TOPIC:

Hey guys, I am in the process of putting my vintage/re-re/custom frog/brat monstroity togther. I have run across one issue, possibly very minor, possibly not. That's why I am going to ask.

What I have found is, that I have sourced most of the parts for the gearbox, between new and used, I have everything.....except for the little 2mm x 28mm rod that goes in between the 2 drive cups for the dog bones. I am dealing with the old style drive shafts, with the octagon ends, not the re-re dog bones.

My quetion is, how important is this part? can I leave it out? So far I found a piece of music wire for oe of my airplanes, but it is not quite 2mm. I think it measures 1.88mm on the micrometer. Should I keep looking for something exactly 2mm? does it help with alignment of the bevel gears? can I just drill the holes in the cups out bigger? I think my next biggest piece of music wire measures 2.14mm, and I have access to many drill bits, so I should be able to find something that size.
Is it possible to find this part? In the re-re's it is permanently attatched to one side.

I am using the old driveshafts because I found them in my old toolbox, and they are still in good shape, so I figured I would burned through them before replacing them with the new style.

thanks, jeff

I wouldn't leave it out myself.
It takes care of the alignment and with too much play your gears might start to wear faster than you want...
Won't be easy (or otherwise probably pricey) to source the original part but I'd stick to the closest matching diameter.


Shouldn't be too hard to manufacture though...

The answer was right in front of my face. I had a real "duh" moment at work today. I am a bicycle mechanic, and take a guess what size most bicycle spokes are. Most bikes, unless they are really expensive use straight 14 guage spokes, which are, you guessed it, 2mm diameter! SO, I was quite literally surrounded by materials to build 100's of these little rod things! I found a junk spoke in the box, cut it to length, and now I am good to go. Nice tight fit. I knew this, after years in the idustry, it just escaped my mind, because how often do you think about putting bike parts in R/C cars?

Jeff

Making the most of what's at hand... very resourceful. And problem fixed!

...all the time! - bike spokes are my main fodder for control rods! Can be a nuisance to cut threads on, if you're not ready for it, but HSS dies will usually address the problem of hard spoke material. Some advice though - not a great idea modifying parts (Eg drilling drive cups) to be able to use a 3p bit of material you have kicking about, better to wait & get something that fits if you can. If you really HAVE to modify bits to get them to fit together, always modify the simpler/cheaper/easier-to-source part

Oh, & that pin will be "Silver steel" rod - it's not as hard as spokes (But they'll work perfectly) & you'll find the 2mm size all over Tamiya cars, so why not invest in a length (Or a pack of various sizes) - it's usually available cheaply enough from engineering suppliers or Ebay & is easier to work with than spokes

eddrick wrote:

Oh, & that pin will be "Silver steel" rod - it's not as hard as spokes (But they'll work perfectly) & you'll find the 2mm size all over Tamiya cars, so why not invest in a length (Or a pack of various sizes) - it's usually available cheaply enough from engineering suppliers or Ebay & is easier to work with than spokes

Spokes are very easy to work with, especially if you have the right tools on hand. We have a threader in the shop, and they cut easily enough with a heavy side cutter or dremel tool. The only thing I can't do with them is put a left hand thread on them. Plus we have access to stainless, galvanized, or titanium (those aren't cheap!) Plus many colors if you want to get fancy. I hadn't though of using them for control rods, but it sounds like a good idea.

jeff

Ha, yes, "The right tool for the job".... I've only ever attacked spoke material with hand tools, & they've only ever been galv'd hard steel ones (Piano wire hardened from galv process?). I've destroyed the cutting edges on high quality side cutters chopping them in the past, so nowadays I either use a diamond file or grinder (Depending how important the length is). Not tried threadcutting them on the lathe (For LH threads), but I suspect it would be hilarious.... Just interested, why would you need LH threads on a spoke?

Hey guys, I don't know who is following my brat project due to it not being in one thread, but all over the place in the form of random questions. But, I am closer to having a working vehicle. What started out as something I thought would be simple has tunrned into a nightmare of buying/swapping/returning parts. All I wanted to do is take an old frog chassis, replace the worn out parts, and put the hard shell from my re-re brat on it with some bigger tires. the chassis was the easy part, thanks to re-re gears and suspension arms. Body mounts also came from a re-re. The wheels are what were proving to be problematic.
I opted for some dyna blaster wheels. Thanks to ebay, not a problem. Rears fit fine with the frog hex adaptors. Fronts= Nightmare!

I first tried just putting the rims on the frog uprights.... no go. the steering arm hits the rim.

Attempt 2. Ordered blitzer beetle uprights..... no go. the dyna blaster wheels DO NOT use the longer blitzer axles. Getting angry and creative now.... Out comes the dremel tool. Back to the original frog uprights. I cut about 8mm off of the end of the steering arm. flattened the remaining arm a bit with a hammer, then re-drilled and tapped for new ball ends. Success!....mostly.

Now steering servo rods were too short! No problem. Centered the servo in the frame, and constructed some new rods form some airplane control rods.

Now I have a roller...almost. I tired a few different tire combos, and have settled on pro-line dirt hawg 1 2.2 buggy rear tires all the way around.

I do have some blitzer front tires that would work fine as well, but I don't like the pin spike rears. I just don't think they would last very long. I also tried proline dirt hawg truck tires. They are just too big unless I want to go to mud blaster body mounts. I was not looking for a monster truck though.

I will try to post some pics when I get back after the weekend.

jeff

Sounds like a very cool setup. Dirt Hawgs are all great tyres.
I had a bit of the same problem with my Humvee...
Haven't even really solved it yet. But I will.


Rear works. Front not so much.
Did you try a shorter servo horn yet?

Looking forward to the pics and more details of your build!