Rc4wd d90 (with sumo motor/tranny and suspension mods)

[TownsendTdi]

Edit- swapped sumo motor for Team Brood mini crawler motor, check bottom of page.

I put a few pics in the "new rc4wd micro" thread but it's spread over 10+ pages, so I'll put all the info here if anyone is interested.

You can get pretty good increase in suspension travel by moving the lower links to the inside of the axle mounting bracket and modifying the stock shocks, but if you want it to flex like one of the micro crawlers we're all familiar with- here's a good solution.

The Redcat Sumo crawler balls have 2mm threads so they screw into the axle bracket. Only a few threads are exposed after going through the frame rails, not enough for the nylon lock-nut part to work, so make sure you use loc-tite. I will thin the rails a hair where they mount if one ever comes loose. I'm not aware of any balls with longer 2mm threads, if any exist please share! The rod ends take 2-56 threaded rod, I covered them with 1/8" x .014" wall aluminum tube.
It's crazy how restrictive the stock links' rod ends are! After:

Just as much as a Losi-based rig:

The stock shocks certainly don't extend far enough though. Instead, I used Losi Mini Desert Truck front shocks, part LOSB1293 (sold in pairs for $10/pr.).

I ground the spring perch off of the shock body and swapped the rod end for the stock rc4wd metal ones. Inside is 10wt oil (bleeding instructions can be found here: http://www.losi.com/ProdInfo/Files/LOSB0202_Manual.pdf), and for a spring I used about 8mm of a losi trail trekker spring. If you want different rates try the Losi micro t option springs (LOSB1600 or 1601). The stock rc4wd shock spring would probably work too, but I made these long before they came out so I used what was available at the time. Use whatever length piece of spring you want- I like mine drooped about 75%.

To mount these, I traced the shock hoops on some delrin plastic (1/8" I think), and mounted these inside the frame rails- the esc tray had to be rotated 180 degrees. I used Losi extended balls for the tops of the shocks- the ones used for the trekker/micro crawler shocks. These fit the mini dt shocks too.



I had a spare Redcat Sumo crawler motor/tranny I swapped in for lower gear range. Very simple- just ground the tabs off until it fit between the rails and mounted it using the stock holes. There is a plastic plate on each side of the tranny to screw into.

Just enough clearance between the motor and driveshaft that it doesn't hit. The front driveshaft was hair short after this swap so I used stock redcat/losi driveshafts. I've yet to break one even with the weight of this rig. In my opinion, the gearing is perfect with this swap. The motor isn't a beast, but it can pull its weight up any incline you can throw at it until it flips.
Here's a few videos with the sumo tranny/motor:
https://www.youtube.com/watch?v=bj0XLj030nU
https://www.youtube.com/watch?v=xXy0XLJBgvM (top speed demo)
https://www.youtube.com/watch?v=nnKeIczAebo
https://www.youtube.com/watch?v=RwPw2Ke5XqE

BTA steering link- straight 2mm threaded rod with rod ends mounted on top of the rear part of the knuckles. Didn't even need a bend! The short link was replaced with 2mm threaded rod and rod ends as well, because the stock one limited suspension movement.


Easy light setup:
LOSB9996 Night Crawler light set. Losi Night Crawler LED Light Set LOSB9996 Comp Rock LNC LCC Scale 2.0
connected with a cheap "y harness" from the servo connection. E-Flite 3" Y-Harness, Lightweight

The led bulbs just pop right in the front headlights, a little hot glue and then platidip painted on the back. For the rear I used a little black styrene and made a little light bucket, with a piece of red cellophane (from some cheap 3d glasses) for the lens.

Finally ready for paint!

My "paint booth". 440 cfm inline duct fan sucks the fumes outside.

I've painted lexan bodies, but this is my first time ever painting a model! One more wet coat to go and some weathering. Painting sure takes some time and patience!

[TownsendTdi]

I pulled a cv axle off my losi mini to check for a possible candidate to replace the dogbone setup up front. I believe the joint part of the shaft will fit in the knuckle area. Would need to turn down the thick part by the hex area. The only problem is that the cv axle is a hair narrower, so the flats on the diff side would be a tiny bit loose, wearing out the ring gear over time. These are Integy brand, I might look around to see if there are any slightly thicker one available.


Seems like quite a bit of work for the possibility of a little more steering, I might give it a shot though.

[Sparks1337]

Very informative post and great work. I was starting to feel the same way about "new rc4wd micro" thread, and you've put a lot of info here in one place.

Once the stock lower links have been untangled, the travel in the links and the stock shocks is pretty well matched, so changing out the links is only worthwhile if you're using longer shocks. This looks like a nice neat way to get more travel though, and not too expensive.

Good to know the sumo motor and box pretty much bolted up as well. It seems to be the simplest solution for the power issue out there at the moment.

Love the spray booth btw

[TownsendTdi]

While I had my front axle apart I took a little play out of the knuckle by adding a .1mm spacer on one of the brass kingpins before reinstalling. Helps, but most of it is caused my that single bearing.

[TownsendTdi]

Finally got around to paint! And Fixing some accessories I broke:

Added some polished sheet aluminum to the side mirrors, I might do the rear view as well next time I remove the body.

Outdoor shots:













I still want to weather it a bit, paint some black window trim, licence plate, etc., but some other projects are calling.

I think I'm going to call this one the "Land Rover D-pumpkin: Rock Crawler"

[TownsendTdi]

Threw some clips together into a video:
https://youtu.be/sbfDE_GDlK0

[TownsendTdi]

New tires, and some of Jim's beadlock rings on HR beadlocks.

[old man 52]

Very good info. Thanks for sharing

[cleanandserenesteve]

Great rig and nice info!

One thing I hate about having a nicely painted body is that I'm petrified of scratching it lol I always get my hand ready to catch it if it's about to flip...

[Aeronuclear]

Great colour! Like the Rok Lox...


Do you mind explain a little bit more about your steering set up? Mine is limited. Want to get a bit more out of stock. Thanks...

[TownsendTdi]

Originally Posted by Aeronuclear

Do you mind explain a little bit more about your steering set up? Mine is limited. Want to get a bit more out of stock. Thanks...

I just moved the drag link to the rear part of the knuckles behind the axle, a straight rod fits perfectly there. It has no more steering angle than stock though Just for looks...

Thanks!

[TownsendTdi]

I weathered the body a bit. Where the paint had chipped I glued steel shavings and sprayed peroxide, vinegar, and salt on the areas for insta-rust.











The redcat sumo motor/tranny works great for rock crawling, but I have other rigs that are actual crawlers, so I'm going to use this one for trails. It needs more power and more speed.
How about a Novak Mongoose mini crawler brushless sytem? Lol



All that wiring takes up a lot of space, so I settled for this Team Brood Frenzy brushed motor. (I'm into mini crawlers too if you can't tell)



Transmission is from a Losi Mini LST with the Hot Racing locked spool gear.



I made some outdrives out of stainless rod and tapped the driveshafts for a 2mm set screw instead of the o-ring and pin.





I temporarily mounted it and worked great, but need to make mounts for the transmission and it'll run. I'll post up when done to let you know what i tear up lol

[Shape_Shifter]

Holy massive jump power batman! A D90 drift truck!

[Cometcyclonemk]

Excited to see how this works out! I'm using parts from this kit to make a mini JeepSpeed Cherokee and have been researching ways to give it more pep. As I'm new here, I'll ask a potentially silly question: Wouldn't a slipper clutch help reduce the chance of breaking the driveline under the kinds of power/speeds you'll see?

[Natedog]

Sweet, love the use of other parts, transmission/motor swap is the best part, linkage do over very nice and great paint scheme! Interested what you do with the cvds, really need better bearing support on the axles too.

[TownsendTdi]

Got the tranny mounted. It looks pretty big, but once you put the body on, the spur tucks up pretty close to the dash, and could easily be covered with a dash, and the motor could be disguised under the top half of a seat and driver. The wiring mess is temporary.







This is the lowest gearing available for the mini crawler (pretty much), and it is a little bit harder to climb smoothly, but it's got plenty of speed, I think it will work well for trails.

The transmission fit the stock chassis rails like a glove, I made brass plates to connect the rectangular tubes and tapped the stock holes in the chassis for 2mm screws to mount.



Climbing test
https://www.youtube.com/watch?v=l5uEQXpwVxM

Speed test
https://www.youtube.com/watch?v=BHt2FSygWtU

Can't wait to test it out on some dirt!

[Shape_Shifter]

Nice work!

[jimbo_wa]

Epic speed!

Good to see another solution to that woeful stock gearbox- have you had any joy with the steering or are you now running with so much speed the limited lock is perfect?

[TownsendTdi]

Originally Posted by jimbo_wa

Epic speed!

Good to see another solution to that woeful stock gearbox- have you had any joy with the steering or are you now running with so much speed the limited lock is perfect?

Still has crappy steering- my only issue with it now, but meh..

Longer video of testing with the mini motor:

https://youtu.be/psHcvmwWuPI

[cleanandserenesteve]

Wow! That speed increase is great! Looks like fun. Although, the limited steering would bug the shit out of me, its baffling they let a product that is supposed to be top end go out like that...