High Speed and Short Run Times...they are related.
So you are either too cheap or cash strapped to buy one of the Castle Creations Mamba Max 5700 brushless systems, but still want to go really fast with your brushed motors. OK but this will take some work, tweaking and there are some pretty significant compromises. With this setup it is for one purpose and one purpose only, going really fast on the road. Additionally, your run times will be about 2 minutes, you batteries and motor may become extremely hot, and off-road use will be non-existent. ...And yes you could seriously damage lots of stuff in the process - consider yourself warned. It worked for me but as I make no warranties to this build.
It goes without saying that I have at least 10 or so ideas bouncing around in my head at any one time - some good and some down right stupid. This was one idea that has some merit.
The thing is I am sick and tired of everyone saying you can�t make a Stampede go over X MPH with anything other than a brushless setup or you can�t severely over gear the Stampede, or you can�t use this or that motor because you can�t gear it properly, this is just wrong.
Yes, under typical situations those statements are correct and a 14 turn motor is the lowest gear-able motor, but you can make a lower turn motor work with the right �tuning�. The notion of �can�t� (gear, motor, or MPH) is contrary to every piece of proven physics and science available. Transmissions, gearing, clutches were all designed to make cars faster, torque-ier, more efficient all with less power. They have 81 MPH bicyclist, not even 1 HP and 81 MPH ...makes you think.
After looking at a motorcycle wet clutch system and hydrostatic systems (I will let you look up how they work), I began to think, if I really loosened my slipper clutch (with dif balls installed) to the point that it would let�s say be tight enough to just get the Stampede moving it would in theory prevent damage to the battery, esc, and motor from severe over gearing. In theory, it wouldn�t fully lock up until about 20-30MPH. It would start to slip as soon as more torque (slower speeds) are required or obstacles encountered, and slip less when more HP (top speed) is needed and as the speed increases. This is not a wheel popping or even decently accelerating setup rather a high-speed only vehicle setup.
Always keep in mind that a slipper clutch has three basic settings and only two purposes. Setting #1 is very loose, #2 is set to slip a little to protect the transmission, #3 is cranked all the way down (like most of us do) and provides little, or no, transmission protection, and performs as a fixed gear retainer (and of course produces those wonderful wheelies). The two actual purposes are to either to protect the transmission with limited slip OR act as more of a centrifugal clutch to control and smooth torque and power transfer between the motor and the transmission. Many race winners know that a looser clutch can be the secret for smooth power output. My setup is way on the far end of the second purpose and slips like crazy. I WANT TO STRESS DO NOT OVER GEAR WITH A LIMITED SLIP OR LOCKED SLIPPER THIS WILL BE VERY BAD.
In a VERY simplistic way this is exactly how a hydrostatic transmission or wet clutch works, the motor runs in its higher RPM all the way through the speed range. At a higher RPM the speed of the motor approaches or matches the speed of the transmission shaft and at that point operates as if it was hard geared such as how we typically operate our Stampedes (with the slipper clutch cranked down).
So what did I do with this new found knowledge, I installed a Titanite 15T motor with 32T pinion and 87T spur, tightened the slipper clutch just to the point where it would move the Pede up a small incline and headed to the road. What happened was amazing. The clutch did exactly what it was supposed to do, slipped less and less until about 35+MPH and the you could hear is stop slipping and actually lifted the front end a bit and acted as though I had just shifted gears and took off even faster. I could still use the brakes, and as I slowed and sped up the whole process started again.
I ran 3, 6 cell packs through the setup geared at 32T/78T, Novak Rooster ESC, Titanite 15T, Moab Tires. The motor was no warmer than it normally is, the same with the ESC, the batteries were pretty toasty, but not hot. The down side of this really loose slipper setup is that you only get about 4-5 long runs (about 5-8 minutes) before the battery runs out of juice. After all, you are running everything at full throttle. Even ran it through the grass for a bit just to see if anything would break. Although the slipper was slipping away, the motor revved high, traversing the grass was way slower than normal but it did work.
Acceleration...is horrible! Geez i'm geared 32T/78T with a slick as snot slipper, it accelerates like a slug but the top end is amazing.
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