MAC FAB Bomber build, TAKE 2

[MasteroFlego]

Originally Posted by MAC FAB

Mamba X allows you turn turn drag brake on and off, right? If so, which one do I want? And for the appropriate radio? If the diffs survive, the lock/unlock feature would be nice to run as well. So what do I need? Thanks in advance.

Yes, all the X series ESCs have the aux wire so you can adjust settings on the fly, you need a whole channel for the aux wire. You could get away with a 4 channel if you put both diffs on the same channel, but a 5 channel is what I would use. As for which X series you need, it depends on how heavy your rig is, and what your gearing is.

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[MAC FAB]

10-12 lbs, variance with how thick of material I use for the body. Gearing, I need to do the math, 20 mph tops. What is the ticket for the multi channel radio and why one over another? Shielding may be an issue with mine (body) if there is one better than the other. ~ $250 getss me a 2200kv sensored and 25v Mamba X. This the way to go? Could always throw a servo in it and run a gasser brake setup on the drive shaft.

[MAC FAB]

Waiting for electronics to be installed. Going to strip the go fast car for the go slow car. Platform to the right of the tranny is for the speedy, servo goes somewhere in the upper left, receiver wherever. Note the center shafts. Should have taken video of the "drop test", I don't have any idea why people think that is cool. I need to clearance/notch the rear arms for minor wheel rub and then its testing time!!!! It has been a 1-1/2 year ordeal to get this far along. And if it "rocks", pun intended, there is plenty of room for the diff lock servos as well. Oh boy.....

20180907_182719 by MAC FAB, on Flickr

20180907_182741 by MAC FAB, on Flickr

[MasteroFlego]

Ooh, looking good

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[MAC FAB]

It's alive......wierd science. There are a few gremlins to kill, the first being the steering. I drove it without steering anyhow. Linkage has to be re-thought. The diffs have a nasty gear mesh noise that needs to be addressed- gremlin. Rear shocks need oil, tighten the slipper clutch- no gremlins there. Then there is the battery box, have to remake that too, my 3s don't fit.
I would say it does about 12 mph with the gearing on it now, I will go up from a 14 to a 22 on the pinion and she'll do 20 easily.
CLICK IMAGES TO SEE SHORT, UNEDITED VIDEO CLIPS Note: No steering!!!

20180914_190402 by MAC FAB, on Flickr


20180914_191716 by MAC FAB, on Flickr


20180914_191914 by MAC FAB, on Flickr

I simply ran out of talent on that 12" drop!!

[MAC FAB]

20180917_081329 by MAC FAB, on Flickr

The guts of my rig so far.
Shooting to have the steering done/installed by tomorrow. No slip in the clutch, she climbs like a goat, low cg and appears to be able to "haul the mail" as well. Happy so far. Anyone run on carpet? The wheelies when on the gas and then nose wheelies when you stop. Priceless!!

[MAC FAB]

Drove it with steering tonight! Its going to need a BIG servo, what I have in it is a gelding. Looking for something inexpensive with mega torque. Suggestions? Anyone use loc-tite on their beadlock screws? Tightening after every run run is getting old.

[Jboucher]

The powerHD chinese servos are cheap and seem tough, JX as well.

For the beadlocks, I mounted eBay wheels with SSD scale bolts and used blue locktite on every screw.
I don't want to lose them...

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[MAC FAB]

Originally Posted by Jboucher

The powerHD chinese servos are cheap and seem tough, JX as well.

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I have one of those in it now, had a flexing issue, so I it should work for now. Needs aluminum bellcranks and a double shear tab to the servo mount I made (flexes as well, and its 1/8" aluminum!!!!). Now I have broken the transmission, I think the pin on the lay shaft went bye bye, we'll see tomorrow evening when I tear it apart (hopefully). I'm really trying to get this out for a crawl test at some point this weekend, running the ~12 mph spur gear until I learn how to go slow. Put a simple flat body on it so she's not naked. I already have a roof and hood, so easy peasy. Motor stays cold, speedy hits 102 degrees. On a happy note, she blazes through the whoops, suspension doing what its supposed to, so I am a proud "daddy".

[TheLetterJ]

I've broken that same roll pin in 2wd Traxxas transmissions a few times and have taken to just drilling the hole out a bit and pressing in a 2.5x10mm pin (wheel hex pin.) Sometimes the top gear needs a little clearancing, other times the pin presses in perfectly. Has held up to a 36x65 3100kv on 4s with a locked diff... so far!

[MAC FAB]

I stuffed an allen wrench piece into my go fast car then welded the gear to the shaft. I'll be trying the wheel pin method this time, much easier. Thanks for the idea.

[MAC FAB]

Its torn apart, the stupid little screws on the spool came loose, so I guess I should be happy that its an easy fix. That was my gear knock, not the rear diff. :^) This thing actually comes apart pretty quickly. Reassemble time and maybe get to crawl this afternoon!!

[MAC FAB]

20180923_155023 by MAC FAB, on Flickr

20180923_154500 by MAC FAB, on Flickr

20180923_174001 by MAC FAB, on Flickr

20180923_173939 by MAC FAB, on Flickr

Ready to test crawl next Sat. afternoon, battery installed, still needing a box for it. Knocked out a temporary body with some scotch tape "fasteners" so she's not naked and afraid. Note the hood mounts. What size are the body panel screws, anyhow??? I have the feeling I will be having to remake the aluminum part of the spool that uses 2 set screws to hold it in place with a steel one that gets welded to the shaft once the taller gearing is in place. Next I need to make new tie rods, so there is more contact with the rod end so they don't pop off when you "send it" and land hard. The rig actually jumps fairly flat, even with the front weight bias. Front springs will be black when done, thats an ugly yellow!!

[durok]

Originally Posted by MAC FAB

What size are the body panel screws, anyhow???

AX31280 Axial Body Panel Screws are M2.6x6mm Hex Socket Button Head Screws...

HTH!

(Nice to see it so close to complete)

[MAC FAB]

Thanks for that info. I will need to find them in about 15 mm lengths for my body stand off mounts. I am soooo anxious to see what it will do. All the weight is down low so it seems to handle well. I'm going to the same place I "crawled" the go fast car and get some video there. Hopefully there will be a YouTube video soon after.

[svt923]

If panels haven't been installed with those coarse thread M2.6 screws, M2.5 screws work just as well and they are much easier to find in various lengths. 4-40 screws would work as well if you have access to SAE hardware, they are just a hair larger than M2.6.

[MAC FAB]

I just couldn't wait for Saturday, so I crawled this afternoon. As far as I can tell, this thing is amazing. Granted, I have nothing to compare it to, but it pretty much goes anywhere and well. Here are a few screen shots from the video I shot to prove it works. Well, I guess that needs to be video. It does need a beefier steering servo. Run time is great, 2 hrs of messing around and it still goes on the first battery.

20180924_180935 by MAC FAB, on Flickr

20180924_180644_59103-1 by MAC FAB, on Flickr

20180924_174920 by MAC FAB, on Flickr

20180924_181329 by MAC FAB, on Flickr

20180924_181312 by MAC FAB, on Flickr

20180924_175404_42110 by MAC FAB, on Flickr

20180924_175404_43276 by MAC FAB, on Flickr

20180924_175530 by MAC FAB, on Flickr

I put it on the roof 3 times, no so much as a scratch or dent anywhere. .040 body takes a beating. Scotch tape is the duct tape of the RC world!!

[MasteroFlego]

I love that rear suspension. How wide is it? It looks wider than stock ar60s.

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[MAC FAB]

Originally Posted by MasteroFlego

I love that rear suspension. How wide is it? It looks wider than stock ar60s.

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13" out to out, so 2" wider than the 11" width Bomber dimension I found. The numbers for w/b and width are close to a Yeti SCORE TT.

[NitroBugg]

Amazing looking rig! And I'm still impressed that you got the inward side of a 3" wheel, inside a 2.2" tire.

Same wheels I run on my Slash 4x4. Hate those damn screws though.