The HPyetI - Roadkill Corvette Kart inspired

[OSRC]

Another spare parts build from my junk-o-rama....

I saw this on Roadkill the other day and thought it was the coolest thing they came up with to date. If you've never seen the show, it's a rotted out C4 Vette that they stripped to the chassis, added a roll cage and went out and hammered it around a track (and in the dirt) - looked like a ton of fun! Since I can't build a real one, I can be at least inspired to make a small one.

2200lbs of C4 goodness


Video link...make sure the surround sound is on: https://www.youtube.com/watch?v=GD3y7ylpqO8&t=4s


I'll be taking a few liberties with the RC version of course. Not really looking to build a scale replica, just stealing the general concept. So I had this Yeti body laying here, and a pile of HPI MT/RS4 parts. Hence the HPyetI (see what I did there? )

HPI MT's and RS43's are great to mess with - Axial diffs drop right in, so I can use pretty much any trans with 5mm outputs and connect them together..or dogbones, or any combination thereof. I can drop in OD, UD, 1-ways, spools...pretty much any combo I can think of. Plus, there are 4 different width suspension arms that bolt up so the track width is very flexible too. It's a great platform to mess with.

Anyway, so I started with the MT chassis as a template and stretched it out 35mm and widened it quite a bit to give plenty of room for a battery and what not. It's just rough cut at the moment, I'll fine tune it later.


Drilled a few holes, clearanced the diffs and dropped on the suspension. I've got MT2 arms on here which are the widest of the bunch. Not sure if I want a wider track or something more scale (ish) - I'll sort that out later. Diffs are HD gears standard ratio front and rear for now. The front is a limited slip setup.


Dropped the body on... Very much a work in progress! At least the wheelbase is now roughly in the ballpark.


I've got to sort out the shock towers.. the front just tucks in, but the rear is way tall and interferes with the cage work. I've got a few options to mess with here thankfully. Should be too hard to custom fab up something if I have to. Whether it'll be square or not is a whole other matter.


Not much to see yet. ...but more hot mess to come.

[OSRC]

Making a little more progress...

First a trip down memory lane. I've got quite a few vehicles stashed away from the RS4 line. The super series were larger than 1/10 (about 1/9, same as a current HPI WR and mostly came in nitro versions. They were fantastic cars - much easier handling than 1/10 sedans and usually had killer detailed bodies. I had a few Kyosho cars, as well as the belt driven HPI cars. I've sold them all off, but kept a few of the super nitro Rally's I had which were based off the MT chassis.

This is one of the few nitro's I have left. It's a Super Nitro Rally that I converted to onroad using RS43 parts. Quite a few hopups on this car - haven't ran it in years, but it went like a bat out of hell. I have an new unpainted F150 body stashed away as well.


This is a SNR that I converted to electric some years back. The motor mount is here somewhere. This one has a Subaru body that's so dusty, I was embarrassed to take a pic of it. It's been on the shelf for years.


The same parts that are on the cars above are on the the RS43 series as well. I picked up a kinda rare drift nitro way back and built it up as a rally car with some spares I had. I figured the center motor would make for a killer rally set-up. I built it up and test fired it, but never got around to driving it (story of my life). Scalers had basically taken over my life by then.


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Alright, enough memory lane, let's get back to business. Got the rear suspension sorted out. Not sure of these CVD's are made for this per-se, but they fit just fine. Found a carbon tower too in my box of parts. May or may not stay, depends on how I have to mount the body.


Front suspension sorted out as well. I have to swap on some new ball cups onto the turnbuckles as these don't fit right but at least I found some turnbuckles that are in the ballpark. Good enough for mock up purposes. Front has some massive CVD's, I'd love to find a set for the rear as well.


Plenty of room on the chassis for laying out electronics. Decided to mount the motor towards the rear. I debated moving it towards the front, but I'm tired of nose heavy Yeti's. I needed some long dogbones to connect everything, and was about to give up when I found an old center shaft from a Redcat buggy - perfect! A Tamiya FF dogbone is the perfect size for the back. It's a little small though...not sure how much power it will handle. Guess I'll find out! Everything spins nice and smooth with no slop right now.


Found a center diff mount from something in my parts box. I vagely remember buying it, but no idea what it came from. Think it's an Ofna something. It's a steel mod 1 spur and center diff. Should do the trick. Needs some heavy silicone in it though, I'll dig into it when I tear everything back apart.


Mounted up the largest motor I had so I could set clearance for the servo. Won't be using this, it's way too big. Looks pretty cool though. A 4 pole 540 will be fine. Probably a Castle 3800 SC motor.


Steering servo is just mounted to standoffs and bolted direct to the chassis.


Needed a way to mount the battery. Dug around a bit and found an old rustler chassis...hmmm..


Slicing and dicing...


Boom! Drilled and tapped and screwed through the bottom. This really is RC Roadkill...lol. I'll add some velcro straps later.


Mocked up a bit to check out the stance. Still may go narrower on the suspension, not sure. It's wide as heck.


Having a ball with this one. I've burned out on scaler builds, this is a nice break. Still lots to do including stripping off all that terrible purple anodizing. YUK!!

[Shinchu]

HOLY MOSES!!!!!!!!!

i shant speak of what fate my yeti and Nitro RS4 may soon endure, or face the banhammer i may... but this is another example of why they should not endure the unspeakable fate!
("acquired" my RS4 right before that drift model came out, almost experienced "aquire'ers remorse" because... well, i love drifting!)

love the custom fab work you have done here. nice inspiration, and even better execution!

i can only wonder how you could use the solid rear axle... but the IRS makes more sense for performance here! haha those tires really are the icing on the cake!
and PLEASE USE THAT HUGE MOTOR!!!! LMAO

*oh and BTW, roadkill and dirt everyday are some of my favorite shows not on network TV!

[OSRC]

The train wreck rolls on...

Decided to tackle body mounts. Found the rear mounts in the Yeti cage lined up (kinda) with the holes in the rear diff mount. I cut up a piece of aluminum and dug out some long body posts. Not overly happy with it, but it works for now.


The fronts were right over the shock tower. A piece of aluminum L bracket and some shorty mounts worked out perfect. Still just mocking up, I'll clean up the mount later.


Boom! Sitting on the chassis now using the stock holes. Perfect! Later I can just drop some other Yeti bodies on if the urge strikes. Which it may since I have the bug and Raptor bodies laying around.


The flat pan chassis wasn't going to be anywhere stiff enough. I used some thinner gauge aluminum to span the diff mounts to the center diff. Looks hokey, but the chassis is now rock solid. I'll trim them up later.


All of the mock up is done, so now torn apart to clean up/shape the metal parts, strip off some ano, and then do the final assembly.

[OSRC]

Originally Posted by Shinchu

i can only wonder how you could use the solid rear axle... but the IRS makes more sense for performance here! ...

*oh and BTW, roadkill and dirt everyday are some of my favorite shows not on network TV!

I've got one with the rear axle. It handles like an unpolished turd, hence the more performance oriented chassis layout.

Roadkill rules!

[OSRC]

Started working on the pile-o-parts today. All of the purple bits are soaking in Greased Lightning, I'll check on them tomorrow. It's basic GL, not the commercial stuff so no idea how well it's going to work.

In the meatime, spent the day cutting, drilling, and filing the metal bits. Hopefully it'll look less like a hardware store reject when I'm done.

Since this is going on road for the most part, decided to lighten up the chassis a bit. Added cutouts under the battery box locations (drilled 2 sets of holes so I can move it forward or back for tuning purposes) motor, and along the side just for giggles. The side cutouts could be better, but I was way tired of filing and called it good.


Realized it was 44 degrees out, so took it outside and sprayed it flat black. Much better!! Paint may come off, didn't dry too well in the cooler weather.


Pulled the diffs, oiled up the bearings, shimmed everything up and cleaned and regreased with some Red and Tacky. HD 13/38 front and rear with the limited slip mod up front. Trimmed up the body mounts and got them painted as well.


Trimmed up the upper chassis parts and added some speed holes. That's always is good for at least 5HP. Hopefully it doesn't look so bulky up top. Not that it matters per-se, this is Roadkill inspired. but I do have some standards. Too dark and cold to paint them black, so left them natural for now.

[calcagno45]

Very cool! The vette kart is pretty amazing. They just did a similar project with a 90’s model c3500 crew cab Chevy with a 454.

[OSRC]

Just watched the episide last night where the Vette Cart got some new Hoosier slicks and beat down an Hellcat on the track....The wheels looked a lot like 2.2 Pro-10's. Hmmm...

GPM anodizing is the hardest I've ever tried to get off. 24 hours in greased Lightning and 3 oven cleaner baths later, I still had to hit it with a wire wheel in spots. Finish looks rough in spots, but at least it's no longer purple! Soaked all the old bearings in oil overnight (some were still coated in nitro goop) and then cleaned and re-oiled.

Rear clip done.


Front done and re-assembled to the chassis. Looks so much better without the purple imo!


Stripped and polished the blue off the driveshaft as well. Starting to look like something here!



Dropped the body on...lots of suspension travel here if I ever want to go offroad someday!

[OSRC]

Starting come come together nicely!!

4 pole 3800 motor dropped in, chassis uppers bolted on, and servo and re-dyed battery box mounted back up.


Took a while to sort out the shocks. Needed something a bit strange since this is an off road suspension being dropped under a low slung cage. Found a set of Integy SCX10 shocks brought the rear down low enough and a set of Associated springs were heavy enough to keep the rear end off the ground.


The fronts were super tricky. Only length that would work is touring car length. Dug these out of my pile and mounted the stiffest springs I could find. It works - the spring rates are in the ballpark though it'll need a bit of tuning for sure.


Ahhhh...that moment when you bolt on the wheels and the project stands on it's own. Great moment whether it's an RC or a 1:1. Found a set of onroad tires and Ofna wheels in my parts box that were for my Exo originally. The look is probably as close as I'm going to get to the 1:1 and the SC offset brings the wheels in perfectly. Good thing I didn't go narrower on the suspension.


Absolutely over the moon with how this is turning out. Stance is perfect!!


Always some issues to sort out. The cage hits the rear shock bolts and won't sit low enough.


The front shocks also hit the cage.. going to have to figure something out here as well.

[4wd4ws]

Love it! And way cooler than the Vette kart.

[OSRC]

Took the body off finally... Now were starting to look like the Corvette Kart!


Fixed the front suspension by using some other holes in the shock tower, added some spacers, dremeling some plastic, and putting Vaterra Twin Hammers springs on the shocks. Actually worked out better since laying the shocks down give a bit more travel - pretty much matches the rear now. The TH springs are super heavy, and now the front feels pretty much perfect. So much win it hurts.


Bit of Dremel work clearanced the rear. Just took enough off to let the body sit down on the posts.

[Ninomaniac]

Badass.

[OSRC]

I wanted some aluminium panels to match the skin of the 1:1 but after digging around on Ebay, I didn't see any other than Integy's goofy panels. So I figured how hard can they be to make? Turns out not so hard! Some thin alminum plate, a little bit of patience, and a lot of filing and boom! Need to shape the hood a bit, but they came out pretty good. Need to detail them a bit still but very happy with the look.



Started working on the front. The headlights were no problem - got them very close to the look of the 1:1. Not sure what to do though about the radiator. The 1:1 has the Vette radiator sticking out front at an angle. I could do that, but it looks a bit goofy to my eyes. Might invoke some "modelers license" and just do a more standard skid here.


Also, I was digging around on Shapeways looking for a 1/9 or so tunnel ram/carb/air cleaner setup. Found lots of blowers and scoops, but nothing that quite matched. Any leads would be very much appreciated! I have some ideas for scratch building if all else fails.

[JatoTheRipper]

I love the wheels. Are they from Duratrax?

I could print two of these at any scale you'd need if you want.

[BigSki]

Way cool !

Roadkill is one of my favorite channels to watch, those 2 knuckle heads manage to not kill themselves way too often.

[OSRC]

I just ordered a Tamiya 240z body to replicate the Rotsun... one of my favorites. 4.3l with a powerstroke turbo? Crazy stuff!

I've been looking for a Charger body to do the General Mayhem, but haven't found one yet.

[alexleblanc]

man your builds rock! love the leftover parts use.

[OSRC]

Couple of quick updates...

In later life the Corvette Kart wore slicks on some steel hole wheels. I couldn't find exactly the same style, but the HPI wheels were pretty close. Plus I think the darker black looks much better against all the gray.


All wired up. Castle 3800 should throw it around just fine. Might need to work on the gearing - have only mod 1 pinion and it's a bit small.


Battery tray worked out perfect.


Filled in the gaping hole in the front. Not sure if I want to put a radiator in there or not. Think it looks better without. 1:1 has one sticking out, but I'm not sure I want to go that route.

[alexleblanc]

I like the rad (intercooler) in, gives it more of the correct look.