Mwe's mrc turned mini monster build

[mwe-maxxowner]

Hey folks. I don't post much here, but I've been hanging around for a while. I've been an avid basher of mostly traxxas stuff for years. A couple years ago, on a whim, I snatched a losi mrc off the classifieds on RC monster. I've enjoyed it, capable little fella.

Anyhow, I find myself not using it much now that I've built up a telluride to crawl. So here goes.

My vision for this thing is a small solid axle monster truck. I'd love to make it similar to one of the Bigfoots(bigfeet?) that were running when I was a little one. I'm shooting for 20-30mph, and opening the diffs. Decent handling would be nice too. Lol

I'm not the first to get one up to speed, or to open up the diffs, but, without being pointed there, info on this is very hard to find on the dubyadubyadubya. I'm hoping to chronicle this build in such a way that those googling for info on speeding up mrcs in the future, or turning them into mini monsters, will be pointed here and find what they want. In short-that it is possible for the average Joe.

I'm gonna try very hard to get a mini revo tranny in. If I can't, I'm going to overdrive the diffs, put a high kV motor in, and gear it to the moon .

I am open to any and all suggestions and ideas. I hardly know it all, or really even know exactly what to do. Please take it easy on me if I ask dumb questions, this is a new type of vehicle for me. It's a far cry from the independent suspension tub chassis style RCS I'm used to.

As it stands, I've torn it down, removed the tranny, started looking at the mini revo tranny, and that's about it.



Nearly complete donor



Front and rear



At first, my idea was simple, drill new holes, come up with spacers, and mount the tranny as you see it below:







I can't though. It would sit much too high. Cog would be bad, it would interfere with the top plate, just a no go. I will have to figure out how to recess that hump in the bottom below the center skid, much like the mini revo tranny sits in the mini revo.





Hack up the Merv chassis to create a mount? Hmm. Food for thought anyway.

[MRCrackhead]

Check this out.

Mini Revo Transmission in Losi MRC

Nothing is impossible, just tricky at times. Keep building.

[mwe-maxxowner]

Any pictures of your Merv tranny mounting?

[JatoTheRipper]

Looking forward to seeing this completed!

[mwe-maxxowner]

Thanks! Tag along and offer up ideas!

I'd imagine she'll do a little foffing too .

[JBcustoms]

Think it was in your other thread, bu I like your idea for using a plastic cutting board as a trans mount/skid. You have the mini revo chassis to measure up and get dimensions off of for the trans mounting, and the losi skid/trans mount to get the dimensions for the chassis plate/link mounts. Do some measuring, bust out the dremel and files, and go to town! Will have plenty of materials to work with if you buy a cutting board specifically for this project. Of course, 3d printing one would be cool, but this may be a cheaper option.

[mwe-maxxowner]

I got the idea because I rebuilt a fiberglass boat one time, and when it came time to mount the fuel tank, instead of glassing in wooden strips to place the tank on (which will rot some day) I epoxied in strips of cutting boards. I may have trouble finding one that is thick enough, and might need to laminate a piece or two together. As long as I can find something to laminate them together strong enough without creating a gap, I think it's doable.

One place where I know I'll need tips is creating functional sway bars. I've found one thread where a fella created a rock racer styled tlt 1 (which was sahweeeet) that had custom sway bars. He didn't go into detail, though, I just caught them in some of his pictures. They weren't close up of the sways, however, so I can only steal so much info from the pics. Still googling for more tlt1 sway bar use ATM. I have an unused set of sway bars from a traxxas 4x4 slash I'm wondering if I can repurpise. I just need to tie the axle to the chassis, right? And only rear, or both ends?

[JBcustoms]

Yeah, I have seen some thin ones, and some thicker. I have two in my kitchen that are more than a centimeter thick.

[mwe-maxxowner]

I would say the ones I used were between half and 3/4 of an inch

The truck MRC crack head linked to shows the tranny mounted twisted at an angle, which is brilliant because it allowed it to all stay above the center skid, and lowered the motor considerably from the mock picture I showed above. Still dunno if it would fit under the stock upper tray on a mostly stock truck.

What I have in mind,mounting it flat, and essentially letting the bulge on the bottom stuck down below the center skid, causes me to lose ground clearance. Not a whole lot I think, but still.

[T_Tank]

Ya know if ya assemble the entire motor/trans together an measure from the lowest mounting tab to the top of the motor can you may be able to figure out low you need to go to clear the electronics tray, or just make some custom electronic boxes an ditch the tray maybe free a battery box from the merv chassis so you have a mostly sealed battery box that you can have maybe sit next to the motor or angled up against to try to keep everything super compact.

actually for sway bars of the 1/18th scale variety should look at how gpm made a sway bar for the mini-T


Basically just need some links with a set of ball ends that have a pass through similar then it just held in by two tabs on the chassis that hold it an let it move where it needs to.

Using varing thickness of I think music wire will give you whatever tension your looking for sway bar stiffness.

I'd also look into keeping a merv sized servo on the axles, yes I know they are not rock crawler brutal strong but sprung an unsprung weight you gotta keep a good balance on for shafties so your tires arent doing all the susension work.

[mwe-maxxowner]

So you'd ditch the 1/10 servo? I would have ditched the tray, I could mount the electronics, I just assumed it needed to be there for strength. I'm assuming just a brace across between the plates front and back would suffice?

And, would the sway bars be as effective attached to the lower links instead of the chassis?

[T_Tank]

Yes you could just run the sway bar along the underside of the lower links with the bottom of the u shaped swaybar being closest to the chassis side connection an make sure everything is zip tied nice an tight.

Also could just run cross braces instead of the electronic tray using whaterer material you prefer.
I personally would ditch the fullsized servo if I could or if I had one laying around one of those fullsized half hight servos.

I use a blue bird 390 servo (common for merv replacement servos) in my mini scaler and it works great though have custom knuckles an c hubs to give me some kpi like the wraith an my rig is light REALLY light uses only weight distribution an mechanical grip to go over obsticles.

But really when your going faster with big tires you need a slightly faster servo to try an keep up with your inputs to keep it body side up!
I think you can find a savox about the same size with similar stats that can even be water proof.

[mwe-maxxowner]

I can't even think of anything else to ask. Haha. I can't wait to get some progress posted

[mwe-maxxowner]

Anybody ever see one of these in person? Maybe your kid has one or something? I'm wondering how well the body would fit. I also found a parma Bigfoot body, but I think it was too big, @ about 18" overall.

[T_Tank]

never seen one of those in person but as mentioned you really couldn't go wrong with a mini LST body as I think it look very close to scale with a monster truck unlike most other bodies that may have about a 8" wheel base they will be super wide on mrc axles.

here are a couple of examples
Parma custom classic truck body
PARMA/PSE 1/18 Custom Classic Truck For Mini LST - Clear Body


Sock mini Lst body (shown on what apperse to be a super modified minigiant)


Losi mini raminator body


I think the mini desert body might work but be on the small side of things.

[mwe-maxxowner]

I just really want a Bigfoot. Haha. I haven't looked wt any mini LST bodies, just tlt-1 bodies. I got dimensions on that new bright hard body. It's about 13" long and 7 wide.

Sophistication:
















You can see that the bottom hump only needs to be recessed ever so slightly. I will most likely literally epoxy and screw these together and build it. Then run it around a little and see if I like the placement, cog, etc. If it seems to work well, this would be a simple piece to create as one, I think.

[MRCrackhead]

Haha!

Now that's perhaps the coolest way to cut parts..... brilliant.

Use what you got, but watch your fingers!

[mwe-maxxowner]

Haha I did. When I was down to cutting the sides off I held it with a pair of channel locks.

[mwe-maxxowner]

Tlt-1 bodies and mini LST bodies are similar in size, correct? I think a mini slash/revo body would work too, right?

[mwe-maxxowner]

Actually seems to have turned out decently. I cleaned it up some with a dremel and jb welded it. It will take a good day to set, then I may build up some other sections with more jb weld, and work with a dremel to shape it as pleasantly as possible. It's off square by just a little bit, gonna see if I can straighten that out too.

I wish I could have caught the front two screws inside the skid. I thought I might make a plate to go below the skid that extends out far enough to do so. Then test this configuration some. If it works out okay, see about having one printed or carving it myself caveman style, and account for that.