Super Wraith Super Low Gearing
 

So after 8-9 months of RTR fun and basic mods, I got REAL tired of flopping.

So I stretched the wheelbase evenly to 16.5" with custom bent and welded links. Its low, has great COG and clearances.
Added Motoworx 40 Series Aluminum wheels wrapped in the 40 series trenchers (my rc4wd iroks will be 9"+ on these wheels) So i got like 4lbs+ of wheels and tires. I got CI outputs, hardened gears, 6mm maxx shafts, 1.5" spacers all around, 7950 and CCpro and whatnot.

Also onboard got 2x 5000mah 3s 40c GA. It also has a FPV night vision system for my snow runs. There is no effort to reduce weight. It is a wide and heavy bitch and will not roll. I likey.

-Point is, its not your ordinary lightweight wraith and will require appropriate power and gearing. I understand it won't be the best at defeating gravity and climbing due to weight, but it really owns rugged terrain-

I started with rtr motor and gearing, went to rtr motor with 87/12. Improved torque and response, but clearly was too much tire for motor, burned out motor on 3s but liked the flatground wheel speed with 7.25" tires. Heat a major issue.

Currently I am running ae2, 3s, 21t 550 Titan, 87/12. Better torque and response and is *close* to having the needed wheelspeed in tough situations but can still be bound up. I *think* the 21t is like 1800kv. This is the setup I have been running for tuning everything else and I am starting to smell the motor. Heat a major issue. No biggie I got a spare and these motors are $20.

I expect the esc to last at least the next 2 titans as it stays pretty cool, but I know I gotta go sensored brushless to get the response, resolution, sheer torque, and tough situation wheelspeed. My questions are more about choosing KV and gearing.

I may soon go to rx8/t8 1350kv 4038 cause it seems to be the nastiest motor/esc out there. So, using the whole 'volt up gear down' idea, I plan on running 2x 3s in parallel for ez trail riding, and using my series harness for 6s when I *try* to defeat gravity or need maximum wheelspeed. I am thinking with a 5mm shafted motor like the t8 60/11 or 66/11 but at best thats only 6:1.

If I use a motor with a 3mm shaft and higher kv (like the pro4 3300), I could achieve 60/6 or 66/6, which is 10:1 or 11:1. But would excessively low gearing cause more heat? No point in running 10kmah if you are defeated by heat in 15min.

Clearly, I am confused.....what is more important in terms of Cool Consistent Torque - KV or gearing? Does a higher KV motor with low gearing create more heat than a low kv motor with 1/2 the reduction? I don't wanna get in a situation where I get a low KV motor and can't get the proper wheelspeed without highish gearing.......nor do I want to spin a smaller 3mm motor with a higher KV cause of a super low ratio. Maybe the pro 4 is too small anyway?

In other words, for cool running, do I get a low KV motor and utilize the torque of the motor? Or do I get a higher kv motor and utilize super low gearing? I drive real easy and don't intend to break stuff, but I have to have the torque and wheelspeed.

In the 1:1 world, this is a typical question between a 4cyl with dual cases vs a 8cyl with normal reduction or off idle crawling vs 2k rpm constant throttle.

Sorry for the long post, clearly I have pondered this alot."thumbsup"

Re: Super Wraith Super Low Gearing
 

You will need a motor with a lot of horse power to turn tires that large efficiently. In reality though, you are building something in a way that you will never have a dependable truck. The Wraith axles will not hold up to what you are trying to do. Using axle wideners like you are doing is going to snap stub axles left and right. I promise. Next up will be axle shafts. And even if you get both of those things handled you are going to shell bearings constantly.

Twin force axles are pretty much your only option with what you are describing.

To try and make what you are doing work, you need big power and low gearing. Everything on that truck needs to be metal to even think about surviving.

If you go with the T8, try something like 60/8 or 60/10 maybe.

Re: Super Wraith Super Low Gearing
 

Yeah, I understand its overbuilt, but its actually pretty reliable so far considering I idle over stuff that a 2.2 will hang, break, bind, and roll over on. A 1:1 will perform better in the rocks with 38s over 31s simply due to rolling resistance. Capability>Strength.

I'm not pushing the truck to its limit. This is an adult driven rig 8) Snow and trail is what I see mostly. Trying to defeat gravity will result in broken stuff, I agree. I roll pretty slow so I get a steady FPV shot anyhow.
Plus, 1:1 is $$$. RC is cheap.

Reminds me of the saying: I'd rather drive a fast car slow than a slow car fast.

So should I get the lowest kv motor and then gear it? Or should I get the lowest possible gear, then select proper kv? Do you think a pro4 is too small? - The goal in mind being a cool runner with great "off idle" torque. I won't get too Western with it.


Thanks Harley.

Re: Super Wraith Super Low Gearing
 

First thing is getting a motor with the proper power output, not just going by a KV rating. The Pro4 is probably capable of doing the job but a T8 is probably a better choice for something running 9" tires.

Re: Super Wraith Super Low Gearing
 

from experience....wheel widners will smoke bearings

Re: Super Wraith Super Low Gearing
 

Got any pics of this monster?

Re: Super Wraith Super Low Gearing
 

^^^ Word ^^^

Re: Super Wraith Super Low Gearing
 

Same here. They must make the chassis look tiny. And I'm with Harley on this one. The drive train probably won't hold up. Might want to throw some stronger axles under there.

Pics or it didn't happen....

Re: Super Wraith Super Low Gearing
 

This leads me to think that you are pushing aside some of the info given in Harley's first post. I don't know where you gained all of your knowledge from as far as 1:1's or working out the gearing (not that its rocket science), BUT I do know that if Harley tells you something or better yet gives you precise information on your RC build......you should listen. Chances are if you decide to only take part of it, you will end up eating the rest of it later. He knows his sh*t "thumbsup"

Re: Super Wraith Super Low Gearing
 

I think what 67mustang is saying is that he doesn't beat on his vehicles to the same level some others would. I don't think he saying Harley is wrong. We all drive differently and building a rig should be structurally relevant to its usage. An example... I have been driving a bone stock xr-10 with all the crappy original parts without a single problem. Mine is one of the first couple batches when everyone was having problems. The reason why is because I'm very careful and don't romp it. Anyways food for thought. I believe Harley gave sound advice if your going to take it to its limits.

I totally agree with that.......my mind just blocks out the possibility of not going balls to the wall :D

Re: Super Wraith Super Low Gearing
 

No, not at all. I understand how it sounds, and I already know what kind of reaction people would give me. I understand Harleys reputation proceeds his post....I've been lurking and reading and searching for a long time. I'm not pushing his advice aside, it's just that I have many hours into this, it's really coming together nicely, and I'm not going to abandon a unique and capable wraith just cause a 10.00 part may wear out or break faster. Or if someone online doesn't think it's a good idea. Alot of time has been taken designing this thing and sourcing proper parts and I'm not going to stop till it's done. Honestly, after scouring the Web, I'm surprised I'm the first one to build it like this. Also, remember this is still brushed and rolls about 60% the speed of stock rtr. It's not a powerhouse.

Reason I am posing the question is because from what I understand, brushless motors don't have a powerband. In 1:1, you gear to your powerband, and cool big power with big radiator capacity. In step with all time taken and invested, if I don't take time to choose wisely, I won't be pleased with the outcome. I am so far pleased with the outcome....and I am on vacation but will get home in a few days and we can break it down with some sweet pix. It's really cool to me. The reengineering is what I like.

Re: Super Wraith Super Low Gearing
 

Pics!!!!!!!!!!!!!

Re: Super Wraith Super Low Gearing
 

So here's a picture just to verify this beast does exist. I will be making a parts order today since I am doubling down on my interest. More pics will come. I will also be going through the build all over again for viewer's pleasure (it is unique, and i think its cool). I have really just been tuning and pondering different mods for the last 4-5 packs. I am running one 3s 5400 at the moment since I haven't been able to overcome the heat issue. I have ditched 4WS, I don't see it being solid and predictable with these rubbers.

This is a picture at 17.5" wheelbase...I have permanent links at 16.5 now. I wheeled it at 17.5 for about 3-4 packs and it will climb stairs like a good little crawler should but I wanted to get my steering radius as tight as possible. I think ~16.5 will be the ticket. Here it sits with a burnt titan 550. Heat is my current and only enemy. To break parts, you gotta have power, and this truck honestly doesn't have the balls to break plastic. Yet. "thumbsup"

5.5" ripsaw is also seen.

http://www.buddinghope.org/familysha...rconstruct.jpg

Re: Super Wraith Super Low Gearing
 

That is just coool

Re: Super Wraith Super Low Gearing
 

I have been very busy but I managed to collect all my parts and I should have this thing finished and built in the next several days. I will chronicle with pics.

Here we see a new Titan 21t 550 that will run on 3S.
6/66 11:1 32P Gearing (lowest possible)
RR Metal Gears
CI outputs (these allow me to run the 66T Spur)
6MM Shafts (Way bigger than the stockers perfect length for wheelbase)

http://www.buddinghope.org/familyshare/trans.jpg

Re: Super Wraith Super Low Gearing
 

Ever thought of getting a traxxas summit for doing the FPV stuff?

Re: Super Wraith Super Low Gearing
 

what about running the dual motor mount?

Re: Super Wraith Super Low Gearing
 

Actually, I was contemplating getting a Summit before I started this. I also have a built aluminum emaxx with a hobbywing esc/3400kv on 2s/4s. So technically I have a rc that is faster than a Summit. A rtr wraith is not as capable as a summit, but I am pretty sure this wraith I have is pretty equal to a summit in the rough stuff. So no, I won't be purchasing a Summit. The FPV camera fits perfectly under the roof of the wraith and mounts to the cage well.

I have considered the dual mount, but from what I understand, that scraps the interior and I am not sure I want to do that.

Due to the link mounts, a big motor simply won't fit. So I will eventually go brushless with a standard length 21.5T or that new Outrunner HH motor. I think that will be enough.