aluminum axle assembly?

[Jerry3567]

Hello to all,

I'm new the r/c crawler world, but not to r/c. I'm a machinist, looking for a project to get back into r/c.

My question about axles: can I find a long aluminum MOA axle with NO mounting links installed, designed for building my own mounting points?

I'm looking for two front axle setups for front/rear steer, that has: hubs, bearings, gearbox, and motor mounts. The rest I'll take care of. I'd consider building my own entirely, but I want to buy a complete set to familiarize myself with the general construction of r/c axles before I dive in.

Expect more questions, about esc/motor setups as well, I was a nitro guy before this lol.

I'll be sure to post plenty of pics of the build. I have quite a bit of carbon fiber I've been meaning to use up so might as well turn it into an r/c .

Any help or advice would be much appreciated.

Thanks,
Jerry

[JeremyH]

Probably your best bet would be to contact RC4WD about two of their Super Bully axles: http://www.rc4wdshop.com/go/product_...roducts_id=669 Maybe they can leave the tubes unfinished for you.

[Jerry3567]

Jeremy,

Thanks for the reply! That is the style I am looking for. I actually like their setup, and might just use their finished product and make my own link mounts. Thanks for such a quick reply.

Jerry

[JeremyH]

Not a problem. Good luck with your build!

[Jerry3567]

Thanks. I'm getting pretty excited about this. So much so, that my motorcycle is now on craigslist. That should let me go all out with whatever stock and tooling I need for the project lol.

[oldhippie]

Ya can also put a long side on the short side of a berg/HR.

[Jerry3567]

I noticed that in another thread someone was doing that. Any significant strength/performance differences between the Berg and Bully axles, or is more of a Ford vs. Chevy thing?

The thing I am wondering about is this: how many super class rigs are there compared to 2.2 rigs? I am mainly building this for me, but I would like it to conform to rules for a class that has someone to compete against. I realize it is a fairly open-ended question but, what is the average ratio at competitions of 2.2 to super class crawlers?

I would like to build a rig that can compete in a class, as opposed to a big freak of nature that won't fit any class rules. Or, I could just build two...

Jerry

[JeremyH]

Originally Posted by Jerry3567

Any significant strength/performance differences between the Berg and Bully axles, or is more of a Ford vs. Chevy thing?

Bergs can be built up to be as strong as Bullys.....Bullys can be built up to be as light as bergs. It all depends on how fat your wallet is... As for the super ratio....well, in our local club, we regularly have about 20 competitors for the 2.2's....and never more than 3 for supers.

[Jerry3567]

Thanks for the quick reply. That is a pretty steep ratio, wow. So needless to say a 2.2 is probably the way to go.

Does anyone run a super compact chassis in their 2.2, and after they finish swap out the links/suspension/full axle setup, and run the super class? I can see that possibly. Twelve attachment points and four plugs is pretty light work IMO.

Jerry

[JeremyH]

That is certainly doable...just make sure that everything fits into both parameters. You might run into trouble with shock length/angles but I'm sure you could find something that would work.

[rc_pimp]

Originally Posted by Jerry3567

I noticed that in another thread someone was doing that. Any significant strength/performance differences between the Berg and Bully axles, or is more of a Ford vs. Chevy thing?

The thing I am wondering about is this: how many super class rigs are there compared to 2.2 rigs? I am mainly building this for me, but I would like it to conform to rules for a class that has someone to compete against. I realize it is a fairly open-ended question but, what is the average ratio at competitions of 2.2 to super class crawlers?

I would like to build a rig that can compete in a class, as opposed to a big freak of nature that won't fit any class rules. Or, I could just build two...

Jerry

Rear steer is not legal in 2.2 comp . I believe it is allowed in super though . Look into dig options . You can find great info on the forums just search , search , and search . Dig allows for tight turns plus allot more and they are 2.2 legal .

[Jerry3567]

RC, thanks for the reply. I looked into the dig info, and it looks like a pretty neat deal, a really cool possibility. The thing I don't know is: how do I set one up? I read about the dig setups for shaftys, but I am going to build an MOA. I like the idea of running a dig setup...but I have no clue how to set one up.

My recent research has been towards what kind of ESC(s) I'll need. I noticed Novak has a new ESC for MOA rigs, and most run dual ESC rigs. I'm not sure how to wire one, is it as simple as a Y-harness running from the reciever to the two ESCs?

I read the rules, and as you mentioned, the rear steer isn't legal for a 2.2 but I would still like to build a Super too (as funds allow). How is this setup into a 3 channel rig? Can I use the third channel as a switch to turn rear steer on/off? If so, can I maintain power to the rear servo when it is not in use so that I won't have my rear steer flopping around on the Super?

Another question I have is about using a brushless system. How can I set one up to have the correct gearing, as well as braking? Is that a function of the ESC? What brushless MOA setups are the top guys using?

Also (I know, I'm sorry, a million questions) what do you guys know about 4-link setups? I grew up drag racing, we run a 4-link in our car as do all of our friends. The common refrence when tuning a 4-link is the location of the "imaginary intersect", and the location front/back, and up/down. It is a very important aspect because it is used basically as a refrence to the rotational axis of the car which in turn effects how much weight is transferred to the tires and what direction the force is being applied to the tire. How much of this plays into the r/c world? I see the link setups where the top and bottom links share a common chassis mount, so it leads me to believe that A: it is not very important, or B: rigs with this setup are experiencing bad effects due to an incorrect setup and the driver is left wondering wtf is going on with the rig. Could somebody possibly explain this? I have read and read but have no answer. I know my experience is a far cry from this scenario, but it has to be valid data in some respect.

Thanks, and sorry for such a long winded and loaded post. Maybe this can be moved out the newbie section into a more appropriate area?

Hopefully, once I get one built I will be able to torture test the geometry and come up with some data. I live on a farm with TONS of crawling terrain...and happen to have a degree in CNC machining and have full access to Haas CNC mills and turning centers, so let me know of any ideas you may have.
Jerry

[JeremyH]

The best working dig setup out there right now is the PunkRC dig:
http://www.punkrc.com/index.php?main...products_id=28
You'll need a Radio that has 3 channels and one of them a 3 position switch.

However, if you plan to swap back and forth, you can easily run dual ESCs with a 4 channel radio (like the Nomadio React or the Futaba 4PK). These radios will allow you to run an indexed rear steer setup (which, BTW, is legal in Super class). Or, you can run a stick radio (like the Spektrum DX6) and have plenty of channels for all of your functions.

As for ESCs, if you run two of them, then you simply wire up each motor to one ESC and then plug each ESC into your receiver. Again, your Receiver will need to be a 4 channel, at a minimum.

If you want to run brushless on your MOA, then you will need two ESCs. I dont believe a single ESC is being manufactured that can handle dual brushless motors. As for the motor, you will need to figure out the gearing. Typically, you'll want to run a low (~2000) kV motor. However, there really isnt a need for brushless, as brushed motors will work perfectly fine.

Yes, you'll want to run a 4 link setup if you go with a sprung suspension. You will need it to be adjustable so you can tinker with things like anti-dive and anti-squat, caster angle, gear case clocking, etc. Believe it or not, these little cars are very sensitive to link placement...more so, IMO, than 1:1's.

BTW, those trucks that you are referring to, the ones where the uppers and lowers share the same chassis mount, yes, they MUST have terrible suspension characteristics. You DO NOT want to set your truck up that way.

I hope some of this info is helpful.

[rc_pimp]

You should look into the dx6i radio . It has 6 channels and lots of program options . It is a stick radio not a pistol . You can find lotts of info in the forums . You can program it to run dig and rear steer on your super and still use it for your 2.2 . Its a great choice for MOA because u can throttle and steer front with one stick and rear with the other . With this setup you can dig anyway you want to . It takes some getting used to but works great . If you decide to try this you would be better off with duall esc setup ( no need for separate dig ). Just search dx6i , and duall esc to one reciever . Hope this helps we in this hobby need people like you . Im sure I will be reading and learning from your posts in no time for sure . So please post your builds .

[Jerry3567]

Thanks for the help guys, i really is clearing a lot up for me.

You both had mentioned the DX6 transmitter, so I did some searching. It seems Spektrum seems to have the Market covered in the crawler dept. Since I am just getting back into the sport (I left the r/c world around 2002...there was no Spektrum yet lol) I figure I will go with proven electronics and tune the chassis before I go off the deep end. What are the advantages to a brush/brushless setup?

I had read some articles about the new brushless motors, they seem pretty neat. How are they torque wise? What about braking?

With a dual ESC setup, how do I effectively and efficiantly power them both? It will be a LiPo powered rig as well. How does this play into the drivetrain setup? I was a nitro guy before I left, this whole ESC stuff is new to me haha. I don't want to spare any expense on motors/ESC, what are the top guys running now?

I think my direction so far is this:
1: Order my axles
2: Order electronics
3: Mill out a jig and set the axles parallel and at the correct wheelbase
4: Make a base plate for the electronics/determine minimum size of chassis
5: Determine suspension geometry/link length/vertical separation/intersect locations, etc...
6: Mount steering servos
7: Create said geometry on the CNC
8: Run wiring
9: Cross fingers and turn on
10: Pray there is no spontaneous combustion of vehicle.
11: Fine tune electronics
12: Crawl!

What do you think about that process? Any steps need to be re-arranged or is this ok?

Thanks,
Jerry

[JeremyH]

Originally Posted by Jerry3567

Thanks for the help guys, i really is clearing a lot up for me.

You both had mentioned the DX6 transmitter, so I did some searching. It seems Spektrum seems to have the Market covered in the crawler dept. Since I am just getting back into the sport (I left the r/c world around 2002...there was no Spektrum yet lol) I figure I will go with proven electronics and tune the chassis before I go off the deep end. What are the advantages to a brush/brushless setup?
Well, Spektrum makes a damn good product....especially stick radios. However, for a 4 channel pistol grip, IMO, the Futaba 4PK is top right now. However, I run a Nomadio React....same functions as the 4PK, it just isn't as cool looking. Oh...and it's about $400 cheaper than the 4PK. As far as brushed/brushelss, that really depends on the gearing of your axles and how much heat can possibly be created. Some Losi Crawler guys prefer the brushless motors because their worm geared axles create a lot of heat in the motor. Personally, I run brushed motors on most of my crawlers.

I had read some articles about the new brushless motors, they seem pretty neat. How are they torque wise? What about braking?
They create a LOT of torque and plenty of braking....if you get a sensored motor and ESC with plenty of drag brake. I run a brushless sensored system (Novak Mongoose) on my 1.9 comp crawler and am happy with that setup.

With a dual ESC setup, how do I effectively and efficiantly power them both? It will be a LiPo powered rig as well. How does this play into the drivetrain setup? I was a nitro guy before I left, this whole ESC stuff is new to me haha. I don't want to spare any expense on motors/ESC, what are the top guys running now?
One battery will power both just fine. On my super (with dual ESCs), I just have both sets of power leads from both ESCs soldered onto one deans that plugs into a single battery. The same can also be accomplished with a y-connector to one batter if you are having trouble getting two wires soldered to one deans tab. As for motors, I really like the Fantom Racing motors. I run their 35Ts in my 2.2 Bully and their 55Ts in my super Bully (well, actually, the 55Ts have a Tekin Pro sticker on them, but they are made by Fantom). If you are looking for a compact motor with a LOT of punch, Holmes Hobbies sells Puller motors that use Cobalt magnets....MUCH stronger than the typical neo magnets. They have a lot of torque, tons of wheelspeed and more drag brake than you'll ever want!

I think my direction so far is this:
1: Order my axles
2: Order electronics
3: Mill out a jig and set the axles parallel and at the correct wheelbase
4: Make a base plate for the electronics/determine minimum size of chassis
5: Determine suspension geometry/link length/vertical separation/intersect locations, etc...
6: Mount steering servos
7: Create said geometry on the CNC
8: Run wiring
9: Cross fingers and turn on
10: Pray there is no spontaneous combustion of vehicle.
11: Fine tune electronics
12: Crawl!

What do you think about that process? Any steps need to be re-arranged or is this ok?
That sounds like a helluva plan!

Thanks,
Jerry

See my responses above in red.

[rc_pimp]

I agree with Jeremy he seems to know alot about crawlers . I would like to recommend an esc . The Mamba Max Pro . I run one and use it on all my RCs . Never had any problems with it . It can handle up to 6s lipo (if your motor can ) , has tons of settings , no turn limit , runs brushed or brushless sensored or sensorless , has a built in fan , an adjustable bec (most people recommend using seperate bec ), and you can link to your computer via castle link for easy setup . I have to mention though I have heard complaints that people have trouble setting drag brake but I have never had any issue whatsoever . Also I recommend running brushed motors but really it depends on your preference . You can try to find local comps to speak with people in person about their experience . Maybe some will even let you drive a few different rigs to see for yourself . As far as 1 battery or 2 I would get a high mah and good c rating if running 1 just so you can draw full amps without the heat . If You have a lipo battery with say 20c and 4000mah multiply the c rating (20) x 1/1000 of the mah (4) you can run 80 amps safely . You prob wont need that much but Im not sure what your amp draw will be . Im sure someone here can help with that . Jeremy we need you bro !

[JeremyH]

Haha....I'm a fan of fairly small batteries. Heck, I run a 1300mAh 4S 40C pack on my super!

[rc_pimp]

Originally Posted by JeremyH

Haha....I'm a fan of fairly small batteries. Heck, I run a 1300mAh 4S 40C pack on my super!

Yeah that allows for just over 50 amps . From what I Understand most duall esc apps draw less than 40 to 50 amps but if u bind both motors and servos you could see big spikes . Prob not last long enough to hurt the battery though . Just curious how much runtime do you get ? I suppose you need high C rating or high mah either way . Its easy to do the math so not that big of a deal . Do you by chance know how many amps you draw ?

[JeremyH]

Runtime is around 30-40 minutes with that pack running 55/60T motors, Dual HH TQ ESCs, CC BEC Pro, and dual Futaba BLS152 servos. I have smoked a motor before when in a bind. Yeah, a high C pack is nice because they are quite a bit smaller than the high capacity...and you end up with the same output...just a shorter runtime. I have no idea what the system is drawing from this pack.