Scrappy Frog - The Poison Dart

[KC_JoNeS]

Be sure and post up with the results of the comp. I am interrested to see how your tuning has been going.

Casey

[jimmyshor]

Originally Posted by KC_JoNeS

Be sure and post up with the results of the comp. I am interrested to see how your tuning has been going.
Casey

Will do that. Will comp with at least 2 rigs (Scrappy and the GreenBitch - shafty). I hope my 2 FX-R from Tekin will appear on-time to complete my XR10.

Did not have enough time to test the new setup of Scrappy on the rocks, though, but i think it will perform excelent. I reduced the amount of wheel weight from 250g (those 2 wheel weights from Proline titus) to about 100g. The rear wheels dont carry any additional weight. Doing that i noticed that the amount of flex reduced......not liking it. Shall i return to 250g ???

[KC_JoNeS]

Dont worry so much about flex. Think about the poison dart as a rock hopper as opposed to a crawler. Personally, I like a little bit stiff of a setup, and I like to just "hop" around the obstacles with controlled bursts of power from the motor.

Casey

[jimmyshor]

waiting for traxxas shocks, too see a difference...

[jimmyshor]

Last minute mods:
a) changed the 14T pinion to a 21T pinion
b) moved front shocks inside
c) returned to Proline wheel weights
d) finalizing yesterday cups modding....they work like a breeze.

Results:
a) speed increased big time and reduced the torque
b) reduced/got rid of tyre rubbing against the shocks. At full steering, the tyres barely touch the shocks and doesn't remain stuck anymore (sometimes got that). Did that in order to avoid wheel wideners (as i realize that those are only additional stress for the rig). No visible torque twist present, and if it's present, it's close to 0.
c) did some basic testing with and without wheelweights (or to be more specific with very little wheelweight). The right amount of wheelweight can get you where you want....
d) @full steering and dig engaged, everything is good. I changed yesterday's steering limitations, no issues encountered...

That's about it for now.

PS. Traxxas shocks arrived, but the springs are quite stiffer, not my taste. Remaining for the moment with Axial's modded by me.

[DRV KRAWLER]

Hey Jimmy,

I am still working on trying to find springs for the shocks. If you find something let me know. A good choice on the rears appears to be Losi #LOSA5146 with a 1.6 rate.

[jimmyshor]

For the front i use a mix of Axial Alu comp shocks, with soft springs inside, from HotRacing. Hotracing produces some shocks with inner springs - hard, medium and soft.

From an aluminium pipe i made spacers, and put those inside the shock, in order to limit the shock travel.

Basically, i use same shocks with different travel rates. The Traxxas springs are too stiff, and if you use oil, they will be hard as hell.

Another shocks that worth to try is the shocks that come with SCX10 (either Dingo or Honcho). I used them in the beginning, i changed them only because of tyres that rubbed them at full steering. When my wheels will arrive i intend to go back to those, as they are just the way i like it. Since they use a dual spring system, it is easier to get to the desired setting by changing those springs (i dont remembere where but i found a website that sells different kind of springs for that).

PS. Hope you understand my English.
PS1. If you try this, also consider changing stock rod ends with other ones (bigger).

[jimmyshor]

After qualifying 2nd (after XR10), in the finals it placed 5th. Electronic trouble. So busy trying to solve mecanichal issues, i messed up with electronics. Even my f. lipo went dead 2 sec after i started. Unlucky. Otherwise, it rocks. On 5th of June i hope i can make it to another round, and : a) after receiveing Gunnar pins b) beef tubes Scrappy will turn to a buletproof crawler. Seriously thinking about replacing HPI Flux Reload ESC to a Tekin - impressed by size/performance. Also, what tyres do you reccomend ? Other than Chisels and Rovers...something narrow...2.2''....same outer diameter.... Regards, Chris.

[Crawling Calvin]

sedonas are good as is on 1" -.875" {just my testing with stock foams}

Rovers can narrow up really easily on narrower rims.

And sorry about the electronics issues, I know that all to well when you go to run your car, get to the rocks and it dies right there, worst feeling in the world!

[Highlucks]

How grippy is the rock that you crawl? A siped set of Boss claws can perform very well. I also like the Panther Leopards. They are an older tyre style but the compound is great.

[jimmyshor]

Scrappy log:

a) new wheels arrived (Eritex) - damn, those are great
b) replaced the rear driveshaft - got broke suddenly
c) got some soft plastic (called ABS here, hope it's the right term). It's easy, soft, 1mm thick. Here is how it looks now











Hope you guys like it. I did all my best, with a dremel, a hobby knife, a DVD pen. I fried my fingers when doing the motor plate (using a heat gun tool )

Also, i gave it a lot of thougt regarding my breaking pins and CVD's. So:

1) stock pins are crap, that's for sure.
2) stock c-cups modded are not a bad ideea, but w.t.f - why use 0 ackerman knuckels if you limit the steering ? So, CVD's seem the correct choice
3) i think under normal circumstances, rolling on a regulare crawling area, CVD's and driveshafts should not be a source of problems. I think so. I saw tons and tons of videos, but the few rocks i run my rigs onto - they are hardcore stuff. CVD's and driveshafts fail when my wheels go deep between rocks and i totally insist to get the wheel out of there no matter what. CVD's also fail when full steering and full throttle occur same time (noticed that). I have a feeling that Gunnar pins wont make a bigger difference on those rocks, but at least i can say i did everything i could.

At the contest i had to use the dig to make some turns that normally, with full steering enabled, wouldn't be a problem. Well, for now i am
a) waiting for a RX unit to permanently attach it to Scrappy,
b) waiting for Gunnar pins
c) waiting for beef tubes

Scrappy should be ready by 5th of June, for another contest.

[DRV KRAWLER]

Looks GREAT, even though. I don't see a JoNeS'N Sticker !

[Highlucks]

Awesome all white froggy.

Did you get the wheels new or used? they look killer.
If you can find a place for it. I suggest moving your esc inside the cab. Where it is now and the fact that it has no case lends it to being damaged easily.

[KC_JoNeS]

This here is another reason I need to send a template with the skid plate. I know you can get that motor MUCH further inboarded than that.
The skins look super cool though.

Casey

[jimmyshor]

Answers:

a) The wheels were new. I bought them following the advise i got here.
b) The ESC is quite protected, the only part that is "in open fields" is the BEC, wich is an unusual kind of BEC (by design though). In the future the HPI Flux ESC will be replaced by a TEKIN, as soon as my budget allows that. Just love the way that tiny thing works. Awesome !
c) Dont remember where i put the sticker ! Damn.
d)@KC - dont forget i also run an DNA dig, with the servo mounted top. Quite difficult to fit everything in there. I would have bought the Vanquish Hurtz but wtf it's out of stock for almost 6 months.

My personal opinion, Scrappy was designed by KC for smallest ESC (like Tekin), smalller Dig (like Vanquish). Anyhow, there is always and amount of chance tot take, so for now, only real risk for me as far as i can i see it is the BEC. Soon to be replaced by something smaller (e.g LRP, 10 amps), as soon as i change the ESC.

So far, i'm still waiting for a 2.4Ghz Sanwa receiver.....damn....

[KC_JoNeS]

I hear ya mate. Remember, nearly all bodliless chassis are hard to stuff everything into. It is very difficult to get everything under the hood, and be able to work with all kinds of products. I basically designed the chassis to work as a Sportsman chassis, but, I proved it could work with a dig (Vanquish is what I have). I also showed that it could be used with a large ESC. I only run Holmes Hobbies BR-XL.

If you can, try to place your ESC on your rear upper links. That should save some space inside for other things.


On a side note, your toobs shipped out, and should be there soon.

Casey

[jimmyshor]

Cant wait to arrive man !

Regarding the ESC, it is placed on the rear UL's. Here are some pics of the early stages of Scrapppy's build...


I think 2 or 3 mm to the left would not make a huge difference, but i prefered to have good fixed transfer case. If i made a mistake, it's too late now, anyway.



You can see the motor i use (LRP brushless) is a "fatty". In fact, Scrappy is not just a stage name - it is build using "leftovers" from all other rigs i owned. It's a unique mix of new and used items...if you like, it was my consolation prize, after failing to build a realiable rig using HR Rock Racer Chassis.

Back to the ESC's position:


I rolled over with it quite a few times, nothing happened.

[Highlucks]

Ah I see, I thought it was an esc with out its shell. The best and smallest BEC is the CC BEC, Tekin FXR is a good choice for a small ESC with plenty of programming options. And if you want to see some crazy electronics placement check this out.

It may not look like it but this rig is RTR.
Eeepee's SSS Sportsman








Not the greatest picture but you can see my ESC mounted on the front links here. Not a small ESC either CC Sidewinder. BEC is under the front four link plate.

My PD

[jimmyshor]

With an FX-R and a LRP bec.....another story. Everything will fit in just fine, but until....i have to manage with what i have.

PS. That sportsman looks sick, can't figure out how it works (no shocks, i've read that is a torsion chassis....but cannot figure out).

[DRV KRAWLER]

I know I gave you CR&% about the sticker. I have to admit that is one HELL of a formed panel over the motor. That was no small task to get right.
I screwed up my skid due to not enough clearence for a brushed motor. Trying to keep inside the rails. On suggestion had to fill in holes with EPOXY. Waiting on a short driveshaft to re-drill skid.