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Old 06-29-2009, 06:44 PM   #1
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Default Schumacher Mi-2 Drive Ratio?!?!

Bought a Schumacher Mi-2 that was in great condition and turning it into a drift car. Was curious if anyone knew what the rear wheel to front wheel drive ratio is or how to find it out? Seems as if most of the power is to the rear wheels.
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Old 06-29-2009, 08:48 PM   #2
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Bought a Schumacher Mi-2 that was in great condition and turning it into a drift car. Was curious if anyone knew what the rear wheel to front wheel drive ratio is or how to find it out? Seems as if most of the power is to the rear wheels.
Equal all around as long as the front and rear pullies are the same size (which they should be). If the front and rear wheels spun at different rates, the car would be undrivable.
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Old 06-30-2009, 07:14 PM   #3
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Equal all around as long as the front and rear pullies are the same size (which they should be). If the front and rear wheels spun at different rates, the car would be undrivable.
True however if setup a certain way the car could provide more power to one or the other while spining at the same rate. Guess in order for that to work out there would have to be some clutch mechanisim between the two rear pullies where the belts run side by side. Almost every real AWD car is setup with more power to usally the front wheels than the rears. Hints why they call trucks that can lock power at 50/50 4WD not AWD.
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Old 07-01-2009, 07:18 AM   #4
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count the teeth on the center and diff pulleys.

internal ratio = diff pulley divided by center pulley. the car you're referencing had two ratio options. 1.80 (36/20) or 2.18 (36/17)

axle ratio should be 1:1 unless your diff pulleys are different sizes. it is not uncommon to run the front diff a tooth or two smaller, but when that car was released, it was. since then, schumacher has released a 35t pulley for both a diff, and a spool/one way.
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Old 07-01-2009, 11:10 AM   #5
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True however if setup a certain way the car could provide more power to one or the other while spining at the same rate. Guess in order for that to work out there would have to be some clutch mechanisim between the two rear pullies where the belts run side by side.



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Almost every real AWD car is setup with more power to usally the front wheels than the rears. Hints why they call trucks that can lock power at 50/50 4WD not AWD.
Torque split has nothing to do with whether its called 4WD or AWD. I can lock the center diff in my subaru STI with the DCCD for full lock between all the wheels, and guess what... it's called "AWD" . Torque split in most AWD cars is usually more to the rear, not to the front.
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Old 07-01-2009, 01:45 PM   #6
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some of the car makers, schumacher being one of them, make a over drive/under pulley for the thier cars, some have even went so far as to take a tamiya pulley (with a different tooth count) and adapt that to the car. IT DOES NOT MAKE THE CAR UNDRIVEABLE, IT may not be suitable for all tracks or track conditions, but it has been done, and can make the car driver BETTER.

as to the orginal question, gearchart.com has the Mi2 listed, you can figure out the gears you need there.
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Old 07-01-2009, 02:13 PM   #7
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How would the front two tires spinning at a different rate then the back two tires make the car drive better? and in what track condition?
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Old 07-01-2009, 02:27 PM   #8
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How would the front two tires spinning at a different rate then the back two tires make the car drive better? and in what track condition?
we sometimes run it on asphalt and carpet, with both foam and rubber tires. it's depends on what else is going on with the setup, but here are some examples...

high grip, when your car is diving over the nose (digging), the smaller front diff will cause added braking bias to the front, off power (assuming no one-way is in use) and will keep the front flatter because you're actually sliding the front tires a bit off-power. on power, the pull of the front axle (which rotates more than the rear) will give more steering. if you tailor your driving to suit a car that requires you to lift early and power through, it's very effective to maintain high corner speed w/o the digging/lifting that is customary of other setups with a lot of steering.

in low grip, the same happens, but the overdriven front end will keep it from spinning out off-power (rather than digging in high grip), and give it more pull on-power.

in both cases you lose some turn-in, but you can throttle off the corner earlier. it's usually a wash, but it's a good thing to tune with if you can't get the car to stay down w/o having a massive push.

any setup that has too planted a rear end (like some foam setups) can benefit from this, since the front tires are making a larger radius turn than the rears (and will therefore bind the car up if they don't rotate faster to make up for the larger arc-length).

in r/c, almost nothing that happens in a straight line matters. it's all in the turns. if you tune for the straights, you'll never get it right.
blah, blah, blah ....
as far as the original question goes, i thought i answered it fairly effectively in my first post. assuming your ratio is 1:1 (and i'd bet that it is), you should begin to look at your suspension for imbalances...
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Old 07-03-2009, 10:46 AM   #9
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i just knew it worked sometimes, thanks for explaining why.
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