somewhat bullet proof jato tranny.... - Page 2 - RC-Monster Forums

Unsullied_Spy · 06:34 AM

I believe they are 32p gears.

A few reasons why 2 speeds don't work well with electrics:

1) BL motors work best with a certain amount of load on them, this varies between motors and setups but you ideally want to find the sweet spot and run it there. If your 1st gear is the gear where it is setup ideally and it only kicks into 2nd when you nearly max it out in 1st I suppose it would be good for a speed gear, but there are a few other issues.

2) A 2 speed will not reduce amp draw, it could actually make it worse. Amp draw of a BL motor is proportional to the load placed on it, when you shift into 2nd there is suddenly a lot more load on it and nothing to absorb the shock (part of reason #3) and the amp draw spikes because the RPM at the input shaft (being driven by your motor) suddenly drops but the ESC is still working the motor at the speed of 1st. The ESC can compensate for this quickly, but the increase in gearing will still require more amps to provide the power needed to get moving.

3) Drivetrain shock. Unless your slipper clutch is adjusted so loose that it slips quite a bit unless you're very gentle on the throttle as soon as it kicks into 2nd gear the sudden RPM change WILL tear things up. Think 2 speed clutches, one-way bearings, output yokes, U-Joints, stub axles, and tranny gears (possibly spur gear if your mesh is too loose).

4) When it shifts into second you will either spin the tires or wheelie, depending on how much traction you get (some nitros experience this same condition when shifting into second). Either way it is very possible you will lose control. This happens because when more load is placed on a BL motor the power output actually goes up unless you can't supply enough amps to feed the motor (in which case things start getting hot, fast). The sudden increase in power and RPM change causes your control problems.

That's about the best I can put into words, but I really think you're best off going with a properly setup single speed.

J57ltr · 09.14.2009, 08:36 PM

1) If I'm trying to do 120 I don't want to run 12S and a really low KV motor. (I know it's less effecient) I'd rather stick with a higher Kv motor in the 3.5K range and more on the 4S-5S range (I use A123's) so that's why I think it would load the motor going into 2nd and allow me to run it up.

2) It's not going to be set for bashing at all just top speed runs. If I had a single speed the amp draw would be way up there when I start if it was locked in 2nd. The amp draw will be less than it would in a single speed and a little easier to get the speed I need without really overgearing it like I would have to do with a single speed.

3) Everything on the Lightning 10 buggy is metal, right now at the power levels I have on my Rustler (up to 1800W peak) the only thing I have trouble with is the stub axles (before I changed to VXL gears in the trans) and they are plastic and metal. Part of the problem is that I use a spool on it. I am not opposed to fixing the transmission it really isn't a big deal. Not to mention it's really lightweight I will be around 6 Lbs, maybe a little lighter.

4) It's a buggy so it sill still have a "center" Diff and I could change fluid to compensate for this couldn't I?

One of the things I don't understand is that if a Nitro engine which has a power curve inversley proportionly to a motor can do it why would a brushless be harder on it. I know the power will actually jump quite a bit with a motor, but I would think the Nitro would be just past it's peak when it shifts and right back into the sweet spot as it shifts. I guess these transmissions have a hard time in the stock application?

I guess you could say I am a hard head but I think I am going to try it anyway. Plus It's a little easier to make a motor plate to adapt a motor to the Jato trans. I would buy the RC monster Stadium 10 mount, but I will eather use the Jato trans or make my own mount.

whitrzac · 09.14.2009, 11:07 PM

you want to do 120 with a jato tranny???

my setup was a novak HV 4.5(5000kv) on a 4s geared 18/56, I would get to 90% throttle and it would start slowing down. blew out the tranny...

even with the alloy gears, I still couldn't keep it together... mabey with a little more time, but its still a PIA

J57ltr · 12:35 AM

What exactly blew out?

You know I totally forgot that I had an additional 3:1 reduction in the Diffs I have to deal with. I guess It may not be such a good idea after all. Even with a 1:1 ratio for the spur and pinion it's still too much.

Jeff

whitrzac · 09.15.2009, 12:18 PM

Quote:

Originally Posted by J57ltr

What exactly blew out?

You know I totally forgot that I had an additional 3:1 reduction in the Diffs I have to deal with. I guess It may not be such a good idea after all. Even with a 1:1 ratio for the spur and pinion it's still too much.

Jeff

the top gear, then the middle gear...