underside. I've no idea if this will be of benefit, but it sure is more Blue  

Metal Balls!

As I said above; unfortunately I couldn't get hold of the Tamiya ones at time of building so I'm running these Xtra Speed equivalents. They seem to fit fine.

Finally the extra 4x 1050 bearings for the front arrived: 

I'm also going to use the M-chassis wheel axles which came in my BB-01 BBX. I think these are steel - not that it matters much, I just didn't want to use the stock plastic ones.

But we have a problem:

Despite running 55 OD M-chassis tyres (53215) the wheel-arch cut-outs on the little Toyota MR-S body were still really tight for the overall wheel diameter. Not helped by the chassis itself being rather wide:

Not ideal.

I managed to shave a few millimetres using these:

It was an improvement, but it wasn't enough for me to retain the Toyota body. More on that in a bit.

Dampers - I went with TT02 CVA dampers, tempted as I was to go really overkill with some alloy dampers this little chassis just didn't deserve them, the more I built the more head-scratching I was doing. Maybe those early reviewers were right to pan the MB-01 after all 

I did perhaps spoil it a bit by using some Ltd Edition "Milky Blue" on road springs. They're actually a bit too stiff for this chassis, I'll likely change them for something softer after the first shake down.

Steering next:

A basic Savox metal-geared digital servo, TT-02 servo saver and a turnbuckle intended for the M-05 / 06. 

 

Hmmm. Plastic fantastic. The manual advises some little plastic bushings which are on one of the parts trees for this bit, but 850 bearings are a direct fit. The steering assembly 'bulkhead' is a Yeah Racing product.

All assembled. I also used (wasted) M-05 Low-friction King Pins on this steering assembly - the supplied king pins are made out of the softest metal known to mankind. Even using the correct Tamiya medium JIS driver, the heads just wanted to become mush. So I had to resort to using these king pins before I made a real mess of things.

The amount of slop is not acceptable, even in the plastic parts, you expect better.

Ran out of picture space, I'll have to make another post...

 

[Kowalski86]

The "cone" things will hold everything together better, that wasn't a bad idea.

I ran mine with friction shocks, CVAs, and even TRF shocks. The TRFs were a complete waste on something so sloppy, the best setup was to just use the kit springs and stock CVAs. Just run a medium pre-load in the back of going RWD.

If you're keen on hop ups, I'm pretty sure that I saw a glimpse of a hopped up MB01 at one of those shows. There will probably be some upgrades once more bodies have been released.

[ThunderDragonCy]

Thanks for putting this build up. It's been very instructive, and it is a real shame to see that the quality is as low as rumours suggested in places. I hope it runs nice once it is built. I also hope the BT01 is a bit better. I rather like the idea of those.