voodoodb

My Feedback: (98)

I have 2 Mabuchi 370 motors. On the side of the can one has RK-370SD-5028 and under that is TN097607. The other motor is identical except it has 2 diodes?? one going from + tab to can and one going from - tab to can and the TN # is TN098702. My problem is that the one with no diodes turns faster RPM. I would think they are the same motors and that the TN # is just a Manf number. Can someone please help? Will the diodes make it turn slower?

Doug

Walt Thyng

My Feedback: (9)

First off, are the devices diodes or capacitors? If they're in fact diodes I don't know what effect they would have, but nearly all brushed motors need capacitors for electronic noise suppression. They have no effect on rpm. Look closely at the cans; does one have a sleeve on it? It's bee a bit since I did much with brushed motors, but as I recall the sleeve will reduce rpms. On the other hand Mabuchi's aren't exactly built to the closest tolerances and the speed difference may simply be a normal variation due to differing tolerances.
Walt

voodoodb

My Feedback: (98)

Thanks Walt, they are capacitors. As for sleeves I don't know. Anything in particular to look for?

Walt Thyng

My Feedback: (9)

The "sleeve" is a 1 or 2mm thick jacket wrapped around the can or casing of the motor. They are nearly as long as the motor, but ends don't touch leaving a slot. Stick a flat blade screwdriver in the slot and twist to spread the sleeve so you can slide it off the motor.
Walt

voodoodb

My Feedback: (98)

No, neither have a sleeve.

Walt Thyng

My Feedback: (9)

Sounds to me like you're stuck with manufacturer's tolerances or one of the motors has more time than the other.

Time reminds me that even a can type motor can have the timing changed.

Lastly what is the application and how much difference is there between the motors?
Walt

voodoodb

My Feedback: (98)

The one with the higher RPM has much more time than the other. It's brand new. I'm trying to use it for a Fuel pump on turbine engines. The old one ran the engine at 135K. The new motor I'm only able to 97K which tells me the motor is not sending enough fuel to get the RPM's up.

Walt Thyng

My Feedback: (9)

AHA! Brushed motors need to be broken in! Until the brushes wear to the contour of the armature you will not get full power. One way is simply to run the motor in normal operation. A better way is to drop the motor into a glass of water and run it until the water turns gray (how gray is a judgment call, but about the color of dirty dishwater is good). As I recall this will take 2 - 5 minutes (I'm sure there must be some info on the 'net). After you finish, just blow dry the motor and put a drop of oil in the bushings.
Walt

voodoodb

My Feedback: (98)

Thanks Walt, I've run the motor several minutes. On these fuel pumps they say the motor doesn't need breaking in, but the pumps do. So I hooked a 1.2 volt AA battery up to it and ran it pumping fuel until the battery died. I also took the pump off and redid the gears on the motor shaft and will try it again with the turbine tomorrow. It seems to be pumping fuel good. I also took the old motor apart and failure was caused by the magnets coming unglued from the can.

Doug

Walt Thyng

My Feedback: (9)

Sounds like everything's A-ok(-:
Walt

drywaller

voodoo, I have been searching high and low for these exact motors. Do you have any idea where I can find them in the USA? Any chance of you selling a good spare?
Any help is really appreciated.

voodoodb

My Feedback: (98)

Sorry but I don't have any spares. I got mine at my local hobby shop. It's a replacement Losi(car) motor called a Frenzy 370, but you can get them from Horizon Hobby. I haven't tried it again yet. But looks like it will work. I might have done something to the pump during assembly. One thing is the shaft is a little longer than the stock motor.

Doug

drywaller

No worries voodoo. I have a factory starter motor for my super eagle. The printed numbers/letters on the side of the can are RK-370SD-5028. I am going to order a few directly from the shop in china. If you need a spare let me know. They are pretty cheap from the warehouse. Shipping is kinda steep but if I order extras I can re-coop some of my money.

john47

Mabuchi motors are the exact same ones as used in GWS motor/gearbox setups