squarehead

iTrader: (75)

Those are 190mm bodies.

If they'd like to submit bodies for approval, they can contact me directly.

IndyRC_Racer

iTrader: (9)

Here is a link to the Bolink 200mm cars (http://www.bolink.com/carbodies.html).

You might want to send a PM to ApexSpeed here on RCTech.net as he would be better able to address that issue. Those bodies look no better (or worse) than the currently approved Parma bodies.

Three

Oops wrong link, thanks for posting the correct one.
But Parma/PSEs Mustang is AWFUL and UGLY !!! And the two Pegasus Mustangs that I bought had dust moulded in the body (but I guess they are usable). WE NEED A JAVELIN/AMX !!!!!

IndyRC_Racer

iTrader: (9)

In the meantime, the HPI 'Cuda makes an okay stand-in. Check out the pictures thread here on RCTECH (http://www.rctech.net/forum/electric...sion-only.html)

Front: Pactra RC264 Metallic Red backed with Pactra RC262 Indy Silver
Middle: Pactra RC251 Sprint White
Back: Model Master #28127 Big Bad Blue (AMC P2)

Three

We need a Javelin/AMX !!!!!!
That 'cuda looks nice. Will probably us the Pegasus Mustang until something better comes along. Just say no to Chevy (just kidding!).

BIG JIM WOODMAN

iTrader: (86)

+1 on the AMX. The AMX would have made a great Pro Stock car. Even today. Looks like an arrow.

k_bojar

iTrader: (30)

Here is my "stand-in"

snoopyrc

iTrader: (2)

It was a 77spur and I cant remember what pinion but I was aiming for a 3.5 ratio. Thats FDR not the motor wind, for use with a hacker 17.5.

Cain

iTrader: (294)

what is the cheapest ESC out right now that has built in lipo-cutoff that can be used with the 21.5 Novak Motor?

Also, is there a difference between the 21.5 Novak SS motor, and the 21.5 Crawler motor? if so, what is the difference?

cherokee

iTrader: (1)

I am intrested in this as well, it looks like the brushless is the wave of the future.

What is the cheapest esc that you can use with other motors, are they rated like brushed esc's are? It looks like you are in a brushless setup for close to $300, that is just to pricey for me. I would love to find a setup for under $150, then I may try the brushless setups.

reenmachine

iTrader: (26)

There's this one for $85:

Associated/LRP Brushless ESC

It doesn't seem to have a lipo cutoff, but with the runtimes you'll get with the 21.5 I wouldn't even begin to worry about it. When the car starts to slow (probably after 30+ minutes) just shut it off and you'll be well above 6V. Even if you add an external cutoff like the Smart Stop you'll still be ahead of the game, money-wise.

I'm sure it's not the highest-performance ESC out there so you'll probably be giving away something there, but it's cheap and will get you in the game. I'd bet if you crank the motor timing you won't be that far off.

liljohn1064

iTrader: (17)

Can you ballpark the pinion and what pitch?

I got an equation directly from RRP that works for figuring out the diameter of any gear.

Without a distance from center to center you have no starting point, but that can be found. If you have a pinion of any pitch that's fits, It can be worked backwards.

I'm guessing it's a 48 pitch spur?

(77 + 2) / 48 = 1.65 inches diameter. The radius is 1/2 the diameter, .825 Inches.

Now, center the motor, slide any old pinion on that and makes contact with the spur and that you know the pitch of, metric will not work. The teeth will not mesh if they mismatch, so don't turn the gearing. All that's needed is the pinion tooth number.

For arguments sake, the pinion number we need to have will put us at 1 1/8 inch.

Again, (77 + 2) / 48 = 1.65 inches diameter. The radius is 1/2 the diameter, .825 Inches.

.825 (the spur radius) + Pinion Radius = 1 1/8 inches (1.125).
So the pinion radius is 1.125 inch - .825 = .3
we need to reverse the equation above. First thing is to double the radius for the diameter, .6 inches.
Now we have (P+2)/48 = .6, this becomes P = (48 x .6) -2. P = which points to roughly a 27 tooth pinion.

Run the equation again for the pinion and add the 2 final numbers together. You now have the distance from the center of the spur to center of the pinion. Now we need the internal gear ratio of the car. I know my TC3 is a 2.5, my e4js is a 2.0588.

As an example my e4js:

(Spur / Pinion) X <the internal ratio of your car> = FDR
(88 / 52) X 2.0588 = 3.484


Now to work it all backwards so the FDR meets the pinion to spur center to center distance. You'll have distance, the FDR and the internal ratio of your car. So lets change the example and keep calculating until we meet the magic distance number. This first one is for a Spur that is too large which is where most of us start from with these insane FDR numbers. This all trial and error on paper, but with this you buy a couple spurs and gears ONCE.

The distance number we need to achieve is still 1.125 inches.

(110 / P) x 2.0588 = between 3.4 and 3.5 P = 65 Sweet! (NOT)

Spur (110 + 2) / 64 = 1.75 inches diameter
1.75 / 2 = .875 inches
Pinion (65 + 2) / 64 = 1.05 inches diameter
1.05 / 2 = .525 inches

.857 + .525 = 1.4 inches or about 3/16 of an inch too big.

So decrease the spur size to calculate the new pinion.

lets try a 104 spur.

(110 / P) x 2.0588 = between 3.4 and 3.5 P = 61

Spur (104 + 2) / 64 = 1.66 inches diameter
1.66 / 2 = .83 inches radius
Pinion (61 + 2) / 64 = .984 inches diameter
.984 / 2 = .492 inches radius

.83 + .492 = 1.322 inches or about 1/18 of an inch too big. Closer though.

Keep going until you can be less then .075 of an inch up or down from your magic distance number. This will allow you to slide the motor around as needed to adjust for good gear mesh.

I found using this method that 94s are the largest spur to consider and 88s the smallest. My pinion collection goes from 40 to 52. I can hit anything from a 3.484 to a 4.838 as needed. I went overboard, I know.

Now to make anyone who has bothered to put up with me this long rest a little easier. I have a spread sheet that shows all of this. It can be adapted to any car, it includes rollout in millimeters and inches based on the FDR and Tire diameter. Not only that, the formulas are built into it. If you put in a spur, a pinion and your car's ratio, it spits everything else out for that row.

PM me your car's internal ratio, or the car make and model, with a valid email addy and I'll send it off.

Spur Pinion Center Ratio FDR
to
Center
88 40 1.031 2.20 4.529
88 41 1.039 2.15 4.419
88 42 1.047 2.10 4.314
88 43 1.055 2.05 4.213
88 44 1.063 2.00 4.118
88 45 1.070 1.96 4.026
88 46 1.078 1.91 3.939
88 47 1.086 1.87 3.855
88 48 1.094 1.83 3.774
88 49 1.102 1.80 3.697
88 50 1.109 1.76 3.623
88 51 1.117 1.73 3.552
88 52 1.125 1.69 3.484

dragracer72nova

iTrader: (114)

John,
You must have alot of time on your hands. LOL!!!

I did not see anything about Broken In Tires, a nicely used set will grow a couple mm as they get used. That will help on the gear ratio too.

When are you going to be racing again(T/A and F1)?
Dave

snoopyrc

iTrader: (2)

Wow.

I just went for a combo that I thought would work and then tried to stick it on there. I just need to go up on both of my gears, evenly. Then experiment from there.

reenmachine

iTrader: (26)

Wow. I can't believe you wrote all that up! That's a great contribution to the community.

Ironically, I went through a similar process just last night to determine how to gear my Tamiya TB-02 to 4.2-4.6 FDR with 64p gears for USVTA 21.5/lipo. The TB-02 motor mount isn't slotted -- you only get 4 choices of motor position. I had to calculate the stock pitch diameters (not the overall gear diameters) and then work backwards to come up with a 64p combo that would not only fit, but mesh properly and also yield the FDR I want. I came up with a combo that should work perfectly and ordered the spur and pinion I need, so we'll see in a few days if it was worth getting that mechanical engineering degree or not...