Tamiya got it wrong?

[Juggular]

Sometimes the same 210mm might not fit, so it's always good to see it beforehand.  Now I really wish Tamiya paired NSU with M06.  

( But... does he really need a machete to unwrap the plastic? ) 

[TwistedxSlayer]

Ive got a design for front motor rwd tb01 chassis. Need someone good with CAD. A 3d printer the urge to work free. Lol

[svenb]

As much as I love Tamiya I think this thread should be.....

Tamiya GETS it wrong!

4wd drive Capri??🤔

[Kevin_Mc]

5 hours ago, svenb said:

As much as I love Tamiya I think this thread should be.....

Tamiya GETS it wrong!

4wd drive Capri??🤔

Agreed!!

[TwistedxSlayer]

More likely to see a 4wd Capri 8n real life than we are ever going to see a 4wd Ferrari or Honda Civic. Putting that Civic body on the tt02 was plain silly in my eyes.

[GregM]

On 9/29/2018 at 6:06 AM, Juggular said:

 

( But... does he really need a machete to unwrap the plastic? ) 

More like a bread knife, when compared to Dave Jones from EEVBlog, who opens mailbag stuff with a true Machete.

Even better is AvE on Youtube who uses a battery powered pocket chainsaw to rip and tear packaging material. You've gotta see to believe it.

[Mad Ax]

This used to be a big bugbear of mine when I got back into RC but I've kind of got used to it now.

RWD / FWD touring and supercar shells on 4wd touring chassis really doesn't bother me.  RWD touring is hard to drive properly on track.  OK, so I do like the idea of a proper front-engine RWD Supra or 240Z, but in reality it would be something to put on the shelf, not something to drive.  That said, there is a conversion kit floating around somewhere that turns a TT02 into a front-motor, RWD layout - it's for the drift fraternity.  Looks awesome and needs to be used with a gyro because RWD drift is just plain impossible without electronic aids.

Now if it was to be an old FR car then it would have to have a live axle, like a CC01.  In fact I've long considered chopping up a CC01 to make a RWD Mk1 Escort for rallying.  Although in truth I expect it would be impossible to drive on a rally surface without 4wd.

Now FWD touring / M-chassis, on the other hand, is a different thing.  I love driving FWD touring cars and wish there were more classes for them.  At my local club somebody was regularly winning with an FF03 against 4wd touring cars.  I adore my FF01 collection.  FF02 less so - isn't balanced right and doesn't perform as well, for me.  M03 didn't seem to suffer the same problem (or maybe we just put up with it because an M-sized FF01 layout wouldn't have been practical).  And the M-chassis has been a popular platform for club racing for ages, especially for those who don't want to get caught up in the touring car rat race.

The M04 was always a terrible contender and IMO was Tamiya's attempt at doing just what's being asked - putting a body on the right drive configuration.  The problem is they ended up selling loads of entry level cars that were virtually undriveable.  The M06 is a very well balanced car (almost like a little mini GT car) and was banned from our M-chassis group because it was too fast against the M03s and M05s.  And I guess the popularity of M-chassis racing means Tamiya wants to sell these bodies on cars that will compete.  The M06 is an oddball because it's a little too committed to be a car park basher but it's not really a 1:12 GT either, so although it's much more balanced than the M04 ever was, it still doesn't really have much of a place in the market.  Or rather, it has a place all of its own that not many people ever go to.

It's also worth remembering that full-size cars would be mid-engine 4wd if they were built purely to race and no other rules or logistics prevented it.  Only recently we're seeing 4wd supercars using hybrid tech or split gearboxes to drive the front wheels.  For a long time the trade-off of driving both sets of wheels from a mid-engine layout hasn't been worth it but suddenly it is with hybrid tech.  It's even there or thereabouts in electric passenger cars - Tesla can offer supercar performance with a passenger body.

For a long time, cars were front-engine RWD because that's all we could make.  We couldn't fit engine and gearbox under the bonnet to drive the front wheels.  Once we could build engines and 'boxes small enough, passenger cars changed forever.

RC has never had to worry about passenger and luggage space, full-size has never had the freedom to run a single gear ratio.

[Badcrumble]

6 hours ago, TwistedxSlayer said:

More likely to see a 4wd Capri 8n real life than we are ever going to see a 4wd Ferrari or Honda Civic. Putting that Civic body on the tt02 was plain silly in my eyes.

Ferrari FF? 

[TwistedxSlayer]

41 minutes ago, Badcrumble said:

Ferrari FF? 

Learn something new everyday!

 

Didnt know it was 4wd. Had to google it.

 

Ill happily eat my words on that score.

[Badcrumble]

57 minutes ago, TwistedxSlayer said:

Learn something new everyday!

 

Didnt know it was 4wd. Had to google it.

 

Ill happily eat my words on that score.

I had the pleasure of looking over one in the office garage downstairs. In the metal, I loved it. But I’m a sucker for a breadvan.

[Juggular]

14 hours ago, Mad Ax said:

 The M04 was always a terrible contender and IMO was Tamiya's attempt at doing just what's being asked - putting a body on the right drive configuration.  

That is interesting.  

From many members mentioning how RWD would have no weight on the driving wheels, I'm starting to think that even for RWD cars, the weight distribution should be 50:50... I'll be happy if there is a front-motor, RWD chassis, even with half-half weight distribution.    

On the other hand.... M04 (below) is a RWD with a motor in the back.  The driving wheels got plenty of weight.  Why is it bad, I wonder... I suppose the problem could be the front not getting any weight.  Only the servo sits in front of the halfway point.  So... even for RWD, the weight cannot be 25:75, because the rear will push hard, but steering won't work.  (But 75:25 may work for FWD, because front steers).  

M06 might work better, because the battery is right along the center line of the chassis (just the motor is in the back).    

 

 

 

 

 

[GregM]

Juggular, take a look at a typical 1:10 2WD buggy chassis (e.g. DT-02), which didn't changed that much for thirty years up to the recent development of mid-motor 2WD long wheelbase buggies:

What you see is the gearbox and motor sitting behind the rear axle. Massive weight on the wide driving wheels.
Doesn't matter too much if the battery is placed longitudinal or across the chassis tub.
Front steering with narrow "pizza cutter" wheels. They NEED to be this thin to be of any use. Next to no weight found here.

 

Take a look at a typical 1:12 GT chassis, e.g. Tamiya RM-01, and you'll see striking similarities in electronic component placement, tire width and weight distribution. Even more so foam tires are needed to keep the car in control.

 

Now look back at Tamiya's M-02, M-04 and M-06 and you should be able guess their performance just from thinking about their chassis layouts, electronics placement and tire width/rubber formulation. What is your conclusion from that? Please share it with us.

 

This is a review about a 2WD touring car that was originally a 4WD car stripped from its front drive components. You see that the front suspension was changed from classic double wishbone to a GT-chassis front.

 

[Kevin_Mc]

On 10/1/2018 at 7:57 AM, Mad Ax said:

there is a conversion kit floating around somewhere that turns a TT02 into a front-motor, RWD layout - it's for the drift fraternity.

Do you have a link to that?

[TurnipJF]

http://driftmission.com/eagle-racing-tt02-frd-rear-wheel-drive-chassis/

[Kevin_Mc]

Thanks, looks interesting 

[svenb]

23 hours ago, Juggular said:

 

On the other hand.... M04 (below) is a RWD with a motor in the back.  The driving wheels got plenty of weight.  Why is it bad, I wonder... I suppose the problem could be the front not getting any weight.  Only the servo sits in front of the halfway point.  So... even for RWD, the weight cannot be 25:75, because the rear will push hard, but steering won't work.  (But 75:25 may work for FWD, because front steers).  

M06 might work better, because the battery is right along the center line of the chassis (just the motor is in the back).    

 

 

 

 

 

If anything the M04 had too much steering hence the rear coming round very easily.

I raced one(badly) in a local club in the M-chassis class, I had the only rwd chassis. I put harder tyres on the front and soft for the rears to reduce some steering. 22r on the rear and 28-30r on the front.

I tried putting weights on various chassis positions and always best on the back. This could just be my driving style 🤔.

Best race I had was when we raced on polished concrete, trashed the m03/5's.

Biggest problem is lack of front brakes!.

[TurnipJF]

An area where Tamiya do seem to get it very much correct is with their F1 chassis. The motor is ahead of the rear axle, where it is in the full-size car, suspension movement is minimal as per full-size, the cars only really come into their own on a well prepared track surface just like the full-size ones, tyre choice is critical as per full-size and like their full-size equivalents they need a great deal of concentration to drive, but if driven well they are capable of seemingly physics-defying performance. 

[speedy_w_beans]

3 hours ago, TurnipJF said:

http://driftmission.com/eagle-racing-tt02-frd-rear-wheel-drive-chassis/

Was there any TT02 left on that chassis??? 

[Juggular]

14 hours ago, GregM said:

Juggular, take a look at a typical 1:10 2WD buggy chassis (e.g. DT-02), which didn't changed that much for thirty years up to the recent development of mid-motor 2WD long wheelbase buggies:

What you see is the gearbox and motor sitting behind the rear axle. Massive weight on the wide driving wheels.
Doesn't matter too much if the battery is placed longitudinal or across the chassis tub.
Front steering with narrow "pizza cutter" wheels. They NEED to be this thin to be of any use. Next to no weight found here.

 

Take a look at a typical 1:12 GT chassis, e.g. Tamiya RM-01, and you'll see striking similarities in electronic component placement, tire width and weight distribution. Even more so foam tires are needed to keep the car in control.

 

Now look back at Tamiya's M-02, M-04 and M-06 and you should be able guess their performance just from thinking about their chassis layouts, electronics placement and tire width/rubber formulation. What is your conclusion from that? Please share it with us.

 

This is a review about a 2WD touring car that was originally a 4WD car stripped from its front drive components. You see that the front suspension was changed from classic double wishbone to a GT-chassis front.

 

4

 

Ooh, is this like a brain-teaser?  I like brain teasers!  

Everything is "guestimation" since I have none of these.... but here it is.  

[M-02]  F:R 30:70 distribution.  I think of the CG (Center of Gravity) by imagining a hammer.  M02 has most of its weight in the rear.  If you grab where the servo is, it would be very well balanced for some hammering (with the rear wheels being the hammerhead. Don't actually hammer, they'll break the wheel)  The front will be useless as a hammerhead since it gets no weight.    

So, driving the M02 would be somewhat like sliding down a snowy slope sitting on a round shield.  Rear pushing hard would make it easy for the car to spin also.  I would put 50 to 80 grams of weight on the sponge bumper (about the weight of 1-2 standard servos or 8-12 coins).  

 

[M-04]  F:R 60:40 distribution. This is "reverse M-02" in that the front has the motor, FWD.  But the steering is also done by the front wheels.  If you imagine grabbing it by the ESC, the front end would be slightly less effective as a hammer than the M02.  The motor is closer to the center than the M02.   The battery is also very slightly more centered.  The servo and the ESC are away from the heavy battery and the motor, spreading the weight to the rear.  As I've said earlier, I think even front-motor RWD should have 50:50 weight distribution.  But this being FWD, Front steering, 6:4 distribution could be ideal.  

 

[M-04]  F:R 40:60 distribution.  Imagine no motor installed.  Then the battery, ESC, and the servo would make the weight distribution almost 50:50.  But if you install the motor, and the weight goes backward.  I think this is a bit more balanced than M02.  The yellow line is where I suspect the Center of Gravity might be.  CG might be similar to M02.  But the distribution is quite different.  Instead of the motor and the battery centered around the CG, the motor sticks out in the back, and the battery also stretches forward.  The weight is more "spread out."  If you put the battery along the yellow line (90 degrees angle from what you see), the CG will move farther back, and that would make the M06 spin out as easily as the M02.  

[CG vs distribution]

As I was writing this, it occurred to me that CG (Center of Gravity) and weight distribution are two entirely different things.  

Think of it as steering a skateboard.  If you stand and steer, you could be nimble.  If you are lying down on your belly on the skateboard, and try to steer, it could be difficult.  The CG could be dead center in both cases.  But if you are on your belly, the weight is far more spread apart.   

Even though M02 and M06 might have similar CG, the distribution is more spread apart in M06's favor.  I'm inclined to think that M06 would drive better than M02.  The longer the tail, the harder to spin when turning, just like skateboarding on your belly.  There is a risk of front lifting if you put motor behind the rear wheel, but that's less annoying than spinning out all the time when turning.  

[DT02 Buggy design]  

DT02 is a sound design.  I have it, and I also have DN01 Zahhak.  Even though the layout looks almost identical, Zahhak is about 1cm longer in wheelbase.  The battery goes back a bit.  Slightly too far to the rear.  Tamiya sells "high-traction chassis."  I didn't know what it was when I bought it.   It's just 35 grams heavier, to move the weight forward.  I twisted both chassis several times, I did not think "high-traction" was more rigid.  DT02 might be slightly better balanced when it comes to weight distribution.  

I suspect DT03 suffers from a similar problem.  I guess to improve the stability, Tamiya made it longer.  Just like the skateboarder on his belly, the longer body would mean better stability.  However...not if the weight is all in the back!  The front might be too light.  DT03 is like an off-road version of M02.  I would guess DT03 is slightly more prone to spin-outs than DT02.  If that's the case, I wish Tamiya had put the servo sideways (like the red square) and move the battery forward an inch.  I think that would have made it more stable (or I would put some weight on the nose).  But I don't have DT03 to experiment.  

 

[Juggular]

I meant to add that it's fun enjoying RC in my head. 

It's never accurate, but imagination is the ultimate poor man's RC!!!  (Until I save enough for XV01, DT03, M06, etc...)

 

[GregM]

Thanks for your evaluations, Juggular.

Here are some of my thoughts in reaction to your statements:

- Instead of an M-04, you've pictured an M-05?

- When thinking about the TRF201/DN-01 "High Traction" chassis, I came to the conclusion that it might be designed to be more flexible than the rigid regular chassis. It might be made for running on a different surface. The friendly guys on http://www.oople.com should be able to help answering this question.

- The DT-03 should be more stable and less likely to spinout than a DT-02, thanks to its longer wheelbase - at least in theory. All things I said about the DT-02 should apply to it as well.

 

So we have spent time taking weight distribution into account. If I were you, I wouldn't pull my hair out for "battery placement an inch forward" or "sideways servo versus longitudinal servo placement", or adding weight "here and there". As long as the chassis design itself is sound, I would rather concentrate on getting the right tires for the surface you run your cars on (use foam inserts while you can), and getting the spring rate right.

 

If you're interested in a former R/C race car driver point of view on the M-02 and M-06, please have a look at Jang's short reviews on them:

http://ultimatetamiya.com/cars/m02/vw-beetle-classic/

http://ultimatetamiya.com/cars/m06/m06-pro/

 

[Kingfisher]

On 10/2/2018 at 8:34 PM, Juggular said:

I meant to add that it's fun enjoying RC in my head. 

 (Until I save enough for RM01, F103, F104, etc...)

 

I fixed your post for you. 

[GregM]

Juggular, I'd like to make one last thing clear: Adding weight towards the front of an RWD car isn't what you want. You're following a misconception.

You should want the majority of weight on the rear to bring the power of the driven wheels to the ground and to keep your car in a stable line. Also wide tires.
You should want as little weight as possible on the steered front, and go with thin tires.

This is why the RWD M-chassis faces a major design challenge: Make a car drive well even though the weight distribution might be not enough rearward biased - having the same type of tire width all around, and no foam tires, isn't doing a favor as well.

For a given car that you want to adjust to your liking: Don't go for weights. First of all, get to know the chassis by doing driving practice. And then, go for the correct tire (experiment with width, softness and pattern) and spring rates to aid your driving style and type of surface. And then practice some more.

On acceleration, you should want a lot of understeer to prevent your car from spinning out on straight sections. So: a lot of traction on the rear, little on the front.
In turns, you should want some oversteer just by decelerating your car, which pushes the front down the ground and make your steering more effective.
This is how RWD works.
 

 

 

 

Then, you could still try weights, but mostly you'll not need them by then.

[Juggular]

12 hours ago, GregM said:

Thanks for your evaluations, Juggular.

Here are some of my thoughts in reaction to your statements:

- Instead of an M-04, you've pictured an M-05?

- When thinking about the TRF201/DN-01 "High Traction" chassis, I came to the conclusion that it might be designed to be more flexible than the rigid regular chassis. It might be made for running on a different surface. The friendly guys on http://www.oople.com should be able to help answering this question.

- The DT-03 should be more stable and less likely to spinout than a DT-02, thanks to its longer wheelbase - at least in theory. All things I said about the DT-02 should apply to it as well.

 

So we have spent time taking weight distribution into account. If I were you, I wouldn't pull my hair out for "battery placement an inch forward" or "sideways servo versus longitudinal servo placement", or adding weight "here and there". As long as the chassis design itself is sound, I would rather concentrate on getting the right tires for the surface you run your cars on (use foam inserts while you can), and getting the spring rate right.

 

If you're interested in a former R/C race car driver point of view on the M-02 and M-06, please have a look at Jang's short reviews on them:

http://ultimatetamiya.com/cars/m02/vw-beetle-classic/

http://ultimatetamiya.com/cars/m06/m06-pro/

 

So it is!  My ineptitude never fails to surprise me!  (Logically speaking, It shouldn't be surprising since it happened more than once)  I was studying M05 instead of M04.  (But M04 looks almost identical to M02 so, in hind sight, with some embarrassment, I am sneaking the M04 into the M02 category).  And did I put "M05" when I meant "M06?"  This is the problem of not actually having any of M-chassis.  I get a wrong chassis, and I don't even know it!  It gives me an incentive to buy at least one M chassis!  

I wouldn't pull my hair out.  At my age, hair could be a rare commodity, you know.  Thank goodness I haven't gone bold yet. (I don't think I would.  But my dad is, so no pulling hairs! No no.)  

And you invited me to think about chassis designs?  Of course, tires would have an impact.  I always (unsuccessfully) think of ways to get tires sticky.  We were talking about FWD, RWD, etc, and how some M chassis are easier to control than others.  I thought, surely the weight distribution of the battery was a natural extension?  

It's all cool.  My idea could never be 100% right.  (Even Einstein thought quantum physics was a nonsense)  But maybe Tamiya could get an idea how we think about things.  They could be like, "look at all these jokers, but... maybe RWD with a front motor could be viable, if the weight distribution is 50:50... why don't we ask R&D to try it?"  (That's a hint, Mr. Tamiya!)

Besides, it's always fun thinking about RC mechanics! 

[TurnipJF]

An easy way to remember which M-chassis is which: odd numbers are FWD, even numbers are RWD.