Hmmmmmm......that picture above is pretty small. Maybe this time I should build a smaller car too? How about this 1/32 scale Lancer body
For the chassis I'm going to rebuild a chassis I built many moons ago, the Charles Cressi "Sidewinder Nemesis". Here's a link to the Jose Rodriguez, Jr. Car Model Magazine construction article and my soon to be rebuilt original chassis:
Those are cool numbers. I built a 1/24 scale version with some numbers that are similar (kinda....sorta...) :
Pattos Place has decals for the 55 prototype. Not sure what I'm going to do yet. I've been thinking of a tribute to Dave MacDonald and his1963 Times Grand Prix winning Cooper Cobra:
This is the chassis I rebuilt. I built it long ago, without a jig. It was out of square (1/16"+ wheelbase difference side to side ) and the pan didn't hang evenly below the center section so it was twisted (left rear of the pan hanging all the way down and the right rear all the way up ):
Also, the body mount system really didn't support the short body sides "Korrectly". Below, it's being rebuilt (in my Rick's Jig):
Yes I'd like opinions as I'm waffling between the yellow #55 prototype and a metallic blue #98 tribute to Dave MacDonald.
That thing looks bullet proof & the weight of a Sherman tank beautifully put together & build plans...
It looks to be a Mura Magnum 880 based on the "68 Mabuchi". I remembered I had a couple of well used Mura "Short Stack Magnum" silver wire arms and a can with a Mura sticker. So the restoration began.
The can got a set of Versatec magnets and a "Semi-can" shim. The Mabuchi endbell got it's brush holders soldered to it's brush hoods:
The next one had, I guess, "thrown" the solder holding the wires to the comm but the wires were still in place. You could slide the wires up and down on the comm tabs. The arm was "dead":
Brass spring post protectors, shunted brushes, my Teflon "invisible" spring insulation, and a "Magnum 88" sticker finished it off.....and it even runs!
For how long it will run is another question. But at least I can see a real vintage Mura rewind, as Rodney would say, "move again".
I also fixed up some Alpha Piranha rears to the same size as the greys (.812" diameter, .500" wide rubber and .585" overall wheel width):
This thing is ballistic! It's crazy fast but has a hair trigger even with an 8 tooth pinion. Maybe I should put a 9T on it.
With the grey tires it's also a bit loose and lights the tires up coming off the corners. With the modern blacks it's got plenty of bite and handles well. But it almost seems like it wants to lift out of the slot and take off down the main straight!
This car would probably turn a faster overall lap time with a bit less motor...........nah.......after all, it's a KING COBRA!
That looks just right Rick! Sounds like just the right level of performance Measured at the "insane" level
Would keep it in there, sounds like the perfect scale representation of the King Cobra ,especially watching those videos of that one hanging the rear end out round the corners
Downloaded the build article and your pictures for a future build, even got a 27/28 double wind silver arm somewhere...
No, you should try it with a 7-T pinion instead of a 9-T ... remember electric motors make max torque at stall speed, so by having the motor run at higher RPM in the turns (lower torque), you'll exit smoother and be less likely to light up your tires.
Interesting Dave. The "old school" wisdom I've read is to gear the car with more teeth on the pinion to make it "softer" to drive.
This car is anything but "soft" to drive! Two screws and a gear puller and the pinion is off so I should give it a try.
Dave is right on the money on gearing theory (again), Rick, read my Batmobile thread posts # 110,116,118,119, and 120. It sure seemed like "the wrong way to go" in my way of thinking, and I was wrong. I know it sounds counter-intuitive to give more acceleration to a car that already accelerates violently, but Greg Gilbert just winked at me and said in a low voice, "Pablo, just try it". I went down a tooth on the pinion and everything smoothed right out.
It really does but that's what's so great about sharing info here. My wife calls it "collective wisdom" and I agree. I will give a 7T a try.
<SNIP> I know it sounds counter-intuitive to give more acceleration to a car that already accelerates violently, <SNIP>
What's really happening is moving the motor's RPM operating range away from its torque peak, thus softening its response.
Rick, back in the day when rewinds similar to yours were contemporary, almost everyone ran 7/34 gears on King tracks. My home track at the time was not a high-speed track, but a custom job with lots of slow tight corners and a no-punch bank. The favorite arm then was the Lenz 27/28 with that infamous Mura green bubble gum insulation. With a heavy motor setup from the day, real traction was lacking and it was easy to have burnouts all the way up the main chute.
Then someone came out with a good quality 6-T pinion, and I bought one to experiment. At first I played with 6/34 gearing - the car was much smoother but the motor peaked out well before the bank. But 6/32 filled the bill perfectly, and that's what I used for local racing until Faas gears first came out. The car had competitive straightaway speed, and tore my competitors up on the twisty backside of that track.
I didn't know the theory back then, but when I first heard the "max torque at stall speed" concept, I had a "Eureka!" moment that's stayed with me ever since. So much that I had observed, but didn't really understand, became crystal clear.
OK, I installed a 7T pinion to go along with the existing 30T crown gear. I tested the car with both the vintage grey tires and modern Alpha Piranha's. My impression is that it is absolutely not worse with the 7T. The more I drove it the more I felt it was better than before. Better meaning it was easier to control coming off the corners.