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Old 03-08-2017, 03:55 PM   #106
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Independent suspension can have rollcenter far lower than pancar style chassis. Or can you get rollcenter under chassis with live axle?
Chassis that use "V-links" instead of a single center ball can have the roll center below the chassis, or even below ground level. The roll center is at the geometric intersection of lines drawn through the links.
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Old 03-08-2017, 04:07 PM   #107
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So we're basically already trying to find technical workarounds to alleviate the pain of driving a 2wd car (here: bringing brakes to the front) while still preserving the 2wd "status"

get it?!?
I understand that the fastest and easiest to drive 1/10 scale car will probably be 4wd. And if fast and easy to drive is the only criteria, then case closed.

But my original post was just meant to ponder possibilities for the sake of realism, I guess. I think it all comes down to a balance between "scale realism" and "fast and easy to drive".

Put philosophically, if all we are concerned about is "fast and easy to drive", then why do we put headlight stickers on our shell, or clear windows? I think it's for some realism. So, rwd fully independent suspension is just another (although more difficult) step towards realism.


Or, someone needs to make Tesla bodyshells - then electric powered all wheel drive will match the shell.
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Old 03-08-2017, 04:53 PM   #108
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I understand that the fastest and easiest to drive 1/10 scale car will probably be 4wd. And if fast and easy to drive is the only criteria, then case closed.

But my original post was just meant to ponder possibilities for the sake of realism, I guess. I think it all comes down to a balance between "scale realism" and "fast and easy to drive".

Put philosophically, if all we are concerned about is "fast and easy to drive", then why do we put headlight stickers on our shell, or clear windows? I think it's for some realism. So, rwd fully independent suspension is just another (although more difficult) step towards realism.


Or, someone needs to make Tesla bodyshells - then electric powered all wheel drive will match the shell.
I like the idea. Without demand, most brands won't take the risk. The new yokomo has my interest. I've only just stepped into racing last summer. More this summer, even giving F1 a shot.
If price is right on the Yokomo, I'll buy it. Another got another person curious. If it works then maybe can get few more. Create our own local class for it.
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Old 03-08-2017, 05:47 PM   #109
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Or, someone needs to make Tesla bodyshells - then electric powered all wheel drive will match the shell.
And we need Tesla's Autopilot feature too
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Old 03-08-2017, 11:33 PM   #110
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...yeah there have been some that have it lower, Pantoura, ART Agitator, and the PH10 to name a few. Not sure how close the new Mcpappy comes.
From what I've found these are all pivot ball suspension... So rollcenter is still high.

From grip point of view, live axle don't have any real advatage over IRS.

CoG part of yout argument might make sense - but difference wil be minimal, as most of weight is in electronics, which are located very similarly in both chassis

Only advantage of pan car styled chassis is direct drive, with its low friction and low weight, it can work better on fast, high grip tracks. But on low grip, technical tracks, IRS will work better.

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Originally Posted by howardcano View Post
Chassis that use "V-links" instead of a single center ball can have the roll center below the chassis, or even below ground level. The roll center is at the geometric intersection of lines drawn through the links.
That's true, but how many RC chassis use this suspension? All I've seen are either pivot ball or T-plate.

So we've come to why RWD touring class won't happen..

People who race AWD don't want RWD, because it'd be too challenging to drive.

People who race RWD with live axle don't want lose simplicity of their chassis.

Both groups will find reasons why it can't work and won't even try.

Those few, who want to try something new are not enough to start new class... FWD has some fans and few manufacturers do competitive class chassis - still, it's almost dead...

Last edited by Papi; 03-09-2017 at 02:51 AM.
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Old 03-09-2017, 12:06 AM   #111
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Xpress K1 and M1 both have 4 wheel independent suspension and rear wheel drive.
Xpresso M1 1/10 Mini MR 2WD M Chassis Kit #XP-90002 - Car Kit
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Old 03-09-2017, 01:41 AM   #112
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You've been given plenty of reasons why it won't work (or is unlikely to work), and you've also been given plenty of examples of people's own experience of a RWD rubber-tyre cars not working.

But I don't think there is any negativity here.

We would all agree that the hobby is about enjoyment. If you will get enjoyment from building a RWD rubber-tyre car - then do it!
All I heard was theoretical rhetoric based on limited experience. I was asking specifically about a reversed one way diff, and if anyone shared my sentiment that it may work to facilitate braking the front tires. And as far as a RWD VTA car, it would "work", whatever that might mean to you. It wouldn't "work" against a contemporary 4wd VTA but that's missing the point. I see a homemade 2wd VTA class, where only the folks that knew what they were doing and understand the physics of these cars could even get on the drivers stand. I know there's other engineer minded nerds like myself out there that would take great pleasure in building a one-off, mostly true to original trans am car philosophy, and competing with it. I'm certain an appropriate tire size/compound could be ascertained. Saying anything can't be done without any experimentation is just plain lazy.
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Old 03-09-2017, 01:46 AM   #113
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You'll find that a 4wd car handles very badly if you remove the front drivetrain.

If you want to get a rwd full suspension, rubber tyre car that actually handles, you've got quite a project ahead of you!
Describe "handles very badly".
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Old 03-09-2017, 04:16 AM   #114
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People who race AWD don't want RWD, because it'd be too challenging to drive.
Unfortunately the hard truth for most of EP DRM drivers today...

On that yokomo - my kids run my old DTM cars at some club races. I think it actually teaches them bad habits. If that yok is priced properly and isn't TOO much of a handful to drive, I will buy them this very car. I like the concept a lot. Plus, less weight when they bang the boards means less breakage
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Old 03-09-2017, 05:51 AM   #115
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Could be interesting, if the price is reasonable... Here in Switzerland, it is available for pre-order for 299CHF... ouch.
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Old 03-09-2017, 05:56 AM   #116
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Originally Posted by roosterreagan View Post
All I heard was theoretical rhetoric based on limited experience. I was asking specifically about a reversed one way diff, and if anyone shared my sentiment that it may work to facilitate braking the front tires.
From the top of page 2 of this thread:

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My first RWD touring car (the Porsche shown above) was initially [B]configured with a TA-06 one-way pulley installed backwards on the front gearbox, to allow four-wheel braking instead of freewheeling. The braking was significantly improved as you'd expect, and it no longer suffered from snap-oversteer when braking, but the acceleration was still terrible and the handling was very squirrelly when applying any power at all. It also shredded the Vaterra 31mm rear tires I used in no time. It's possible those HPI tires would help (I think they have them as wide as 34mm?), but ONLY if they're made out of a properly-sticky compound -- S-compound isn't good enough, and D- and M-compounds are a complete waste of time. Pro compound is the only thing that will come close to offering enough traction with only two drive wheels.
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Old 03-09-2017, 01:03 PM   #117
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Describe "handles very badly".
I'm not kidding. I suspect there are some ~reasons~ for this.

4wd covers up a lot of sins. Including that of "lacking weight transfer". Touring cars, seem to be set up extremely stiffly, and expect chassis flex and a spool up front to do a lot of the work for them.

While this does simplify tuning, it is a very different philosophy from how ~real cars~ do it. (There's a succesfull racer or two at my local track who've told the stiff chassis theroy to pound sand, and are running soft springs on a very, very stiff chassis.)

I expect that softer springs, and a stiff chassis would lead to a reasonable to drive car...
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Old 03-09-2017, 01:57 PM   #118
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4wd covers up a lot of sins. Including that of "lacking weight transfer". Touring cars, seem to be set up extremely stiffly, and expect chassis flex and a spool up front to do a lot of the work for them.
I'm hoping you put "lacking weight transfer" in quotes to point out the seemingly popular yet incorrect assumption that stiff chassis and springs don't transfer weight. Of course, weight transfer occurs with the same total for a given car at a given lateral acceleration regardless of spring stiffness; the springs (and dampers) just allow us to change the proportioning of weight transfer between ends of the car during cornering.
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Old 03-09-2017, 04:00 PM   #119
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that Yokomo on asphalt with GT-R CRC tires and 17.5 w/2S.. Hmmm...handful of fun!

My RC10 DS was a blast and would keep up with the TA02 cars, but then the HPI RS4 came out...
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Old 03-09-2017, 09:03 PM   #120
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Enjoying my RWD



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