cool. Let us know how that center diff works out there. I know the mgt is a long truck. That is what I like about it.

Well it's up and operational.
As usual, my projects aren't pretty, just functional :)

Here are the latest specs, pics, and a short video:

MGT Stock pieces are the chassis and suspension.
BlueBird (BMS) 621MG Steering Servo
(2) 3s 3200 FMA/Kokam Lipo packs in parallel (3s2p)
MGM 12012 Speed Controller
Feigao 8L Motor (15T Hardened Steel Pinion)
OFNA Ultra Center Diff (51T Nylon Spur)
(2) 12v CPU Fans

<img src="http://i20.photobucket.com/albums/b239/1joeyoung/Brushless%20MGT/Overhead_With_Batts.jpg" alt="Image hosted by Photobucket.com">
<img src="http://i20.photobucket.com/albums/b239/1joeyoung/Brushless%20MGT/Motor_and_ESC.jpg" alt="Image hosted by Photobucket.com">
<img src="http://i20.photobucket.com/albums/b239/1joeyoung/Brushless%20MGT/Overhead_No_Batts.jpg" alt="Image hosted by Photobucket.com">
<img src="http://i20.photobucket.com/albums/b239/1joeyoung/Brushless%20MGT/Left_Side_Close.jpg" alt="Image hosted by Photobucket.com">

http://www.rcpics.net/view_single.php?medid=64321

I'll be soldering up a 10L and seeing how that handles it compared to the 8L. The speed control got up to 130 pretty quick with the 8L, so I'm hoping for lower temps with the 10L.

Great Job Batfish!!! I am still trying to decide between stock tranny, center diff or modd'n an Emaxx tranny into it. Is the diff on its side?

Sweeeeet, Joe! I am very curious how this performs on a track with this center diff. Looks pretty good for the hack job you described!

Nice! How do you like the handling on the center diff compared to before?

Now you have no slipper in your driveline, correct?

Lookin' good! From the vid, it looks to have about the same power as my MT2.

Joe, may I ask what's your Final Gear Ratio? I guess the MGT has some kind of 8th scale buggy diffs.

Just curious.

Thanks for the nice words :)

Now some answers and more details.

Yes, the diff is laying on it's side. Since the diff mounts are indented on the sides I figured that would be the best way to mount so I could put the motor overhead. I wanted the motor in-line in the center of the chassis, not off to one side. I would have had to mount the motor on the side if I stood the diff up normal.

There is no slipper mechanism in the drivetrain now; correct. This should be offset by the diffs overall (I hope).

The handling feels more stable to me. I think it's a result of a lower CG now. In the video I tried to get it to flip sideways and I'm very pleased that it showed no signs of doing so :)

As far as the gear ratios, hopefully one of you math-magicians can get the final stuff based on this:
A - According to AE, the MGT diffs are a 3.31 ratio.
B - According to info at Tower, the OFNA diff has (2) 18T gears and (4) 10T gears.
C - 51T spur and 15T pinion.

Here's a marked-up pic. There are descriptions of each number below the picture.
<img src="http://i20.photobucket.com/albums/b239/1joeyoung/Brushless%20MGT/Left_Side_Close_marked_up.jpg" alt="Image hosted by Photobucket.com">

1 - Three parts that show how I mounted the diff.
*The arrows on the bottom point to underneath where I used the original OFNA center diff top plate as a template for drilling two holes to mount the diff.
*The two circles in the middle show where I cut/filed the top posts to allow the diff to fit a little better. I cut/filed about 4-5mm off and ended up putting washers in to get some of it back and even the front and back so the diff would be square with the motor.
*The drawn part on top is a piece of aluminum I had previously drilled to be my template when I was going to mount the Ultra diff in my Hyper 7. I used half of it to keep the diff from pulling the mounts apart during running.
(As a note on the diff mounting, It's currently held in by only 2 screws because I don't feel that the diff needs to be mounted as securely as in a buggy because it only serves to turn the dogbones and not as a platform for brakes or anything else.)

2 - Shows where I filed and dremelled about 2mm from the chassis to allow the spur to fit.

3 - Shows the ESC. The drawn purple is showing the foam under the ESC. I used part of a 2.2 truck tire foam shoved underneath. The zipties are run through the holes for the nitro engine mount. I'm very happy with this setup and will only change it if I have a need to mount the ESC somewhere else.

4 - Shows the fan setup. I raised the rear body posts to the second hole, which allowed for the two CPU fans to stand and be ziptied to the rear tower and post mount. I wired the two CPU fans into the battery leads on the speed controller (another great thing about PowerPoles; I just pushed the wire into the connector and taped it there :) ). The fans put out a very nice airflow on the 11-12v from 3s lipo.

5 - Shows the motor mount attachment. I used two of the original tranny mount holes on each side. The screws are long screws from my XXX-T screw kit and the 'spacers' are 8 E-Maxx wheel nuts from my E-Maxx screw kit. Using different spacers can get the mount higher or lower, plus I cut the mount to allow for moving the motor up and down about 1cm for different gearing options.

6 - Shows where I cut away the original battery box. I needed the room to mount the lipo pack. I left the plastic "wall" from the battery box as a possible mounting location if I do end up using a receiver pack at some point. I can just attach the pack to the wall via zipties or velcro.

I'll be bringing it with me when I race this coming Thursday night. I hope to get a run on the outdoor track before the indoor racing begins.

Let me know if there are any other questions :)

You may want a couple more screws holding the diff. "only turns the dogbones" is true, but this means power and brakes for a heavy/large truck. You have until Thursday to address this! :).
Also, rather than spacing the entire motor mount, you could remove the material at the motor mount itself(where the screws go through) in stright lines (up and down), so the motor itself could slide upward or downward instead of the whole mount. This would be easier to adjust, as well as allow the flat section of the angled aluminum to rest flat on the chassis-more stable as well. :)

Nice write up. I enjoyed this post! Thanks for sharing.

I thought similar things as Mike. The diff mount has to hold up against quite a bit of torque. A few more screws wont hurt.
I would suggest mounting the fans closer to the motor and ESC. One on the motor, one on the ESC, for example.

Still, I like your work. Must be an awesome RC.
btw, Joe, you're quick! I suggested this Centerdiff like 2 weeks ago, and now you have it running!

I had planned on attaching the mount directly to the chassis, but the aluminum I have isn't tall enough. I have 1.5" and need at least 2" to accomplish it. You can actually see the cut-out I made to allow it, but the motor needs to be high enough to mesh with the spur, which means I'd have to go at least 1cm higher. As you can see, my aluminum elbow won't allow for that. Also, I did channel the aluminum to allow moving the motor up and down. That's described in a previous post :)

I plan on moving the fans once I'm sure I have things where they will stay. In the meantime, the 'fan tower' keeps them out of the way while still allowing for cooling.

The diff is held in with a little more than just the 2 screws, but not much more. I shoe-gooed the aluminum piece on the other side of the diff to the chassis. I can get at least a 3rd screw (if not a 4th) into the other side. I never bothered to mark the chassis on that side so I'll have to take it all apart to do it.

Noone has given me my drive ratio! :) Have you guys lost your touch? heh

Hey Joe,
Nice work, I like it :cool:
The internal gears of the ofna diff won't effect the overall ratio.
So, with the 3.31 ratio of the diff and the 3.4 ratio of the spur/pinion your overall ratio is 11.25 to 1.

I now have the 10L/12012 combo set up with 12/51 gearing on the center diff.

This Thursday night (10/6/2005) should be the first night we run electric monster truck on the indoor track :)
I'll have my MGT up against a G-Maxx with the HV-Maxx as well as at least 2 E-Maxxes running stock Titans. The 2 E-Maxxes have some suspension upgrades, but no powertrain upgrades (as far as I know).
This will be the first race outing for the Brushless MGT.

I'll report back on the success :)

I take you must like the setup. I watched the video of you testing it. It looked to handle good. Let us know if you beat the boys down.

how is the hv maxx systeM? i know it's no where near as powerful as other combo's but just wondering

You can think of it as a power progression:
Low = stock Titans
Medium = HV-Maxx
High = various assortments of the systems you see here at RC-Monster.com, including BK/MGM/Feigao/Lehner.

They also rate the same in relative level of difficulty to install:
Low = stock Titans (easiest since the vehicle is RTR)
Medium = HV-Maxx (drop-in replacement, only the possible need for pinion/spur adjustment)
High = systems sold here (requires soldering connectors, changing pinion/spur in most cases, matching motor to controller, finding mounting locations for the controller, adding proper cooling where needed)

If I didn't know these high-voltage/high-power sensorless systems existed, I'd be ecstatic to have an HV-Maxx. Heck, I'd still put one in my stock E-Maxx if it didn't cost as much as the other systems sold here. :)

Nearly all of my driving is on a race track where anything over 30MPH is pretty useless. The HV-Maxx fills this requirement while barely breaking a sweat. The other systems here will do that with even less effort and are capable of much, much higher speeds.

Hope that helps!

cool yeah...cause for a moment i was thinking of getting it for this truck cause i didn't wanna tear it apart but i figured for the same price i can go higher quality...i'll have ot find a way to mount a fan and all though

I have decided that, since I never bash with this truck, I'm going to see what I can do about making it into a solid race truck.

First step was better tires, so I got Pro-Line Velocity Maxx size wheels and Pro-Line Crime Fighter tires.

Second was to see if I could lower the ride height and still be able to race/jump with it. At this point it may be too low, but it's very stiff so it may work out okay. These pics are where the height is now.

Once again, I'll be trying this out on Thursday to see how it does. If it actually stops raining and dries up a little, I'll be able to test in my yard sooner. I can run it off of my deck, which is about 2ft high to see how it reacts, and my bumpy lawn is similar in roughness to a rough racing track. We'll see how it goes.

<img src="http://i20.photobucket.com/albums/b239/1joeyoung/Brushless%20MGT/MGT_Front_2.jpg" alt="Image hosted by Photobucket.com">

<img src="http://i20.photobucket.com/albums/b239/1joeyoung/Brushless%20MGT/MGT_RSide_2.jpg" alt="Image hosted by Photobucket.com">

what kind of shocks are those? they look like jato or revo shocks. got a picture of the chassis?

Yep, I got a picture, but I'm going for a little suspense until I find out if they work okay first ;)

Looks great fishbat! :D

Hey, I might be picking up an mgt for a project. It has the basic necessary upgrades but not much else. I'm looking for a fairly easy/durable conversion to do for 12 cells. I figure i could mess around with battery mounting myself, but i need a setup for the center driveline/motor mount.

What would you all reccomend? Gorillamaxx Single Speed? Ofna Mbx?

I'd run the 7xl. Thanks.

gorillamaxx single speed.

-corey

http://www.rc-monster.com/forum/show...4&goto=newpost
Here is a nother mgt thread you chan look at. It has the driveshaft lengths and such in there.