Motor advice

[jpw59165]

I have a 1986 Kyosho Turbo Optima that still has the stock LeMans 240S motor in it. I bought it in 1990, and it has been sitting in storage for 20 years. I recently dug it out and . . . it still runs! The only problem I am having is the motor gets sooo hot running 8.4v NiMH 4200MaH batteries that the wires wont stay soldered on the tabs after about 2-3 minutes of running. I tried adjusting the timing for 6, 3 and 0, nothing works. I even tried cleaning the motor out, still no luck. I debated on getting one of those ol' skool heat sinks, but I don't want to waste the money if that fails too.

I am also debating on upgrading to a different motor, maybe something that can handle up to 9.6v power, longer run time, or bigger can. But, I still want a fast motor, and be era specific. Which of these motors would be ideal?

Kyosho LeMans Speed 480T (this is my 1st choice: supposeably 9.6v capable, 26.5K rpm, 8 min run time, 19 turn)
Kyosho LeMans Speed 240T (this is my 2nd choice: supposeably 9.6v capable, 28.5K rpm, 4 min run time, 16 turn)
Kyosho LeMans Pro High Torque (this is my 3rd choice: supposeably 9.6v capable, 30k rpm, 4 min run time, 16 turn)
Kyosho LeMans 240SB (this is my last choice: 8.4v capable, 30k rpm, 4 min run time, 19 turn)
Kyosho SPA 240WS (I like this motor, but I can't find one for sale: 9.6v, 31k rpm, 4 min run time, 18 turn)

What is the best battery I can run with these old motors: 7.2V 2800MAH, 8.4V 2400MAH?

Any suggestions would be appreciated.

[Coelacanth]

The 240 line of Le Mans motors should all be capable of handling 8.4 volt batteries. An 8.4V NiMH is no more powerful than an 8.4V NiCd battery, they output the exact same volts. The higher the "mAh" rating number, the longer the battery life is, it has nothing to do with power.

If your motor is getting so hot, I'd be looking at what's causing unnecessary friction--assuming the motor itself isn't shot. Do the wheels all spin freely? Does the car roll smoothly? If you roll only the rear tires on the ground, do the fronts spin smoothly with the chain?

Is the Optima fitted with full ball bearings? You said it was a Turbo so I imagine it has full ball bearings. Do all the bearings spin smoothly?

Are you running the car in grass? That by itself is very hard on a motor.

EDIT: I almost forgot possibly the most important detail, what size pinion gear are you using? I would suggest an 8T to 10T, anything more than that would cause things to heat up.

Nobody really used heatsinks on Le Mans motors back in the day, the included motor spacer was usually enough. And that was with offroad racing and 8.4V. So if your motor is overheating that much, there's something else going on that you have to troubleshoot.

[jpw59165]

The wheels do spin freely
The car does roll smooth, I cleaned it and lubed all moving parts.
I removed the chain back in 1990, it is now belt driven
Yes, it is a ball bearing car, not bushings
I have just been running it in the streets
I am running a 14t pinion with the Kyosho torque limiter, maybe I'll try a 11 or 12t pinion.

I know it needs new brushes, maybe I'll throw in a new set and see if that helps.

Where can I get brushes for it, and what kind of brushes should I look for?

Thanks for the info!

[Mr. ED]

How long do you run it? It was only intended to run 4minutes at a time.
Also make sure the meshing is not too tight

[jpw59165]

Ha Ha, well, I have a 4200MaH battery . . . so a little more than 4 minutes, but it is popping the solder after 2.5 to 3 minutes.

This is why I was debating on upgrading to the LeMans Speed 480T (8 min run time, 26,500 rpm, 19 turn)

It's actually the same turn rating as the 240s, but it is 1,500 rpm faster, plus it runs twice as long

[Lonestar]

Ha Ha, well, I have a 4200MaH battery . . . so a little more than 4 minutes, but it is popping the solder after 2.5 to 3 minutes.

This is why I was debating on upgrading to the LeMans Speed 480T (8 min run time, 26,500 rpm, 19 turn)

It's actually the same turn rating as the 240s, but it is 1,500 rpm faster, plus it runs twice as long

maintenance, maintenance, maintenance...

if the motor overheats, then it means it draws too much current and/or it needs a rebuild. I guess it's never been to a lathe in its entire life, so first have the comm trued and give it new brushes, have a pro do this for you maybe (assuming any 2012 "pro" knows anything beyond Titans and velineon ). Then check for any bind in the drivetrain, that'd create some crazy resisting torque that the motor has to fight. If you use the stock gearing, you should be fine.

last but not least, check your solder joints... cold joint => high res => high temps => melts.

there's no reason for all this to happen with a mechanically/electrically healthy car

and don't run the old lady on 8.4 or 9.6V...

r e s p e c t

Paul

[Mad Racer]

If the buggy is all free in the drive train, gear mesh is correct & not running on grass as others have pointed out then more then likely it's the motor.

All those motors were made in the 80's. (over 20 yrs old)

Problem is the magnets are gone. Even if the motor is rebuilt with a re trued com, new brushes, re alinged brush hoods, oiled up bearings & etc the magnets will still be weak from age. This leads to a motor thats inefficient motor that will cause heat build up.

Try a newer motor like a Trinity or check point 19t motor..

[Coelacanth]

A 14T pinion is way too high for a 4-minute motor...the 14T was a good pinion for the 480 Gold (8-minute motor). 10T is the highest I'd go with a 240 series. That's why the Turbo Optima kit only includes tiny pinions like that--I think the 10T was the included pinion gear with the Turbo Optima, but you could buy 8T and 9T gears as options.

I chose a 14T pinion gear for my Turbo Optima-based CYANide car, but that has a less powerful brushless 17.5T motor, belt drive conversion and smaller-diameter wheels & tires.

[Mad Racer]

Standard pinion in the Turbo kit is a 9t.

That was for the 8.4v pack too.

[jpw59165]

Thanks for all the info. In the end I decided to sell the car. It was going to costs me $100 for a NIB Kyosho LeMans motor, and even then it's still a 20+ year old motor. If I wanted to upgrade it to a brushless motor with new ESC and 2.4 GHZ transmitter/reciever it was going to costs me around $350.

[Mr. ED]

Who said you had to buy a new moter for it??? oh well, somebody's gonna be happy with it. I hope you got a good prize: enough to get what you want instead.

[Coelacanth]

Who said you had to buy a new moter for it???

LOL Good question...I sure as hell wouldn't be buying a new-in-box motor from the 80's when I could rebuild a used one for $25 - $30. Certainly, the 2.4 GHz radio gear and an EZRun brushless setup would end up costing about $150 to $200, tops. A good brand-name RTR kit these days would probably cost more than what he'll get by selling the vintage car...maybe $300? I don't know, I wouldn't be interested anyway. That's why I'm on THIS forum, and not a forum dedicated to new RC cars.