Project: NO ROLL... (shafty without torque roll!) Update 1/20.

[JakeDaSnake]

When I got my first real Crawler it was a Jugg drivetrain, custom chassis, E-Maxx tranny and Clod Tires, the thing I didn't like about it being a Shafty was the bad amount of torque roll it had, So I sold it and got a Clod... the clod having the exact same chassis design and 4-link alittle different was a much more "technical" crawler, I saw my Clod do stuff with stock sized tires, My friends E-Maxx crawler (17 inch wheelbase w/ JumboKongs) couldn't do... but the drawback to that design was the center diff action, that was bad becuase I was still running 13 tooth pinions, not to say the motors were in all sorts of dangers being that low...

The Project Im starting now is a Shafty because I've thought up a way to totally exliminate the torque roll and High CG, that are the only problems my last truck had...

Im going to use Twin Force axles, Twin Force "tranny" with a custom fitted 56 tooth spur gear from RRP, a GD-600 and Kyosho 550 motor, the GD-600 has a 9 tooth RRP pinion on the output shaft also... This would put my gearing some were around here:

TF Tranny Ratio: 2.35:1
X
TF Axles Ratio: 3.31:1 = 7.78:1
X
Pinion/Spur Ratio: 6.22:1 = 48.38:1
X
GD-600 w/ 12 tooth pinion: 3.75:1 = 181.43:1

Final Drive Ratio = 181.43:1 I was aiming for around 175-180 so I got lucky lol...

My NO ROLL plan is to reverse the rotation of the Front driveshaft so the Front and Rear are spinning oposite each other, this would be done using a differential (unlocked) with a driveshaft attached to the sprocket output on the TF gearbox and one side of the diff, the diff would then be mounted to the gearbox, this would cause the other output shaft to spin reverse of driveline rotation, I would then reverse the rotation of the axle so it would spin forward and not reversed by flipping the ring gear to the other side of the pinion on the TF Axles... My driveline would then be "pushing" on both side of the chassis and not only on one side, and would center itself... but all 4 tires would still be rotating forward...

I have to come up with a 4-link system for the TF axles, find a way to mount the Diff on the tranny and lock my diffs, maybe I can get some pics by tonight

Let me know what yall think about it...

Later
Jake...

[Jeckler]

I brought this question up on RCMT over a year ago. Said it couldn't be done. Glad to see someone is taking the initiative. Good luck.

[TwistedCreations]

sounds like alot of work.. im glad my Maxx doesn't have the torque roll too it..

[Jeeper]

sounds sweet. good luck.

[SR5Dave]

Sounds like a great idea; but you're going to create a TON of force on that center diff. It's REALLY going to try to tear itself apart, use good parts in it ;)

Hurry up and get to it! :P

[JasonInAugusta]

A diff on the output?

What's your plan to keep it from unloading and leaving you with 2WD?

[jtothec]

another way to attack the problem is to add a tmaxx diff to the top of the axle pumpkin (and with the twin force axles you can rotate the input straight up) attach the drive shaft to one side of the tmaxx diff and then it will attach at a right angle to the top of the pumpkin. this will bring all the gearing to the axle IE multiping the gearing at the axle+ it changes the leverage point on the axle. At least this was my thought.

[Ace]

I was gonna make my worm gear crawler with opposite spinning shafts to counter body roll, but I wondered if it would make much difference...

Main problem here in a contest situation is a shafty is in a near vertical climb about to roll over backwards. Any throttle input tends to twist the front axle which pushes on the near vertical rock face and pushes the rig over backwards.

I didn't see opposite driveshaft spinning fixing that situation... In fact, if the front axle twists the opposite way than the rear it could actually make the vertical near tip over situation worse...

But then again what do I know? I say try it and prove me wrong. I think it will really help body roll when the truck is more horizontal though, which might be reason enough to try.

I can think of three ways to eliminate or "near" eliminate shaft torque roll.

1. Use 4 drive shafts, each front and rear combo counterrotates.
--- I was going to try this but I wondered if articulation would bind up the transmission...

2. Have the output from the axles go straight up, like a 2.5 ton army truck front axle. That way the 4-links could fight the torque.

3. Have really high axle ratio. Like 20:1 or more. This is what I did on my worm crawler and it seems to work well. I see some axle torque but no more than I observe on my Clod... With 20:1 you'd see 10 times less axle torque than a rig with 2:1 axles. At least if my theory is right.

YMMV!

[JakeDaSnake]

Thanks guys...

Jason: the diff would be functioning all the time... its gonna be spinning the internals and the outside is staying still...

jtothec: I dont think I totally get the way you would do that, but I see your concept... might try that in the future...


Ace: Yea there really isn't any way to combat that, but then agian Im not crawling up walls very often down here, there's more flat terrian with alot of rocks on top, not so much moutains like yall lucky guys get to crawl in, lol

Thanks everybody, Im workin as fast as I can!!!!!

Later
Jake

[Calata]

flipping the ring gear to the other side of the pinion on the TF Axles...

Sorry to burst your bubble, but that CANNOT be done. I just had my diffs apart to install lockers and the casing is molded differently on both sides.

The only way you may be able to do it is by using 2 of the long axle tubes.

[JakeDaSnake]

Calata: I just had my diff cases apart and reversed then, its the same diff opening on each side, there interchangable... I measured it and its the same in the inside...

UpDate: got some pics for tonight as I said...

My GD-600 dirt/rock guard:



The Pinion I wanted to use (RRP 9 tooth) is to small so Im gonna go with an 10 oe 11 maybe a 12... in a way it kinda sucks but I'll see if it needs lower gearing:
This is a Pic of one of the axles Im working on... Im just gonna use the 2 mounts already on the tube to mount my links and Triangulate them to the chassis like a TLT-1 and also so they will clear my shocks...



Complete tranny w/ 16 tooth pinion (test fitting) its gonna run a 12 prob.




Let me know what yall think...

Later
Jake

[toyofast]

This can be done...

Just offset your tranny outputs and make each have it's own gear. I can see it working...


Sorry about my crude drawing But you can get the idea.....

[Calata]

JakeDaSnake, you are correct. I am wrong !!. When I looked at the casing on the inside, I thought the little nubs from where the screw heads would go would prevent the ring gear from going in. I test fitted it and it works. My appoligies.

[SR5Dave]

Originally Posted by toyofast

This can be done...
Just offset your tranny outputs and make each have it's own gear. I can see it working...
Sorry about my crude drawing But you can get the idea.....
http://www.rcrockgear.com/BC/Dual_ou...set_tranny.jpg

Thats what I was thinking. Those last two gears will get soooooooooo much force

I think the truck will also wag.. the front will try to torque one way, and the rear will torque the other way... The net result shouldn't mean much, but it'd look funny

[JasonInAugusta]

Originally Posted by JakeDaSnake

Thanks guys...

Jason: the diff would be functioning all the time... its gonna be spinning the internals and the outside is staying still...


Later
Jake

Gotcha. I was having a hard time getting a mental picture of it all.

[Lucus]

i had a similar idea to this awhile ago but couldnt find the bits i needed to make i work. what about driving one shaft throught a plantery gearbox and mounting a second plantery on the diff with the annulus mounted to the diff housing so that the output from the gear box was reveresd through the first plantery then corrected by the the second? having the annulus moutned on the diff would cause the torque reaction to be reversed. i think it would work quite well. does the make any sense?
if your wondering if the opposing torque forces idea would work have a think about those crazy russian choppers that use contra rotationg main blades and no tail rotors...they didnt spin around

[JakeDaSnake]

Calata: dont worry about it... I made sure the hole thing would "in theory" would work, now we just gotta wait for it really work, lol...

ToyoFast & SR5Dave: your right that diff it gonna get some crazy stress, but its around the middle of the driveline, so I think it wouldn't crap out the Maxx diff I was originally gonna use wouldn't last 5 seconds, but I gonna order an 8 Sypder gear Unlimited Engineering Kyosho diff... its got the aluminum casing and 8 spyder gears, it should hold up, but I didn't think about driveshafts, lol!!!

Jason: Yea I was alittle hary on spelling out my idea, lol

Lucus: Yea thats the same thing Im using the spyder gears in the Diff for... but just a simpler deasign than the 2 planetaries...

Thanks Guys
Later
Jake

[Lucus]

plantaries would be alot stronger because as u probably know diff spider gears arent ment to be rotationing all the time.
will be good to see how it turns out thought

[JakeDaSnake]

Yea, I was thinkin about the way it would do when you hit the throttle, the front left and rear right would lift, it would look cool... but it might effect the performance... it kinda hard to say, if I get it all done and it doesn't work well then I'll switch to an E-Maxx tranny...

Later
Jake

[JakeDaSnake]

Got the Tuber started last night, had a couple of hours work into it... its gettin to the shape I want, lol... I'll post pics when I get home...

Later
Jake