I need some help with gearing

[NickTheGreek]

Someone please help a brother out with some understanding about gearing (and motors)

I had been out of the hobby for like 25 years....n in the past 2 months, how else can I put this....Im freakin hooked.
2 months ago I hadn't thought about an rc car in 25 years.....Within a few weeks, I got a Slash 4x4, unearthed my original rc10 and Supershot n got them running, got the rc10 re re and copped a gold tub for parts (or to run) off ebay.....n now anxiously awaiting the Worlds Car .

Here's where I need some help.....For the re re I bought a Dynamite Tazer 4 pole 4000kv brushless system. I had the guys at the hobby shop install the electronics n they put in a 23 tooth pinion.

When I built the car I must've left the spur gear too loose (or maybe too tight?) and after a few runs, the diff balls melted into the spur.
So, on my parts car I had a spur that was 54 tooth, so I threw that in there temporarily(till my new 81t spur comes in),went down to the hobby shop n they told me that an 18t spur gear was fine.

The car runs fine now (doesn't get hot) ....it's just in the manual for that type of motor they recommend like an 18t pinion for the 81 tooth spur. This got me a lil paranoid with my current setup.

I could say "ok,the car runs fine, I'm gonna leave it like that" ....but I wanna at least kinda know what I'm doing.

What gearing would be optimal for that motor. (4 pole 4000kv)

Another question I have is say you hypothetically had a 90t spur and a 30 tooth pinion.....and you changed that to a 54t spur and an 18t pinion....being that the gear ratio is the same, what would be the difference??

I also have a Velinion motor laying around and wonder what the performance difference would be between that and the Dynamite Tazer 4000 kv.

As far as the car itself......The lil brotha flys.

Any help would be greatly appreciated.

Thanks for reading.

[Ducati Mechanic]

I wish I could help you, I'm in the same situation. haven't looked at cars in 25 years, I've been flying a lot of planes these days, and recently I decided to purchase an original A-stamp RC10 Gold tub. after restoring it, I purchased a 1990 gold tub C-stamp in the box, and I just purchased a brand-new factory RC10 team truck 2.4! On eBay I picked up a new, Reedy 3300 KV brushless motor, 500 ESC, and 2s 25c lipo's. I'm also wondering what pinion gear to use?

[DMAT]

I did this when I first did brushless. My used the velineon motor with a 3s setup. I know crazy right. so odds are your motor is close to the same. if your melting the spur, then its spinning too much. you need to tighten it up more. What this will do is put more stress on the spur gear teeth and idler's. I didnt melt my spurs anymore but you might have slight chance of losing idlers.

I think when I did my 6 gear on lipo. I did a 18-23 pinion and a 87 spur. they were all 48 pitch.

as to the 90,30 vs 54,18. I think the more teeth that are engaged at once, the less likely you are to break a gear tooth.

I'm not sure if your going for all out speed but I wouldnt try to push more than 50 mph on a 6 gear.

There is a company in the UK that sells alloy idler gears or did sell. no clue how much old stock they may have now. you could try them. Or do like other people have and take the outdrive gears and machine the outdrives off. They are identical to the idlers.

this is something i havent tried yet but considered it. You can try a b4 spur gear with the pads. It shouldnt heat up as badly as the diff balls do. I'm probably gonna try this if i can find a set of pads.

[Ducati Mechanic]

It looks like mine calls. For a 19T with the 3300/3900 KV motors. It comes with a 48t idler

[NickTheGreek]

Slowly I'm getting an understanding of things....and I guess some of it will be trial and error, but still, trying to figure it all out can leave you scratching your head at times.
I get the higher kv/lower turn motors equal more top end and less torque.
I get that higher kv motors can't take as much voltage so you can get a lower kv motor to run faster than a hiigher kv motor by upping the battery......
I get that if you have a motor with more torque than you need, you can gear it up

My thing is Im gonna be running a 5000 30c 2s lipo. So that takes the voltage out of the equation.Thats gonna stay what it is. I'm not gonna be racing so it's not that I need to follow any type of specs, so no need to worry about that. Just wanna figure out what would be the best motor to throw in the re re on a 2s lipo so when I take it out with one or two friends who have modern short course trucks with 3s , that my buggy still performs impressively.

Actually, right now it's pretty damn impressive as it is, but it's not like I chose the motor that's in it...The owner of the hobby shop where I bought the car recommended it....n it performs great....but that doesn't do anything for my understanding as what (and why) would be the best motor on it for performance , on a 2s lipo.

the motor I have is a 4 pole 4000kv.
It's my understanding that a 4 pole is a lot of torque, so I would think that I'd be able to gear up a lil...which I have.
At the same time I don't wanna put too much stress on the drive train, so I have no idea if what I'm doing is right or wrong.
Right now I have a 23t pinion on it......hopefully i'll get a chance later today to take it out for its first proper run.

I say first proper run cause when I first built it I had forgotten to put grease on the inside on the diff pinion, had left out a bearing in each of the axle drive gears and had left the diff too loose which melted the bearings into the spur gear after a couple runs....
Finally, it's good to go.....Now I'm just paranoid whether or not I have the locknut just right not to have that problem again with the melted gear.

.....as far as the motor and esc combo...The dynamite tazer 4 pole 4000kv and esc combo.....which is waterproof.....(I obviously don't know much about these things, and understand you get what you pay for....but for the few minutes I got to spend with it before gears started melting, it got some nice performance to it) ....I got it at my local hobby shop for 100 bucks even. Thats pretty damn cheap. Cheaper than I've seen it on line which is a bonus, cause I wouldn't mind paying a few more bucks to buy it from him n support his store rather than buying on line in any case.

If anyone can suggest what motor (kv or turns) would be ideal (and why) for a the re re running a 2s it would be greatly appreciated.
Thanks again for the responses.

[kaiser]

that thing is wayyy to much motor IMHO for a six gear.

to be perfectly honest i don't see the point in running anything faster then a 17.5 (about 2000kv) in an oldie.

3s has no place in 1/10 scale, another opinion of mine.

but if you are not racing and just trying to keep up with some 3s powered trucks then you might have a challenge on your hands.
then again if you are running on some sort of track you'll probably school the 3s powered trucks because they are too fast to stay on the track. (overpowered)

[JK Racing]

The 4 pole motor will hurt your trans eventually, even the 3500kV Velineon will kill it, this I know from experience

the RPM ratings of the motors are RPM per volt, so a 4000 kV motor @ 7.4 volts will get you just under 30K rpm. 23/81 @ 30K rpm is moving quite well, probably close to the 3S short bus trucks your running with. You said the 81 melted and you dropped on a 54. I can only assume you went from 48 pitch to 32 pitch (54 * 1.5 = 81), if you were running a 23 on 48 pitch, you should be at a 15/16 on 32 pitch. Your 23t pinion should not work on a 54t spur gear (if my assumption is right). If you are running a 18t -32 pitch pinion, the equivalent will be 27t in 48 pitch.

A good overall, FUN motor is around a 4000 kV, probably a 10.5 range. Get a 2 pole motor (standard race based 540 motor) and have a blast. Many guys on here have had great luck with the 9T hobbywing motors, not sure of the kV, but they seem milder than most motors on the bottom end, with plenty of top end for speed. You dont need stump pulling torque with a buggy.

[NickTheGreek]

Thanks for the responses!!

I made a mistake on the gearing I had mentioned. Initially it was a 23t pinion with the 81t spur.
After the spur melted, I threw in a 54t spur and a 13t pinion. I was under the impression that it was18t, until I changed out the spur back to an 81t the other day and saw the pinion was 13t. Now I'm back to 81 and 23.

I'm just waiting for some of this snow to melt so I can give it a go. I haven't ran it yet with "everything right" on th car.

The velineon can do some damage huh?? ....I had a feeling it wasn't the wisest of desicions to throw a velineon in my vintage Supershot. .....n I've been tempted to take it off training mode too. ....Rookie mistakes.....not do nothin', even on training mode that thing boggles.

Being that I'm gonna pick up a stealth as soon as it becomes available, how strong a motor can those things handle??

[JK Racing]

Stealth will handle more power, but 4 pole motors are monsters on torque. In a light buggy, you are asking for a grenade to go off in your trans

6 gear VS Velineon motor:




I cant find the pictures of what was left of the insides, lets just say the idler gears didnt survive very long.

[NickTheGreek]

Ah man, being new to this, Im not even exactly sure to what I'm seeing. ^^ All I know is I'm witnessing a mangling.
Damn....This is heinous.

Like with my Supershot....I pulled it out of the garage after 25 years and had no idea how to get it up and running. All I knew was that I didnt enjoy it in my youth the way I should have, I had a few bucks to spare, and it was finally time to get to enjoy the thing. So I took it to a hobby shop and had them do a restoration. The owner grew up in the hobby so I had faith in his work....Only thing I didnt really like was when I was talking to him on the phone after he had the car for a while,I mentioned that I wanted something brushless BUT MILD. ...and he goes n throws the Velineon in it. I think he just had velineons in stock and wanted to make some money off the sale. He didnt charge me alot in labor and I know he spent a lot of time on the car so I didn't complain. I can always swap motors down the line. He mentioned that he set in on "training mode" which is 50% throttle and recommended I leave it on that cause the car wouldn't handle the full power.
Do you think even on "training mode" that that car will hold up??

..............................

Another shop around here is where I bought the rc10 re re.......The guy that runs that store is a good dude.
Helpful...gives great prices, etc.....
But being a noob, when it comes to electronics, I'm using these guys judgements.
After I built the car I go in there looking for a motor/esc. I ask him "what's good for this" ....n he pulls out the Dynamite Tazer (4 pole 4000kv ). Me, I thought it was cool he recommended that for only 100 bucks n told me "why spend 200+ on that, when this is fine". He could've sold me whatever he wanted to. That's why I like going there......but, what good is it if I'm gonna end up blowing up my car....
That's why I ask on this site.....I know Im dealing with experienced people in the know,in general, and especially with these particular cars. I dont need advice from a 14 year old kid on some other websites forum.

Not having drove an RC in over 25 years, and suddenly seeing the power of these new motors, it makes you feel like a kid again. You wanna take a car out to a parking lot, press the throttle n say "holy sh*t"" ......at the same time, I don't wanna ruin the things......

N look at what I'm working with....A vintage Supershot with a Velineon in it n a Re re with a 4 pole 4000kv motor.....Seems I'm just asking for problems....lol....You live n learn.

........

With the 4000kv motor on the re re.....How would you gear it?? Would you gear it a lil higher to take away some of the torque?? Would the gearing in general not make a difference, being the torque on those motors is just too mush whatever you do???......
Being what it is though, what size pinion would you go with on a 81t spur for that setup??

The manual states don't go lower than an 8turn motor, so I was under the impression that 4000kv was somewhere around 11t....I thought I was all good...

If you had two motors, both being 4000kv with the only difference being one was a 2 pole and the other was a 4, would they be different in turns??

Thanks fellas.

[JK Racing]

Let me state this is my opinion...

Leaving the supershot with the velineon system, in training mode, you may be good, but unsure if you will be happy with the speed.

Not knowing what radio you are using, can you "turn down" the speedo? Using the "high" or "forward" epa (end point adjustment), just dial it back to 75~80% on the cars and just be mindful when launching from a stop. If you jump, dont land on the throttle, coast through the air. You may be able to run for quite a long time with the Tazer system, it is a great system for the money. Dont think the shop took advantage of you, they gave you great bang for the buck.

When you can, I honestly suggest a motor like this one for the re-re to use with the Tazer speedo:

http://www.hobbypartz.com/3330kv-rc-brushless-car-motor.html

Its a bit slower than the 4000, but will be more gentle on the drivetrain.

To answer your question on gearing, run the 23/81 for 2 minutes and measure the temp of the motor, around 100 is great, 150 range is okay, but I wouldnt increase gearing. If your in the 100 range, drop a larger pinion for more top end. With the 3300 motor above, I would bet a 23/25 pinion would be great. Keep in mind, I run on a track 98% of the time, so my gearing thoughts are biased.

[NickTheGreek]

Thanks for taking the time to respond and the input.

The guy at the hobby shop I go to is a good dude. That's why I like giving him my business. I had bought a used Slash from him a couple months ago which was my reaquanitence with rc. I walk in there 2 weeks later like a kid in a candy store looking to spend some money on upgrades....So I ask him "what do I need" ....He goes to me "Nothing,you're good to go....save your money" .... Someone else would've went behind the counter , handed me 5 bags n told me "that will be $150" . I know he gave me a good deal on that Tazer. $100 bucks for the combo....Can't go wrong with that.

The velineon at 50% seems pretty powerful on the Supershot. I haven't taken it to a wide open space to really see it run, but from the couple minutes in front of my house , I was impressed. It's just kind of a waste to have a system that I only use 50% of its output. Just seeing it run after all these years for me is just awesome.
How are vintage Tamiyas internals as far as durability??

On that one, my remote is a Kyosho Symcro KT201. .... I wish the manual was a little better...
It has EPA and a couple of throttle adjustments....I'll just have to figure it out. I don't wanna ask too much and sound like a moron ... Right now, I'm just learning my A,B,C's.

The Rc10, it's just using a regular traxxas remote that came with my Slash.

I'll keep that motor in mind. I'll give it a few spins with the tazer and get a kick out of the power....n swap it out for something that won't be "destructive" . I won't be surprised if I end up keeping it in there a lil too long....till the damage is done....n then start over....lol.

[Ducati Mechanic]

If you're not racing a specific class, You should do what I did' on eBay you can get BL 700esc and a 33 or 3800 KV reedy motor New for under $100! on 2s these things are more than fast enough and don't destroy the equipment. Go with the 3300 and you will have the option of 3s

There's a guy on there from sunshine hobbies that breaks down the ready to run kits, and sells off all the parts separately.

Essentially I ended up with a brand-new team truck 4.2(team addition kit) and installed a buggy stock power set. Now I have a high-performance chassis with the stock class motor that I can run at any club meet. Compared to the 540 brushed motors we were running back in the day, even the mild brushless stuff is overwhelmingly fast! And like others have set on here you can usually go much faster with the proper power to weight ratio.

[NickTheGreek]

It seems like every day I'm coming home from work and searching for info on various rc related topics,.....
Trying to find the answers for myself, so I don't have to be asking questions that might seem elementary to most.

Ive mentioned befor that I'm running the Dynamit Tazer 4000kv with the re re....
Right now I'm running a 23t pinion with the standard 81t spur. I have plenty of torque to spare and my temps seem fine.
I don't have a temp gun, but the motor and esc are barely warm to the touch...(granted, I'm not running that hard).

Can I keep going up in pinion or dropping the spur as long as my temps are alright or does there come a point where it becomes too much strain on the drive train regardless of temp.?? ....Im not saying to have a ratio of something like 20/40 ofcourse....I just mean if I upped the pinion a few teeth or dropped the spur a few teeth.

Is there a number that you don't want your FDR to be above or below??....(where youde be taxing "something")

I'm asking about the FDR because I've seen others ask about gearing and get responses of "what's your internal gear ratio......"
Does having a 1.83 internal gear ratio as opposed to a 2.25 or a 2.65 make a difference in how you would gear the same exact car with the same exact motor in relation to damaging the drive train??

............

Also, I was having a problem with the diff balls melting into the spur,which I hope I resolved by tightening the diff pretty tight and setting the punch at 75% (I might even go to 50%)
My question on that is would changing the size of my pinion have any affect on those (diff ball melting) results, or if it has nothing to so with it.

Thanks in advance..
I genuinely appreciate your taking the time.

[JK Racing]

Temps are the biggest killer of motors/speedos/batteries. Get a cheap temp gun (I think I paid $15 at radio shack), test motor/speedo/battery. What gets taxed is different parts of the system. Motor @ high revs too long, motor hot (geared too low), motor lagging hard, speedo hot (pulling too many amps, geared too high), battery hot, you are pulling too much from the battery for the combo (to low of a C rating on the pack).

Gearing up (FYI, as a general rule, 3 teeth on the spur usually equals 1 tooth on the pinion, so pinion changes give larger results) will put less stress on the diff balls/spur, but as mentioned, that is a torque monster. By the time you gear it enough to soften the blow, you may have a flywheel on the motor instead of a pinion