What should my MM7700 go in???

[zueslilbuddy]

I have my Mamba Max 7700Kv in my rustler, its a blast but I feel I may be wasting the power of this motor in the Rustler.

I really prefer offroad so street cars are out

What should I get with my tax refund to put my MM7700 in?

[GSMnow]

Get a Losi XXX-4 and a 12 tooth pinion.
I just put my 5700 on 2S in mine with a 16 tooth pinion and it flies. I can probably gear a little higher, but I am taking it easy until I get it dialed in. With your 7700, you should be able to hit about 50 mph on a 2S LiPo. Best part, the XXX-4 will take normal size batteries.

[zueslilbuddy]

I guess I should add I wont be racing much mostly bashing.
There will be a new indoor track soon but I really wont be getting into the racing scene.

[GSMnow]

I just ripped it up and down my street, and this thing is a total rocket. With some tires better suited to road, it would run right up with the best touring cars, and it has suspension travel to handle rough terrain and even jumps. Some people say it is on the fragile side, but I would put it crash survival rating up there with anything Tamiya has made. What type of surface are you bashing on, and what type of obstacles will you encounter?

[zueslilbuddy]

My home course is a mix of all surfaces, dirt, grass, and pavement,

[SpEEdyBL]

I have a xxx-4. Just double up the graphite shocktowers (use two at a time on each end) and get the front aluminum pivot brace/blocks and you are set. The drivetrain can handle pretty much anything.

[GSMnow]

I got about 30 minutes of track time on my XXX-4 yesterday. WOW, I have finally gotten a glimpse of the power of a Mamba Max. I only have the 5700 and it was wild fast. The track was in pretty bad shape. All blown out from the truggies with ruts and bumps and rocks all over. The surface was hard packed, dry, and very dusty. None of it mattered. with the 4WD it hooked up and launched to top speed (about 35 mph with current gearing) in about 25 feet. I was able to place it just about anywhere in the turns and it jumped perfectly. I was lapping everythi9ng else at the track. Of course I was the only 4WD running besides a poor running 1/8 nitro. They were all complaining that the track needed grooming and water. They were right, but the XXX-4 just ate it up and ran away.

[zueslilbuddy]

Got a pic of your current set up GSMnow?

[rccardude04]

GSM, do a whole battery pack of double backflips (and no cheating, you have to land on the lid every once in a while. ;)) above head height and don't break anything, I'll agree it's as durable as the DB01.
-Eric

[GSMnow]

Why would I want to do back flips??

The CG of the XXX-4 is so low, it barely lifts the front end under full acceleration. It is hitting 35 mph in just a few feet, so it not that it is not pulling hard, it just plants and shoots. I can't get the slipper clutch to not slip though. I am sure if I pinned it locked, it might float the front tires, but the traction of this chassis is just wild. Come out of a turn as fast as you dare, and HAMMER IT. Almost no wheel spin, turn radius just widens a tick, and it rockets to the next turn. Balance holds almost dead neutral. Coast or light brake into a turn, and it can get a little loose, but mash the brakes and it will push on entry with the strong brakes on all four wheels. My fastest laps of my cul du sac test area (I used a sewer cover, water shutoff lid, and a pot hole as three points to make a course) was achieved by braking right before the turn, lifting to a nice neutral to slight oversteer on turn in, then rolling on the power until straight and them full on til the next turn. The end turns are 200 degrees, and the middle one is about a 90. I did flip it a few times on the 90. I was able to carry it much faster since it is only a kink, and the tires bit too good once they got hot and it traction rolled and ended up flipping about 4 full rolls. When the tires were cold, it would do a 4 wheel drift in that turn, and just step about a foot sideways. I reversed the lap direction, and it took about 3 laps to get the line and back to insane sped. And sure enough, I flipped it going the other way at the same point. I wish I knew how many G's it is pulling at that point. It must be over 2G's as it looks like a cartoon changing direction that fast.

So, yes, I did flip it on it's lid, about 5 times total today, 2 of those were very violent and I was very concerned I broke it, but so far, no cracks anywhere. I just put it on it's wheels and kept driving.

I will get some pics soon and post them. I will miss yet another race night. I have to go to Vegas for work. But hopefully Sat. I can run this beast up against all the B44's. It handles, it jumps, it accelerates, and it brakes better than ANY RC car I have ever driven before. And I have driven many. I drove a Novak 5.5 powered B44, and my Mamba Max will blow it away. The B44 did handle good, but I like the fel of my XXX-4 better. It seems to be more stable, not as nervous, yet not pushing, it just has more grip, and we are on the same tires. And I think the track was in worse shape when I drove mine as it was a practice day with no grooming like the end of the race night when I tried the B44. I can't say the B44 is a bad car at all. It is a great car, and I think with some dialing in, it could do what the XXX-4 is doing, but I am just using the out of the box setup, and it is dialed. Toss in my extra power with the "basher" power system, and it just plain rocks. I will report what (if anything) breaks once I actually race it on course, with competition.

[rccardude04]

LOL I was just giving you a hard time. Backflips were my durability test. Had the stampede out but I got some kite string (little brother) wrapped around the front tire and I didn't have tools with me, so I busted out the Durga. Double backflips are impressive by the way. Single is cool, but 2 is just a big grin waiting to happen.

I know the feeling with the acceleration... I think it's a Mamba Max + 4wd thing. My co-worker is pretty sure if we raced a relatively short distance, it'd take out his 1/8 onroad car with the $700 11-port novarossi from back in the day.

Oh, and your car sounds like a typical Losi. You build it right, throw it on the track, and nothing else in the world will handle better. They might get close but never quite there. :D

-Eric

[tireshredder]

XXXT MF1 is fun with SideWinder 4600! 18-78 w/ little 2-5/8” foam tires. Ran about 30 min. then motor revved up and it came to a halt. Diff was loose, DOH! (didn’t hear it runnin with those noisy nitros). Tightened it very tight (thought it maybe OK). Made another 5min. and it slipped again. This time I got nothing! (Diff was still super tight and only friction drive to either wheel). Oh well, nothing that time and money can’t fix! BooHoo! Way too much torque!

End of full run, about 13 min.
IB4200s 125F
ESC 102F
Motor CM4600 138F

Tight road course

GSM, Likely more due to cleaning the line than tire heat. We run parking lot tacks and traction goes way up after running a few pack and blowing the dust from the racing line.

I don’t think a MM7700 is a good basher setup for anything. Best for a 1/10th 4wd on-road sedan 6 cell NiXX, great race setup.

[929rog]

I have a 7700 in a xxxt with lipos and its awesome. Probably way too much to race and a handfull to drive... BUT... Big smiles,broken parts, and leaves non RC people in total amazement. I'm going to buy a 5700 or smaller as well as I might try racing, but the 7700 works great. It was getting a little hot but I got a heat sink on the motor and a fan on the esc runs a little cooler. I did not think the 7700 was that crazy on 6 cells geared down. Lipo is a whole different story.

[rccardude04]

tireshredder: Next time you rebuild the diff, when you put it back into the truck, put the screw head on the side opposite the spur gear (left side when viewed from driving position).
Also, the 7700 is WAY too fast for a track. It's intended solely for bashing, but also works for speed competitions and drag racing apparently.
-Eric

[GSMnow]

I turned my diff around when the outdrive were getting very worn from the torque. I had no trouble with the diff the other way. It is just much tougher to adjust it. When I put in the new outdrives, I did flip it back around to have the screw on the left. With any Mamba Max (or SideWinder) you really need to run the diff TIGHT!! if you want it to live. I run mine just short of where it is no longer a diff. I test it by lifting the front tires just off the ground and moving it side to side on a smooth surface. As long as the rear tires roll in opposite directions, you still have a working diff and may be able to run it even tighter. If the tires skid on the ground, then you are too tight.

[929rog]

Whent to the sand pit next to my house today with my new sand paddles.. 35 MPH wheelies!! Way too much fun. The motor did not get hot but the ESC get pretty hot. It works pretty hard in the sand. Losy another Diff after about 15 minutes. My fault, I run them real tight too but I find you have to check them Alot. I've lost 4 diffs with the 7700 now. Good news is I always have them in stock. Back to the pit tomorow!!

[rccardude04]

GSM, what I've found over the years is that when the screw is on the same side as the slipper, it tends to want to loosen itself. I always build those trucks with the screw on the left so that they naturally try to tighten themselves.
-Eric

[929rog]

so put it in "backward" from stock? Makes total sense.

[GSMnow]

Actually, screw on the left side, opposite of the slipper is the stock direction. For the screw to loosen itself, the thrust bearing would have to be binding, and you would need to be turning right. The torque on the adjusting screw should be nearly the same with the diff in either way. If it slips, it might be more likely to loosen with the screw on the right, but that is still very unlikely the way the diff is designed. The screw head is on the thrust bearing to one out drive and the nut is keyed to the other out drive. The only relative movement in normal operation is the diff action as the car turns. With the screw on either side, the diff action will always tend to tighten the screw on left turns and loosen it on right turns. But again, the only torque trying to do this at all is if the thrust bearing is not rolling smooth. I use the Losi heavy duty thrust bearing kit. I think it was LOS A-3018.

[zueslilbuddy]

popcorn popcorn

This is all a good read guys but its way off topic and I'm not really sure I even want a XXX-4

The topic is .............................................

What Should I Put My MM7700 In?????

[rccardude04]

Some other 4wd buggy. I have a Durga (Tamiya DB01 chassis) and it is phenominal with my MM6900. I upgraded to a Hacker C40-7T and I'm not as happy with it as I thought I would be. The 7700 should run well in there, but make sure to pick up somewhere around a 15t pinion. My 6900 was about right with the stock 17t pinion, but the 7700 will no doubt overheat with that combo.

The high power systems really work best with 4wd, especially buggies because of the lightweight wleels/tires compared to an equivalently sized truck like an HPI RS4MT if you remember those.

2wd is fun if you like wheelies, but the 7700 is a bit too high of rpm for most applications.

You could always get a touring car... TA05R, TC3/4/5, XXX-S, or even that new drift car (Drift-R). It comes RTR but it wouldn't be hard to swap over your brushless and the high torque of the BL system would be nice for a drift car.

btw, big text is annoying. :)

-Eric

[zueslilbuddy]

lol I know but I've been looking at what to buy on tower and other sites and just looking for suggestions and the thread got a little off topic.
Nice to make a thread with a bunch of posts but just would be nice if half of the posts were topic related. :D

[ksb51rl]

popcorn popcorn

This is all a good read guys but its way off topic and I'm not really sure I even want a XXX-4

The topic is .............................................

What Should I Put My MM7700 In?????
Perhaps an ebay auction? I like my MM7700 Rustler just as much as the next owner, and probably mmore :) but I saw 160ºF temps last weekend just from driving around a dirt oval (75ºF ambient.) Geared 13/86, I believe. Bashing is just gonna make those temps climb, and extended running in the grass is out of the question. I'm much more confident with my MM5700, but even then my IR thermometer never actually goes in my pocket, but is clipped outside of it.

[929rog]

I have a Novak fan on my MM ESC and used a Novak brushless heatsink on the motor. Helped no question. If you get the heatsink it looks like a V, you have to make a cut in the back to make it fit. What are you using for batteries? When I went to lipo motor temps went way down, but the ESC was still pretty hot.

[GSMnow]

As far as the original topic here...

Where do you want to drive?
what is the surface?
How big? how rough? Flat? bumpy? jumps? clean? dirty?

The MM7700 is a very high current, high rpm motor setup. You need a vehicle that will allow you to gear it down to let the motor rev up, otherwise it will get hot. By nature, offroad racing is not a good fit because of all the slowing and accelerating done lap after lap. For example, my race last night had a top speed close to 40 mph, but the lap average was just 11 mph. I think it was a bit faster than that, because it uses an estimated lap distance, but you get the idea. The 7700 is well suiteed to a lighter car that is run in a very open area where you can keep the speed up. A touring car on a large open track or a big parking lot. The XXX-4 that I run is a great car, but in the real world, you really will be on the ragged edge to gear it low enough to keep from melting the 7700. In theory, a 12 or 13 tooth pinion should do the trick, but the current will be very high and the battery will be totally stressed out. The real problem in your case is that the spur to wheel ratio is just 2.1

I do believe that a 4WD off road chassis would be the most fun and versatile. Just by changing the tires and suspension setup, you can run on virtually any surface. My car is equally at home flying through the tough dirt track, or flying across pavement at insane speeds. Touring cars and 4WD off road cars share alot of development, and even parts. I could run my 4WD buggy on any touring car track or parking lot, but you could not run a touring car on a dirt off road track.

[Bnoland]

I have a 7700 in my B44 with a 19T on it and it's great. It fully unloads the front suspension. Front tires are bald and I have only run about 3-4 packs thru.