brushless xmod project continues on.

Clint · Post by **Clint** » Sun Sep 25, 2005 9:48 pm

some of you guys already know about this from other sites, but i'll introduce it here as well.

Airtronics MX-3 Radio
Novak XXL FM 75Mhz Receiver
Hitec HS-56HB Servo
Mamba 8000Kv brushless and 6800kv
Mamba 25 ESC
2s and 3s 340mah lipo
30 tooth pinion
AWD
full gpm drivetrain

the esc is just slightly smaller than the v2.2

servo and receiver comparison

8000kv motor, lucky it's the same diameter as the 130's. very easy to mount. just cut the top and bottom off any xmod/gpm motormount.

still tweaking this plate. but it'll all fit on here no problem.
so far ive made 4 of these plates. since i dont have access to
a mill, none of them are perfect. this is the only part that's
got me dragging my feet on this project.
i really should just break down and
buy the zero/tinyrc carbon fiber pro chassis and be done with it.

couple pics of a test fit with plastic parts. it'll end up on my blue gpm'd
xmod with deans ultra connectors all around. still reworking the lipo
placement..but if i separate the 340 mah's, they fit under the driveshaft
and will retain AWD.

very roomy.

for the pinion, 1/8th bore 30 tooth alum gear from robinson racing,
i'm using an adapter that converts the 1/8th bore pinions
to the 2mm shaft that comes with the mamba. this adapter makes
building a brushless xmod a peice of cake. these are only a couple bucks.

http://sparrowproducts.com/index.asp?Pa ... &ProdID=55

evoraptor · Post by **evoraptor** » Sun Sep 25, 2005 10:06 pm

what im thinkin is that mamba will shred all those little plastic parts to pieces... so how much did it cost to do that? i might want to do that in the future once i get the cash/time. anywhos, its great seeing one of these around

Clint · Post by **Clint** » Sun Sep 25, 2005 10:17 pm

evoraptor wrote:what im thinkin is that mamba will shred all those little plastic parts to pieces... so how much did it cost to do that? i might want to do that in the future once i get the cash/time. anywhos, its great seeing one of these around

shred of course. the final buildup has no xmod plastic other than the diffs and awd cone gears. this thing is going to end up in my full alloy car.

prices are
comp-x kit was ~119$ from bpp
novak xxl was 35$ new ebay.
hs56hb servo 26$ from lhs.
75mhz crystals were 13$ pair from ebay.
airtronics mx-3 new 50$ from ebay.
2mm pinion adapter 2$ from sparrow
30tooth alum pinion gear 4$ from robinson racing
bunch of deans ultra 6$
full gpm alum from cj hobbies and rcmart. dont feel like pricing that.

whats cool, is that it'll all fit perfectly in any 1:18th when ur done
messing with the xmod.

betty.k · Post by **betty.k** » Mon Sep 26, 2005 2:38 am

nice work man, that's a tidy layout

my only concern would be chassis flex. the power going through that thing will make it warp like a funny car on takeoff. you planning a top brace of sorts?

Sporttracguy · Post by **Sporttracguy** » Mon Sep 26, 2005 2:54 am

Looks like an awsome setup, i thought about using a brushless system on an overland or something similar but just cant fund another brushless system (just did my 18t)

Any concerns with heat buildup? everything is crammed in there pretty good and atleast on my setup stuff gets fairlly toasty in there. just a thought

Keep up the good work
STG

Tuner1989 · Post by **Tuner1989** » Mon Sep 26, 2005 11:16 am

Glad you took my advice, im loving the pics keep it up man.

What if he used pieces of aluminum flashing same as under the plastice chassis to reinforce the funny car effect....

viperdout · Post by **viperdout** » Wed Sep 28, 2005 7:55 pm

Holy bejesus, I've been de-throwned! That thing is 2 steps past insane.

betty.k · Post by **betty.k** » Thu Sep 29, 2005 12:15 am

viperdout wrote:Holy bejesus, I've been de-throwned!

from what?

this'll be good!

Clint · Post by **Clint** » Thu Sep 29, 2005 4:53 am

betty.k wrote:
viperdout wrote:Holy bejesus, I've been de-throwned!
from what?

this'll be good!

na, viperdout's will always be #1. he's just being nice.

viperdout · Post by **viperdout** » Thu Sep 29, 2005 6:18 am

Clint wrote:
betty.k wrote:
viperdout wrote:Holy bejesus, I've been de-throwned!
from what?

this'll be good!
na, viperdout's will always be #1. he's just being nice.

Pluh-ease. I've been waiting for someone to drop the 8000 in and go faster. Your gear ratio and 2 cell put it very close, but the 3rd puts it over the top. With my gearing combo and an 8000/3 cell setup, I calculated it out to be a theoretical 120mph assuming no friction or wind resistance.

I'm wondering if the reduced torque would allow it to be driven without tearing up bevels so fast. If that's the case, I might just sell the 6800 in there and go 8000. Anyway, good luck controlling it and tell me if it doesn't eat bevels so fast.

gnubee · Post by **gnubee** » Thu Sep 29, 2005 4:52 pm

i run the 8000 in a mini-t 3s. heat is a problem. if it is geared too high it puts out even more heat.

gearing too steep also can cause the motor to cog on startup. when a brushless motor cogs it is a very uneven application of torque.

basically it is a race between melting the gears or snapping the teeth clean off.

sounds like fun, just have lots of spares handy.

i ended up using a whole lotta aluminum for heat dissipation and used a metal gearbox to keep the gears meshed well. also had to let it sit awhile between 60mph speed runs to let it cool down.

SuperFly · Post by **SuperFly** » Thu Sep 29, 2005 5:55 pm

When you guys are talking speeds of 60mph-120mph, are you talking scale speed, wheels on a speedchecker or actual radar-gun, on-the-street speed?

viperdout · Post by **viperdout** » Thu Sep 29, 2005 6:00 pm

SuperFly wrote:When you guys are talking speeds of 60mph-120mph, are you talking scale speed, wheels on a speedchecker or actual radar-gun, on-the-street speed?

Well, 120 is a calculator number without factoring in friction from the ground, air resistance, drivetrain resistance, discharge rats of the battery, etc. Even factoring in all of that, I think that if you have enough range and traction, 100 can be broken with an xmod.

gnubee, the size of the xmod tires makes a huge difference in gearing. The 6800 in my old 18T would get warm with 14/60 gearing, but on my xmod with 28/24 gearing, it runs cooler than a stock S1.

Clint · Post by **Clint** » Thu Sep 29, 2005 7:22 pm

I dont like running the 3s on the 8000 in the xray m18 for longer than a couple minutes either, it does get hot quick, but omg does it put a smile on your face. also im still using composite pinion gears on it, which actually works out to be a "motor saver". The inside of the pinion gear will melt causing it to spin loose if the motor gets a bit too warm, but it is still way under motor overheating temp. the kokam 3s 1250 lipo is a huge bitch and just barely fits in the xray, but it handles the mamba with ease. I bought this lipo so i could use it for both the xray and the blade cp.

in the xray i normally run a 2s 1200mah on a 19tooth 36 spur with no cogging. im using an alum hs/motor mount on it and i can run for 20+ minutes without heat problems(motor or lipo). 2s+8000kv is an excellent all around no issue basher which is why i picked it for the xmod.

hey viperdout, with that sparrow pinion adapter you should be able to re-gear your xmod easily. 30t alum robinson racing pinions are real smooth
and give it enough room to maintain AWD. you would just need a thicker spacer to lift the motor mount.. the xmod plastic yellow bushings work great for this and you can thin em out to create a perfect gear mesh.

viperdout · Post by **viperdout** » Thu Sep 29, 2005 7:45 pm

Clint wrote:I dont like running the 3s on the 8000 in the xray m18 for longer than a couple minutes either, it does get hot quick, but omg does it put a smile on your face. also im still using composite pinion gears on it, which actually works out to be a "motor saver". The inside of the pinion gear will melt causing it to spin loose if the motor gets a bit too warm, but it is still way under motor overheating temp. the kokam 3s 1250 lipo is a huge bitch and just barely fits in the xray, but it handles the mamba with ease. I bought this lipo so i could use it for both the xray and the blade cp.

in the xray i normally run a 2s 1200mah on a 19tooth 36 spur with no cogging. im using an alum hs/motor mount on it and i can run for 20+ minutes without heat problems(motor or lipo). 2s+8000kv is an excellent all around no issue basher which is why i picked it for the xmod.

hey viperdout, with that sparrow pinion adapter you should be able to re-gear your xmod easily. 30t alum robinson racing pinions are real smooth
and give it enough room to maintain AWD. you would just need a thicker spacer to lift the motor mount.. the xmod plastic yellow bushings work great for this and you can thin em out to create a perfect gear mesh.

Yeah, I'm probably gonna build up an M18 with that setup, except with either the new Thunderpower cells or the PolyQuest 1800s.

Yeah, I've been thinking about changing the gearing, but the spacers are made to mesh perfectly with the 28 tooth, so I don't wanna mess with it, though I might still. I want to get it to not chew up bevels first, which seems to be even worse with the metal bevel. Have you killed any bevels with the 8000? If not, I might just switch to it.