building a crawler

shoebox-airbrushing · #1 06-01-2011

So im looking into building a crawler... and ive put together a list of things i THINK i will need (minus electrics)

Here goes...

3mm grp (for chassis)
3racing axial gearbox (green)
Proline "tuber" cage and shell bits
Losi 3 piece wheels
Tyres (NO IDEA WHICH ONES)
3racing CR01 oil dampers
Venom heatsink motor + transmission mount (for AX10)
Axial high clearance linkage set

1 problem though.... I HAVE NO IDEA WHICH AXLES TO GET

...

any help will be much appreciated

Thanks
Rich

colmo · #2 07-01-2011

Axles decide a lot of things - shaft or MOA, worm drive or not? Shaft means you need a transmission, and opens up the possibility of a dig and a lightweight outrunner motor, MOA means you need a 2-motor (and possibly dual esc) setup, likely brushed gear - I wouldn't put outrunners on axles, their rotating can would be too exposed!

A central transmission means you have to be sure the ratios are right - Axial axles on a Losi transmission would fly, for example, whilst the slow worm drive Losi axles and Axial transmission would be geared very low.

Atm, MOA appears to be the way for competition rigs; if this is a fun runner, it doesn't matter.

shoebox-airbrushing · #3 07-01-2011

Whats a worm drive...

Also... ive decided not go with "MOA" bexaus i'd need 2 esc's and thus 2 sets of batteries ??

colmo · #4 07-01-2011

Quote:

Originally Posted by shoebox-airbrushing

Whats a worm drive...

Also... ive decided not go with "MOA" bexaus i'd need 2 esc's and thus 2 sets of batteries ??

http://en.wikipedia.org/wiki/Worm_drive

Benefit of a worm drive is you don't need a drag brake to hill-hold - however, it can't freewheel at all, either, which can be a problem (perhaps when using a dig, which decouples drive from one of the axles) as well as a benefit.

MOAs don't need two batteries, though often you'll see two small packs, one on each axle, instead of a bigger one in the centre. They also don't need two escs - one can drive two brushed (but not brushless) motors - Novak are at the forefront of the top end crawler escs, but any brushed esc can do if it can cope with the modest amp draw of two high-wind, high-torque motors (usually in the 35T-75T range).

shoebox-airbrushing · #5 07-01-2011

Ahh... will a trinity 19 turn be torq-y enough :S... i have an orion rocket pack (3500mAh)... and a novak xrs speedo... will these be any good ???

colmo · #6 07-01-2011

Quote:

Originally Posted by shoebox-airbrushing

Ahh... will a trinity 19 turn be torq-y enough :S... i have an orion rocket pack (3500mAh)... and a novak xrs speedo... will these be any good ???

The 19T might be a bit quick for an Axial setup, and I've heard the Losi is hard on brushed motors, but cannot comment as the brushless outrunner worked first time.

The battery would do, but a massive 400g NiMh high up would make for a top-heavy rig.

I don't know much about the Novak - can you set 100% drag brakes? If not, its better for a Losi than Axial.

That gear is better suited to a trail rig like the Axial Honcho, that a true 2.2 (refering to wheel size) crawler.

colmo · #7 07-01-2011

Quote:

Originally Posted by shoebox-airbrushing

Ahh... will a trinity 19 turn be torq-y enough :S... i have an orion rocket pack (3500mAh)... and a novak xrs speedo... will these be any good ???

The 19T might be a bit quick for an Axial setup, and I've heard the Losi is hard on brushed motors, but cannot comment as the brushless outrunner worked first time.

The battery would do, but a massive 400g NiMh high up would make for a top-heavy rig.

I don't know much about the Novak - can you set 100% drag brakes? If not, its better for a Losi than Axial.

That gear is better suited to a trail rig like the Axial Honcho, than a true 2.2 (refering to wheel size) crawler.

johnnygibbon · #8 07-01-2011

ross mods are big on crawler stuff and have dual escs and allsorts give em a bell for more advice
01705 250007
hope it helps i loved my crawlers but never found enough competition
so racing took 1st place in my rc world

shoebox-airbrushing · #9 07-01-2011

Quote:

Originally Posted by colmo

The 19T might be a bit quick for an Axial setup, and I've heard the Losi is hard on brushed motors, but cannot comment as the brushless outrunner worked first time.

The battery would do, but a massive 400g NiMh high up would make for a top-heavy rig.

I don't know much about the Novak - can you set 100% drag brakes? If not, its better for a Losi than Axial.

That gear is better suited to a trail rig like the Axial Honcho, than a true 2.2 (refering to wheel size) crawler.

Its not a ni-mh... its the carbon fiber looking lipo... i get muddled up with names so i judst call em the rocket pack

terry.sc · #10 07-01-2011

Quote:

Originally Posted by shoebox-airbrushing

1 problem though.... I HAVE NO IDEA WHICH AXLES TO GET

...

Based on the list of parts, using an Axial transmission and linkages the easy option is Axial axles.

I assume from your list you are planning on building something that has pretty good performance, so my answers will reflect this.

I presume you are making your own chassis sides, but if you are also using the Proline tuber body then you are basically going to end up copying the standard Axial chassis plates so the tuber body can fit it, and the Proline tuber is more top heavy than a normal body. It's okay if you like the look of it but just about anything else will perform better.
As you are planning on making your own chassis why not build something similar to the Beetljuice? http://www.rccrawler.com/forum/showthread.php?t=276237

Dampers are one of the most important parts of the suspension, which is why everyone uses the Team Losi threaded crawler shock set. No more expensive than the 3Racing ones and come with springs rated for crawling.

For tyres, the choice is yours but the top competition tyre right now are Hot Bodies Sedona in white compound.

The Novak XRS is pretty useless for a crawler, there's no drag brake and no instant reverse, both of which are pretty important in a crawler. There's a good reason most experienced crawlers use the Tekin FX-R. If that's too much then there's the Mtroniks Rock Crawler ESC, nowhere near as good as a Tekin but considerably better than anything from Novak.

Motors. A 19 turn has way too little torque and way too much speed. For your Axial transmission you want a motor between 35 and 55 turns, depending on whether you want more wheel speed or more climbing ability.

Your battery pack is way too big for a decent crawler, you will only be able to fit it right on top which limits the climbing ability. You only find full size packs in kits as they are an easy option but ditching it and using a small lipo or a pack of 2/3A cells as used in micro cars helps you get more weight off the top of the chassis. I still get 20-30 minutes out of 1500mah 2/3A packs in my twin motor crawler.

If you want advice on crawling then the shops are last place to go as none of them have any experience of crawling, and that includes Rossendale Models. The only shop that has had any involvement with crawling and has been seen at any competition is MK Models. Any of the UK crawler sites, UKRCRC or the more competition oriented RCCrawling will give you all the advice you need.

mrspeedy · #11 08-01-2011

Or just buy an Axial crawler and mod the crap out of it

shoebox-airbrushing · #12 08-01-2011

Quote:

Originally Posted by mrspeedy

Or just buy an Axial crawler and mod the crap out of it

Yeah i could do that... but it would still just be an axial :/

welsh wizad · #13 25-01-2011

i converted a axial with a bullly chassi and it climbs just as well as a bully