All, for the coming Danville event the only issue I have with rules for the event is the scale speed of my tanks. I have a King Tiger with a Shumo gearbox reducer which brings that vehcile in line but those are expensive pieces of kit.

Is there a solution for this that is non-mechanical? I was thinking a kludge like limiting the travel of the controller stick or somehow lowering the voltage to the motors.

If this was posted I apologize for missing it. Looking to slow down a Tamiya Jagdpanther and a Sherman.

Thanks. Joe

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I am scrambling to do the same thing.
I am looking for 8t pinion gears, the stock pinions are 10t.
They are cheap and will slow the tank and add torque.
BUT, they need to be metric pitch, which is hard to find. (0.6)
Oh, the other thing you need is a pinion puller.
I have one which you can borrow this weekend.

You can try adding a serial of diodes in oposition to have reverse. 2 diodes low the voltage by 1,4 volt...etc. You will notice a lower full speed but who cares about. You can add several diodes and will have a lower voltage for the same angle of the stick. This doesn't add steps of course just works as a fixed voltage reductor that will not change with the current. Diodes must by 100V 5 A minimun.

<div style="margin: 0in 0in 0pt">Guys ,</div><div style="margin: 0in 0in 0pt">The only good way to slow down these R/C tanks is with a different gearbox or and add-on gear-reduction .</div><div style="margin: 0in 0in 0pt">( by the way , the Shumo gear-reductions is a knock-off of my original gear-reductions I used to make and sell . I am saying knock-off , since I did mine customized for each tank and Shumo just offers a generic one )</div><div style="margin: 0in 0in 0pt">Anyhow ,</div><div style="margin: 0in 0in 0pt">Anything what you do with just slower motors and just dropping down from a 10tooth to an 8tooth pinion ( mainly on the German tanks ) is not enough ,
since these tanks are way to fast out of the box .</div><div style="margin: 0in 0in 0pt">Go to my tanker section ,
http://www.customrcmodels.com/Tanks/
you will find there more when enough reading material about gearing and gear-reductions , since I been doing this for these tanks since more then 10 years now .</div><div style="margin: 0in 0in 0pt"></div><div style="margin: 0in 0in 0pt">Please remember , in regards to these speed-rules , we just using here on-road speed !</div><div style="margin: 0in 0in 0pt">Which is still fast for each tank !</div><div style="margin: 0in 0in 0pt">If you asked me , it should be off-road speed !</div><div style="margin: 0in 0in 0pt">Which would require for sure new gearboxes or some serious gear-reductions for each tank .</div><div style="margin: 0in 0in 0pt">The advantage with a good gear-reduction or good configured gearbox , you have much more torque after you been hit a few times and your tank runs much more efficient and looks a lot more to scale</div>

I am running stock Tammy gearboxes and 480 motors.
I tried to install MPI 1:3 gear reductions, but they came with a 4mm shaft.
The closest pinions I could find were for 1/8" shaft.
I do not have the ability to accurately drill-out the pinions to fit .
I have ruined 4 pinions already.

I only need to shave between 1/2 and 1 second (at 25 feet) off my road speed times.
So, I figured dropping to a smaller pinion would give the the correct speed.<br type="_moz" />

<div style="margin: 0in 0in 0pt">You are talking about an US tank , like Sherman or Pershing ?</div><div style="margin: 0in 0in 0pt">Yeah , then the 8tooth pinion will do the trick .</div><div style="margin: 0in 0in 0pt">Or just the long can 380&rsquo;s , most of you guys call them 480&rsquo;s ( since some manufactures call them like that , which is not correct ) ,</div><div style="margin: 0in 0in 0pt">and just adjust your servo throw ( on which ever channel you have the throttle ) lower ,</div><div style="margin: 0in 0in 0pt">or use the dual-rate , if you have that &hellip;.</div><div style="margin: 0in 0in 0pt">which you will not find on the cheaper 4 channel transmitters .</div><div style="margin: 0in 0in 0pt">Then you have to make up a mechanical limitation on your stick .</div><div style="margin: 0in 0in 0pt">But the big debate about speed is mostly about all the German tanks ,</div><div style="margin: 0in 0in 0pt">since they are way to fast out of the box</div>

I have run my Sherman with the stock gearboxes and motors at Danville and it tested out OK, not too fast, so you can probably leave that one be unless you have upgraded to faster motors. For the German tank just follow one of the suggestions already given. Limiting the travel on the control can be done with programming depending on your brand and model of radio. I know my Spektrum DX6i can do it.
Steve

Any digital radio can reduced throttle input by % increments, unless you're stuck with an analog.

Willy, thanks great information!

Joe<br type="_moz" />

Just an FYI, the 8 tooth pinion from Heli Max has been discontinued. They're making a 9 tooth now. I haven't tried them, but they should be workable...although the 8 was a very nice mod to a Tam. TU.

If you've got a Spektrum radio which is digital. One can adjust the travel (on a Spektrum it's the "Travel Adjust") to any percentage you want, but it doesn't work out too well in battle with lots of hits on the tank. At a high number of hits, it pretty much won't move. Not the greatest option, but good if the only one.

As to DaveBCool, I've had some success drilling out pinions with a small vise and a cordless drill. I too had ruined several pinions, but found that if I didn't drill the pinion all the way though from one side (i.e. drilling 1/2 of the way from one side, and then drilling the remainder from the other side), they worked pretty good. Kind of low tech, but it worked.

You could try using a Life battery, depending on how much you need to slow it down.

Depending on how they are running the inspections you could just make a throttle stop that goes onto your TX and limits the throw</p>

of your actual stick movement.  Though with this quick band aid solution you may lose torque on last hits as your not hitting "full throttle" anymore.</p>