My car weighs 9lbs 13oz

The tires will completely spin if I give it full throttle. Its too much torque even with that gearing. Its around 1.7:1 for a final drive ratio. 64 pinion/36 spur.

Wow. I clearly underestimated that motor. :oh: Although the rotor is the same size as your spur gear!

That's good to know. Thanks!

Not to be a pest, but someone out there must know where I can get a set of beadlock wheels for 1/8 buggy tires. That, or I could try slicing a set of MT beadlocks...

B4maz, how much does your car weight as a roller and how much does your 8s lipo weigh? I bought a DM1 cause the specs says it was lighter than a GTP Ultra. DM1 roller is 6lbs and some odd oz. Total weight with everything on it is 9lbs 4oz. My motor weighs 12oz and my lipos are 1lb 11oz.

Blunten, his LiPos weigh in at ~25 oz. as does the motor. I don't know what the roller is, I never weighed mine either.

Yea, you're right. Motor is 25oz and so is the two 4s 3300 mah Thunder Power packs. I'm not sure hot much just the roller is.

Hey B4maz, where did you get your spur gear? My motor mount doesn't allow me to gear much higher, so I need to get a smaller spur. The spool axle is a different diameter than everything else so I'm having trouble finding gears that will fit. I'm looking for a ~40T delrin gear.

I got my gears from http://www.sdp-si.com/web/html/gears.htm

Go under spur gears and pick out the one you need. I ended up using 32p gears. I think the Ultra GTP comes with mod 1 gears. so you'll have to play around with the menus to see if you can get a 40t mod 1 delrin gear that will fit. The spool diameter is 8mm and you can get gears with a bore diameter of 8mm. I think this should work:

Nice find. That is exactly what I was thinking of. But daaaaamm- $26?

Its pretty darn good for a "custom" size gear. I've bought 4 gears from this place and they are all high quality. I never thought the delrin gear would hold up to the 6.5hp I have in my car, but its doing well after 7-8 high speed passes.

How's this?

Differential Ratio: 3.142857142857143
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 40
Pinion Tooth Count: 30
Total Voltage: 22.2
Motor KV: 2200
Tire Diameter (inches): 4
Tire Ballooning (inches): 0.1
Motor Current Draw: 100
Motor coil Ω: 0.006
Spur/Pinion Ratio: 1.33 : 1
Total Ratio: 4.19048 : 1
Tire Circumference (inches): 13.19 inches (335.15 mm)
Total Motor Speed: 47520 RPM
Vehicle Speed: 141.69 mph (227.61 km/h)
Estimated Adjusted Speed: 112 mph (180 km/h) - 21% loss
Effective KV Value: 2140.54
KT constant: 0.61 oz-in/A
Motor Torque: 0.32 ft-lbs
Final Torque: 1.34 ft-lbs
Final Power: 2220 watts (3 HP)

Plus, checkout how much a 51t steel gear ring from OFNA costs!!! $26!!!:


http://www3.towerhobbies.com/cgi-bin...?&I=LXBM52&P=7
http://www2.gpmd.com/image/o/ofnc3840.jpg

I think that should work

Eeek! My kit came with that one, but I bought the plastic 51T from Mike.

Another problem now is; where can I get a steel 30T M1 pinion? Sdp-si only has them in 303 SS which is really soft, isn't it? I'd be comfortable if it said it was 304, that stuff is mean (it killed my rotary tool).

They have 32-36 tooth mod 1 in carbon steel with 8mm bore and 6mm face.

wow what a car. It took me a while to read this whole thread, looks good though.

So after reading this thread I am gonna buy the Ultra GTP rolling chassis and convert to brushless.I have a Neu 1512/1.5D and a MMM when its fixed.Can I use the center spool with Mikes rcmonster motor mount.What about bodies?Can I use the rcmonster battery tray?:whistle:

I saw those. It would have to be 5mm bore to fit the motor shaft. :(

Thank you, sir. :mdr:

Yes, and yes. Nice to see I inspired someone to empty their wallet! :wink:

About the bodies, Tower has two: Viper and Porshe.

They have 5mm bore mod 1

So I got the gears- those acetal w/brass hub and set screw ones. A 30T (pinion) and a 40T (spur). They fit great, and it's REALLY fast- as far as I can tell on my street. Only problem is I can barely start from a standstill. It cogs horribly with the tall gearing. You (B4maz) said you weren't seeing any cogging with your setup, which is also what I would expect with your gearing choices :P.

Do you think it could be the controller? The Sentilon may not perform well under high starting loads, agan being an air controller it wouldn't have to. Would more capacitors on the ESC help this at all or is it most likely a firmware issue? Should I discontinue running it until I get a MMM??? :mdr: I know they start very smooth and the slow speed control is excellent.

What a cool project, :yes: you should race Lic when he gets his 4 Tec running..:whistle:

I wish I knew more about the Sentilon controller. I didn't think cogging would be that bad that you couldn't even get the car moving. It sounds like a controller issue because I know people that run the same motor/batteries but use a Castle controller and don't get cogging that bad. I'm sure the MMM will be much better. I don't think capacitors will help much with cogging. I would definitely upgrade the firmware to the newest version. They might have fixed the problem with firmware.

B4maz: I don't think the Sentilons have upgradable firmware..... I want to buy a new ESC anyways because I hate the mechanical brakes. I put the second disc back on and they still fade to nothing after a few stops. There's just too much heat present. I'm thinking HV110 over the MMM, should I ever want to go FASTER.

TDC57: When, and IF. :lol: So long as the course has no turns, I think it's in the bag.

Have you tried to use high timing on the speed controller? That might help with the cogging.

No, I will try that. It was so excessive that I doubt it would be readily driveable after just a timing change. :cry:

Well I still don't have a controller, but I have braces! :lol:

http://i52.photobucket.com/albums/g4...d/DSC00210.jpg
http://i52.photobucket.com/albums/g4...d/DSC00211.jpg
http://i52.photobucket.com/albums/g4...d/DSC00212.jpg

Just made them last night. It's some 1/4" aluminum tube with the ends flattened/drilled/sanded. Those are my (hopefully) uber traction tires. They are Proline 1/8 buggy MOABs.

Wow. It's been a while. Oh wait- we're in a recession and I have no liquid assets! That's why! :na:

Anyhow, I ordered up some 12"x24"x0.08" (2mm) 7075-T6 aluminum plate a couple weeks ago. The other day I got around to cutting it up. Here's what it looks like now:

http://i52.photobucket.com/albums/g4...h_DSC00342.jpg http://i52.photobucket.com/albums/g4...h_DSC00341.jpg http://i52.photobucket.com/albums/g4...h_DSC00340.jpg

I also ordered a 12"x48"x0.025" piece of polycarbonate to make the sides and the internal support structures. It came today, so hopefully next week I will have time to cut it up a bit. I'm going for the "speed wedge" look, with a twist- I'm going to design a venturi into the top so that it will create a vacuum inside the body and (hopefully) help stick the car to the road.

Hmm, sounds like the pike's peak racers that have the huge tunnels that produce downforce...

I found that Lola style bodies work like a charm at speed. Problem is none are made that are wide enough to work on a gtp...

I like those Lola's too, for 1/10 TCs. IF they made one for 1/8 cars, it would be too high in the back for real speed runs. Too much rear downforce. That's flip territory. I suppose you could chop down the rear wedge a bit. Maybe replace it with a normal wing.

I finished outlining the body's profile on the polycarbonate. I am going to buy a thinner blade for my band saw before I even attempt to cut it out (1/2" blade on there now for cutting Al). I think a jig saw would make a really rough cut, and I don't want to crack/chip the edges either.

Here are a couple pictures of my design. The "notch" is at the front of the car. It's where the venturi will draw air in from underneath the car.

http://i52.photobucket.com/albums/g4...h_DSC00355.jpg http://i52.photobucket.com/albums/g4...h_DSC00356.jpg

Now for the million-dollar question: Should I put a wing on the back??? :neutral: It would be made from the same polycarbonate/aluminum as the body.

looks cool, how much will the body weigh?

I don't know for sure. Maybe 1-1.5 lbs.?

Sooo... I'm poor as s#!7 right now and as such I haven't been doing much on any of my projects. I did finally buy some parts for this car- An RC-M 8T motor mount, and the OEM 8T CD mount/brace kit. These will allow me (hopefully) to drop in the Slipperential I bought 5 months ago. I need a short dogbone for the front (these?) since it will be FWD and I want to move everything forward. Oh and I've cut out the polycarbonate body panels. I'll get pics up later today.

Awesome, 'bout time for an update on this beast!

Ok, I forgot to take pictures before I tore it down.... :oops: Oh- and I read that the Slipperential was a drop-in for the 8ight so that's why I bought the diff mounts. Guess what? Mine isn't! It came with 8x16x5 bearings. I need some 8x14x4 flanged bearings. ..... Mike's 8ight motor mount is frakking sweet though. I like how you can remove the motor- with the screws still in it!

So I'll get the bearings and take some pics when it's all back together.

Where'd all the pics go ? I've read the whole thread and it's pictureless -1 of your build ?
Sounds like a great prodject and would like to "see" more.

I've organized my PB account and the links to the pics no longer work. Hold on a sec....

Here are some recent pics-

http://i52.photobucket.com/albums/g4...P/DSC00342.jpg

http://i52.photobucket.com/albums/g4...P/DSC00341.jpg

http://i52.photobucket.com/albums/g4...P/DSC00340.jpg

http://i52.photobucket.com/albums/g4...P/DSC00355.jpg

You have definitely put a LOT of time,thought,theory,$$ into this speed demon.
I sincerely hope to see it work out well for you,so many variables I struggle to keep up.
I look forward to seeing more now that I'm subscribed to the thread.
Good luck.

Thanks Bondo! :yipi:

Fly Straight and True Like a Warriors Arrow of Death, My Young Speedy Samuri......



http://i88.photobucket.com/albums/k1...ctfully_bw.jpg

So... long time no update I guess? :oops:

The speed project is postponed until the spring- it's getting chilly here now and rubber loses traction fast in the cold. I purchased a new battery tray, 164x55mm so the FP pack can lay down. It should help the CG quite a bit. Trying to decide whether to stick with the 1515-1y and MMM, or break out that LT-6s150 that I never got around to running (sorry Lutach), OR buy the Tekin RX8 2250 truggy combo. I'm actually leaning toward the Tekin 'cause I like the sensored startup soo much. The MMM has the BEST sensorless startup, but if you run very tall gearing (ie. speed runs) it still suffers a lot.

Hopefully the recent spike in the market will make people come spend their money so that I can have money to spend!