Another MBX6T Race Build.
 

Well, based on the current performance and recent development of brushless setups along with the quality conversions being offered today I decided it was time to get back to racing. I've been away from racing for several years now (~5'ish) so it was refreshing to see where things have come. Coming from a custom hyper7 extended, UE VBS/Racer-X setup years ago it was also nice to see the quality kit Mugen has put together. Very impressive indeed.

So based on my plans to build a racer I went with the mbx6t, RCM brushless conversion, Slipperential, Tekin RX8/1700kw truggy setup, lightweight driveline components, AKA's (cityblocks), etc.

Right now I'm trying to decide on batts. Planning on going with Hyperions but not sure on capacity or cell count. Originally I based the motor size on a 5S app for racing. I'd like smooth power with something in reserve without really overpowering the chassis/track. I'm thinking 5S is where I want to be for this app (shooting for 9'ish lb truck rtr).

The other concern is capacity. For a race setup, 2x-things to consider. Capacity and weight (for me anyway). I'm planning on having to run with the Nitro guys so a batt change will be in the cards for me. That being said, I don't want to stuff 6k worth of capacity into the truck due to weight.

Thinking 3000-4000 is where I want to be. Based on the specs from Hyperion, looks like roughly a 4.86oz savings from the 5k to the 4200mah setup (5S). Going down to the 3300mah setup saves me an additional 3.56oz and the 3000mah setup is another 1.41oz lighter still. Assuming the heats are ~5min plus warm up and additional lap and mains are in the 15-20min range, what are you guys who race running?

Pics to come tonight. :mdr:

Good choice man! I converted a 6T at the end of last summer (pre m-spec). Everything went together beautifully and converted smoothly. I have been running the rx8 2000 combo on 4s. Yesterday at the track I did 16 minutes from start to cut-off (full-on race conditions. No letting off at all). That was on Flightmax 5800's. I have been contemplating a 5s set-up, but am still happy with the performance and runtime of my 4s set-up.

The 6T with the slipper and Mike's battery tray are hard to beat. Get the Hotwire so you can really customize that esc. Everything is so predictable while driving. Here are pics of mine and the track I race at (that's a 25' double in the foreground). Also Running the 4.0 Calibers and Revolvers this year, those are bashing Panthers on there now, because the track has yet to be groomed this season.

http://i255.photobucket.com/albums/h...g?t=1269886580
http://i255.photobucket.com/albums/h...g?t=1269886620
http://i255.photobucket.com/albums/h...g?t=1269886692
http://i255.photobucket.com/albums/h...g?t=1269886615

Tedo,

Thanks for the response. I had actually been following your build here for a bit. Very very similar to what I'm putting together.

I planned on going with 5S solely for the efficiency boost plus it allows me to run a lower kv motor so a little more torque/less work/heat. At least that's the concept right now.

Mike's setup has been great to work with. Simple mod from my end (I did all the custom machining on my hyper7 conversion) so this was an easy bolt together option. Overall, the layout is clean and simple. Battery tray is large enough to offer options regardless of setup and the motor mount works perfectly for my needs. Hopefully it'll translate to fast laps and an easy to drive truck.

Love your body choice too ;) Same setup as mine actually. lol

How have you found the slipper to work for you? Being a mechanical designer, I can really appreciate the concept especially for direct drive guys. Any driveline protection is good protection provided it doesn't make it less reliable. I'd actually like to see Mike incorporate the Mugen outdrives for a small weight reduction (anything helps).

Overall, seems like your getting decent battery life based on what looks like a very fast track layout. Hoping I can get similar from a slightly more efficient setup running on 5S.

Truck looks wicked!

You should be able to use your Mugen outdrives (and many others for that matter) with the Slipperential. I'm not sure what outdrives come with the Slipperential, but the inner diameter was too small for my CVD shafts so I used my stock Caster ones (basically same as MBX5T) and they fit fine.

The slipper is a must. I was driving a converted 5T w/o a slipper and I separated a few rotors. Then again, it was the early days of the T8's (Tekin always took care of me, and had me running by the following weekend). You can adjust it throughout the day once the track starts getting loomier. Plus with the throttle profiles on the RX8 your motor stays very, very happy. I haven't run a fan since late September, and the hottest my electronics have gotten are 120 F. Pretty damn good. I am also geared conservatively. Started out 17 x 46, now I am at 15 x 46. The difference from 39-36mph is barely noticeable at our track. I can still dust the nitros before their clutches spool up (maybe a little exaggerated, but you get the point).

Also, I am on my second outdrives. The fist ones ovaled out (weak materials in the early versions), and Mike sent me 2 new ones for free. They are beefier than the stock 6t cups, but with our brushless power, I am okay having a little insurance. Plus we can save weight elsewhere: tires and batteries. Everything on the stock mbx6t is pretty damn good out of the box, and not many things to upgrade, if at all.

Oh, stock up on the 5 x 21 bearings (the weird size ones in the hubs), those get gritty all the time which increases rolling resistance, which decreased run time.

Get some pics up!

The stock ones on the 6T are not compatible with the slipperential. Mike's new hardened ones are the ticket.

Not working. The Mugen (MBX6 version) has a smaller dia. Both the outdrive shafts and pins are smaller so they don't work with the end plates of the slipperential (or larger spider gears). Unfortunately I tore them both down trying to make it work. No luck....

The other issue I had was one similarly reported here. One of the outdrive pins is/was too long. I did preassemble them prior to installing the plates to the diff housing but it actually didn't fit in the slot of the large spinder. I had to knock off roughly ~.060" to make it work.

Otherwise, went together smoothly...

So are you talking about the big boys that hold the drive pins in the cvd's? Those are some odd bearings. Can't wait to see what those cost... lol

Since your truck seems well sorted, how are you finding the handling on it compared to the nitro guys? I'd assume from everything I've seen, they really put power to the ground but I've yet to see someone putting down good consistent laps (least via video's). Overall, hpw does brushless truely hold it's own out there? I was originally going to stay nitro but just felt like going brushless was something I wanted to give a go. Seems like there are a lot of pluses once one gets them setup.

Yes, the inner bearings. Actually Avid has them for $1 a piece. I got the rubber / metal shielded ones. Put the rubber outside facing, and the metal side inner facing.

Man, as far as handling and holding it's own—there is no stopping it! The only other truggy that can touch it at our track is my friend's 2.0 (he is also the best driver). On one of my good days, If I am out front, no one can catch up unless I screw up (which happens to all of us). I guess this year there is a Z01T and a RC8T CE now... we will see what happens there, should be a good fight.

Bottom line, it holds it's own if not exceeds the nitros. The acceleration is instant and smooth. Very predictable every time. I also have slightly thicker shock oil than stock. I personally like that set-up, and I built my diffs 10/7/3K. All of these things come into play with the handling, and of course it's always different per track, and driver's preference.

I just got a Flip Minnow HD (I designed some of the graphics), so I will get some vid up in the next couple of weeks.

Again, great choice.

Ted,

Definately sounds like it should be able to put it down with the nitro boys. lol I actually raced 12th scale 6-cell mod about 15 years ago and it's been nitro ever since so this is a step in a different direction, one which I'm very much looking forward to.

I'm hoping I can get it setup pretty neutral initially and tune from there. I'd expect the 1700kw 5S setup to provide some pretty solid motor regardless of track size. Hoping the Tekin setup does what I'd expect it too. Seems like quality kit overall.

Love your truck. I'm actually in CT so I'm sure I'll see a few of the guys around here :yes:

Pics in the am. Cable at work :grrrrrr:

Update!
 

Well, finally got some the truck together. Took me a few days longer as I was waiting on a few pieces.

Overall, the build was smooth. Mugen has done a great job as has Mike with his clean integration of a brushless setup. No real surprises at all. I still need to revisit my ESC wrie routing and get my antenna sorted but figured I'd grab some snaps.

Overdue pics :mdr:

http://i23.photobucket.com/albums/b3...9/DSC_6649.jpg
http://i23.photobucket.com/albums/b3...9/DSC_6650.jpg
http://i23.photobucket.com/albums/b3...9/DSC_6652.jpg

Hyperion charger should be here Wednesday along with a few other goodies. Got my batts all wired with TRX connectors (prefer over all my deans stuff). ESC is cal'd and truck has moved under it's own power. :party:

Nice to see my M8 and KO digital still serving the cause. Also got my Spektrum module in and setup. Should work well.

Few things this week. Need to mod my 400watt Corsair Power Supply for charger duty and get my proline bulldog painted! Can't wait to get this out this week for some shake down runs!

Curious what you guys are doing for general break-in on a new mill and batts? Do I need to be overly cautious initially?

Also, with the RX8, when does/should the fan come on? It runs through cal but once I get through the initial setup, it powers down. I'll assume it's temp/load dependant...????

The fan comes on on pwer up and is dependent on temp.

Awesome build. You did a great job. You will love the Slipperential.

Can't wait to see it with it lid on.

I gotta say, the metal to metal gearing is a little loud. I seem to have a touch of run out with my slipperential so my mesh is a little lose right now.

Should work though! We'll see....