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Why do 2 wheels spin forward, 2 spin backward?

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Why do 2 wheels spin forward, 2 spin backward?

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Old 05-05-2007, 07:48 PM
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Default Why do 2 wheels spin forward, 2 spin backward?

Hello,
Just put my Kyosho mp777 sp2 together. I put it on the starter box, and turn over the flywheel. The two back wheels spin forward, the two front wheels spin backward. What's happening? Do I have something put together backwards?

Thanks,
Bill
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Old 05-05-2007, 07:55 PM
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Flip your diff around
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Old 05-05-2007, 07:55 PM
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you have the front diff in backwards.
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Old 05-05-2007, 07:58 PM
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or you have the back diff in frontwards
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Old 05-05-2007, 08:02 PM
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Ok I can try that. But one more follow up question to that then - how come if I spin two wheels (front set or rear set) forward together just with my hands, the other set spin forward too? It's only when I turn over the fly wheel that I get the two fwd, two back thing.
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Old 05-05-2007, 08:26 PM
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Old 05-06-2007, 12:22 AM
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I take it that means you've never heard of such a thing before...?

Could it have something to do with the polarity of the starter box? In a normal situation, should the flywheel be spinning clockwise or counter clockwise if you are looking at the car from the front?
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Old 05-06-2007, 12:26 AM
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When you have the car lifted up so all four tires are not on the ground, and then spin the wheels (front or rear) none of the diffs are in action. It's just like the car would be rolling naturally. Doesn't have anything to do with the starter box or anything else.

Because it's your front wheels that are spinning backwards, your front diff needs to be flipped around.
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Old 05-06-2007, 12:40 AM
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thanks! I'll give it a try.
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Old 05-06-2007, 12:40 AM
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Originally Posted by Aaron Waldron
When you have the car lifted up so all four tires are not on the ground, and then spin the wheels (front or rear) none of the diffs are in action. It's just like the car would be rolling naturally. Doesn't have anything to do with the starter box or anything else.

Because it's your front wheels that are spinning backwards, your front diff needs to be flipped around.
Bingo.

Had a new guy at the track get his SP2 put together and engine broke in and he started it up and put it on the ground and it sat there and left black spots on the ground.

Most chassis' have a notch in them so you can't put them in backwards otherwise they bind. I'm pretty sure Kyosho's do.
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Old 05-06-2007, 08:00 AM
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I just got back from a race. The night before my buddy was laughing at me in the hotel room because I was rebuilding my car. He said he had both his cars ready to go, that he came prepared. Guess what- the next morning both his cars had the diff in backward.
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Old 05-06-2007, 09:02 AM
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Haha, talk about eating your words.
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Old 05-06-2007, 10:59 AM
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I pulled the front diff off the chassis, and yes there is a notch in the chassis that the gear fits into. Is there something else I can flip around, because the gear cannot go any other way!

There is a notch in the rear of the chassis too for the rear diff. Can the center diff have something flipped in it to cause this?
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Old 05-06-2007, 12:04 PM
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To my amazement, I pulled off the rear diff, and the gear is on the wrong side (not fitting in the notch). It never was bound up though. Weird. So I'll get it flipped. But since the rear was spinning forward and the front backward, in addition I must have the polarity reversed on my starter box. Thanks for all the help.

Bill
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Old 05-06-2007, 12:22 PM
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Originally Posted by ozandangel
I pulled the front diff off the chassis, and yes there is a notch in the chassis that the gear fits into. Is there something else I can flip around, because the gear cannot go any other way!

There is a notch in the rear of the chassis too for the rear diff. Can the center diff have something flipped in it to cause this?
one or both of the diffs are backwards. The center diff has no direction.

Last edited by quietstorm76; 05-06-2007 at 12:21 PM. Reason: spelling
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