A new toy for me!

[lincpimp]

Originally Posted by sikeston34m

What I wanna know is, How is the 2 speed kit going to work on this Transmission?

The Radio that came with this does NOT have the additional channel for shifting.

However, there is a small knock out window in the chassis that appears to be where the shifting servo goes.

There is also a blockout plate on the transmission that appears to be for a sensor like the Revo has.

Could this setup automatically shift to 2nd gear based on RPM?

THAT would be cool!

And auto shiting sensor based servo actuated shifter would be cool, would allow forward and reverse from the electric motor without needing a one way bearing. The complete 2 speed kit is listed for the emaxx at $55 IIRC. Plus it has different ratio gear options like the revo and tmaxx.

[sikeston34m]

Originally Posted by lincpimp

And auto shiting sensor bases servo actuated shifter would be cool, would allow forward and reverse from the electric motor without needing a one way bearing. The complete 2 speed kit is listed for the emaxx at $55 IIRC. Plus it has different ratio gear options like the revo and tmaxx.

Is there a website that has pictures and details about that?

Tower hasn't posted any details yet

[lincpimp]

Originally Posted by sikeston34m

Is there a website that has pictures and details about that?

Tower hasn't posted any details yet

Look at the parts list, middle of 3rd page under transmission #3998"
http://www.traxxas.com/products/elec...905-071218.pdf

also:
http://www3.towerhobbies.com/cgi-bin...?&I=LXTKP9&P=7

[sikeston34m]

OK, correct me if I'm wrong here.

It looks like to me this will be the gearing options.

Existing gears inside the transmission are 33/18 or 1.83:1

The close ratio set is 21/18 or 1.16:1 Which is a much higher 2nd gear.

The wide ratio set is 26/13 or 2:1 Which is a slightly lower 1st gear.

[sikeston34m]

Remember this setup that you said looked a little slow?

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.83
Other Ratio: 1
Spur Tooth Count: 40
Pinion Tooth Count: 25
Total Voltage: 14.8
Motor KV: 920
Tire Diameter (inches): 5.75
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 1.6 : 1
Total Ratio: 8.33354 : 1
Tire Circumference (inches): 18.06 inches (458.83mm)
Total Motor Speed: 13616 RPM
Vehicle Speed: 27.95 MPH (44.9km/h)
Effective Speed Rate: 1.89mph/V (3.03kmh/V)
Effective KV Value: 920
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...

That's because you were just running it in first gear!
Look at it go in 2nd!

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.16
Other Ratio: 1
Spur Tooth Count: 40
Pinion Tooth Count: 25
Total Voltage: 14.8
Motor KV: 920
Tire Diameter (inches): 5.75
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 1.6 : 1
Total Ratio: 5.28246 : 1
Tire Circumference (inches): 18.06 inches (458.83mm)
Total Motor Speed: 13616 RPM
Vehicle Speed: 44.09 MPH (70.83km/h)
Effective Speed Rate: 2.98mph/V (4.79kmh/V)
Effective KV Value: 920
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...

Now let's use the 36 tooth spur and put it on 6S.

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.16
Other Ratio: 1
Spur Tooth Count: 36
Pinion Tooth Count: 25
Total Voltage: 22.2
Motor KV: 920
Tire Diameter (inches): 5.75
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 1.44 : 1
Total Ratio: 4.75422 : 1
Tire Circumference (inches): 18.06 inches (458.83mm)
Total Motor Speed: 20424 RPM
Vehicle Speed: 73.49 MPH (118.05km/h)
Effective Speed Rate: 3.31mph/V (5.32kmh/V)
Effective KV Value: 920
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified

I'm sure the motor would give up the smoke before 73 mph. I don't think it can put out enough watts of total power without blowing the winding. Motor temps will determine it's limits though.

I'll be sure to put the motor cooling fan on this to help raise the bar. I think the 920kv motor will be best. It will make more torque than the 8 turn wind. The 920kv motor is also rated for more voltage from the factory.

Before I settle on choices, I'll do some more checking. I'll also get all 3 spur gears to allow for some fine tuning.

[lincpimp]

Yes, I ran all of those numbers, but figured that you would use the existing tranny gears for your setup. If the 2 speed is an auto shifter via the servo and some sort of rpm sensor, then your 920 kv motor will most likely get it over 60 mph without much of a heat issue. It would be killer cause 1st gear would let the outrunner startup easier and not put as much load for light bashing, and then when you really get on it 2nd gear will allow for some killer top speed. Or gear it for 45mph in 2nd and have some killer torque in 1st gear!

I have noticed this with my teckno converted revo. I still have the 2 speed tranny and it will run fine with a small aveox motor (l can size). Plus you can go low speed with it, just don't go fast enough to engage 2nd gear. It will almost pull a wheely when shifting at full throttle!

Is the 920kv good for 6s? That is 20k rpm which should be fine.

[lincpimp]

Also for the different gears to fit correctly in the tranny a different size idler will have to be used. The input and output shafts are a set distance away from each other and the 18 / 21 setup will have to have a larger than 20t idler to fit and mesh correctly. Wonder how they will do this?

Both the 21/18 and the 26/13 would fit in the tranny as 1st and 2nd gear respectively and could use the same size idler for both, as the radius of both sets of gears added together is the same.

EG. 21t=23mm/2=11.5
18t=20mm/2=10
___________+___
21.5mm

26t=28mm/2=14
13t=15mm/2=7.5
___________+___
21.5mm

So I guess that when installing the 2 speed the original single speed gears will be discarded. Sounds cool, can't wait.