Suggestion for the Castle Guys - RC-Monster Forums

pinkpanda3310 · **Suggestion for the Castle Guys -** 05.14.2009, 08:42 AM

I read on one of these threads that castle is reluctant to suggest any gearing due to the infinite number of setups. I'm sure most have seen the graph from traxxas for the velineon system. Of course they know the setup of the cars.

My thinking was to have something relative to any setup-power/weight/gear ratio. Given the system is a constant 2200 combo or 2650 all you really need after that would be the batteries used- voltage+amps, weight rtr, and castle might suggest a FDR.

No mention of pinions and other things that are just part of the bigger equation. Trying to keep it simple. I know castle has great back up service but something like this might ease the repairs department.

What do you guys think?

suicideneil · 05.14.2009, 04:52 PM

( I think ) Anyone with any common sense will be able to realise whats a realistic and whats an unrealistic setup given their setup- larger, heavier vehicles will require heavier duty lipos and limit/ reduce their gearing as required. As it is, using a calculator (like BrianG's, though there are others out there) will tell you the required ratio to hit any given speed, and gearing for a certain speed is the key thing- manufacturers can provide info on the tranny & diff ratios and tire diameter etc, then you just factor that in with the rpms (kv x volts) to get the required gearing for any given realistic speed.

Like I said, common sense + gearing calculator = success.

pinkpanda3310 · 05.15.2009, 04:30 AM

But not everyone subscribes to the awsome RCM forums or similar. It does seem that simple to some people (especially here), but these products are available in rtr kits which may have recomendations for that particular setup but for those who are going to up grade or make a conversion may be doing so on the assumption that there car can do x-mph with out any insight to the finer points.

I'm not saying that the majority of people are stupid, just the a portion need more information when making such a decision. Doing calcs on Brians calc sheet will not give a temperature analysis (of course it's impossible) so a power to weight to gearing ratio might give a starting piont.

As stated by Castle the people on this forum are likely to push the boundaries of any given running gear so a beginer (i don't like to think I am but when I get on this forum it is apparent to me) one might get the wrong idea on what's a 'BULLET PROOF' system.

Don't get me wrong I know there's no 'BULLET PROOF' system but everyone wants something that won't leave them sidelined and/or out of pocket

05.15.2009, 04:38 AM

ANYTHING can be Bullet proof, if its a shelf queen

pinkpanda3310 · 05.15.2009, 05:00 AM

So you have a 'BULLET PROOF' flux?

Unsullied_Spy · 05.15.2009, 05:01 AM

Quote:

Originally Posted by Freezebyte

ANYTHING can be Bullet proof, if its a shelf queen

NOTHING is bulletproof. If you can't break something send it to me and I can break it. If I can't break it I can at least prove it's not literally bulletproof.

This lipo was a shelf queen after it completely crapped out, didn't do it much good

The problem with a gearing guide is, as neil said, there are too many factors involved and if some n00b followed their guide and burned up a 2650 and MMM trying to run a Truggy geared for 70 MPH they'd be pissed at Castle and talk a bunch of smack about them because they're an idiot

pinkpanda3310 · 05.15.2009, 05:13 AM

The n00b is who I am thinking of, and it is not so much a 'what's safe for 70mph' but whats safe for the batteries they plan to run, ie-power/watts/votage+amps to weight. The mmm combo can not be out done unless you've got a costum build or 1/5.

What the pain in doing a, power to weight, gear ratio?

brushlessboy16 · 05.15.2009, 06:38 AM

Quote:

Originally Posted by suicideneil

( I think ) Anyone with any common sense will be able to realise whats a realistic and whats an unrealistic setup given their setup- larger, heavier vehicles will require heavier duty lipos and limit/ reduce their gearing as required. As it is, using a calculator (like BrianG's, though there are others out there) will tell you the required ratio to hit any given speed, and gearing for a certain speed is the key thing- manufacturers can provide info on the tranny & diff ratios and tire diameter etc, then you just factor that in with the rpms (kv x volts) to get the required gearing for any given realistic speed.

Like I said, common sense + gearing calculator = success.

+1 on that

Unsullied_Spy · 05.15.2009, 05:14 AM

If they could work out a good formula and get people to use it properly it should work fine.

1truckerdan · 05.17.2009, 06:21 PM

Would anyone other than me like to see a "rev limiter" feature for our MM's and MMM's that we could set ourselves?

MetalMan · 05.18.2009, 12:00 AM

Quote:

Originally Posted by 1truckerdan

Would anyone other than me like to see a "rev limiter" feature for our MM's and MMM's that we could set ourselves?

It's been discussed many times in the past, and in the view of many including myself it's not such a good idea. The problem with a RPM limit is that it doesn't account for motor loading. So if your truck is geared for 60mph and you set the RPM limit to a level which achieves a top speed of 30mph, you haven't actually reduced the load, only lowered your top speed.

Ideally you should account for top speed changes with gearing or cell count. I realize there are some situations where a motor is geared properly but is still too fast, but lowering the cell count can take care of the problem instead of RPM limiting.

1truckerdan · 05.18.2009, 03:46 AM

The main reason I was thinking of a "rev limiter" was for when we go airborne we "unload" the motor.

I have a MM /7700kv in a 1/10th scale 4x4 convertion on 2s and when I do large jumps it really "unloads "quick.

suicideneil · 05.18.2009, 11:17 AM

Let off the throttle when you leave the ramp/ jump, just nudge it forward or back to control its angle in the air as required.

As Megaman said, rev limiting doesnt remove the load on the motor- its the same reason why dialing down the throttle EPA isnt a terribly good idea, though thats more to do with esc efficiency (esc will run hotter at anything less than 100% throttle being used for prolonged periods).

SpEEdyBL · 05.18.2009, 08:09 PM

Unloaded rpm isn't that much high than max loaded rpm. Id say there is usally less than a 5,000 rpm difference based on my eagle tree data. Motor kv will only be about 100 rpm less at the most for castle motors. If you do see a big difference unloaded vs. loaded, it's because your batteries are insufficient.