Gauging interest: Greyscale Racing MR-CG chassis

[eztuner12]

Hello color01,
This thread is great, did not know of its existence. Thanks to hrdrvr, responsible for sending me here.
Hope to see & read more info throughout the development of this very nice chassis.
Cheers

[color01]

Right now it's all about optimization... the last outstanding problem we're having at the moment is flex plate deflection, so I'm thinking we can counter it by beefing up the flex plates but mounting them differently as to avoid increasing roll resistance. On top of that I've added an adjustable center spring in the space between motor and battery pack.



The new "look":





The geometry of the chassis braces has been changed a bit to stiffen the most critical areas more. I also successfully integrated all three body mount styles (94MM, 98MM, Lexan) into one upper deck, and increased the size of the disk damper to use standard damper disks if desired.

eztuner- you had asked me about a ball-link/center-point style steering setup; while I can't provide that for you personally, one servo saver, two balls, two rod ends, two metal rods, a couple screws, and shoe goo for the servo should be everything you need.


At this point in time I definitely don't want to instill any false hope for anyone, so let's just say the car will be ready as soon as I'm all set up to go, in "summer '08". I will keep everyone posted, of course, especially if I manage to find help in machining parts. I do want to see a few of these compete in the PN series this coming summer, so I'd better get crackin'.

[Cherub1m]

Hi color01

I am really liking the new design. I cant wait to see the final product.

Keep up the excellent work

[eztuner12]

Hi color01
First, thx for providing the optional linkage steering system, I certainly do not misestimate the actual system you design, which I will give a tray at first.
One question, regarding the flexing your confronting. Is this flex deflection occurring from the front -to- rear of the lower chassis plate? If so, did this deflection occurred when the batteries where on the up-front position as your previous design?
Cheers

[color01]

The deflection is side-to-side, and caused by the "beams" of the flex plate bending in the wrong direction. The chassis flex itself is completely cured thanks to the chassis braces.

Back to the flex plates: from all the proto parts I've made it now seems obvious that any long, thin flex plate will suffer from deflection to a certain degree, the previous cars getting it the worst because the flex plates were both very long and made of softer G10 (rather than CF). The new flex plates will have a negligible amount of sideways deflection when running, much like the Kyosho carbon plates for the Mini-Z F1.

Thanks for the comments guys!

[Tjay]

Hey Color01, I was just wondering. Did any of the guys from RCX run your car? I want to know how it did. I know few guys were running different chassis not just MR02...

[color01]

Nope, unfortunately I missed that opportunity thanks to hardware gremlins (i.e. what I'm trying to fix in these last few posts). In the short term I'm looking at having cars ready for the TGR Hurda Challenge in the DC area, the NYC championship, and the PN Regionals (whenever those dates are finalized). I'll of course bring me and my car to Inside Line every so often starting the summer, so I'll try to find you sometime and see what you think about its performance.

[Tjay]

I can definitely drive your car with the kt-18 tx, now that I've been practicing with it . Definitely looking forward on running/testing your car...

[eztuner12]

Hello color01
Yes, any long, thin flex plate will suffer from deflection to a certain degree, even with CF, if it is to long without a support point, or compensate by providing a thicker plate. Adding a thicker plate will indeed add weight to the chassis; to avoid this extra weight, you can drill holes to the brace plate to reduce its weight wile maintaining its strength. Another option can be a double deck flex-brace, one plate on top of the other with a couple of mm of space between them, attach with aluminum posts or screws, at each extremes of the plates and on the center of the plates or at its weak points, where some flex my occurs, Also to reduce weight, holes must be drilled. Something like a bridge beam.
This is only a thought, hope it assist.
Cheers

[color01]

TJ- thanks!

Richard- So you're suggesting that I use two flex plates on each side? I'm not sure I understand what you have in mind. If it's anything like I'm imagining right now, the roll resistance will be off the charts.

[eztuner12]

color01
Yes, that’s what I meant, but did not considerate that it would affect the chassis roll that bad, only that it would stiffen the chassis, and yes achieving a less chassis roll doe to the chassis twisting effects when under pressure. Sorry didn’t help. I am very enthusiastic about your chassis.
Cheers

[color01]

Richard- if this were a t-plate car I would welcome more roll resistance, but since it uses side plates then unfortunately I'm stuck with a compromise. I do like your idea of cutting holes in the flex plates to tune the way they flex though. Maybe like this?



The slot would help the flex plate twist a little bit in the roll direction but would keep the bump-direction bending to the long beam to maintain consistency.

BLT- Hardware gremlins as in the current flex plates not functioning perfectly. Not to worry, this'll be taken care of soon.

[eztuner12]

Brian.
This is an excellent blueprint angle pic to view the complete rear end suspension geometry design.
Yes, the holes are great, considering it wont make the flex plate fragile.
Have you considerate, adding springs to the side plates, where you have the screw & nut that attaches this side plates to the rear flex plate? And some how connect it to the upper rear plate, where it seems you will place the rear body post, some thing like the spring you placed under the friction disc.
Cheers

[color01]

Originally Posted by eztuner12

Have you considerate, adding springs to the side plates, where you have the screw & nut that attaches this side plates to the rear flex plate?

Yes, that's more or less how the last few cars had their side springs setup. I didn't really like it since you couldn't change bump resistance without affecting roll resistance. So now the plan is to have the center spring handling bump resistance and different flex plates to control roll.


Edit: In light of PN's FM V3 motor mount I devised a way to lower the motor in my chassis another 1mm. Now that we seem to be having a CG war, I might as well do something about it.

[color01]

Hi everyone,

I need some opinions on a new front end design; having two standoffs and a top brace to replace the original upper arms seems to be the only way that I can fit PN MR02 anti-roll bars to this chassis. I think they will be a useful tuning tool in concert with the MRCG's stiffer-than-average rear roll resistance, plus this design should be faster and easier to machine than the current upper arms. I just wonder if it will clear some of the more low-slung MR02 bodies.



(The PN anti-roll bar kit is modeled directly from the blueprints in their instruction manual, so it should be at least 95% accurate. Moving the standoffs back was the only way I could get the entire bar to fit in there.)

Any comments appreciated, thanks!