Demo Derby Trucks!

Metal Masher

V.I.P. Member
I built these trucks years ago but recently decided to bring them back for more action! here is the original thread on RCC: http://www.rccrawler.com/forum/non-crawler-rcs/144080-demo-cars.html


The body's themselves are relatively easy to reform so my main focus this time is the bumpers. I have not been happy so far with the bumper designs I've come up with over the years. they are just not strong enough. Most 1:1 demo cars use hardened steel bumper that rarely bend themselves. they more often just get pushed into the body.

I wanted something in the middle that was strong but could still bend if hit hard enough. so like normal I scrounged through my scrap pile and found some old steel closet doors I took out of my house when I refinished the kids rooms. they feel really flimsy to hold but when cut into smaller chunks just might fit the bill, and the bonus is I can weld them which is quicker then gluing.

to begin I took the door and cut just below one of the edges to form a C channel



for this cut the 2 edges were the same length



next they were cut in to the length I needed



I decided to make another set but this time leaving one side longer then the other.



lastly I cut another length and put it in my sheet metal brake to make a narrow channel



now I soaked them in stripper to get most of the paint off



holes were drilled in the back plates in order to plug weld them to the smaller channels



the small channels were drilled to match the "stubs" on the cars.



some of these stubs needed fixing as the last demo really took it's toll



next I mounted the small channels



then plug welded the inner C in place



before I put the outer C on I wanted to round the ends over to keep the bumper ends from slicing through the thin bodies.



finally I was able to tack weld the outer C in place.



the front bumper will use the C with 2 different lengths that allow them to lock into each other



the rear bumper s were but welded together using the C's with the same length ends





time will tell which is stronger but butt welding them is a lot easier.

Now all that was left to do was paint and mount them.





Hopefully they work the way I want and it up's the realism "thumbsup"
 

Metal Masher

V.I.P. Member
Time to update this.
I took the demo trucks to ECSC this year and they were a big hit! (pun intended) There were some interference issues with the old AM radios but otherwise they ran fine.
Here are some pics from the demo courtesy of DaddyJeep and a vid from the GCM guys. I have vid as well that I hope to have up by the end of the weekend.










https://www.youtube.com/watch?v=qy86pq2trbA


Again the trucks held up real well except for the bumpers which most broke off early in the demo.







The most damage came to the gray truck which took a good hit on the drivers side door.

I’ll show how that got fixed later but first I need to address these bumpers.
The reason why most of them broke off is because I used brass and solder to hold them in place. It was ok when I was using aluminum for the bumpers but as I increased the strength with the thin steel it became the weak link. So I took all the brass stock off the chassis.

Then I bent up some more U channels using the same material as the bumpers

and screwed them to the front of the chassis.

Then I took the bumpers, removed the brass bar inside and cut reliefs for the new bumper mounts.


Tested the fit

Then just burned them in place red neck style

Finally I tacked the back of the mounts to the frame.

For the rear I again ditched the brass mounts

But this time I just welded the mounts right to the chassis

Then repeated the process to attach the bumper


Now they should stay put!
 

Metal Masher

V.I.P. Member
Well before i go into more changes, i forgot to post the best carnage of the weekend at ECSC.



Yep the A arm broke clean in half! :twisted: Still ran though. "thumbsup"



And just because, here is one of the smoked motors8)





Now one of the other thing that's been bugging me with these trucks is that the bodies are beginning to tear at the floor and allowing the cab to heave up funny.



To attempt to fix this i decided to use some more of that thin steel i used for the bumpers.

I simply cut some into sections.



trimmed them to fit.



And screwed them under the chassis.



Time will tell if it does any good.

Now it was time to fix the door on the gray car.

The process is quick, simple and appropriately nasty looking.

first i beat the door back into shape



Then i "welded" some patch panels in place to strengthen it.



then after a quick shot of paint and a repainted number i was back up and running.



While i was at it i decided to repaint the car for my son who will be driving it the next time we run.







Up next is more destruction!
 

Metal Masher

V.I.P. Member
It's about time I updated this.

to pick up where I left off last fall, after I fixed up the cars I had a family derby with my brother, his kids and my bro-on-law



I decided to try doing the round-e-round thing this time for a few rounds to make it last longer for the kids



that didn't turn out so well



The charger wasn't as bad as it looked.



the roll bar I added did it's job

some of the other cars took more damage then expected.





so we straightened them out and decided to just go into the regular demo and after 3 rounds they were looking pretty ragged.



















now it was time to fix them up for another round
 

Metal Masher

V.I.P. Member
I'm getting ready to run these soon so i'm going to try and get this thread up to date.

This is still from last fall but after the run I posted I took inventory of the damage.

76 fried another motor so it wasn't that bad





this was the worst spot. i'm going to need to do something about the doors now that the bumpers are getting stronger.





15's body held up well for it's first run.





the leafs started to separate though



of course the drive shaft is what ultimately took me out though.



the lack of steering didn't help matters.



Amazingly the frame is still strait!



13 took some brutal hits









the caster block snapped but the pins were not bent.



the floor started to curl. I may need to address that in the future





the front may also need to be reinforced when I rebuild them.



driving around without a wheel takes it's toll but I think it will be fine



I'll show the others later
 

joe122

Well-known member
Best "crumple zone" photos ever!, Hilarious, your skills at metal forming are crazy! These look just like their 1:1 counterparts. Well done!
 

Metal Masher

V.I.P. Member
Best "crumple zone" photos ever!, Hilarious, your skills at metal forming are crazy! These look just like their 1:1 counterparts. Well done!

Thanks. I would not say they are exactly like the 1:1 counterparts but i am getting closer.

So it's taking me a while to get this updated but here are the rest of the cars from that run.

02 took some major damage but amazingly kept running up to the end!









if only there was an engine to look at! :hmmm:



I love this shot!



so far this one has be the closest to looking and actink like a real demo car would and it was quite by accident. I never thought the car would last this long and for sure didn't think it would look this good!

other then the ends bending up the pan looks really good.



it did belly out but oddly enough the more hits it took the better it drove.



the 54 truck died early from a stripped spur so it took very little damage.











i was really not happy with how the brackets bent down. they are going to get flipped up for the next round. Oh and one thing i forgot to mention was the addition of more reinforcement to the bumpers, in the form of 1/4" bar stock, to keep them from bending. this was done before the derby.



the real damage was the rear bulk head braking at the upper link mount. the temporary fix worked though :biggthumpup:





now the best for last! the 69 truck took a beating!









the cab tore at the door









I also destroyed the passenger side C hub



and the spindle



ripped the bumper mount



and the bed mount



well i had my work cut out for me but it was time to do some fixing for the next derby
 

2Beers

It's me again.
In shock..
But giggling so hard over the carnage..

Love reading and catching up on this thread masher..
It's a good kind of .....Crazy.
Keep it coming and luck on the fixes my friend.
 

tommy7026

New member
sorry if im doing something wrong by asking this but the RCC link is dead, is there a fixed one as i am wanting to copy this project with my own twist
 

Frizzen

Active member

Thanks for bringing this thread back up, i always loved seeing the demolition work he was doing with these.


Some local rc Demolition Derby groups use their own rules about chassis, body, wheels, and everything. The group near me runs cars as 2wd Slash on small slick wheels in a wooden arena.

Be sure to start your own build thread, i want to see yours!
 
Last edited:

tommy7026

New member

Thanks for bringing this thread back up, i always loved seeing the demolition work he was doing with these.

Some local rc Demolition Derby groups use their own rules about chassis, body, wheels, and everything. The group near me runs cars as 2wd Slash on small slick wheels in a wooden arena.

Be sure to start your own build thread, i want to see yours!
i plan to once i get it figured out, rn the plan is to use traxxas rally and trx4 suspension parts for proper scale (trx4 getting a portal delete and widening kit to get the same track)
 
Top