TOPIC:

On Monday Poor Boys RC Youtube channel revealed the chassis to use for this years speed run challenge.
And it is the orginal ORV chassis so no Blackfoot King etc with the later transmission.
Only MB, BF, Mud Brat, Frog and Brat allowed, and the Lancia if you`re brave.

More infor here with all the rules etc.


I will start with the F150 replica I started earlier as it`s complete and clean.


First thing I bought for this year was a new gps


The starting point...


Like last year I will run a Zakspeed Capri body, a new one as this has seen better days...
As you can see the MB front suspension is far too wide and since I don`t have all the parts for a Frog suspension, I will make a bolt on with M chassis suspension arms and TL01 c-hub and upright to get wheels under the wings.
Bonus is that I can use 12mm hex wheels up front.


Start of the prototype. This did not work that good at all...




Next setup was much better.
I have also borrowed the shocks from the speed run Hornet. Made them fit by using 18mm threaded pipe and a set screw for the rod end.


M03-05 suspension arm and a bunch of spacers.
Using the brass collars/sleeves to take the 4mm hole in the bracket so I can use 3mm bolts.


That was PITA to do!
The screwpins is too long to get fitting while the bumper bracket is still in place.
So I had to unscrew the 2 bolts to the frame, angle the bracket get the arm fitted and then retighten them. Bottom screw is probably mangled now as it sits directly behind the screwpin, but it`s tight. Not comming off till this is done.
I`m running low on spacers so washers and shock disc`s have to do.


Much better!
I might be able to use TL01 suspension arms as I have about 1cm from outside of tire to the wheelarch..
If I do I think I will cut screwpins in two and screw it on from each side of the arm. That way I don`t need to worry about the bracket bolt.


This afternoon I finished the front suspension for now.
As the chassis needs to sit at a certain level and there is no room for shocks even I had a shock tower, it would not clear the hood.
So easiest was was using some High Lift leaf springs fitted to the body mount and resting on some spacer bolted to the shock eyelet on the arms.
Have about 6-7mm of travel which is perfect.


Hope I have it test ready soon.

This year my goal is 120kph/74.5mph in brushless class.

Got a few more parts for the build....


Fitted the new wheels and tires.


Low the fat lip on these!


Lovely fat 31mm tires!


Adjusted the steering and fitted the new servo saver. Steeringbump is now nearly gone.


Steering rod just clears the chassis now.


Now I need to make the steering on the other side.

Swapped out the wheelaxle on front for the free wheeling axle from M01 and swapped out the rear wheelaxle for one with longer than stock. Sadly only found one.
So I need to order driveshafts and wheelaxle as I convert to dogbone.
And since I run fat wheels with ofset I need wheelhex that is 5-6mm wide and has 5mm hole straight through to fit that wheel.
Don`t want wobbly wheels at 60mph+
The 15mm wheelhex I used on the Hornet will not work as tires will sit too far out.

When checked today the battery door bottoms out when I push the suspension at rear. 
So the 18mm spacer on shocks needs to be changed to something longer. Think the next one I got is 23mm.

As soon as the roller is ready I`m going to start on the new Capri body.

Today I have played with the hight setting of the body.
I think this is more or less how it going to be.


When max`d out there is about 2mm from rear wheels to body.
I hope these tires will not balloon too badly, or worse, explode!
If the speed calculator is right, this chassis with my setup will go 100mph+!!
Let`s hope I will nail it on first try!


Servo bottomed out so I had to move it up from I had it.
Also servo is located a tad backwards from stock.
Added one more leaf to the leaf spring pack as it was a tad too soft. There is about 5mm of travel now.
I would like it to stay like it is as 5mm about max before front tires rub on body.
Also fitted body post stiffners made of rod ends, threaded links and set screws.
If you look closely, you will spot black TL01 body post at transmission, these are the ones I will use with the new body as it support the body a tad more backwards.'
There will will be a brace that will rest on the transmission to support the body post.


And finished the steering linkage.
The HPI servo saver was perfect for this. 
Used some long 4mm ballstuds.



I still need these parts:
# Bearing kit    TAMICO  Priority
# 9808039 wheel axle      Priority   Ordered
# 9808038 drive shaft (dogbone)    Priority    Ordered
# 19t steel pinion    LHS   Priority
# 0005161 C parts - trailing arms mostly as mine is worn -on the way in the mail.
# Pressed metal bag parts bag - in case I want to swap back to Frog front suspension -on the way in the mail.
# 9808040 Rear arm stopper- Mine is very worn, I do have a few more in stock, just need to find a pair of good ones.   TAMICO
# Traxxas 8269 12mm steel hex with 5mm hole.    LHS   Priority
# Traxxas 1985 5mm teflon coated washers for bearings (shims)   LHS  Priority
# Carbo transmission side plates - These hinders the diff skipping. Don`t think I have ground clearance for 3d printed transmission support bracket.    EBAY
# Paint for the new body. Plan is to use red flurocent on this one with mayby a black racing stripe.    LHS   Priority
# T3-01 front wheels- In case I want to run Frog front suspension. These are M chassis size, but with bearing fitment.   TAMICO
# T3-01 front tires - To fit T3-01 wheels.    TAMICO
# Hot Racing Blackfoot 48T Aluminium Diff Spool - If i want to make sure gears will hold up.  EBAY
# Hot Racing Blackfoot 17/52 Aluminium Spur - If I want to make sure gears will hold up.  EBAY
# 53255 60D Hard inner sponge - I`m running 60D M chassis tires on Rush wheels up front.  TAMICO  Priority 
# 2.5x25mm flat head screw. Nobody in Norway seems to have this in stock. It`s for holding gearbox joints together. Tamico might have.  Priority


Servo, esc and motor will be taken from my 2025 Hornet Speed Run project.
Controlled by Radiolink RC6GS transmitter. Receiver is currently fitted to my snowblower project.

Awesome setup Richard.  👍

Thank you Flo!


Today I trimmed the new body and fitted the body posts.
Front body post are Parma universal, rear are TL01


Front spoiler are 5-6mm of the ground, when at speed I think this will go down to 2-3mm and then the rear sag will compensate so the frontspoiler will lift a tad.


Fully compressed suspension


Rear tire to body is about 2mm so I hope they don`t balloon beyond that
These 31mm HPI tires are 69mm tall so a little taller than the Tamiya wide ones and much much more stickier!



And first thing I will do is to cut the rear of the body open.
Learned quickly last year that the rear valance is acting as a parachute and when you step of throttle and the downforce no longer push the body down it will make the rear end lift off the ground that in turn will send the car into the ditch.
Calculated again the topspeed this afternoon and it is calculated to whooping 120MPH!!!! Don`t want a liftoff a that point that`s for sure!
But everything above 100mph I will be super happy about!! 
Biggest issue is to avoid diff skipping. I have a plan for that involves a 2.5mm tap bit for the gearbox joint. With a 2.5mm bolt it will act as a balldiff tightning bolt.
When I find the right "freeplay" I will use green machine loctite to secure it forever.

Had to change the rear body post again as it turned out they was in the way for the motor.
Changed them to the long M05 rear ones as they swop back nearly the same, but higher up to go past the motor.




Rear of body needs to be fine tuned as there is about 1.5mm clearance from wheelarch to tire when body is in center.
I made a panhard mount for the body post system to hold it stable.


Just enough space to fit electronics


Naked...
Also had to put on one more preload spacer for the shock as the bellcrank effect of the suspension made it softer than on the Hornet.


Tried to make it as tidy as possible


Only receiver to install left.
I use a leaf spring shackle as wire holder for the battery. 
Still not going anywhere as I missing correct dogbones and wheelaxles.


Hope this motor will be as hassle free as last year.
Last year it got me to 67.4mph, gearing with fast gear set is faster with ORV so we will see more speed than that as long as gears hold up.


My 3s 2200mah battery will not fit on itself, so I use half of a 3d printed battery size adapter that is ment for a 2s 2200mah battery. Is too thick with the other half fitted.
With this adapter the battery fits snuggly side to side as it has the size of a old nimh battery.
This 3s battery is also the most powerful I have with 35C rating. My other 2200 ones has 25 and 30C
Also the same battery I used to go 67.4mph with my Hornet.

 

WOW! Any room for a parachute in the back?? 😉👍

1972 wrote:

WOW! Any room for a parachute in the back?? 😉👍

Hehe, might be needed!!

Routed my motor wires a different way as the body sat crooked with the wires goes forward.
Shocks also got a bit tweeking, 50 weight oil and one more preload clip. Not sagging anymore.


With body on


Off


Also made new steering links as homemade is not allowed in my class (was using allthread). Might swap to turnbuckles.


Receiver is now fitted so now all is working.
All I have to do on the radio is to change it from Hornet to 2026 Speed run.
My receiver as two antennas. I used a pair of Tamiya 4mm rod ends, short set screws and antenna holders. Simply screwed the ball ends to the chassis.


While I have the dogbone setup on their way in the mail, I have now a complete setup with the orginal hex driveshafts. I don`t know if I dare to do a speedrun with those lol.
Just missing the 16t pinion.


I have built a second transmission with new re-re sideplates and plastic housing, while the gears are new vintage ones together with the white plastic.
Several in the Poor Boys RC speed run chat on messanger has already melted their gears when they tried a few test speed runs.
To prevent this, I have used gasket sealer to seal the gearbox and plan is to run a small amount of oil to lubricate the gears and also keep the cool.
Time will tell if it work or it leaks like a iceblock in Sahara 
I have gone for the speed setting in this, aka 49 spur and 19t pinion. Will be running Traxxas 3949x steel pinion.


The other transmission will get Blackfoot / Monster Beetle gearing, aka 52t diff, 17/52 spur and 16t pinion. If the speed transmission fails this will likely to hold as gears are wider to tackle more load. This will also be run with oil.
Both lead time and cost prevent to buy the alloy spur and diff from ebay.
Cost of that can be used for a stronger battery..
 

Rebuilt the other transmission with the the BF / MB gears.
Sealed it with something called flangesealer, seems to me some some sort of antisize, but thicker that hardens over time. It will handle petrolium products such as oil.
I plan on running about 5mm of oil in the bottom. Some of the speedrun contestants has already melted their gears. I belive they have also tried too big tires for the gearing, which the Frog gears won`t tackle. There is a reason Tamiya made the gears wider and one piece for the Monster series of the ORV.
Fitted new bearings as well. Diff bearings with rubber seal in hope to hold the oil on the inside of gearbox.


Found some narrow hexes and now the rear tires tucks inside the body with about 1.5mm of clearance on both sides. Should be enough.

Also fitted new bearings on the front wheels.
Laid the bearings in isopropanol to remove the grease, dried them and the added a few drops of Yeah Racing bearing oil.
Now tires run for a long time before stopping.
One side needed 2x Traxxas 1985 shims (0.5mm each), other wheel needed nothing to take out the slack.

The high speed Frog transmission is now fitted and ready to be filled by with some oil.
I think I will keep the oil out till right before I run in case there is a leak. But the flangeseal should keep it sealed.

New bearings is also fitted to the trailing arms.
Will also remove the grease from them and oil them to make them run a bit more free than now.
Also need to take a smidge off the left side wheelhex as it`s approx 0.1mm too tight right now.

If everything goes according to plan I will do a test run next weekend.
Still need a few parts to finish and I`m waiting on my payday.

And for this year I will invest in a new battery and my choice is this Gens Ace 3s 3600mah 60C HV. This should give 216 amp if it delivers as written.
Should fit the ORV, might need to make support for sides as it`s a shorty pack,
All the winners in my class last year used HV battery (13.05V fully charged vs 12.60V for normal 3s)

I made a shorty pack stopper with two extra battery stoppers and some spacers.
Battery could not have fitted better!




I used a pair of Axial plastic rod end balls as spacers


Found out that bottom of the TT02 receiver box did fit on the front bumper.




Just fits behind the grill


And reason is to fit this cute battery (3s 300mah) for my lights.
I will use the same 3mm COB led strip as on my snowblower, front and rear.
Have a nifty idea for the rear....


And these two batteries above came in this haul.
Gens Ace 3600mah 3s 60C battery
Gens Ace 300mah 3s battery for the lights
DJI Osmo Nano action camera.
64GB memory card
JST charging cable for the 300mah battery.
Hudy knife blades.
Traxxas 1942 rod ends
PS5 Black paint
PS20 Fluor red paint
Tamiya tire glue jig
1UP Racing steel bent glue tips
Tamiya 9808038 dogbones
Tamiya 9808039 wheelaxle


Love my new little camera and the magnet based mounts.
Even more happy after I watched some videos on it when I came home.


Several of the Poor Boys RC racers this year are using the same camera, and are very happy about it.
For me I will likely use the cap mount as pictured on the car above.
And now I have the GPS speedometer I will never have to guess the speed of my vehicles anymore 
I see both the camera and speedometer as an investment for the future.