Snowmobile

[BrianG]

I'd like to build an R/C snowmobile, but have some questions:

1: I've never really looked at how a real snowmobile is built. Do they have a rear suspension? Ideally, a diagram showing cutaway views would be great.

2: Are there any tracks/treads out there that will handle fairly high rpms and be durable? I've seen some tank treads, but they don't look all that good and look like they would fly apart.

I'm thinking 8th-10th scale in size. I have several BNIB MM and MMPro ESCs laying around, so I'd probably use one of those coupled with a decent 60-70mm motor running on 4s or 5s. Top speed around 25-30mph would be plenty.

There are probably kits already out there, but I want something very durable with easy/plentiful parts replacement access.

I have lots of spare parts floating around (chassis, diffs, bulks, arms, tons of different shocks, etc) but I'd almost rather stick to Traxxas parts since my LHS has a good inventory of those parts. Sucks having to order stuff online when experimenting and then waiting again when that idea doesn't work and have to order something else.

One idea I had was to use an 8th scale diff with VERY thick oil in it (>200k) and then use only one side of the outputs to drive the track. The other side would be unloaded, but since the oil is so thick, it would act like a slipper. Or, just fill it with putty or JBWeld.

Another idea is to tear my Slash apart and use the FLM tranny and whatever else from that vehicle. This would allow me to keep the motor in front and put the battery in the "seat".

I've seen several skis I can use, and the front can use Revo shocks for the suspension. I'm thinking a fairly narrow setup like a Slayer/Slash or an 8th scale buggy (minus the driveshaft/diff). The body could probably be easily made from a chopped Proline truck body or something similar.

[Arct1k]

I have a spare pair of tracks...

[BrianG]

I'd probably have to mod them to appear more like a snowmobile. How do they hold up under power?A set of two would be great because then I'd have a spare.

[Bondonutz]

Parts are availible for this, http://www.brentfordrc.co.uk/Scripts...?idproduct=833

Not a whole lot on Ebay but did mange to find a track
http://cgi.ebay.com/BL10B-Kyosho-Nit...item518e9f3736

[redshift]

Just for an idea, 2010 Yamaha Apex MTX mountain sled.

[BrianG]

Bondo: Yeah, I saw those, as well as the selection here, but don't know if they can take the power and speed of BL.

redshift: Those pics do help. What I want to make won't look that fast, bit it gives me an idea of the rear suspension. To make things simpler, I might not even use a rear suspension, but a lot of that will depend on the track and chassis design.

[redshift]

Suspension is really not needed for an RC. Even if you're jumping, you're still gonna have a soft landing...

But a mock suspension would look cool and maybe give some adjustability.

I've wanted to do one for a long time, the only issue is the track. Not something that's easily custom made. I looked at that ArtAttack sled on FD's site a few years back, and was not impressed. Thing just looks old, has a low hull and is probably useless in anything more than about an inch of snow.

Wallyworld sells (or used to) some really cheesy ones, other than that I'd have no idea where to start on the track. Arc's tracks look maybe a bit narrow. I'm surprised there aren't more mfrs doing them. The market would be fairly substantial I think?

[_paralyzed_]

i've got a wally world sled. it's a new bright. it easily accepts hobby grade electronics, i just haven't done it yet

the kyosho blizzard tracks handle power and speed well. can't wait to see what you come up with.

[redshift]

Well I didn't ignore the Blizzard track(s) suggestion. But I think there are a few problems with that. Only using one I don't know if there's enough 'flotation' because they are so open. Also they are made to use over the wheels and might not flex tight enough for a small radius, so the scale appearance would be lost. Not sure how you'd use those with sliders, AKA Hifax. The drive I would do direct, I don't see a need for a slipper or any kind of clutch.

Keep in mind 25-30 mph will take about the same amount of power that it would take with a similarly sized boat. Or more.. sleds are huge HP wasters. Even 20 mph would be very impressive.

[redshift]

Originally Posted by _paralyzed_

i've got a wally world sled. it's a new bright. it easily accepts hobby grade electronics, i just haven't done it yet

Yeah NewBright. They aren't bad, and will like you said accept good elecs. A buddy and myself had one to look over real well, and we decided it looked like it just wouldn't take much power. On the good side they are BIG, you open the cowl and it's like "where's the beef?" lol there's this tiny 540 in a massive hole.

[redshift]

I did find a nitro modded one on YT, not gonna bother posting... but did find this also- http://www.rcuniverse.com/forum/m_6554521/tm.htm

[BrianG]

A newbright sled would make a decent starting point, but they are out of production. Besides, getting certain replacement parts (mostly cosmetic) would be difficult at best. Hence my desire to use parts from current products, modded as necessary.

Before I start this, I really want to find a tread solution that has the "float" (thanks redshift for that point) and durability I'd need. Chris's tracks, while small, seem like a good solution once modified as needed. I would disassemble them and restructure the wheels/drive unit to be more flat. If I can do that, it looks like it would give me around 5-6" of tread length. May be a bit small for 8th scale, but certainly fine for 10th scale.

Yeah, sleds are power hogs, but I do have a Medusa 36-80-2000 motor currently not in use. That should be enough power on 5s for a 10th scale vehicle I would think.

Suspension is not really important to be honest. If the snow is hard enough to make it required, I would be using a wheeled vehicle anyway. This would be for the fluffy/deep stuff that would cause a normal vehicle to simply dig itself into a hole. If I put suspension, it would be most likely in front only and mainly for looks.

Chris, where can I get a set of those treads you have in your pics?

I'm sure you have seen some of the ones on youtube but, check this one out. It is pretty cool even though it is gas powered. http://www.youtube.com/watch?v=6nas51B21cI&NR=1

[redshift]

Yeah I guess the concern I had for Arc's was the relatively shallow paddles. That could be improved with some small aluminum angle pieces possibly. And are those straight friction drive, or do they have some cogs/positive drives?

There really is a lot to consider with an RC snow vehicle of any sort.

[_paralyzed_]

Originally Posted by BrianG

Chris, where can I get a set of those treads you have in your pics?

discontinued radio shack fare. they really weren't that great, i had a set of 4 and the tracks dried out and just crumbled apart.