Fred_B

iTrader: (1)

There comes a point when you physically can't fit any more wire on the motor. The 21.5's are pretty full as is and they might not be able to put even more wire on to get the speeds back down.

There are alternatives to receiver packs.

2wdMod

iTrader: (42)

hey fred whats up!!! Not saying this is the way to go, but has anybody considered winding a light guage wire version of the 21.5, or the 17.5 ??I know the "light "versions of the 6.5 and the 7.5 are very different when compared to their standard counterparts.I think a 21.5 light on 2s li-po would be worth a shot since one of the mahor differences in a "light" motor is the limited torque.I think that it may bring the viable gear ratios into a little bit more acceptable ball park to attain stock speeds with a 2s li-po. Just a thought.

Fred_B

iTrader: (1)

I played with lighter winds in mod and it just made the motors run hotter.

The 17.5's and 13.5's are both double winds so they could be wound as singles (and screw up all the 6 cell classes). I don't own a 21.5 but with the number of turns I would guess that it's a single wind.

I hope that whatever we come up with it won't need to have new motors unless all of the classes need new slower motors. That's a ways out.

2wdMod

iTrader: (42)

Like i said , Just a thought. And like you said, its a ways out any how.I am sure that with all the ideas floating around this thread a solution will be found by the time it's needed.I personall am liking the single cell option sticking with the current motor classifications.Whether it uses a step up converter or a rec. pack, it really doesnt matter to me.

trailranger

Novak had a 25.5 motor in proto type and the gearing was so tall it was hard to even speculate how high the roll out would be. The 25.5 didn't make it out of testing because the 21.5 proved to be a good 13.5 4-cell replacement at equal weight and 3200 max capacity battery. The 25.5 was reported to be very very hard to wind.

The 2S solution pretty much starts for Light Mod and Modified, Nothing Lower.

The 1S solution for the short term could be hard convince, but it can provide speeds for Stock, Super Stock, Light MOD, MOD which will make everyone happy. The RX pack is just a short term thing since BEC modual and ESC's for 3.7V will be out soon.

Carl Giordano

iTrader: (32)

Future of 1/12th scale.

I had a chance to race 1/12th scale this weekend after taking a break for just over a year…although I was four laps off TQ (posted by a national champion) there were a few moments of glory for me…my fastest lap was only 2ths off his, my average 5 laps were 3.5ths. My lack of track time showed as I "wall" tested my Rev 4.5 more than once.

I basically decided to go, have fun and hang-out with old friends. The nights leading to the race were frustrating as my NIMH battery packs would not take a charge…I purchased 4x new 4600’s (2x SMC Green Cells & 2x Trinity Red Cells) during the summer and frustrated to find a few cells with zero volts. The fact that the packs were new in the box sitting around for 5-months and would not take a charge is another story…but I was able to salvage two packs by mixing the cells…

I purchased a Novak 17.5 motor at the track and frustration was building as I thrashed to get ready for the first qualifier. I used the 1st qualifier to set speedo and radio and get use to the track. I knew I had 2 more qualifiers left. The fact is the use of a brushless system is AWESOME. The LRP brushless speedo (1st generation) was easy and I quickly got use to the feel of the motor.

The fact that I never touched the motor made the day enjoyable. With limited time…the ability to go to a track and not have to deal with motor maintenance is great…IT WILL ENHANCE THE SPORT…this is not surprising and I’m not saying anything that has not already been said.

IMO - The introduction of a LIPO system (whatever it may be) is going to make the future of 1/12th scale that much better. The fact that I discarded over a $1000 worth of NiMH battery packs at the hobby shop's recycle bin is a disgrace. (Various cell types ranging from 3300 – 4600)

ROLAND S. - Project

At the end of the race, Roland allowed me to drive his 1/12th scale, which was wired with a 2s LIPO and a small Mamba motor (not sure what size). He had posted a few photos of his conversion on this forum and his comments have created some controversy.

My impressions of his project are as follows:
1. layout looks as if it was put together with a dremel…LOL
2. Very light…Could not believe how light the rolling chassis was
3. The power and throttle response was EXCELLENT. Felt no different than my 17.5 & 4-cell NiMh.
4. The chassis had chunked tires, but I suspect the light weight made the car drivable. Although it was not set to my driving style, I was still able to get it around the track.
5. Endless run time.

Conclusion: I have a Tekin Rage system hanging around doing nothing. I will convert a second Rev 4.5 I have from Brushed to the Rage Brushless with a smaller motor to go and have some serious fun.

I know 1/12th scale racing will not move in the direction of a Rage system. But the use of a 2s pack seems to make sense. I like the 1s concept but from what I hear, some of the current speedo’s will require software upgrade to make the 1s work properly over an 8 minute race…(yes…even with a RX pack – which I used).

If a 2s / 17.5 combo is too fast (like a carpet 1/8th scale on steroids) perhaps the fix is the use of a 21.5 brushless?

PS: If anyone is interested in KO Brushed Speedo and Brushed Accessories (motor dyno, com truer, brushes, brush cutting tools..etc)…please send me a PM…I’m dumping everything...

trailranger

I found a company that can make packs in either 1S, 2S, 3S to fit a 4-cell tray right now with current stock cells. The catch is the cells are not rated rated above 15C but make up with in capacity.

Compare
15C X 6300mAH = 94.5A
SMC 28C x 4000mAH = 112A

At 25A average discharge for 8min equal 3300mAH used on a battery. Typical of what 13.5 and 10.5 would see in 1:12 racing. In Theory, the SMC would have better punch at the start, but the 6300mAH pack would have a stronger finish in speed as the voltage could be 0.30V higher or 10% more top speed on the last lap.

If they will make me 3.7V 6300mAH (92mm x 46 x 19mm ) for $60 shipped I'll order one for testing. It won't hurt my feelings not charging a NiMh for Oval or 1:12 practice but I don't want to be spending a fortune on practice pack either.

rsperson

In a heavier car with all that drivetrain -probably a lot closer to each other. But isn't 1/12 scale the Formula-1 of Electric RC? every 0.0001 counts

Fred_B

iTrader: (1)

I haven't logged any brushless runs but I know that back in the day 12th stock spiked up to around 65 amps for a short time. A low C rate battery probably would work for 12th stock but it would take a high C rate cell to run mod.

The TA guys get the cars the "same" by fixing the allowed gear ratio's. This would only work with a class that has fixed tire size (rubber). Even with fixed tires and ratio's there are grey areas in the rules.

trailranger

Fread that was the rated Continous Discharge the Burst Amps is in the 100's

Roland S

iTrader: (11)

Carl:
Don't laugh at my dremel job. It’s one of the many cars I tested with 2-cell and micro motor. It is my homemade chassis more than 10 years ago.

You might have forgotten; I told you that I purposely use those chunked tires to prove my point, with a much light chassis, the need for traction from a perfect shape and softer tire is not really that necessary any more. I did an 8.1 second lap with it earlier on, simply because being the owner of the car and transmitter, I’m used to the car better. The car as it, it’s not really at it’s best, but my focus right now is to find out which motor will give what performance.

If not for the trophy race that we had over the weekend, I would have tried harder tire, I’m definitely going to try magenta in the rear next week.

If you are going to try the mini rage motor, I would suggest 0.955 roll out in inch for the PERFORMANCE 5.5 kv motor or 0.883 roll out in inch for the HI-PERFORMANCE 6.9 kv motor and if you have the EXTREME 8.1 kv motor, my friend, you’re on your own.

Quote:
“…But the use of a 2s pack seems to make sense. I like the 1s concept ………..”
A little contradictory here, don’t you think? Just kidding….

Anyway, in my post #78, it has all the details how to mount the motor.

I'll send you PM later.

Local racer

I don't think making the jump to lipo is the way to go,if you look at touring car the cost has not been reduced as they said it would.The constant change in the lipo battery's are the same as nickel metal.

I have seen guys at my local track go thru for lipos this season and at 80 dollars a pop that's very expensive.

If you care for your nickel metal cells they will last a good long time.

John St.Amant

iTrader: (1)

Thats because you guys abuse your cells trying to over-charge them or charge them too fast. Or are you all having problems reading the warning labels included in the package. I don't have cells dropping out ,, shorting internally,, blowing up,, or for that matter even catching fire (cause I use li-po's exclusively). And I charge them responsibly! You all should too. And my battery are as good or better than when I bought them. Are you guy's having your mothers typing on the forums for you ? PLEASE END THE MOCKERY ABOUT LIPOS!

Local racer

I am not bashing lipos I was just pointing out some facts.I don't think racers are only buying new lipos because of mis use,they are buying them because better packs are coming out, just look for yourself we started at 20 c and we are already at 35c in under one year.

John St.Amant

iTrader: (1)

Right .. and that c rating is a vernier and is calculated. The smc pack are 28c but have more punch than my 3800's with 30c. What's that tell you ..
Hey , If you believe half of what you hear and half of what you see.. you won't do half bad.