Slipperntial my way. Maybe.

[Patrick]

I'd say they used idler gears in the e-maxx transmission, because if they didn't then the input shaft would sit about 20mm lower. Good for center of gravity, but the 66t spur gear would be hitting the chassis and probably drive shaft. The motors might also sit too close to the batteries, making them too hard to get in and out.

You could put make a mount for a center diff and put that in the maxx, but the problem is that the motor will probably be sitting so low (this if if you put the motor in the center, above the diff with the pinion going straight onto the spur) that it could hit the chassis. Depending on what chassis you have you might be able to make it work, but could be hard.
Do you want it to have a center diff or constant 4 wheel drive like the maxx transmission.

[squeeforever]

Originally Posted by Patrick

I'd say they used idler gears in the e-maxx transmission, because if they didn't then the input shaft would sit about 20mm lower. Good for center of gravity, but the 66t spur gear would be hitting the chassis and probably drive shaft. The motors might also sit too close to the batteries, making them too hard to get in and out.

You have to take into account the fact that without the idler gears, the ratios would be different. So it might not be a 66T spur. Also have to think about the fact that the upper shaft gear size would probably be different.

[lincpimp]

The idler gear has no effect on the ratio in the tranny. Emaxx 2nd gear has an 18t top gear and a 31t bottom gear. The ratio is 1.7222222 = 31/18. Because both gears engage the idler it spins at the same rpm. This is true of any 3 gear tranny. The idler is only used to space out the two gears for packaging reasons.

[Finnster]

Originally Posted by lincpimp

The idler gear has no effect on the ratio in the tranny. Emaxx 2nd gear has an 18t top gear and a 31t bottom gear. The ratio is 1.7222222 = 31/18. Because both gears engage the idler it spins at the same rpm. This is true of any 3 gear tranny. The idler is only used to space out the two gears for packaging reasons.

Its true it has no effect on ratio, as both gears are directly tied to the idler, but nearly every tranny I've seen has an idler, so was wondering if there is some engineering purpose other than a spacer. They do reverse the direction of rotation as well. Many brushed motor have timing in the end bells, so perhaps its there to make sure that the rotation is the same direction as travel, instead of requiring an unconventionally built brushed motor. Obviously w/ BL or 0* this is not needed.

[zeropointbug]

I agree, it's just used as a spacer in almost all applications. I don't think it has anything to do with the brushed motor direction in direct drive apps, because you COULD switch the motor around to the other side of the tranny... simple design change.

[Finnster]

Originally Posted by zeropointbug

I agree, it's just used as a spacer in almost all applications. I don't think it has anything to do with the brushed motor direction in direct drive apps, because you COULD switch the motor around to the other side of the tranny... simple design change.

True, but I was think more of the rustler, RC10T4 and the like. :)

[Hickoryhead]

My thinking of all this is if you can gain power and torque you might not need such a big motor like my 1950 1800kv to power a Maxx size car. You might be able to use a 1920 size or similar one. Meaning having a lower transmission or slipperntial powered by a smaller motor. That would cover the motor size worry and give you a lower ceter of gravity. I am not sure if it would work but I will try to see if I can get one built. I understand the gear issue to. It will take some playing around to find the ratio that will change.

Finnster—I don’t want to draw attention to myself or sound like I am bragging but I feel I do “think” differently than other people. I failed certain math classes in HS because the teachers demanded I show my work. They could not understand how I came to solutions yet I had the answers. I took some pre tests for college math and I tested out of most of the classes. I know how to solve the problems but I go about it other ways. I take that route with alot of problems in my life. Drives my wife nuts. My brain does make up for it in other areas. I have a picture perfect memory and other talents. No offence taken. I can take a good ribbing.