Dna's Ultra 4 Bronco Buster

[dna4engr]

Got the bronc running this weekend. Really happy with the jumping ability and landing ability too. Handling was suspect as its setup very soft to handle jumps.

Obviously it was time for a sway bar. Got the bars drilled and tapped. And the links to the rear axle.

Also got the apache interior trimmed up and placed. Need to paint it up and get the helmets ready to go.

Had some time to rip around this weekend and test it out.

Key takeaways:
- Trailing arms definitely require a different driving style on the rocks.
- 3500kv on 3s is more than enough as far as speed goes.
- Traxxas et3s definitely runs hotter with this pro4 than my old mmp did.
- May need a front sway bar too. Remains to be seen.
- Switched from mmp software 1.46 back to 1.32 for the cooling fan operation differences.

Dna


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[dna4engr]

After doing some more testing (I.e. Jumping) I finally took out the integy knuckles. Cracked the threaded hole ear right off. Had to drill a hole just to get her up and running with a bandaid fix.

After a very very long wait, my replacement gears for the tziworld winch arrived.

Got her mounted up in the front of the rig.

Only bad thing is the cheap esc I have wired in for winch control only arms on 2s lipo. Since I run almost exclusively 3s, I need another solution.

With the DW foams the tires are pretty stiff. I started siping the tread to help things out. Still might need to shave those sidewalls a little bit.

One last thing. After getting some time on the rocks and racing around, I wasn't happy with how hot the esc was getting. Dropped from a 14 down to 11t pinion and she's cool as a cucumber.
Even more torque and acceleration now. Less top speed obviously, but speed isn't always the key in U4RC

Later,
Dna


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[northkona]

What servo does tzi use in his winches ?
I was thinking of getting one, did it take much abuse before failing ?

 

[dna4engr]

What servo does tzi use in his winches ?
I was thinking of getting one, did it take much abuse before failing ?

From what I can tell, it's not anything normally used. He's just using the gear sets and motor anyway as the rest is all custom. When the gear slipped in the set, of course I scavenged through all my scrap servo's gear sets and nothing was close. The 2 idler shafts in the gear set are larger in diameter than normal servos use (even hitec, futaba, savox). Plus I couldn't find anything that had the exact pitch and tooth count.

After talking to JYI, he said that the failure I had is something he's experienced. It took so long to get new gears due to shipping issues, not his customer service.

I ran the winch in a 10lb 2.2 scaler for about 6 months. Usually on 3S with a Tekin FXr for control. I didn't use it a whole lot to be honest but lifted the rig completely off the ground more than once. I was in a normal pull over some difficult rocks when it stopped retracting even though the motor was turning. The issue was the primary gear that contacts the motor pinion. It is a larger dia gear with a smaller one pressed into it (just like the non titanium one in hitec "titanium" gear servos). The small gear spun inside the big gear. JYI said this happened when he tried the winch on 4S.

Overall its a damn nice winch. Being that you are much closer than I am to TZIworld, it should serve you well to get one and if it has any issues, you have easier access to the vendor.

On this rig I know it will get little usage so I have no concerns. On that scaler I went with a KMS K3 servo winch as I know what servo he uses and can get replacement parts that way if needed.

Ltr,
Dna

 

[northkona]

Cheers for the info, I had a Savox steel gear turn inside a larger brass gear once so I know what you mean, interesting that its not normal 1/10 scale servo stuff he's using.
I have an epic trip that I am trying to organise up a local mountain and I want it to be all under the power of the trucks. one tricky bit in the middle is going to be a heap of winching , one of these might fit the bill.

 

[dna4engr]

Been tooling around with this thing for the past week.

After breaking the knuckle ear and having a cheap fix it broke again. Time for some vanquish knuckles.

Also got the drivers all painted and decaled up. Ready to race.

Then I mounted the front hinge on the hood. Not 100% sure on the plan for securing it. Either magnets or Velcro.

I replaced the bearings in my pro4 HD and put in a 13t pinion. Now she's up where I think I need to be top speed wise. 19.1 mph. Torque and acceleration are still outstanding.

Finally had some more work to do on the fabrication (sadly I painted it already, oh well)

Added support and mounting nuts for the boatsides.

Then I added 2 support rods for the battery tray (these also help the frame stiffness)

I added a tab to thread in a bolt for the spare. Along with a hoop to provide some support. It will likely be mangles after the first crash but oh well.

Last but not least was a winch fair lead. I hadn't planned on using one but after the test runs I realized the light bar is susceptible to rocks and this will narrow that chance.

A little trick I've used for a while with servo winches is to take the flared end of a price of brake line and use that in the hole of the bumper or fair lead mount. Then just drill a hole in the mating part to match and braze it in.

Then cut off the excess and grind flush.

All brazed into the frame.

To finish it off. A carter fab Delrin fair lead.

G6 and U4 race next week. Well be ready.

Dna


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[djjiz]

Dlux knucks would have been killer.

Nice finishing touches on the bracing. It's the little things like this that set chassis apart and good luck at the G6. Really wish I could make it. If there's any last minute shit needed to get this running don't hesitate to ask. You can have anything in Chucks toolbox:mrgreen:

 

[dna4engr]

Dlux knucks would have been killer.

I have a set on my TTC truck. Just couldn't justify the extra $70 vs. the vanquish on this one. We'll see how she works. Probably will go through bearings faster than necessary.

If I can just have a rich uncle leave me some money I'd put Dlux knuckles on all my rigs!!

Dna

 

[djjiz]

I have a set on my TTC truck. Just couldn't justify the extra $70 vs. the vanquish on this one. We'll see how she works. Probably will go through bearings faster than necessary.

If I can just have a rich uncle leave me some money I'd put Dlux knuckles on all my rigs!!

Dna

Most vendors accept over the pants hand jobs as payment. That's how I get all my cool shit.

 

[dna4engr]

Now that I can mount them its time for boat sides. Using some relatively thin al.

First to make paper templates.

Then to mark, cut, bend, and drill

Now the rig is painted and ready for assembly.

Prep for this weekends g6 and U4 race means some more goodies from Dlux. Sway bar for the front and some slw spacers.

For the frame I had brazed on 2 nuts as the mount for the torsion rod. A bit surprised at how thin this rod is compared to others I've got from hot racing and axial. I moved the shocks outboard of the mount and put the sway bar links in the center.

Next I put all those little damn cap screws into both vanquish light bars and installed both. I don't understand why those aren't installed at the factory.

On the road for work all day tomorrow so I'll have to kick this into high gear on Friday.

DNA


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[djjiz]

I had to run almost half the thickness on the 1.9 wraith and it still was a little too stiff. Should work pretty good on your rig.

Got a total weight yet?
Wheel weight?
Height?
Width?
Eye color?

 

[dna4engr]

I had to run almost half the thickness on the 1.9 wraith and it still was a little too stiff. Should work pretty good on your rig.

Got a total weight yet? She grew into a pig with a 5000 3s batt = 10lb rtr
Wheel weight? No extra wheel weight, actually was trying to run less unsprung weight, but ended up having to use true beadlocks vs the glue on wheels
Height? Not sure
Width? 12.25" with the dlux spacers, outside tire to outside tire
Eye color? Blue, and I'm single, ready to mingle

Dna

 

[djjiz]

Pretty sure my left hand is single. I'll ask when I see it again.

 

[curts1g]

Awesome build. I would have never thought of cutting the body into panels. It fits a lot better than I would have expected. Nice work!

 

[dna4engr]

Spent some more time getting this thing ready for the g6 and U4.

Stuffed the electronics under the driver.

Some more of the rig as she comes together.

Dna


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[Ballistic17]

That is looking really good. "thumbsup"

 

[dna4engr]

That is looking really good. "thumbsup"

Thanks Lee!

Had some issues at the g6 yesterday. 10 feet into the course and I thought is be cool and splash some water in a mud hole. Sure enough I got water on the Rx and she quit working. Took it apart and dried it out. Ran my 2.2 ttc truck instead.

Got her back together for the U4 race. Was ready to go.

I had worked my way into first place and on the hill climb with about 3 laps to go I was really struggling to make it to the top (got passed by etype at this point). Came back around the next lap and was climbing the hill again and got hung up and the rig rolled back a couple times. One of the Marshall's yelled that something had broke in the suspension. Needless to say I couldn't even get close to catching the leader. Luckily I made it across the finish line before he lapped me.

Failure was a lower front link snapped a traxxas rod end. I was digging a link into the track for 1.5 laps and barely new it. Time to upgrade to rpm versions.

Rig handled really well and I need to do some tuning to the shocks.

DNA


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[djjiz]

Might wanna avoid the rpm revo/slayer sized ends. They're sloppy on the balls and limit articulation. Some like that. I don't.

 

[djjiz]

Pm your address and I'll send you some. I'm never gonna use them.

 

[dna4engr]

Got her put back together with the new rpm rod ends. Went out to the boom site in Stillwater and bashed around with etype, grunt, and dieselkawboy. 2 yetis and a wrexo.

Had some fun in the mud by the river.

Then after a pack and a half. The dang rpm rod end broke in the same spot.

Going to have to do something different with the suspension links and how loads are transferred.

After getting her put back together tried the pitbulls on for size. What y'all think.

Ltr,
Dna


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