Direct Drive
 

I'm on spring break and friday night i went to the beach with some friends. Well, come to find out that the dorm closed at 9am sat morning, so I wasnt able to get ANY of my stuff! No clothes, no nuthin. So I got to charlotte to see my mom and told her the whole story, and we went shopping. I got all sorts of new clothes and all and at Target, i picked up a MS sport.

It steers better than my clones, but is much slower. I played with it a bit and it seemed to get faster each time, but still nowhere near my clones. Well i got bored and was lookin at it, then i started thinking about the pan bit, and direct drive. I figured out that if i mounted the axle directly under the motor, the MS could be direct drive, eliminating the transfer gear, and giving it a faster ratio. Well i filed a slot deep enough to make the gears mesh right in the bottom of the chassis under the motor and used some aluminum foil and tape to hold the axle on. I wiggled it some to free it up, and charged it up.

Well, its fast, and likes to spin out. By moving the axle back, I effectively put more weight on the front wheels, so its REAL tail happy. A traditional dual cell would be great, with the extra weight on the rear, it would probly make it handle great and not pop wheelies so much to be hard to race with. I'm gonna try this again when i get back to the dorm and instead of aluminum foil and tape, i'm gonna use some more appropriate materials, and try this with dual or tri cells. Oh, another thing, without the transfer gear, it runs almost silent. Theres no little gritty transfer gear rattling around sound. I'm hoping that the wheelbase is appropriate for zz bodies, but i'm not sure. I'm sure i'll have to make a body mount outta something. I'd like to hear if anybody else has tried this.

Wow, what a coincidence. I was thinking of that this morning. That's a great idea. You would have to switch the forwards and backwards wres though to make it run correctly.

um....................... yeah...................... sooo.................
................i says the the guy........................... um

PICS!!!!!!!!!!!!!!!! :D :D :D :D

heh Serious man this is a wicked sounding mod, you gotta score us pics or somethin.....

if I understand correctly shouldnt the chassis be lower now too? again..pics please :D

so now it looks like you pan bit in your extended bit chassis?? i saw that pic. it must look sweet man. props to you

Well I cant get any pics yet cuz my camera is at school, and its not really much to look at anyway considering the aluminum foil and tape. Just picture your normal ms with the axle moved back til its right under the motor. The gear on the axle reaches the pinion just barely, so you file a slot (more like a little trough) to let it up just a hair. The slot also helps it rotate right. I dont think the chassis sits any lower really, but if you either made the slot a lil in front or behind the motor then you would have to make it deeper to reach. This would lower the chassis. It really looks nothing like the pan bit, just like a ms with the axle moved back. I hope i gave better imagery this time.

Ok darnit has anybody tried this yet?

Sounds sweet.....but I want some pics! :D

ok guys, i'll get you some pics tonight.... This is SUPER simple. I dont see what the deal is, but i'll put off some homework and get it done propper.

Ok, good, I want to see how this was done. I may do this myself....

I wonder if you could get the ratio to be 2:1 using K.I.T. gears. Man that would be fast. Give it a hard push in the beginning so it accelerates faster.

dustn-

Do you have to give your car a boost at the start? Or can it start at a normal speed, and gain more speed?

Does it go faster than normal gearing?

Does it have about the same amount of power as stock gears?

Well, when i tried it with the 1.6 (torquey) it starts from a stop and accelerates to top speed pretty quickly. It does go faster than normal gearing but the acceleration is slower. It is, however, tons quieter, there is not ANY gear noise, and i suppose that bypassing the idler you are losing some friction losses, but i dunno how much. When I tried it, I only had the 1.6. Now that I'm back at my dorm, I have clone motors, a 2.6, and a 2.2, so I'll be trying those. This mod would be best with a 2 or 3 cell mod, so that there is more weight on the rear axle because even with the 1.6, it would spin out very easilly.

K... I glued on some little bits of .03" thick abs plastic to support the axle fore and aft. the notch in the chassis itself is very shallow, just deep enough to allow the spur to reach the pinion. I was going to use a bit of folded up paper and tape to hold the axle in but couldnt find my tape, but i think you all got the idea. I also showed the possible location of a second battery. As for bodies, I believe you'd have to use a zip body and make a new rear mount, cuz the wheelbase is longer. It is precisely (on mine) 1.47" You could make it shorter or longer by using a bigger spur (from the 12:1 gearset) and then make the notch in the chassis in front of or behind the pinion to take up the extra room. The depth will also determine where the axle goes, so i'm sure you could get this to the precise zip wheelbase. The axle fits directly under the pinion with the stock gears, and the new gear ratio is 3.83:1.

next pic

next again

possible batt location

Sorry for the poor pic quality. I'll take more with better lighting later if anybody needs clarification

Whoaaaaaaaaaaaaaaaaaaaaaaaaaaa!!!!!!!!!!!!!!!!!!!! !!!!!!!

How can I get the body back on?

you cant... thats one of the probs. You could make a body adapter from thin aluminum to make the chassis fit a zip body.

WOW, that's one crazy mod...

Do you know the gear ratio? Divide the number of teeth on the axle by the number of teeth on the pinion gear.

3.83:1

So, xatu have you tried this yet? You seemed interested.

Haven't tried it yet... But I will! It will be another addition onto project Frankenbit.... A shen that will be brought back to life :D

Does it spin out more often? And what are the downsides to this mod?

Oh yes, and technically speaking.... Wouldn't you need to reverse the motor wires to make it go forward when you press forward? Or do you just leave the wires alone, and use reverse as forward, and forward as reverse?

Yeah, you should switch the wires. I just used reverse, but I'm gonna switch the wires. Read my original post and the ones after, i answer all your questions in those.

Its very easy to move the axle back to the normal location without hurting anything, so this mod is very easilly reversed. I cannot really think of many downsides other than it spins out a whole bunch. Again, more weight on the rear will cure that and make it handle like normal. You cannot get a bit body on after this mod, but i have yet to try a zip body... that may be the key. By not using the idler gear, you increase efficiency and reduce noise tenfold. The gear ratio is faster, so you will need a torquier motor or multiple cells. The gear ratio is 3.83 to 1 with the stock ms axle and 6 tooth pinion. I really wanna see other's takes on this.

thats interesting. i bet you go through a lot of pinion gears.

How does that work? You wouldn't go through alot!

hmmm ive been think about this for a while now........ just keeped on forgeting to post it here........ now that your not using that idle or whatever gear it should now be alot simpler to add another motor rite?? have you thought about this dustn??? can soem one tell me why you need to switch the forward and reverse wires??? i dont get it.......... anyways once again pretty cool mod now its sorta like a miniz cuz the mini z uses direct drive i think........ not sure..........the downside that i see is slower accel. but does it give better top end speed??? why would it where gears out quickly hogjowlz

Strakka-- You would have to switch the wires, because you are removing a gear. Here, I will try to draw a diagram here.....


This design, the wheel will go forwards.

motor>spinning counter clockwise
O
<^> crappy idler gear, spinning clockwise
OOO
OOOO wheel, spinning counter clockwise
OOO

now, without the idler gear:

This design will go the opposite of forward.

motor>spiining counter clockwise
O
OOO
OOOO wheel, spinning clockwise
OOO

Do you get what I mean?

Ok, well, that didn't turn out so well.....

xatu - what did nt turn out so well?? anyways i got what you mean thanks

My diagram didn't turn out so well.

basically the motor turns the pinion gear clockwise causing the idle gear to go counter-clockwise which in turn cranks the axle clockwise.

over - under - over

think of it that way. so, if the first gear is going clockwise and the next gear is going counter-clockwise then your car is now going in reverse since you removed the middle gear.

has anybody else tried this? c'mon its easyyyyy

guys, guys, not all at once... I promise you will like this mod.

"Great minds think alike!"
 

I did it! This might be hard to believe, but I finished it before I saw this thread. I used dual motors with white pinion gears. Check it out! My Kart.