So I've been thinking about those mini (think they are 1/16 scale) nitro RC cars/trucks. I think it would be so cool to have one of those in such a small scale. What's the story on these little guys? Are they worth the price people are asking for them? What about performance? Regardless of price, which ones are the cheapest most reputable ones out there? I think they would be cool just to mess around with in the driveway or something, to get my nitro fix that I used to love many years ago. Thanks for any insight guys! [img][/img]
I bought one a few years ago for similiar reasons. I bought one for the bling! But I knew what I was getting, so no big deal. I just don't jump it, or at least not big jumps.
More accurately, I bought it for the price. I considered others, such as X-Ray and the OFNA CRT .05 (if I got those names right), but wanted a package deal and a cheaper price as I knew I was buying a novelty. The MB1 isn't something I'd recommend, although it met my criteria which sounds a lot like yours.
In my case, I bought the Team VTX MB1 buggy. There's also a Truggy version which I think is all the same except for the body and tires.
I didn't expect much, and I was more or less right. The radio has terrible range, and the wheel bearings need to be replaced as they can cause drag on the wheels causing constant turning no matter what. Also, the steering servo is too weak, and the diff gears need a little TLC or they will wear out prematurely (or so I heard, although mine are still fine). The GO engine is very touchy to tune as it won't start unless the tune is close, so it's not necessarily for the beginner.
But it's a blast. To see that little nitro car race around my driveway is fun enough, but to hear it shift into 2nd gear always makes me laugh. I've also had fun with it on snow creating some impressive rooster tails when drifting.
I've cut and pasted a bit of info I wrote a while back that should help clear things up with the MB1, but first some links:
I think TeamVTX is gone now, but a few places still sell them along with parts. Note that it's a bloinged up version of the old IRC Vulcan, so there may be other sources for parts.
Lots of pics in this link
And there are better engines, such as here (incredibly low price!):
On a side note, I've been thinking of getting this combo for another project... great deal:
Now, back to the stuff I wrote a while back:
Both loose and sticky were my first observations. Starting with loose, I found some of the screws that hold the axle hubs on had backed out. Tightened them all up with thread lock. At the same time, I greased the outside of all the brass cups that the screws tighten down. I pulled the whole servo saver/steering unit and greased the pivot pins still fastened to the chassis. I removed the stamped aluminum tie-rod link and flipped it over. That way, it puts the rounded edges against the other moving parts reducing friction and wear. I did a slight chamfer of the aluminum where the brass screw cups go in, and added grease as well. The stock steering servo just wasnât up to snuff, so I replaced it with a HS-65HB. Used the Â˝ servo-arm that came with the new servo and used the innermost hole for the ball mount. You need to trim off the tops of the servo mounts, and trim the slot in the rear one for the servo wire. Other than that, it was a pretty easy install. I think the stock servo might be OK, but mine seemed glitchy so I didnât mind replacing it. The throttle servo worked fine.
Too coolâŚa 2-speed! OKâŚlots of work on this one. First of all, let me say the MB1 came with the heavy duty steel spur and clutchbell, so the old plastic spur wasnât an issue for me. The spur/CB mesh was too tight from the factory, so I adjusted the engine mounting to get a tooth lash with just a âtickâ of play. I did notice the top shaft (input shaft) could move back and forth a b it, so the spur/CB mesh didnât line up that well. A thin shim inserted on the input shaft between the first input shaft bearing and the first gear fixed this. If you donât have a proper thin washer, two can be found under the âEâ clip holding on the spur gear. Use one of them for shimming, and then find a thick washer to make up for the 2 you removed from in front of the spur gear.
On the bottom shaft, I noticed the gear houses the shifting dog mechanism wobbled a lot. The bearing it uses is a loose fit in the plastic gear. I carefully used some epoxy to hold the bearing in. Careful here, you donât want the bearing to be locked up from glue.
Normally one makes sure all âEâ clips are installed with their sharp edges away from any force that might pop the clips off, but in the transmission, it is better to have the rounded edges facing anything that might be rotating fast. Youâll have to figure that out as you go.
Now the fun beginsâŚâŚI wanted to preset my shift point. I did some math and figured out a good shift point would be around 3500 rpm for the shaft holding the shift dog. (If I remember my math right, at an engine rpm of 15,000, this shaft rotates about 3650. At a vehicle speed of about 10 mph, the same shaft rotates around 3350. So I used something nice in-betweenâŚ.3500 rpm). So I chucked the shaft (with gears) into my drill-press. Small gear closest to the drill chuck. Unfortunately my drill-press would only go up to 3000 rpm, so I adjusted the shift set-screw so the top gear just stopped engaging when I the drill-press came up to speed. Then I tightened the set-screw another Âź of a turn which presumably would put the shift point up around 3500 rpm. Note: Later I found that this caused a shift way too early (and hard to notice). A shaft speed of about 4900 rpm, which was a road speed of 15 mph and an engine speed above 19,000 rpm, seemed to be more appropriate. I have yet to verify these numbers, but will eventually. [Note: I don't remember anymore where I set it, but I set it to shift fairly early....it's easier on the tranny that way]
What can I say? It is without doubt that cast aluminum gears will not last all that long, but until I figure out what to do about that, I thought Iâd see what I can do to increase their longevity. First of all I looked at shimming. However everything was tight. No shims were needed (quite impressive actually). Next I looked at the grease used. Looked like some sort of clear silicon or perhaps lithium grease. Just the kind that can fling off and leave the gears dry after a few runs. So I added some of that HPI high pressure green grease. Very sticky. I probably should have cleaned the other grease off, but feeling like a mad chemist, I thought Iâd leave a mix of the two in place (or perhaps I was just too lazy to clean everything up). Note: so far the diffâs are holding up well, although I did re-grease after about 1 litre (1 US quart) through the engine.
Yikes, what a pig to get going. Major blisters. And some blood. Anyway, the problem is there were no factory settings in the manual, other than the idle stop opening. And that turned out to be quite important. I adjusted the idle stop for a 1mm carb opening by using a drill-bit as a gauge and that kept the engine idle rpm decent (during break-inâŚit can be closed a bit after break-in). But this didn't keep the engine from starting as I raise the throttle trim a bit for cold starting. The major problem was the LSN was way to lean from the factory. You need to start with it about 1 turn out from flush. Before I did this, I could get it to run, then die, and then I had to re-prime again. Once the engine breaks in, the LSN can be leaned out a bit.
Itâs also important that you check what radio trim position gives you max open carb, because thatâs where youâll set your trim after your engine warms up and you can reduce the throttle trim required for stating a cold engine. Pull the air-filter and watch, and youâll see what I mean when you hold full throttle and adjust the throttle trim at the same time. Just a quirk of the stock radio gear.
One thing I didn't like was the fuel and pressure lines. They seemed to tear easily due to sharp edges on some of the barbed line fittings. Tougher fuel line was a quick, easy and cheap fix.