A Very Yellow 1/6th Scumvee

[tcanin00]

As implied, something big and yellow is going to be called into existence in the name of toy turcks. Something about big scalers has taken a hold of me. Since stumbling on the New Bright F-150 outside of my LHS I have been obsessed with finding and building sixth scalers. Before I could finish the F-150, I derped the interwebs, sale groups, and craigslist for whatever I could find. This relentless search netted two Nikko H1's. Something I have been looking for since I was deployed to Kuwait 4 years ago, I now owned two of.
The idea of building an independent suspension crawler seemed like a challenge that I wanted to take on. While in Kuwait I was able to find a 1/10th scale Nikko H1 on this boards' for sale section. Here is the build thread on it:
After too much time on this thread, I decided I needed to build an H1
This project was dissembled, turned back into a drift car, and the body, wheels, and tires are sitting on a shelf waiting...
In the meantime I figured I would scale up the experiment. In a very similar manner, an on-road chassis was the organ donor. A 1/8th Kyosho Inferno GT2 that had been cannibalized for it's electronics long ago became the basis for this build.
Here is the initial sizing up of track with compared to the H1 body:


And mock up with RC4WD 2.2" Humvee wheels with Rock Crusher XT's:


I decided JConcepts Scorpios would be the right tire for this build:


And by that time, the yellow H1 arrived:


Now that it was in my possession the debauchery could begin. First order of business was to figure how to mount 12mm wheels on something designed for 17mm hexes:


I decided the easiest method would be to bore out the center of 12mm hexes to 8mm and cross drill them for the drive pins:


Seems to have worked out:


The center of the wheel had to bored out as well:


Then spacer rings were made from 1/2" O.D. tube. The O.D. was turned down to 11.5mm and they were cut into 4mm spacers:


Fitted into the wheel hub:


And secured with home made bolts. The heads were cut off 5x0.8 cap screws and they were threaded into Locked Up RC 5mm scale hubs:

[tcanin00]

The next thing to make the wheelbase of the Kyosho match the H1 body. I did this by making an extension out of 3mm aluminum plate:


I also narrowed the rear tack width by taking almost a 1/2" off the lower control arms. I failed to document the hackery, but you can see the difference in track with here:


I'm using the Kyosho chassis as guide for testing and as a jig to build a proper ladder-type frame. These rails were 1" square tube bent to shape and cut in two:


Progress can't be made without body-on test shots:


Even though the difference in track width compared to width of the body is not significant, it bothers me enough to do something about it:


As stated, I had narrowed the rear so the tires clear the fenders:


And how can I resist flex shots?




Here is the first drive train test configuration:


An R2 two speed trans with an old cordless drill motor on 3S, Holmes Hobbies BRXL, and a Savox steering servo:




Now for the initial test run:




Although it looked promising, the test run revealed a few flaws. First is gearing. The R2 two speed has much higher gearing than the R2 single speed. The fix is a Great Planes GD-600 reduction unit:


This allows for a reduction of 3.8:1 going into the trans, and it corrects the motor rotation. The next problem is the open differentials. The temporary fix is to use pins through the housing to lock one of the spider gears stationary:


The ring and pinion are helical cut and hardened. Thanks Kyosho! What lurks within the diff carrier:




A second pin threaded through the opposite side of the diff carrier will act as the locker:


I Dremeled out the back side of the spider gear so the pins would clear and prevent it from turning.
The next issue is the steering. The original servo-saver was preventing full steering throw. So the logical thing to do was make a solid one from 1/2" tube and 1/2" flat stock:


Resulting in this:


Now the servo can transmit full power to the steering linkage:


Another issue is the lack of down-travel in the front suspension, roughly 11*:


So with some hole drilling:


And the use of the Dremel I was able to get an improvement in droop, 60*:


I removed some material from the Hub carrier and lower control arms for better wheel clearance:


And now for some mandatory poser shots in the basement after getting these problems sorted out and tuning the shocks with 40WT oil and softer springs:










Now to make a real frame for this thing.

[Gula]

Looks legit. I have a similar build I need to finish

[tcanin00]

Originally Posted by Gula

Looks legit. I have a similar build I need to finish

Thanks Gula. I tend work on something for a bit, then move to something else. Do you have a build thread on yours?

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[tcanin00]

If you insist Taco Crawler, I'll try to stay the course. I can't make any promises, though.

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[Rickleo]

This rig is sick! Your build are always awesome.

God is love

[RootBreaker]

loving it.. keeps the axle look stock.. not a SAS done...

wish they made those rims in 1.7 as 8 lug is something i desire...

[tcanin00]

Originally Posted by RootBreaker

loving it.. keeps the axle look stock.. not a SAS done...

wish they made those rims in 1.7 as 8 lug is something i desire...

Thanks, RootBreaker. After searching so many builds of these that had been SAS'ed I knew I had to make it independent suspension.
Gear Head makes an 8 lug wheel in 1.55" called the ute. They might have something in 1.7" by now.

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[tcanin00]

Originally Posted by Rickleo

This rig is sick! Your build are always awesome.

God is love

Thanks Rickleo! I try to learn something from each build and improve my skill set.

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[Gula]

Originally Posted by tcanin00

Thanks Gula. I tend work on something for a bit, then move to something else. Do you have a build thread on yours?

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Haha, I do that with just about all my project RC's, yeah sure do. It's been a really long time since I've worked on it though. Large scale MAXX based H1

[tcanin00]

Thanks for posting that. I remember reading it while trying to figure out how to build this.
My problem is that once something is operational, it's good enough and I'll finish it later. Days, months, or years could pass in the meantime.

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[tcanin00]

Nothing has been done to the Scumvee, but I figured I would point out why it needs a proper frame:


The Kyosho chassis hangs down almost an inch below the body. Not very good for cwarliring. I must admit now that I'm not going for a 100% anatomically correct build. I'm trying to get it close in appearance and performance.
Being a wheeled mechanic in the PA National Guard with a couple of non-combat deployments have given me a fair bit of experience and knowledge of the infamous Scumvee. With that, I plan on making a few changes to how the real thing is built.
For instance they use Torsen differentials, which work for cars like BMW, Mazda, and Subaru. They are not true lockers in the sense of mechanical engagement, instead they use torque applied and wheel speed to initiate and maintain lock up.
Another thing used are portal hubs to improve drive line angles and ground clearance. I plan on using locked diffs for simplicity and I don't think portal hubs will help this set up enough to fully take advantage of them.
This concludes my rant over toy turcks versus their real counterparts.

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[tcanin00]

The Scumvee has been sort of back-burnered with everything else going on. But none the less, I made some progress on cleaning up the bends and cut surfaces of the frame.
First order of business was to strip the Kyosho chassis so that I could figure out how to hangulate a chooced together contraption:

From the front, showing one of my two dog's unfazed by toy turcks:

Rough location of the motor and trans. I would like to have the battery and electronics up front under the hood:
And mock up with a spare H1 body that isn't as heavy as the yellow Scumvee:
That's all for now.

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[JatoTheRipper]

Incredible work! It looks great.

[Highmark]

Very cool build! I bet it's a ton of fun to drive.

[rustneversleeps]

I have to agree with the rest of the guys very cool and a different kind of build......
Can't wait to see it with rails....

[tcanin00]

Originally Posted by Highmark

Very cool build! I bet it's a ton of fun to drive.

Thanks Highmark! This is the first sixth scaler I've driven and with independent suspension it is a different animal as far as lines and approach angles.

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[tcanin00]

Originally Posted by rustneversleeps

I have to agree with the rest of the guys very cool and a different kind of build......
Can't wait to see it with rails....

Thanks rustneversleeps! I'm pretty anxious to get on rails too. Having the original chassis plate hang so low kills any decent break over angles.

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[tcanin00]

About to make a pass with the Chinese Freight welder:

It can join metal to plastic, weird?
90% of the weld ground away:
The front differential, suspension, and steering are now attached:
Just need to finalize shock location. The rear suspension is also attached. I still need to make the second part of the bracket to welded on, then grind away the splatter pattern.
Once the diffs are attached from the top of the frame I'll make skid plates for them and tie them into the frame with 3/16" solid rod.

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[tcanin00]

A bit more progress has been made:
Close up of the bracket for the front suspension, the rear is very similar.
Here is the suspense of suspended suspension:

Moar:

From the top:

Moar to follow...

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