Cross RC BC8 8x8 Build

[soze]

It's actually pretty crazy how big this is when you think about it.

When you look at pictures like this you don't really give it a second thought.


But when you look at that picture again, and then have your SCX10.2 or TRX-4 sitting right next to you to see how big this would actually be...

[jamesbernatchez]

Originally Posted by soze

It's actually pretty crazy how big this is when you think about it.

When you look at pictures like this you don't really give it a second thought.


But when you look at that picture again, and then have your SCX10.2 or TRX-4 sitting right next to you to see how big this would actually be...

Absolutely. So hard to judge from a photo. Gotta get the whole effect by seeing it in person.

[HumboldtEF]

Originally Posted by jamesbernatchez

I wanted to bump this as more people should check this rig out. I wanted to say thanks to OP for this thread. Mine just arrived last night and I spent 12 hours getting to the point where it was running chassis minus the body. The size and weight is not expected, even when you know it’s a big rig. The torque in 1st is insane. I may even try to pull my car when it’s done.

I noticed they included servo spacers, two different sizes. I used the tallest ones, and the front servo hits the body. Will need to drop it down some. Powerful servos are needed. I’m running Savox SW-1210SG for the steering and they have no issue turning on carpet at full stop. Again, it’s heavy. You could workout with it.

Everything is going together well, minus the few small hiccups so far. I really hope they come out with a better trailer for it. I have no interest in the logging trailer.

Locktite is your best friend. So many screws thread into metal. Get a tube and you should have plenty.

The front skid alignment was off on the bottom two holes. I needed to elongate them a bit.

Hands down one of the best and most impressive kits I’ve ever put together. It is my first foray into Cross RC and I’m a fan!

Thanks James



I did try to tow my car a 91' Civic hatchback (2400 lbs) but it was on a polished garage floor and with the lack of traction it was only able to move ever so slightly, like 2-3 inches at a time. But the promo video where they towed a vehicle had a BMW wagon that should weigh 3500 lbs.

I could hear the voltage drop dramatically when doing this, since its so heavy and the whole towing thing the voltage would sag dramatically like it was a Nimh or something.


It truly is a massive truck and what it can do even with its weight is pretty impressive.

[jebster]

I was curious how this monster has been holding up. I'm saving my pennies to get one of these to add to my fleet.

By the way, how does the included sound system work? Does it sound good?

[HumboldtEF]

Originally Posted by jebster

I was curious how this monster has been holding up. I'm saving my pennies to get one of these to add to my fleet.

By the way, how does the included sound system work? Does it sound good?

I dont really go too easy on this rig but time wise I really haven't driven it a ton to be honest. I usually just want to drive it for and hour or so and then switch to a scaler. It chews through batteries like there's no tomorrow (though they were shorty 3S lipos) and if you're out of juice you're carrying a 20lb truck back. I've since modded my battery tray so I can toss in some giant 7600 mah batteries.
It is worth noting there is a ton of slack in the driveline (like an old school 2 speed) where you can roll it back and forth a good 4" or so. that could lead to damage if you aren't attentive.

The sound kit is fairly quiet and I have a hard time hearing it over my brushed motor. It seems like it doesn't rev up much at all as I speed up but again it is hard to head over the motor. One guy mentioned that turning the volume up all the way was causing it to brown out. That said I'm not really a sound kit kind of guy anyway, though I will switch it on for short spurts now and then.

I was checking the US website and they do finally have some spare parts available which wasn't the case for a while.

[jebster]

Originally Posted by HumboldtEF

I dont really go too easy on this rig but time wise I really haven't driven it a ton to be honest. I usually just want to drive it for and hour or so and then switch to a scaler. It chews through batteries like there's no tomorrow (though they were shorty 3S lipos) and if you're out of juice you're carrying a 20lb truck back. I've since modded my battery tray so I can toss in some giant 7600 mah batteries.
It is worth noting there is a ton of slack in the driveline (like an old school 2 speed) where you can roll it back and forth a good 4" or so. that could lead to damage if you aren't attentive.

The sound kit is fairly quiet and I have a hard time hearing it over my brushed motor. It seems like it doesn't rev up much at all as I speed up but again it is hard to head over the motor. One guy mentioned that turning the volume up all the way was causing it to brown out. That said I'm not really a sound kit kind of guy anyway, though I will switch it on for short spurts now and then.

I was checking the US website and they do finally have some spare parts available which wasn't the case for a while.

i'm surprised at the amount of slop you are seeing in the drivetrain. I haven't seen many comments on that but then again there aren't a lot of people with build threads on this rig.
too bad about the included sound system. my plan was to go more scale on this that most of my other rigs by having sound and exhaust. if the included sound system isn't up to par I may look into the ess sound module.

[HumboldtEF]

Yeah I have a back up plan if the tranny goes boom, since theres plenty of room I can likely swap in any tranny I want probably an Axial 3 gear.

I have a feeling the ESS sound kit beats this one though I've never heard one in person.

I will be taking this rig to Proline BTF in a few weeks and that will be its first good outing on the rocks which should be awesome.

[soze]

I purchased the HG Model HEMTT. Would be cool to compare it side by side with a BC8.

[jebster]

Originally Posted by soze

I purchased the HG Model HEMTT. Would be cool to compare it side by side with a BC8.

That would be interesting. Not sure my wallet can afford to have both side by side in my workshop! :-)

[HumboldtEF]

Originally Posted by soze

I purchased the HG Model HEMTT. Would be cool to compare it side by side with a BC8.

That would be sweet, I know you said you wont be coming to Proline BTF but you might consider coming on Friday or Sunday, some of our group (including me) will be showing up Thursday night and staying till Monday morning. If you just come and hang out you wont need to pay, unless you want to do the events.

Originally Posted by jebster

That would be interesting. Not sure my wallet can afford to have both side by side in my workshop! :-)

Plus the amount of space they take up, I could fit 3 scalers on the shelf I keep the BC8 on.

[CODYBOY]

Originally Posted by HumboldtEF

That would be sweet, I know you said you wont be coming to Proline BTF but you might consider coming on Friday or Sunday, some of our group (including me) will be showing up Thursday night and staying till Monday morning. If you just come and hang out you wont need to pay, unless you want to do the events.



Plus the amount of space they take up, I could fit 3 scalers on the shelf I keep the BC8 on.

And Casey you could enter it in concourse and WIN.

[HumboldtEF]

Originally Posted by CODYBOY

And Casey you could enter it in concourse and WIN.

Thanks, At the last RPP Jamboree it came in 2nd at the show-n-shine. I think partly because they do it based on applause and lifted the other truck to get a reaction, but with my truck being so heavy they left it on the ground and just pointed down at it, lol.


I'll be putting 2 new rigs and this one in the concourse at Proline BTF

[jebster]

so i'm getting close to pulling the trigger on one of these but had a question. based on the steering setup how strong of a servo do you feel is necessary? its been a long time since I've work with anything but solid axle with a drag link. I don't want to burn through servos but if a $120 holmes shv500 (or something similar) would be overkill I wouldn't mind saving a few bucks!

[HumboldtEF]

I'd say you should go for the most powerful servos that you can afford after all its a 20 lb truck. It does use 2 servos for the steering BTW.

I used 2 Savox 2290's (black edition 6V: 555.5 oz-in; 7.4V: 694.4 oz-in) and they're adequate but you wont be pushing any boulders out of the way.

[jebster]

Originally Posted by HumboldtEF

I'd say you should go for the most powerful servos that you can afford after all its a 20 lb truck. It does use 2 servos for the steering BTW.

I used 2 Savox 2290's (black edition 6V: 555.5 oz-in; 7.4V: 694.4 oz-in) and they're adequate but you wont be pushing any boulders out of the way.

OK. so no going cheap on a $1500 rig. got it!

[wermart]

I started to use on all my crawlers 20kg servos i am buying from Amazon and it has been 8 months and they work fine, they run around $18-20. I recommended same servo to a few guys and they are also happy with it. For bc8 i bough 25kg servos for $25 each. Just dont feel like spending ~$300 for brand name servos.
I dont compete for speed on BC8

[jebster]

Originally Posted by wermart

I started to use on all my crawlers 20kg servos i am buying from Amazon and it has been 8 months and they work fine, they run around $18-20. I recommended same servo to a few guys and they are also happy with it. For bc8 i bough 25kg servos for $25 each. Just dont feel like spending ~$300 for brand name servos.
I dont compete for speed on BC8

I've bought similar servos an use them in some of my 1.9 scalers and they work ok but even in those cases I find myself looking for a little more torque. and i'm not worried about the speed of a servo for something as big as the bc8, its the horsepower to turn the wheels when and where I want to.

[HumboldtEF]

I'm trying to rock crawl and do more demanding stuff than just trailing so I prefer a high torque servo. I've also cheaped out in the past and it often ends up being more expensive because of having to replace a broken or inadequate servo. In the end you might end up buying 2 cheap ones or a cheap one and an expensive one.

That said I know not everyone has expendable income so do what works for you


I decided to do another wash on the paint, I've gotten better at weathering and the first round of washes was really light and hard to notice in pictures.

I mixed up some red and black to make a dark red (1 part red 4 parts black) using less water so it was a bit thicker. I think the thicker wash dabs off better, it doesnt act like water which tends to bead up and pull away (surface tension?). Even this wash is a bit hard to pick up in photos.

[jebster]

got a question. I didn't see it in your build but did you install the rear winch that is available for the bc8 from cross-rc? I see it listed as an optional part. i'm considering getting it but I wanted to see if anyone knew how strong it is. looks similar to a custom winch I have on one of my builds that uses a 540 motor and worm gear transmission. also curious if it comes with the controller.

hoping to put my order in soon. been collecting a few other parts (esc, servos) but haven't dove in on the big purchase...yet!

[HumboldtEF]

I didn't pick up their winch. I would hope its strong because it would need to be. It weighs .5 lbs so its probable a 540 motor and from the picture it looks like the motor wires go to what I assume is a controller board before it terminates with a servo plug.
https://www.rpphobby.com/product_p/czr-97400569.htm

I got a few good shots at Proline by the fire on Friday morning while it was pretty quiet. I ran into the Element Enduro team and I believe the engineer was really enjoying watching the BC8 do its thing.







And I took it out on a night run Saturday where I ran out of battery for my radio and ended up having to carry it back to camp. I think I made the mistake of storage charging my radios battery instead of charging it, DOH! It did pretty good on the course intended for mostly 1.9 rigs, but I did need to pick it up twice and help it to avoid scraping the entire side off the truck once or twice.


It collected some really nice rock rash from the 20-30 grit granite rocks lol