Monster truck - refactor - Kyosho Mad Crushers

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johnnydmd

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Thought I'd started a thread on this, but can't find it - I think maybe I just posted about it in some other thread. Last year I decided to revamp my twin Kyosho Mad Crushers which was mostly just ditching the cartoony Monster Jam Bakugan Dragonoid and go with a more old school (which is trending up even in Monster Jam these days) look. Jconcepts Ford F250 bodies were a perfect fit.

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I wanted some original cool names, and came up with "Angler Management" for the red truck. For the blue one, I came up with "Inflated Eagle".

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Anyone who's followed my previous thread on these trucks knows these are pretty heavily modified from stock. This year I was gearing up for the No Limit World Finals at Diggers Dungeon, but got derailed by other plans (kids, ya know), and missed out. The other event I had slated in July was cancelled. Drag racing was taking precedent as well, but I did manage to get these trucks out and run them for a day in July.

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I got them dirty, bruised, and beaten up nicely. Red truck's rotostart came apart, ending it's day after a few hours. Blue truck was intact but receiver battery died, and it was then raining, so called it a day. All in all, got a few hours of practice, shakedown, and testing in. Both trucks handled well with the beefy tires and earth ripping treads. Huge difference from when I struggled with traction at last year's events with the Jconcepts Firestorms and Renegades.

After this day, I put them up on the shelf, and went back to working on my drag cars. I felt kinda bad about them. Like, they just weren't getting used, and they weren't getting love. Both trucks were dirty, loose, and in need of some changes with the steering, which was simply just too sloppy. Maybe a Winter project to make changes was in order.

Then I got the call from the organizer from the event I raced in last July, inviting me to drive up a few hours to race. Labor Day weekend - definitely had to check with my wife - but she was like "Hell yeah!". Checked with my doctor, and he said "Well you could train for a marathon if you want, you'll be fine". Ok, that seemed a little extreme, plus I effing hate running, lol. So, all systems go! Wait - I only had a week to get my neglected trucks ready...

Replaced the rotostart, got both trucks cleaned up, tightened up, and fired up. Got the tunes good, and took them out in the backyard for a rip or two, and practicing on my ramps. Oh that steering slop. Good god. I love Mad Series trucks, but the steering setup is simply pure garbage in design. The blue truck was a little more manageable because it's just two wheel steering, but even still - it's just a horrible, horrible design, even with the improvements I made with the custom designed bell cranks. I had to make a decision, and get it done fast. Deal with the sloppy steering and just make sure everything is as tight and tuned as possible, or rip it out and design an axle mounted servo bracket and just get these things RIGHT. I went with the latter...

I figured the bell crank mount I had was a good starting point, so I whipped up a design that was as tough and beefy as I could make it and have it fit in there. This five link suspension makes things a little dicey with space. I measured things up, and printed one out to see how it would fit. Got it right on the first try :)

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I conveniently had a Hot Racing servo savor that I'd bought for this very purpose last year...

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Then I had to figure out what to do with the rear steer. Turning radius was gonna be quite less with this setup but I actually found that the blue truck was much easier to drive with two wheel steer, so I decided to keep this as two wheel steer, and printed out a locking block for the rear.

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If, later on I want to re-add rear steer, I'll just print out another servo bracket and bolt it up. If I do that, I'll put a pot in to allow adjusting the amount easily. For now though, gonna just keep it two wheel steer. Most racers only use the two wheel steer from what the more experienced guys are telling me. I think I can see why - as the four wheel steer seems to cause you to move in a more serpentine path at times if you're not really good with it (like me).

I took the truck out last night and ran it around the yard again. As expected, lower turning radius, but super easy to keep straight, and ALL the slop GONE! It drove like the blue truck, but a lot more responsive and tight feeling. I didn't have time to re-do the blue truck, that'll have to wait, but man I am finally happy with the steering setup design. Got rid of all the Kyosho junk, saving a little weight too. Printed out a bunch of spare parts for this weekend's races - though I think this design is more than tough enough. The way it's printed, the bolts hold the layers together, and it's a pretty beefy, solid piece of plastic.
 

johnnydmd

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Weekend in Walton, NY (middle of nowhere) was awesome! First part of the day was having us set up in the fairgrounds next to the full sized monster's pits and demo and test our rigs. The organizers allowed kids to even rent time running a few of their trucks on the little course we set up. I ran my trucks a bit, testing stuff out, practicing (boy I needed some of that, super rusty). I finally started getting warmed up and hitting some nice combos on the grass track. As similar as the two trucks are, they are quite different. Red truck, with it's new steering, tracked amazingly well and was easy to control. I fiddled with the tune, and had it running consistent, but given it's weight, it's still the slower truck in terms of acceleration despite the stronger power plant. The blue truck on the otherhand is a wild, unpredictable bucking bronco, wheeling all over the place and getting the kids riled up. Definitely need to change the steering on that one. Has a better turning radius, but really doesn't track or jump nearly as well as the red.

Then we moved to the main stage of the event. At intermission, we set up the course in the middle of the track, and we first did a quick 3 round race, and then a freestyle. I decided to race the red truck because it was Penda-style drag course, and the dirt was loose and dusty, thought the heavier truck would do better, and I thought that the blue truck with all it's crazy power would be more entertaining in freestyle, plus less expensive parts to break, lol.

It was very hectic, as we were very constrained time-wise. I had to fire up my engine really quick and get to the line, had no time to warm up or tune. The temps had dropped a bit, and with the engine not warm, I was running rich. Got to the line, and it was idling good, but I knew better than to just punch it, so I took off kinda slow, and yeah, pig rich blowing smoke everywhere - kinda embarrassing showing for nitro! But, the truck suddenly came to life and I blew past my competitor running an SMT-10. Unfortunately the sudden burst of power also caused the truck to veer and I wound up missing the ramp at the end, and I was DQ'd.

Then we did freestyle, and I was up first, had a bit of trouble keeping the blue truck lined up with ramps, but I got a couple of good jumps/crushes in, and did a cyclone at the end that got the crowd screaming. All in all it was really fun, and many thanks to Big League RC for inviting me. With all of the running and racing during the entire day, the trucks held up very well. Red truck had zero blemishes. Blue truck broke a rod end and a shock, but that was it.

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