Brushless Traxxas Jato - Page 3 - RC-Monster Forums

Batfish · 08.06.2005, 09:13 PM

The batteries are sitting on the plastic bits of the chassis plastic. The front of the pack sits over the steering and the back nearly touches the motor. I was talking with rc-monster Mike about this and I'm contemplating making a motor mount that would raise the motor up and allow a battery pack to sit directly on the chassis, under the motor. Since the battery pack will nearly always out-weigh the motor, the CG will be better with the pack down and the motor up.

The speed is actually more than I'll every need bashing at my house or racing. I don't know of a track that allows for regular running at 35+ MPH.
That said, I posted this statement to the Traxxas Jato board as well: If there's anyone in central MA with a nitro Jato that wants to race me, I'll stick my 3s lipo and maybe add a couple teeth to my pinion...should be no contest ;)
Assuming everything holds together, 3s lipo should put me near 57MPH, which is 2 more than the RTR is rated for. Plus, I'd expect to get there a bit quicker than the nitro beast :)

rchippie · 08.06.2005, 10:08 PM

Joe you have to repersent for your BL brothers:eek:

I also like the idea of your motor mount.

Batfish · 08.06.2005, 10:52 PM

Good point...maybe I'll do a run with the 3s anyway, just to clock the speed.
Perhaps I shall git my speed in da hizzie wit da shizzle....or something to that effect :cool:

08.07.2005, 01:35 AM

Looks nice. Now you just need to get the transmission to shift.:D

Dafni · 08.07.2005, 06:09 AM

Awesome Jato, best one I ever seen!

But, did I see a nitro engine in the background there :eek: Just kiddin'.

How do you like the mechanical break? Did you disable reverse?

Batfish · 08.07.2005, 08:41 AM

I think I forgot to mention that I did adjust the two-speed. The speeds I posted are in second gear.

Yep - there are two nitro engines in the background. If I could actually make them run I might be able to put up with the smell, sound, mess, and maintenance ;)
In the meantime they're just waiting to go up on ebay.

The mechanical brake has been okay on the grass and the street, although not as strong as I had hoped. Once I try it on the track I'll have a better idea.
Two things that make it less effective than I'm used to are the speed of the truck and the weight distribution. With so much weight up front I think the rear tires don't have as much grip during braking.

Serum · 08.07.2005, 08:45 AM

You are missing the brake power on the front wheels... ;) ;)

Batfish · 08.07.2005, 08:58 AM

Quote:

Originally posted by Serum
You are missing the brake power on the front wheels... ;) ;)

Heck yeah :)
I was so used to the 4-wheel braking on the MGT and buggy...that's how the Jato met my garage at about 15MPH :)
It had been more than a month since I drove a 2wd stadium truck. It's still a great class, but I do like the control of 4wd.

coolhandcountry · 08.07.2005, 09:28 AM

Do you have a weight on that jato there bat? I am curious.

Batfish · 08.07.2005, 10:17 AM

I've only got my bathroom scale to weigh with, which weighs in .5 lb increments.
Using that scale, the Brushless Jato weighs 5 lbs ready to run with my lipo pack.

Heavier than my XXX-T, but I think the weight helps it to be controllable.

Batfish · 08.09.2005, 07:39 PM

I got the Brushless Jato to the track yesterday. Here's the layout of the track. It's not exactly to scale, but it's a good representation made by one of the drivers.

So you have an idea of the size, the back straight is 96ft.

When I first got the Brushless Jato going on the track it was apparent that there wasn't enough weight in the rear to get enough traction, so I added a 4-cell dry pack with 4AA batteries into the rear battery holder. Even with the extra weight it took a light throttle finger to keep the back end in check.
The owner likes technical tracks. Normally this means that there are jumps with specific timing, or they're located close to turns to force thoughtful driving. This is the first track that's technical due to the placement of turns rather than jumps. The jumps are actually very easy to land (overall), but I couldn't get over about 1/2 throttle due to the frequent turns. Even on the cleanest laps I ran I couldn't push the truck anywhere near it's limits.
The Brushless Jato was *extremely* stable in the air. I was very pleased to see that it was perfectly level and jumped more smoothly than any stadium truck I have driven. This includes XXX-T MF, T3, T4. I think it has to be the changes in the way Traxxas designed the Jato that allows it to be so stable even after such a radical reconfiguration. The only thing I expect to do in finishing up the suspension is to raise the ride height in the front and possibly add stiffer springs to the front. It sags more than my liking during braking.
Sorry, no video of the track runs yesterday.

One new configuration note: I hooked up my Nomadio Sensor to the Jato (since the MGT is in pieces right now). I really love the radio and telemetry information.

Batfish · 08.19.2005, 07:09 PM

The Brushless Jato entered it's first race last night. It was a less-then-stellar performance....
2 qualifiers and the main.

Qualifier 1 - on the second lap my motor mount moved and disengaged the pinion from the spur...
Qualifier 2 - on the first lap the pinion actually fell off...I didn't find it until the end of the night. At least the shop had a few 32-pitch pinions that let me get it back up and running. I hadn't lost a pinion or even had one come loose in all the testing...go figure.
Main - about 3 minutes into the race the motor mount moved again...game over, man.:C:

The bonus is that I now know a few important things.

1. This battery (2s), motor (lehner basic xl4200), and speed controller (MGM12012) is a GREAT combination for racing the Brushless Jato. Controller temp never went over 108 and the motor stayed only slightly warm. It has too much power to hit full throttle on the 96' straight, so I have no need to make it go faster. This is the same setup I GPS'ed at 36.8MPH.

2. The problems I had are easily fixed (once I get to work on it, that is). I already put a drop of threadlock on the pinion. Now I just need to get the motor mount to stop moving.

3. I need to work on reducing weight overall, focusing on moving the weight that remains down and to the back. It's still about 1lb. heavier than a "normal" electric stadium truck.

I hope to get it back up and running reliably and see if I can actually race again next week.

Dafni · 08.20.2005, 12:53 PM

Sounds good. Great update, Batfish. Thanks for sharing this with us.
Too bad about your bad luck with this pinion. Fortunately your problems are easy to fix. Can't wait to hear from your next race. Good Luck!

Do you race against Nitros or do you have a BL stadium class?

This Nomadio Sensor telemetry, what information can you get out of this??

And, what are jumps with specific timing?

Thanks
DAF

Serum · 08.20.2005, 01:14 PM

Sounds like you need some loctite!!!

;)

Is it always one screw that's get loose on the motormount?

Gustav · 01:55 PM

Dafni, the Nomadio sensor can give you voltage readings and temp and can give you beeps and vibrations on the transmitter for pre-set high temps or presumably low voltage aswell.I think it comes complete with sensors and it sounds perfect for brushless.
Maybe could be used instead of LVC for Li-po.
There's a little video explaining it herehttp://www.rcuniverse.com/magazine/a...article_id=525

If Batfish reckons it's worth it I might get one.