Rc4wd gru 2:1, 3:1, 4:1

[rockwerks]

This is excellent Advice... I've e-mailed Mike and he said that their units are tested with Brushless, but he doesn't think they will last very long since they "don't have bearings"... Not sure what that means, exactly, but I've e-mailed with some follow-up questions...

I'd like to see the inside of one of these, so if anyone has any pictures, could you please post them?

Their site has this pic, which kid of gives you an idea of how they accomplish the gear reduction:






The warning on their site says this:

Important note: this product is designed for regular 540 brushed motor, its not designed to run on high power brushless motors! It will work, but it wont last a long time.

It looks like it's all bushed, and that there aren't any bearings in there... Not sure what a "long time" is considered. I'm guessing that, due to the smallish gears in there, it's not possible to fit bearings, otherwise it might have them??? Will have to get one on the bench to find out for sure...

I think I'd skip this for most applications. We have enough power in most cases to power direct-drive anyhow... If you MUST use a geardrive, then a Hughey or Fine-Design set would be more appropriate I would think...

These guys build cools stuff but dont put bearings in anything! everything is bushed. But Im sure the bushings are in common size so bearings should be possible. I have several of their trannies and none of them have bearings.

[Flying Scotsman]

Like this if you have a motor that is running a bit over what you need for proper prop speed a GRU unit will decrease the output RPM and increase the torque. hence the ability to swing a bigger prop without an increase in amp draw and hopefully higher top end.

A bit over...a motor rated at 1400Kv will result in a motor capable of running half the expected RPM with a 2 to 1 ratio. Direct drive is the way to go...unless you run scale boats

Douggie

[Darin Jordan]

A bit over...a motor rated at 1400Kv will result in a motor capable of running half the expected RPM with a 2 to 1 ratio. Direct drive is the way to go...unless you run scale boats

Douggie

Actually Doggie... what guys have traditionally used geardrives for is when they have a HIGH KV motor and they want to use it where a lower KV motor would be more appropriate... Like using a Neu 1515 1D in a 4S application... You could gear it down 2:1 to make it a 2050KV motor, but increase the torque... so you could use a 2S motor in a 4S application...

Check out Jay Turners article in RCBM where he converted his Mean Machine from 24-Cells to a 4S system by using a geardrive setup...

[Flying Scotsman]

Darin, I understand that, but a gearbox results in more possible problems.

Douggie

[Darin Jordan]

Darin, I understand that, but a gearbox results in more possible problems.

Douggie

Granted... but you have to remember that these were mostly used back in the days of brushed motors, BEFORE there were so many choices of motor KV out there...

And... if a 9XL isn't quite right at 1.8:1... you could then just swap gears and make it 1.7:1 or ??? You can adjust the KV without having to spend another $$$ on a different motor, which may or may not be in the target KV...

They only reason we don't use these more today is because of Fiego and Neu and Hacker and Aeveox and cheap Chinese Motor companies are offering every motor size under the sun...

[j.m.]

Why would you pay $40 for a gearbox!?!

And they aren't even planetary!

http://www.hobby-lobby.com/drives.htm

[Ub Hauled]

Jm,
$40 is pretty steep ($47+ shipped), considering they are really compact and light weight, it may work
better in boats (riggers) where space is limited. The ones you showed us are a bit longer
and with the motor mount angle it may be too long for the hatch to close.

[Darin Jordan]

Why would you pay $40 for a gearbox!?!

And they aren't even planetary!

http://www.hobby-lobby.com/drives.htm

Hmmmm.... I wouldn't for 2:1... But they (RC4WD) offer a 1:2 now don't they....

Can you find me one of those $30.00 inline jobs that offers that??? If so... do tell... because thus far... all I've seen are the underdrive/gear-reduction units...

[AndyKunz]

Don't forget you lose about 5-10% efficiency with a gearbox. That goes into HEAT and NOISE. You guys sure you want to do that? Not me!

Darin - you can run a 2S motor in 4S, but it will probably run real hot. For the cost of two of these gearboxes you can have a really good BL motor that's more appropriate. And since these gb's don't have bearings, they are guaranteed to shortly become the failure point.

Think a little about this before jumping in, guys.

Andy

[rockwerks]

Don't forget you lose about 5-10% efficiency with a gearbox. That goes into HEAT and NOISE. You guys sure you want to do that? Not me!

Darin - you can run a 2S motor in 4S, but it will probably run real hot. For the cost of two of these gearboxes you can have a really good BL motor that's more appropriate. And since these gb's don't have bearings, they are guaranteed to shortly become the failure point.

Think a little about this before jumping in, guys.

Andy

Hey Andy who owns speed record for N1 you or Darin? LOL

We are not needing something for circuit racing.

[rockwerks]

Why would you pay $40 for a gearbox!?!

And they aren't even planetary!

http://www.hobby-lobby.com/drives.htm

those are for smaller dia motors...29.5 dia wont fit over a 36mm can will it?

[old guy]

Just a heads up there is one for sale on RCCRAWER now for $25 it was listed to day under the name Red Rockcrawler
Old Guy

[rockwerks]

Just a heads up there is one for sale on RCCRAWER now for $25 it was listed to day under the name Red Rockcrawler
Old Guy

Darin was looking for an over drive unit not under drive..........RCC is a great resource

[AndyKunz]

Hey Andy who owns speed record for N1 you or Darin? LOL

Darin currently, but prior to finding model boating I set records in N2 Hydro, P Hydro, O Sport and P Sport with ESCs I designed. And I think you'll find my name etched in copper on his M2 ESCs also...

Darin and I are in constant communication, don't worry He knows what I'm playing with and why - and why nobody else here does.

Andy

[Darin Jordan]

Darin currently, ....

I actually only hold the 2-Lap record... which is totally cool...

But Mr. Bill Oxidean just recently upped the N1-Mono SAW record... He went an AMAZING 33mph with an OM21 and brushed power on Lipos... I think the older record was 30mph or maybe 31... The IMPBA record is currently 29 and change...

I'm looking forward to hooking up with my bud, Wilmer, and doing some good natured battle for this record next spring!