Structo dumptruck conversion

[frizzen]

I wanted to build a light dumptruck, this is mostly based off of the tonka conversions of smallhaul and several others i've seen on here. (Steal oll the ideas!)

For the donor, I picked up a 1/16 Redcat rock crawler. 4wd, solid axles, locked diffs and trans, and axle hexes were about the width i needed.

Originally i wanted to convert my 1930s style nylint, but once i had axles it looked too narrow with the fenders, so I grabbed a 1960s Structo hydraulic dump truck tandem axle with the pow-r-r-r motor noise maker.



My plan was to just go quick and dirty on this, use the original stamped frame and try not to get too crazy in hopes of making the indy show.

Tires are just the modified stock hard rubber that's been under it since it left the factory.

I ordered a set of tamiya semi springs, but what i got is too long. it's like 3 inch eye-eye. I can't figure a way to get my front axle under the fender and not have to chop off the front bumper to get spring shackles through it.



Pics will be here as soon as photobucket starts playing nicely. Photobutt is awful and should feel bad.

http://www.tnttoytrucks.com/Structo602.html. it's pretty close to this truck.

[frizzen]

The 20 min edit rule isn't good.

[frizzen]

So i'm painfully aware now that tamiya # 9808091, 9808092, 9808094 was the wrong type of spring. 4.75" long spring was way too big, but it's what amazon had.

Anybody know what springs i was actually wanting to buy?

[C-MurDaA]

i think you want the ones for the tamiya highlift (f350 or tundra)

[PrimeRigg]

the springs for the hilift are longer than the semi set, you might want to modify the ones you have.

[frizzen]

I curled up the 'b' helper springs, and got the front end looking a little better. Once i got the front of the springs mounted, and played with shackle lengths on both ends.



And mangled a hole in the chassis, got the trans mounted up to some brackets.





And i still have some suspension travel when it's got a load of dirt on.



Cab mounts i went really easy / lazy: I stuck a bolt through the bumper rivet holes and cab, threw a nut on those, the bolts slide into the original chassis rivet holes, then the stock tabs slide into the original slots.

[frizzen]

Bottom view



Got the interior back in. Trans clearance wasn't as brutal as i expected it to end up.



I know by the stunned silence you've all been wondering who would run such a modern, immaculate, classy, and well preserved vehicle in their fleet?



I haven't come up with a great company name yet... We better hope i get creative before my dragline crane becomes part of that guys other division Mike Oxbig Erection and Mining.

[frizzen]

Much fun at the Indy 2016 show on friday!!!





shook a spring loose, hit the shop


hit the general store for lunch

[frizzen]

Here was the truck before i started modding, i had yanked one of the tandem axles off since it only had enough retainer clips for one rear. I was hoping for a stance more like this than my big lifted truck.

[frizzen]

So lessons from indy:

Rock crawlers aren't fast. Taking the 3.770 tall tires off and replacing them with 2.315 tall tires means that you need to pull over and let everyone pass. Seriously, everyone passed me. I can reach top speed in under a yard. I have more torque than the tires could ever use. Must regear the trans!

Drilling brass bushings from round stock by hand makes a really wobbly setup. I need to either redo wheel pin drive using tubes, or grind the tires to the new round, or get different rim/tire combo.
I also learned its possible to have a car shake the rear suspension apart, um, in like 1 battery pack. but the crowd seemed to like it

Setting the suspension up for heaping load of dirt doesn't work that well for crumb rubber. Full load of rubber, no movement.. this didn't help the out of round tire situation since there's no real spring or any dampening. Once i got home I loaded the bed with soda cans, and learned the rear springs didn't get near max out until 6 pounds, i need to pull a leaf..

My transfer case still needs lowered since my drivelines are horrible, i need to shorten the rear springs. i need to put deans plugs on so i can use better battery and charger. I need some lights, a trailer hitch, and mudflaps. i've also got a few ideas for some interior detailing...

Kinda getting tired of talking to myself though.

[frizzen]

If anyone may be interested in these donors, here's a bit more i've learned.

Turns out I used a 1965-66 only configuration Structo hydraulic dump truck. I still have no clue if it's supposed to be based on any kind of real truck, or just a generic truck.

Stock steering on the Redcat Everest / Exceede Maxstone donor is kinda bad and understeers a lot, here's the biggest part of the fix:
http://www.rccrawler.com/forum/newbi...tuning-10.html
Redrill knuckles for zero ackerman, make new draglink and tierod. Eliminates tire scrub, it's still turning a 4 locked truck, but atleast you can steer the same direction.

On the trans, up to 370 brushed motors fit, and stock esc will support them.

The differentials have a 14t pinion, 38t ring. Which is 2.714 to 1.

The motor pinion is 14t. i don't yet know the spur size, or the trans total ratio.

Any specs or dimentions that might be helpful?

[frizzen]

So what's the most important part for a DUMP truck to have?

Yeah, you'd really think so...


But instead of getting that part so it can DUMP: i made light mounts, hacked servo board so the lights can be activated from the tx, made a trailer hitch, started working on a trailer, and made the steering wheel i'd thrown in there look less like a round servo horn.

Other than softening the rear suspension a little by pulling the smallest helper spring, i haven't done much of the planned mods.

Thinking i may try adding Plastidip to the tires to see if it helps with the traction situation. I knocked more rust off the hubcaps, but didn't try for too shiny, this trucks not about that life.

[frizzen]

I picked up a Helion (4300 rpm) 370 motor to replace the stock 260. So i moved up from an inline 6 to a flathead v8. It took making the motor mount holes ugly ovals, and a little file work on the skid mounts, and taking a ridge off the side of the trans.

Stock pinion is 14t, to 61t spur. not sure about 3 gears in trans. Axles are 14t pinion, 38t ring

I also picked up a delrin cutting board to use as spacers for a t-case drop.

[roadranger]

Nice work on getting the ol' girl running again!
The hood/fender contours link like a 65-66 Chevy/GMC, but that grill looks like an IH…

[frizzen]

Thanks roadranger, it's getting there. Most of the driveability issues were because i wanted to keep the stock wheels, or rushing to be able to drive at Indy.

I'd put out the help wanted signs a while ago, these 2 nicely dressed germans inquired about jobs while i was at RuralKing. They said they overspent on christmas and agreed to work for me at half price just to have a job.


They look awful clean cut for Mike Oxbig, but we know the interview isn't usually the real guy anyway. We'll see how they work out...

[RCP57]

Haha. Nice!

[Rvjimd]

Frizz,

Could you post a few pictures of the underside of your truck? I'm going to abandon the independent suspension and try something more like yours.

I need pictures and design ideas for the axel and suspension and drivetrain. Not sure if or how I am going to be able to use my dromida truck diff parts since they are NOT solid axels, but I'm gona see if I can figure out something...

Jim

[frizzen]

Post 6 has a pretty good top view, and post 7 has an ok bottom view. The t-case has been dropped, and spring shackles changed to aluminum since then.

Anything specific you'd like when i grab some better pics?

[Rvjimd]

I don't know how I didn't see those? I thin the post 7 is what I need. How did you attach the axel to the leaf spring, some sort of U bolt? Is that in one of the pictures in the thread?

Thanks!

[frizzen]

The leafsprings i used had 3 holes already drilled. Axle to leaf attachment was just a bolt through the leaf into existing hole in the top of the diff, post 6 kinda shows on front.

U-bolts would look better and be more scale, this was just trying to reuse existing hardware from the donor crawler so i didn't have to hit the hobby shop.