1/5 Scale Brave Motorsports U4 Car

[WesTX]

Loved this chassis and car for a long time, know the guys at Brave here in Houston. Was going to build a 1/5 scale mega truck with F-150 body, but decided I really wanted to do something not done and cool and build a U4 car.

Here is what will be in it hardware wise:
- Summit 2 speed trans with LEM dog carrier to reduce slop
- Kershaw Designs twin 700HO motor setup
- Mad Force Axles - 15"-15.25" WMS-WMS - More on these later
- 3.8" Wheels - May make custom, otherwise some RC4WD units
- RC4WD Rok Lox or Rock Crusher tires. Need someone to make some 40 series Trepadors to match the 1:1 rig!
- Custom Driveshafts
- Suspension - more on this later as I sort it out

Going about building this one way different. Im not good in cad, and cant picture things well. Didnt want to scrap a ton of tube when building this (0.375", 0.049" wall main tube, 0.250", 0.35" wall support tube). Decided I would design the chassis using dowel rod with putty to hold the joints together. Then i can take that, use it for checking my measurements and thats a ton cheaper for making mods to design as I go. Ill post a picture of this process later - dont want to muddy up this post with the awesome pics of the 1:1 rig with my hack job work.

This will be a long term build, but wanted to get the thread started. Looking to hopefully complete by the fall sometime.

Wes

[WesTX]

First - this thing is gonna be huge. Wheelbase will end up about 23-23.5". Overall length around 32" or so. The 3/8" dowel rod I am working with looks massive compared to other things Ive worked with before in the RC world. One of the biggest struggles I am currently having with myself is the shocks. I want this thing to perform just as much as I want it to look good, so scale wise the shocks should be like a 0.425" OD body, but thats tiny. The HPI Savage shocks are closest length/diameter wise, but I am unsure they will be able to perform well. We shall see how things go.

More details on scale of it. Width at the center (A & B pillar) is 11.2". Width at front and rear of chassis will be 8.8".

Here is a pic of the start of the chassis from dowel. This is the first 12 pieces cut. Will continue measuring and cutitng today and likely start putting things together tomorrow morning to start to visualize this thing. Yes, those are 8.5" x 11" letter size pieces of paper under these pieces.

[WesTX]

Now for the axles. Bought a mad force on fleabay pretty much just to rob the axles. These axles are known for being serious beef. Perfect for me, and easy to customize. They have a 4.75mm OD dogbone as the inner shaft and the stub is 8mm OD.

Stock inner shafts are 114mm on the long side and short side is 86mm long. This makes the axles about 11.75" hex to hex. I am having custom tubes machined from aluminum by a machine shop that I work with for work. This will make my axles use (2) 135mm inner shafts. That will widen the width by 2.75", to get my hex to hex with to about 14.5", and my WMS-WMS about 15". This will get me pretty close to the 1/5 scale number, it will be a bit wider than the brave car is, but I think thats needed for the R/C model to keep stability and actually be able to perform.

The reason I keep saying WMS-WMS is that I will be using these custom hubs I built. These go onto the stub shaft and will lock onto them using a roll pin. This will keep me from having to worry about what hex a wheel uses, and the bolt pattern for the hub matches the RC4WD 40 series wheels.

Would like to end up with a CV instead of dogbone and cup setup. The HPI CV shafts with 8mm stubs are nice, but I would have to cut and weld them to the right length. Will continue to research that and see what I can find.

More updates on these as I get stuff machined, etc.

Wes

[Mike Flea]

Sounds like it's going to be a well detailed and engineered build WesTX, I'll be watching and learning, this is going to be a good build!

[Almighty Malach]

Hell yeah I was checking this car out at KOH and it is super clean. Looking forward to updates

[twissted]

run these wheels.
Baja 5T Front Off Road Wheel Set for 1 5 HPI Rovan KM | eBay
http://www.ebay.com/itm/HPI-Racing-1...MAAOSw~OVWuPpt
I have my roklox mounted to 1/5 scale bead lock wheels and they work better than 40 series wheels do.

[WesTX]

Originally Posted by twissted

run these wheels.
Baja 5T Front Off Road Wheel Set for 1 5 HPI Rovan KM | eBay
HPI Racing 1 5 Baja 5T 5SC Truck Front Outlaw Black Wheel 4mm Offset 2 HPI3331 | eBay
I have my roklox mounted to 1/5 scale bead lock wheels and they work better than 40 series wheels do.

Thanks for the info. What is the rough OD of those wheels? Thinking of making some custom wheels similar to the DCW beadlock wheels from plastic with the bolt pattern for my custom hubs.

Wes

[twissted]

I think I have some 1/5 beadlock rims that are very close to what you a re wanting. I will look into it and get back with you.
On the axles that you building are the hubs like what I'm using?

[WesTX]

Originally Posted by twissted

I think I have some 1/5 beadlock rims that are very close to what you a re wanting. I will look into it and get back with you.
On the axles that you building are the hubs like what I'm using?

Yes, very much like that.

Wes

[WesTX]

The dowel thing was kicking my ass this morning, and it has been a slow day at work. So I taught myself Sketchup to draw this chassis up in. Glad I did as my original scaling wasnt really right. So now I was able to scale it up and get the wheelbase and the scale look right.

This makes the chassis about 35" long, wheelbase is going to be between 24 and 25".

Heres a couple of screen shots of the model so far. I still havent sorted out how to make the lines tubes as well as start adding in suspension, etc.

Wes

[twissted]

[WesTX]

What is the diameter of the bolt circle on those?

[twissted]

I will look into it. I can't wait to see the video of this build of yours. The performance should be very high.

[twissted]

Get a hold of this guy he has the parts you need.
Project Time! The Losi Desert Buggy DBXL | RC Driver

[WesTX]

Originally Posted by twissted

Get a hold of this guy he has the parts you need.
Project Time! The Losi Desert Buggy DBXL | RC Driver

Looks like he had them made by Bishop Racing Products. Ill have to hit those guys up.

Wes

[WesTX]

More screen shots of the chassis split apart by the layers for each item. Also started to break pieces out into Google Sketchup Layout to dimension and print sheets. They arent 1:1 printouts like Harley does with his chassis, but its enough for me to work with. I still have to switch to decimal dimensions before printing, but this is going better than I thought it would. Note that I have not drawn curves where there will be some curves from bending tube. Since I dont know the radius I will be able to bend as my bender isnt here yet, I havent drawn the bent pieces into place in the model.

Working on shock mounting brackets to be laser cut next. Then hopefully by the end of the week I am cutting up tube. Ordering that today.

Wes

[WesTX]

Here are the shock mount plates sketched up. Sent off to the laser cutter to have them cut from 1/8" plate.

Im not smart enough to draw these up in Sketchup as well as in DraftSight (2D cad) so youll have to imagine them in the same place as the mounts on the 1:1 rig.

Wes

[WesTX]

Also, ordered the following via fleabay:

AX31259 - Yeti XL Front Axle Stub
AX31225 - Yeti XL Front CVD Shaft
AX31222 - CVD parts

Going to cut these shafts and lengthen them about 11mm to make them the width of the custom housings I am making. This should get me into CVD's instead of dogbones and shafts will be easy to find and replace.

Wes

[WesTX]

Ordered more parts from the laser cut shop today as well as got the bender ordered. Tube will get ordered tomorrow. One big engineering feat I have yet to sort out is the trailing arms. Will be able to get a better look at that once I have parts back from laser cutting and machining which hopefully happens over the next week or so. Getting fun for sure.

Wes

[WesTX]

Ordered pivot balls from HPI 5B for the trailing arms. Still havent sorted out building them yet. Also ordered tube today.

Here is a shot with the tire size and wheels mocked into the sketch. 24.5" wheelbase, 8" OD tire, 3.8" OD wheel.

As soon as I sell some RC Boats Ill be ordering the new motoworx 3.8 wheels, super nice looking and beadlocks. And I can build some new custom hubs to still fit my custom axles.

Wes