Rjohns Tekno U4/crawler

[Rjohn929]

Rjohns Tekno U4/crawler "Dark Side"

The time has come to convert my beloved SCT410 to a U4 bullet. This may be a slow build but it will be done. I understand 2.2/3.0 tires aren't legal and I'm sure some others things won't be either but seriously.... who cares! His isn't for comp, this is for fun and to prove a point.

Phase 1 - How high can you go? I put the stock rear shocks on the front and put some EB48.3 rears (137mm) out back. Full droop puts me at 2.5" with stock (4.5") SCT tires. Now this will all change as the stock shock towers will be cut and the shocks will be mounted to the cage but factor in some 5.75" tires and I'm riding pretty high. I'd like to be 3-3.25" full droop to the center of the chassis when I'm done. I expect static droop to bring me to about 1.75-2.0" at rest.

Some pics. Nothing special here. Looks just like a SCT should look. The cage will be based of the Lasernut FIS U4 buggy.

I'm going to lock the center and rear diffs but I think I'm going to run 20mil up front to allow a little diff action. Not sure yet.

 

[Rjohn929]

Just a little teaser. I have to make some tires to fit my 2.2/3.0 bead locks.

 

[MattTheGenus]

Can't wait to see it!

 

[Sneetches]

Be cool to see it, I'm just about to convert my Slashetti over to the HCG chassis for better clearance on the tub. How much clearance is there with those growlers? Pic related is about all I could get from the Slash, the 5.5" trepadors helped a little bit more.

 

[Rjohn929]

Static

Pushed down

Full droop

 

[Sneetches]

I'll be interested to see how you do the cage. I've had the same idea for a bit now after watching the Lasernut buggy as well. For now, the Yeti cage does the job for me and is surprisingly durable, but I'd like to make the rear end look a lot better.

 

[Rjohn929]

So I totally forgot I have some Axial Ripsaws mounted on some 2.2/3.0 wheels. I'm going to use those to mock it up until I get something permanent.

I locked the diff with diff locking putty and filled the front and center with Badhorsies locking grease. The grease still allows decent diff action so it should still turn and accelerate very well. I also dropped in a Speed Passion Blaze 2100kv 1/8 scale motor and 18t pinion. This thing should haul ass on 4s!

Got to go pick up the other 3 tires tomorrow.

I picked up another set of EB48.3 rear shocks for the front when it comes time to build the cage.

 

[slowmethinks]

Ive got a DHK Hunter and ECX Torment laying around. Dependimg on how yours turns out, I may give this a try... I like it!

 

[cmbscx10]

Awesome work so far. Definitely following.

 

[Rjohn929]

Should have a small update tonight involving some wheels and tires. If that goes well I'll get out tomorrow and rip it around to see how it's going to handle.

 

[Sneetches]

I feel like tires are the most awkward part to these "conversions". Short course wheels suck and short course tires are all <4.2", and cutting up expensive crawler tires sucks and you have to tape them because they just explode when going above 25 mph. The crawler compounds also weren't intended for the amount of wear that a SC truck could put out as well.

 

[Rjohn929]

Halfway there. I modified some DW tall foams to work. Wanted to use standard ones but I screwed up the first one. Don't feel like waiting for a replacement.

 

[Rjohn929]

I used silver compound to keep them a little stronger and the U4 have a good amount of ribbing down the middle.

 

[Sneetches]

I had a set of Blue U4s that I thought about using but decided against it at the time, I think even Matt @ Ottsix was a bit hesitant about it when I asked him. If you get to run them then I'll be interested to see if they will hold up.

 

[Rjohn929]

The blues are holding up well on my Yeti and it's pretty fast and takes a beating (3s pro43500hd with a 16t pinion). I'll keep my fingers crossed.

 

[Sneetches]

I did forget about the O-ring trick, but I haven't tried it yet. Apparently on McMaster-Carr you can get "Hard Buna-N O-Rings" that work well as disposable ballooning containment devices. You just get a size a tad smaller than the tire OD and pop them on. I know guys were using this on their 1/8 6S trucks so they should hold up for a bit.

 

[Rjohn929]

I remember that too. I don't think I'll be hitting those kinds of speeds. We'll see what happens. The tracks can only take so much.

 

[Rjohn929]

 

[Rjohn929]

Tires came out great! I did glue a bead to the inside as well. It's not just clamped in there.

 

[Rjohn929]

It's right at 12.5 wide and 12.75 wheelbase right now.