Mary Shelley's MRC

[MRCrackhead]

As it's name suggests this mini build has been, and still is something of a Frankenstein creation. I picked it up used off craigslist not knowing anything about the rig or crawling.

Typical life story is that my heart is fully into this rig, but the money for all the goodies just isn't in the budget.

Therefore, I decided to build as much as I could and buy only the things I couldn't make myself. The problem with this plan is I didn't know squat about RC rock crawlers.

I dove in head first anyway, and made a lot of mistakes. My friend Chris and I started calling my first chassis the Frankenchassis because it was cobbled together, worked, and re-worked tons of times till it was just a big mess.

The mess it became was all due to testing, tuning, reading, and learning what really makes these rigs go. Here is where I've been and where I'm at now....

I decided to use lexan for my material because it was cheap and easy to work with. The plan was to get this thing working properly, and then use it as a template to cut it out of some aluminum, G10 fiberglass or carbon fiber. First, I needed a working template.

Side plates

Skid plate

Roller

Front and rear 4-link plates

[MRCrackhead]

No surprise, my very first chassis wasn't so great. So I scabbed on some tabs to move the shocks around and get some rake to the skid.


Shaved the steering arms and clocked the hubs for better steering.


Fabbed up some weighted beadlock rings.


Built a rockpile in the back yard (much to my wife's dismay....haha). Then I was testing and tuning without having to drive somewhere to do it.

[MRCrackhead]

Just didn't have the forward bias I needed so I fabbed up some knuckle weights.

[MRCrackhead]

Of course, those dinky weights just didn't add enough. I also wanted to add some track width so I cut the guts out of a set of Axial 8 hole wheels and made some beadlock faces that would mate to SLW hubs.


Added some more weight to the knuckles.


Chopped the tabs of the axle to lower the servo and move it back to better my approach angle. Made a custom plate to do that and fit my new short Losi mini late model shocks and keep them out of the tires when I turned.


Added some crazy steering arms to the knuckles to try to get something close to zero ackerman steering.


I was really happy with how things were turning out at this point.

[thomass14]

nice building, good ideas

[MRCrackhead]

Though the rig was coming along and was starting to really crawl well, I just couldn't seem to make my crazy steering work the way I wanted it too. I had a decent turning radius, but there was no good way to get the drag link and tie rod solid with the servo horn pointed up.
After much research and testing/ re-working my steering, I decided it was time to do something drastic.
The Frankenaxle was going to fit beautifully under what had become known as the Frankenchassis.
I wasn't completely happy with the idea of clamping the XR housing over the top of the MRC tubes for whatever reason.
A bunch of measuring and many hours of research and deliberation I decided to order the parts but go a slightly different route.

I picked these up at the hardware store.


Shaved the MRC housing and began cutting and beveling the brass tubes to fit.



Just the slightest amount of shaving inside the XR hubs made for a nice press on fit over the brass tubes.


Measure about 35 times and cut.....as you can see this was going to leave me with nearly all of the original plastic and the thickness of the brass tubing to drill and tap holes for attaching the tubes to the axle, and the hubs to the tubing.


Everything slid together for the first time.

[MRCrackhead]

Oops, forgot the pictures of the universals. Can't go far without em...

[MRCrackhead]

I needed somewhere for my links to mount so I made up this bracket and tied it into the existing stuff from earlier.


Fabbed a couple mini tabs to make the links double shear and to aid in mounting the brass tubes to the MRC housing.


Here's the roughly ready axle next to the original. I think it looks about like a Dana 30 parked next to a Dana 60. Not including the ring gear/locker, I think this will be a much stronger axle.


Next I made up some new wheel weight brackets and the weights to go with them since I had new knuckles.



Cut out some steering arms and I was back in action. Notice my sweet cab. I had friends waiting on me at the park and needed something to protect my junk.....it did the job.


Another shot of the new axle in action on my rock pile.


Somehow I ended up with the steering horn pointed up again....that didn't work again.....so I abandoned the idea of having the servo way back. I made up some mounting brackets to level the servo and keep my pinion angle out of the rocks. It doubled as a gap for the tie rod to hide behind the drag link which kept everything as far back as I could stuff it.

[winnerone23]

Bravo sir, Bravo!!!! :thumbup::cool:

One thing.... Nah, just kidding!

Excellent pics an story of how she came to be. I myself appreciate the time an efforts you put in. Glad to see a thread on it an So can't wait to see it on the rocks!

[chris.martell]

Merc you have truly done an amazing job on this mini! It truly is a Frankenstein rig considering the condition it was it when you purchased it and has come a long way from the motel crawling we use to do in allentown! :thumbup:

Sent from my SPH-L900 using Tapatalk 2

[MRCrackhead]

Thanks guys.
It was getting late and I needed some sleep. Haven't been getting much lately with the comp so close and two rigs only partially built.
I'll try to post up the rest of my saga this evening.

[Crawllife]

It's great to see xr axle options for these. I have the plastic xr housing sitting next to my build and I'm not thrilled with the idea either. This is clean and strong looking. Good stuff!

[winnerone23]

Originally Posted by Crawllife

It's great to see xr axle options for these. I have the plastic xr housing sitting next to my build and I'm not thrilled with the idea either. This is clean and strong looking. Good stuff!

Just bring them front axles an stuff for the mod to the comp.. ;)

I myself like the XR housing. At first figures I wouldn't cause of the bulk an loss of ground clearance but in the long run, it actually helps voice over the rocks easier an holds up extremely well. IMO

[MRCrackhead]

Most of what I read about it, I remember issues with the tubes spinning, or wanting to spin. My theory was this setup actually locks around the diff gussets and prevents that. My screws only hold the tubes from sliding off. They don't need to counteract the drivetrain rotation.

[winnerone23]

Yeah, I read them issues as well.. none here tho. Solid!

[kbuby]

Great work there, you´re a gifted one.

Excelent

[MRCrackhead]

Now that I had a rig that was steering very well, I decided to rework the chassis to get rid of the madness it had become.
My thought was to base the dimensions on the Frankenchassis, but make it adjustable. I didn't want another monster to come alive....
This time I made the shock arms as separate pieces so they could be redone if need be, without starting all over.



Then I made a new skid with a recessed center to keep the trans as low as possible.



The new chassis was a lot lighter than the old tank.



It's hard to take pictures of a clear chassis. A lot of what I thought were good pictures were terrible blown up on the computer. Here are a couple of what I do have.


Attachment 249524

[MRCrackhead]

In the midst of this, I got some time on the rocks and realized my front weights were working a little too well. It was time to give some love to the completely neglected rear axle. I still run stock lockouts because I had bad luck with the Losi straight shafts. First time out, I bent one. I straightened it and chalked it up as a bad wreck. Second time out, bent the other one. I had never given my rear axle much thought up to that point. So they came back out and I've had no issues since.

Anyway, I picked up a couple 1/2" locking collars at the hardware store. They needed to be drilled just a bit to fit. (5/8" I think).


Made some half weights. Notice the broken tap in the far right one..bummer.


Only the two were tapped and I welded them to the collars. Then the rest bolted on as usual. The set screw seems to hold them just fine and they're fully clockable. I'm currently running them just slightly rearward.




Now the rig was starting to balance and handle up, and downhill.

[MRCrackhead]

I decided to paint this version of the chassis even though I'm not fully happy with it. I needed to move forward and learn more.

I didn't like the wide cab for tight spots and rollover recovery. I made up a couple of "stiffener" plates to keep the chassis legal. Then I moved the cab pieces inside the chassis. I gave it some taper with a mixture of spacers.




Last but not least, I cut some thin lexan for panels and shot them with some paint.





This panel is questionable.


It was late, I was tired, lazy, and I don't fully understand the wording of the rule where it states "3.5 square inches of solid surface".
I believe there are 3.5 square inches of "solid surface" there (I can't poke my finger through any of the red surface......). But, is a surface with a hole in it "solid"?
A smooth surface would help prevent hangups on the motor. Again, I was just tire and lazy. Look how much work I've done in the last two days! HaHa
Tech guys will help me out on that one.


Until then, no stickers for that panel. The rest are going to get some stickers just to break up the red a bit.

Thanks for looking. I still need a lot more work on this rig. However, I feel ready enough to test the waters at a local comp.

Like everyone else, I'll update as I go. Doing it all at once is kinda like work...

[winnerone23]

Red!?.... looks as orange as ur springs.. lol..
I'm thinking ya better make a new panel for ur motor side.. unless you can fit 3x 1" cubes on it an still have extra material. 3.5 square inches..