89redranger's MRC Pro Spring Rebuild

[89redranger]

After beating on my MRC Pro for about a year now and bending/breaking a lot of the factory components, I've decided to skip Spring cleaning and dive head-first into a rebuild of my favorite mini-crawler.

I have found that I wanted to change a lot of things about the Pro model purely to suit my own driving needs.

Thus far I've built a centered servo plate for my 645MG (for now), shorter upper front links to facilitate the BTA steering, longer rear upper links,all new lowers with bent rears top and bottom, converted the front knuckle and king-pin hardware, and replaced a lot of the cheesy factory hardware with stainless where possible, and anything but those damn button-heads everywhere else. I'll sacrifice a little hang-up to avoid the constantly wrecked factory junk.

I'm also running the factory Pro alloy shocks in the rear with a single-hole piston in the right and a double-hole on the left, and 1/2" of pen spring to suck it into droop. The front is mini late model shocks with about 3/8" of pen spring, Pro alloy shock caps screwed on with the eyelets cut off the late model shocks, MRC rod ends, 3-hole pistons, and 35WT all around.

All links were built with 3/16" aluminum tube with 3mm threaded rod through the center and a combination of factory and Traxxas rod ends. The servo plate is .065" aluminum plate

Anyway, these are mockup pics with no electronics and a broken chassis plate. Have questions please ask.

By the way, the tube is about 3.8" tall. I'm right at 3.75" directly under the center of the tire at max flex. Not bad considering how low it sits. With the Blue claws I have 1 7/8" under the belly. With the Rovers I'm putting on narrowed wheels I'll be at around 2"-2 1/8" under the skid. Perfect for the crawlin I do. Nice thing is, using 2 of my originals and 2 of the late model shocks left me two more of each shock so I could rebuild an identically valved set without the limiting springs for courses with more break-overs and ledges. with the shock towers down like they are now, I can also mount the body about 3/8" below stock, as well as how much lower the chassis still sits below stock. I think the body is over an inch lower than stock now.

Check the adapter I made that allows me to run shortened upper links so I could run BTA steering and keep the 4-link!!!

 

[89redranger]

So, parts are getting a little harder to find these days...

I'm still tinkering away with my mini, and plan on getting a brushed motor and another ESC, but it looks like parts production has pretty well ceased.

Anybody know where I can get a motor to work with the Tekin FX-R I plan on getting? I'm looking for something comparable to the Contraband motors as far as speed and torque.

 

[cboggs]

The Team Brood Frenzy is a nice little motor that should work well for you or there is the handwounds also."thumbsup"

 

[Hittman]

Very nice amount of castor you have there. I like it"thumbsup"

 

[89redranger]

Very nice amount of castor you have there. I like it"thumbsup"

It actually kinda looks insane in person, but works VERY well. The castor coupled with my Mini E-Revo front pinion make this thing "almost" reach out and grab rocks. You can here the lugs on the rear tires dragging as the front pulls it around with authority! No more lining up for my line multiple times and missing it because there's no front bite...

It's kinda nuts to watch this thing climb, tearing up earth, scratching tires, poppin the front wheels now and then, and goin' like hell. Just can't wait to get some wheels, tires, wideners, and a quicker alternate to my Mongoose setup!

I don't know if I mentioned it or not, but the inner knuckles were drilled and tapped to accept the button-head 3mm screws while I was doing the castor mod. The 3mm screws fit a little tight in the little brass shouldered sleeves between the knuckle and inner knuckle. I used a small file to VERY LIGHTLY open up the through-hole in them. Took about 30 seconds each.

3mm hardware in the knuckles is the only way I could stop stripping, ripping, and breaking knuckle hardware. It was cheap and easy and got rid of a lot of the slop in the front-end as well, and no more tiny allen wrenches. The bigger head, believe it or not, actually seem to slide over rocks easier as well.

With any luck I can get the few short videos I have and some more current pictures up. Please pay no attention to the body and wiring. Still under construction!

 

[89redranger]

So, it's been a while. The crawler has received MIP CVDs, and some moinor tweaking here and there. But, big news!

I built a crawler course in my front yard with my neighbor. Some 1.9 videos and comps are gonna happen soon hopefully. Here's a few pictures of the crawler on the course. More pics of the course will be posted after it is finalized.

 

[winnerone23]

New pics didn't show, tho I like the looks of what you already had goin on! Great work

 

[EverettY]

That should hopefully work ;-)

 

[hillbillyrc]

neat course you have there 89red.

 

[89redranger]

Just ordered MORE part. Lots of aluminum. I'm also soon going to post the transformation of my gift to my daughter for her 4th Birthday. She's getting an Exceed Maxstone 16 with a few mods just for my little girl! I bought the RTR, stripped ALL the green anodizing, polished all those parts, painted the drivelines, spur cover, and bead lock rings all PINK, and I've done a "few" minor mods to make it crawl a little better. Pictures of both rigs very soon!

 

[89redranger]

Details in the AM. Just got off work, it's late, but I wanted to get up the progress shots that I got before work today. We all know what the parts are, and yes I did take a few steps backwards...

 

[89redranger]

Alright, the mods-

Castor adjusted on new axle housings

Went back to Pro Roller factory links

Went back to the front mounted battery tray/servo mount

Went to a Hobby Wing brushless hoping for a little more wheelspeed

Rebuilt shocks again and eliminated the pen springs inside the shocks


Now, the parts-

Infectious RC Ti chassis plates

Losi aluminum zero ackerman outers and brand new aluminum inners

Losi one piece aluminum lockouts in the back

Billet rear hexes

Junfac Wideners

Hot Racing billet trans gears and spur

MIP Driveshafts

Turnigy TGY-1501MG Servo (230oz for $13...)

Hobby Wing 18T Brushless

And probably more that I'm forgetting


So, I took a few steps back toward the original Pro Roller layout. This was mostly due to the fact that using short upper links on this chassis almost makes it impossible to dial out the torque twist. I also added a little beef where I had some breakage after my daughter got my rig wrapped up in a tarp.

I still have my Novak setup, but after 2 years it needs bearings, and I need a little more wheelspeed. Haven't got to run this yet, but I'm sure I still have some tuning and tweaking to do...

 

[winnerone23]

Looks good, nice parts list! were you running the mongoose on 2s? I just got mine but running it on my 3s batteries.. wow! Plenty of wheelspeed an torque. I may even run a 62/15 gearing with it.. what was ur gearing

 

[89redranger]

I was, and still am, running on 2s. I had been running a 60/17 setup with the E-Revo pinion up front, but couldn't run any higher with Summer heat. It kicked the thermal protection on a few times with an 18T pinion. With this HobbyWing brushless setup it screams! There is some cogging, which I think I can tune 90% out of it by adjusting the punch and timing (came with a tuning card). I still have the overdrive mod up front, and I'm running the 60T billet spur, and a stock MRC 14T pinion. No heat to speak of...

 

[89redranger]

Hey guys, just wanted to let you in on a little trick I just figured out. I had built brass kingpin sleeves out of 5/32"x0.014" brass tube and greased them, and converted to all M3 hardware. Obviously, an exposed part covered in grease gave me some grief.

For stuff like zippers and such I've been told all my life to either use candle wax or bar soap. Well, any parts you have that need lubed without attracting dust can be treated by rubbing them down with a candle. I just rebuilt my CVs, lock-tighted the set screws for the drive pins, then waxed the cup, ball, and the hole through the ball of the joint. As I said, I did my kingpins, and pinion as well. So far, no dust and smooth as a baby's ass!

No more squeaky or loud dry parts, and no dust covered greased parts!

 

[89redranger]

Here are a few more random shots to show a little more of what I've done so far and some crawlin shots from today.

Stainless M3 knuckle hardware, brass kingpins (5/32"X0.014" brass tube), washers to kill any slop in the knuckles, and custom tie-rod and drag-link. Both had to be fabricated to clear with the caster mod, no way the stock stuff would've fit.

Just a perspective shot showing the clearance, caster, how tight the linkage is. Most of you already know this though...

Ti chassis plates from Infectious RC, Hobbywing 18T non-sensored brushless setup, Airtronics MXSport Radio setup, and the inverted and limited stock shocks out back, and modded Mini Late Model shocks up front.

Today, crawlin around on our neighborhood effort course.

Mellow descent. you can see how low it really sits. about 2 1/8" under the belly. New tires and wheels btw. Got another Pro Roller in trade for a Crapper King, and it's donating some parts.

Mellow climb. Looks like torque twist, but isn't. There is a rock under that front far wheel. the whole rig is leaning.

Nice level shot on top of our faux "Lion's Back" to get a little of the stance. Trans skid up at the rear, body down at the rear, and body in need of replacement.

Climbing again. It goes well. Wish I would've figured this setup out before running my own crap setup and links for the last 6 months. Honestly, other than the front shocks, I pretty much copied Del Monte's Comp Pro Roller(link placement, shock pistons, even oil...). There's a reason why that guy runs this setup!

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A short crap video of the bridge jump in our course. Thus far, I'm the only one to attempt this. There is another jump I recently found, which I need to get video of still.

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Just a quick spin up the bridge. It's stupid fast for a mini!