DarkHorse

Video: Xray M18MT RTR indoor crawling around.


...Xray-M18MT-RTR-stock-crawling.wmv 24MB 4.5mins 50fps
WMV (server too slow? try latter.)


The weather is pretty poor here and it's dark before I get home. Not enough room to test the top speed and don't expect it to be that fast on 9T but it's a bit of fun crawling around some obstacles. 9T to 12T pinions are included options.
One advantage that a cheap brushed setup has over brushless is greater ability at low end torque, something I never bothered trying with the brushless m18t kit which was setup for greater speed on the flat and would suffer greater cogging on slow starts (made worse with a poor motor choice).
Nothing particularly dramatic in the video, although the truck does show it's angry side a couple of times and it might give an X-ray newbie some insight about the M18MT RTR version. As you'll see I'm still getting use to the stock Tx steering wheel on full rates lock to lock. On medium thick carpet in a 6ft by 9ft area, after some ball diff 'break in' cycles, tightened to medium resistance (some slip to reduce plastic CVD strain or transmission shock), oh and I haven't bothered to fill the 8 shocks with any oil yet. Not sure about runtimes, that was 4mins of edits from a 10min run, left for a day now so the NiMh pack will naturally discharge some more anyway (~10% on first day), I'll edit here best guess later... EDIT: ~15mins of high power low speed crawling. With a bit more room I'm sure more could be done. A bit dull with no music but you can always choose and add your own .

Mini_Me

I'd put at least oil on the shafts for the shocks. Without oil, you will destroy the seals.

DarkHorse

Yea thanks. Some one at the factory had the good sense to put some oil on them.

WalkerBoh

My Feedback: (7)

Ok, so how in the heck have you "bashed the hell" out of your truck? I can't even run a full pack through mine without breaking something. So far I've broken a driveshaft, a steering knuckle and a front upper arm. Since parts are difficult to come by, it's really put me off of this truck. Anyone else have problems with this composite being very very brittle? Anyone want to buy my truck?

-Aaron

gemroz

did you get your truck sold?

Mini_Me

Where you playing in very cold weather? (Michigan) That will increase the tendency of plastic parts failing. If you like T-bone bumpers makes a wide front one for the M18t/ Which will help protect your front end under heavy bashing.

http://t-bone-rc.tripod.com/id67.html

DarkHorse

> So far I've broken a driveshaft, a steering knuckle and a front upper arm.
I can see that could happen if you regularly hit solid objects at speed, something I avoid at all cost. Glancing blows, rolls, flips, 10+ cart-wheeling end over end, anything but the hardest instant stops, that are most likely to stress the steering/servo assembly and front suspension. On a stock power system and gearing I wouldn't expect it to be that easy to sustain the type of damage you mention, though temperature and bad luck would be influencing factors [].

With my original kit brushless build, a +500g truck at +30mph dead stopping on a curb [X(] is very likely to break something on any truck this scale. I have gotten away with it by impacting totally square on the front chassis, leaving the suspension undamaged. The battery was not very happy in such a shunt. Once cart-wheeled end over end so aggressively hard as to rip out the mounting thread from a Himaxx brushless motor and managed to pull the end cap off another Arc130 brushless motor hitting small jumps at speed. But the truck stayed in good working order.

If and when I break a suspension arm, depending on the break location, I was thinking of dremel drilling each break and inserting a 20mm M2 thread (cut the M2 head off) to screw fit join the broken arm together. Might be easier said than done though .
Loose or worn knuckles can be made tight again if thin layers of CA glue are applied to the sockets and left to dry or just back the screws with a washer to prevent detachment. If you over do the CA glue, it can be carefully strategically scraped away until you get a reasonable fit.

The front CVD can pop but again if the diffs are locked solid and full power is applied at full steering lock (high angle for most universal joint stress) then a plastic CVD could let go. More likely if landing at speed with the break on plus full lock with tight diffs. The joints are only about 1mm plastic spikes on a ball. There are some fixes for them as long as you have all the bits, haven't tried using any heat shrink wrap but did drill through to insert new ball spikes successfully (dremel cut down ~1mm drill bit end/blank).

...yes, I'm a bodger/fixer .

WalkerBoh

My Feedback: (7)

Yes it's cold here, but all of my running has been 60+ degrees (F). For all my complaining, I did manage to TQ and place 1st in the A Main in our local race this week. I broke 4(!) driveshafts in the process in 3 races, breaking both fronts (one of them an Atomic "Strengthened" steel shaft) in the A, finishing in 2wd. I guess I'll shut up now and keep tweaking until I get it right. Thanks for your tips!

-Aaron

Mini_Me

Congrats! Yea, those atomics aren't that good (had some myself at one point).

Here is a tip, don't remove those bottom rod extendors for the hub. They help protect the hub from going at too much at an angle jamming the universal which will either bend it or break it. In fact, keep that bottom one a little loose, and add a big thick dab of silicone glue (like shoo goo) on the bottom top A-arm where that rod hits. Sometimes under hard bangs, that rod can get jammed untop of the bottom a-arm and takes someone popping it back to get racing again.

DarkHorse

I don't know much about NiMh packs as I prefer the better energy density of lithium (given their handling constraints). The pack in the video was a long slow charge. I gave them a good cooking on 700mAh for 1.5hrs and they performed much better when hot. Not sure how this effects life span but a hot NiMh pack gives better performance and a fun ride .

DarkHorse

Weird , today in 37ºF (3ºC) my mate's m18t broke 2 rear hubs at the lower arm suspension points from 2 separate cart wheel crashes. Then I broke a front upper arm, a front hub at the lower suspension joint and bust the steering arm hoop connector. The m18t was building up to speed with the power at 100% and managed to hit my mates foot (sports trainner), he said it wasn't a bad impact but my m18t was mashed! [X(]. Couldn't believe it, after all the other days of bashing without damage. Sure, some accumulated composite material stress cracking could have occurred but this was a lot of damage on 2 m18t in circumstances we did not expect breakages. Take into account that both these setups are brushless 3s 11.1v powered (30-40mph), so the energy levels involved are way over stock specification. Maybe we got used to seeing our trucks blazing and are pushing them harder, even so I feel that the lower than normal temperatures played a significant role in crash tolerance of the composit material (more brital).


Temporary emergency fixes :

Upper arm fix: The arm broke in 2 places where they separate into a wish bone. I drilled out ~6-8mm angled into both arm stubs and the same into the remaining arm chunk, them inserted M2 bolts with the heads cut off (leaving a thread), slapped on some CA glue and threaded all together. Pretty good effort, time will tell. (update: think a while about getting good geometry and fit first, this fix has lasted ages without issue)

Hubs (identical front and rear): now when these break they can break clean around the joint or worse case split through the screw hole like mine did today. It broke in such a way that a fairly large chunk of hub rim was still attached to the screw fitting (knuckle fitting). This gave a large surface area to initially glue the rough break together. Left to dry and inserted the screw. Then with a ~1mm pilot drill bit, with a dremel, make holes across the hub case between the inner and outer walls, to pin through the breakage and into the hub wall . This is a bit tricky and you can easily spill the drill out of the 2mm thick hub wall. Then snap the ~1mm drill bit at the base to cover in CA glue and insert into the holes to help pin the original break. For some extra bracing reinforcement, wrap the area with cotton or CF thread and soak in CA glue. Just remember that you have to be able to get the inner hub bearing past whatever mod you make and that the CVD has to be able to rotate freely in that hub centre area.
This is all breakage dependant and in this case seemed the most feasible approach.
(update: this fix lasted a few sessions but did break again eventually. Suggest you swap left and rights or front to back to protect repaired joint by moving to top arms where the repair will probably be under less load stress from crashes)

Mini_Me

That T-bone bumper I linked to earlier is really a life saver for those "crisp" air runs.

DarkHorse

The RTR M18MT has had an easy life indoors, so has no damage and nothing to compare.





Breakage repair update: The temporary fixes on the m18t kit build (see spec below) held for a good on road bashing 9ºC (48ºF). It is apparent that the damage is accumulative and it's becoming a case of patching up problems as you go (not surprised the way I drive). Broke a rear plastic CVD (ball spike), replaced with one from the front. Though I have not bought any spares since the first initial upgrades a few months ago (front metal CVDs), which is soon to change...
The body shell is boot laced together in places with fishing wire, so many knocks that almost all the paint has been bashed off (even after a second spray job), the tyres are super bald, this truck is pretty ragged now but on the road.

m18t kit with metal front CVDs
Eflite-400 4200Kv
11.1v 3s 1320mAh Thunder Power Prolite
Quark 22A Pro Car
54T/17T ~35mph on a fresh charge.

bigairlife

Those t-bone bumpers are great. I am probably gunna order one enxt week for my carpet racer

DarkHorse

Still rolling...

Noticed that the plastic hubs that a few of us have been breaking at low temperature bashing/crashing are all from the older m18t kits. I had to use a couple of replacements from the M18MT RTR for my battle hardened m18t. The newer hubs in the later Xray trucks are slightly different, remember I said the tolerances felt different, well they are because the newer hubs have been beefed up and are about ~1mm thicker where they normally break around the rims where the knuckles screw in. Haven't been bashing long enough to know if the new version hubs hold up any better...

RC Huligan

I know ours are nitro, but we have been through a half gallon of fuel and here's the damage we have experienced with [link=http://rcglowplugs.blogspot.com/2007/12/first-tip-for-xray-nt18mt.html]our XRAY NT18MTs[/link].
[ul][*] Broken front shock: The receiver battery pack died and the truck took off. It hit a stationary basketball goal.[*] Rear differential: We have been adjusting our diffs and one of us locked the rear diff. It burned up.
[/ul]
Ours have been very durable. We've been really happy with them so far. The quality and performance is uniform through all 4 of them.

DarkHorse

Yes, given the quite excessive amount of crashing, we've had many hours of fun only carrying a few spare hubs and tie bar hoops. Compared to my old ThunderTiger ts4n nitro's which had a fun to fix ratio of about 1:10 and a lot more fragile, the Xray trucks a miles better value.

I saw the 4 M18NTs on your site, would be great if you could get some video of all 4 blazing around. There's only 2 m18t's on the attack here and that gets frenzied, so 4 nitro's should be great fun.[8D]

> one of us locked the rear diff. It burned up.
Ah, so that's what can happen if they are over tightened. Also puts a lot of stress on stock plastic CVDs.

> receiver battery pack died and the truck took off.
nitro's, yea I remember now... Grrr!!!![:@]

RC Huligan

I just got a new video camera and found out that Windows Movie Maker for Windows XP will not accept the MPEG-2 files from my camera. So now I'm trying to find the right video editing software. I'm definitely going to post the videos. It's only a question of when.

DarkHorse

haha under water Xray M18MT experience...

Yep I'm the lucky one hey, cart-wheeled out of control, down the bank and into stagnant farm land water pool. [>:] For less than 5 seconds, up side down fully submerged! [X(] Oooh, dashed over and scooped out the nearly new truck and could smell the Quark22A Pro Car ESC, all twitching an steam hissing nicely out of the ESC before I could rip the power leads off... cry cry. Drove home with a dripping wet stinking of electrical burnt components... stake and hair dry for 20 mins.

Does power up, BEC is just below 5v output and seems to work in my hand, forward, break and reverse. Still a hint of electrical smell, other wise normal. Spun up to throw the water out the bearings, diffs and motor. I loosend the diff housings off the chassis and didn't see any water. The metal geared servo and Rx are probably still a bit contaminated but functions. Your supposed to wash down with distilled water to remove deposits but I'm going to chance it. It's difficult to wash out those bearings and stuff on purpose when you feel you might be doing more harm than good. We shall see...

Anyone care to guess at what part of the Quark was hissing? Hot electrical tracks around the FETs maybe?

RC Huligan

Ouch! I feel for you. I'm surprised you're able to laugh about it now. I wouldn't be able to do that at least until my [link=http://www.teamxray.com]XRAY[/link] M18MT was running again.

fisheydude

Could you guys give a bit more detail about what happened when stuff broke [sm=50_50.gif]? Did you hit something head on, did the car/truck fall a big distance, hit the corner of the tire on a solid object?

I only ask so I know what to avoid when I get mine . The other 1/10 truck I have, I learned no head ons and landing from a high fall on all 4's. I have flipped the Vast Bonzer end over end, side over side, and landed in every way. The only time something broke was in head ons and when the truck lands evenly on all 4's from large jumps (which SHOULD be the way to land, too much stress on the shock mounting places I guess).

Anyway, what should I really watch out for?

bigairlife

Mine has been very durable so far. The only thing is that i am starting to hear a grinding noise at takeoff from one of my diffs. I pretty much locked the rear diff, but not all the way, and my front is really loose. Any advise? Anyone know what shims work? Do the rc18t ones work? I'll keep an eye on it, and i'll shim it, and then i'll replace them if i cant fix it, but i think a simple shimming should do the trick. It's just that i dont know which shims to use.

Thanks guys =-]

Mini_Me

No, you dont need to shim it. You also dont want to lock the diffs. That may in part be why now your hearing noise as the diff had no leeway, and so the drive gear took all the brunt of punching the throttle or landing from a jump. So you might need to but a new idler gear and loosen the diff gear so you get smooth action without it slipping.

bigairlife

Alright. I'll just order a new diff w/ idler gear just to be sure, and so i'll have a spare in the future. Thanks mini me

Mini_Me

It cost more, but carbide diff balls (especially in the thrust) help as well with diff life.