Another DR10 to RB10 conversion, now DR10/RB10/B5M/B6.4 Mashup

[nullandvoid]

A DR10 was sitting idle with only a dozen runs on it, each one ended with the car sliding on its roof.

After reading this thread https://www.rc10talk.com/viewtopic.php?f=114&t=47939 I started ordering parts.

The chassis, shock towers, and front bumper were dirt cheap off of ebay. The v2 shocks, exotek steering, slipper eliminator, and 17.5 motor and esc combo were ordered when I got carried away with dreams of indoor carpet racing which I have never done.

I used the hobbywing g2.1 17.5 and xr10 combo, geared 26/72 per the rules. The mesh can barely be set as the motor contacts the transmission.

All up weight with a shorty pack is 1509g, just squeaking in over the minimum.

One thing I'd like to figure out is a front sway bar. I removed the stiff rear swaybar.

Before

After

[nullandvoid]

So I like a challenge sometimes.

I had built the DR10 to RB10 conversion car to race on carpet, it did pretty well. Then a B6.4 and a B74.1 followed me home and picked up the carpet duty. I'm a slave to impulse, what can I say?

My local track unloaded the rental fleet of RB10 RTRs for dirt cheap so I had to grab one. But what to do with it? The 3d printer and cnc router have a layer of dust on them so time to go to work.

Mid motor RB10, using as many of the stock parts as I can!


Well, that also proved problematic. Flipping the gearbox around created way too many conflicts, mainly with the rear suspension mount. Time to dig though the Associated manuals online to find compatible parts. Here is what I came up with.

Purchased:
ASC72036 - Team Associated DR10M Front Chassis Plate & Gearbox Mount Set
ASC91607 - Team Associated B5M "3 Gear" Gear Box
ASC91518 - Team Associated B5M Rear Shock Tower & Camber Mount
ASC91532 - Team Associated Comp Arm Mount Set B5M (I could also have used the B6.4 mounts but that's a lot more expensive)

Total was $39. I'll be able to use the complete RB10 front end, rear suspension minus arm mounts, gearbox internals, and motor mount if I countersink the opposite side.

I'll be making the chassis, trans brace (B5M part is long out of stock) battery hold downs, and chassis front end brace.

To get to this point has taken a week of parts searching and very fiddly measuring. Oh, and 17 revisions of the 3d models. here are some in process pics of the stubby test chassis that I've been using.

Here are the parts that will not be used.

3D printed test chassis

Stubby test car against the B6.4

The ASC91531 B5M rear bumper was not to be found so that goes on the list of things to print.

[nullandvoid]

Fusion 360 for those who are interested. I created the models that have to fit existing parts by inserting a lens distortion corrected picture as a canvas then scaled it based on the screw hole spacing then tracing it on a sketch layer. First try success for everything but the motor plate, I could not correct a cell phone pic and could not be bothered to break out the real camera.

Bottom view.

My sketchy metrology. I'm really impressed with the folks on this site who are preproducing accurate parts and making it look easy.

And here is the current model of the chassis and related bits that I'll be making.

Oh, I did not mention. The chassis will be 3mm carbon fiber, Nylon for the printed parts . I've not used these materials before so I'm sure there will be much hilarity.
The nylon filament is drying, another day any it should be ready.

So far this project has been fun. I'm getting awfully tempted to make a RC12E from scratch using as close to the original materials as I can get.

[nullandvoid]

I ran in to a problem. I wanted a 280mm wheelbase. The printed test chassis had a 172mm wheelbase. If I extended the chassis 8mm then the rc10 protector body would not fit correctly. The solution was to add parts from yet another car, B6.4 rear arms, which are not swept forward like the rb10 arms.


I was worried about working with carbon fiber. First off, a vac filter upgrade had to be done. The chassis holes and corner radii required a 2mm max diameter cutters, which are fragile and not very cheap for the decent bits. Plus the carbon sheet cost. Yep, kinda nervous.

All the homework paid off and all went well. Chassis came out great on the first try.

It was time to make dinner but I put the car together instead. I only put one upper brace on to check fit. There is one rb10 rear arm and one b6.4 arm on in this pic.

[nullandvoid]

A few more pics. Here's all the test chassis that were printed while trying various thing out.

The hard part was of the design was getting every one of these holes in exactly the right spot for the front clip, transmission, and rear suspension mounts. I want everything tight so the holes are bored to 3.0mm but that gives no room for error.

Another view. The upper brace was not really needed but I want a side bumper to support the body.

What's next? Standoffs for the upper braces and print a new trans brace in nylon. A new body is on the way now. It'll be Camel yellow. I also need to decide if I want to run this 21.5 or mod. I think 21.5 is the wise choice but I only have 13.5 motors on hand. And this was supposed to be a cheap project.

[nullandvoid]

A bit of a redesign. The carbon side braces were too high. Once the battery box was installed I found that the carbon sides made removing the battery strap very difficult. Also, I had to remove the left side to get the motor out.

I went with cf filament for the transmission brace and the battery holder base, and used some scrap 7075 for the new side braces.

I might redo the battery retainer but it's plenty secure.

Next up is fitting a body.

[nullandvoid]

Oh, I can add yet another car that this monstrosity is using.

DR10 trans internals, suspension with exeptions
Dr10M front end, the bit that everything screws to.
RB10 front tower, steering, probably motor and esc from a rtr.
B5M trans case, rear tower, wing mount, rear arm mounts, v2 shocks
B6.4 rear arms
B74.2 battery strap

[nullandvoid]

Ran in to another problem, my smallest esc would not fit between the battery and front bulkhead. After quite a bit of fiddling I gave up on the transverse mounted battery.

A couple of hours later a new chassis brace popped out of the printer. There is plenty of room for the esc and rx now beside the battery.

I've decided on 13.5 blinky as that's the best of what i have in the junk drawer.