Losi MMT concept/prototyping

T_Tank

Well-Known Member
As I been lurking more in the rccrawler forums while working on a set of custom axles I ended up also designing something fun for those that might want a smaller monster truck build.

So here it is the Losi MMT
Scale:1/18
Wheelbase 209mm aprox
Width (tlt-1 tire/wheels) 210mm aprox
Hight 150mm aprox
Body compatibility:mini LST bodies or similar sized bodies
Servo size: 1/16 traxxas sized servos
Shock length 77mm











Current setup in the photo doesn't show well but that is infact a 540 motor and the VXL designation is for the trans plate setup to use a 1/16 traxxas trans!

Still working on figuring out a good option for batteries though may just go setting it up to use thunder power air batteries since they are best size,capacity,output I've looked at.

ESC mounting is till being figured out aswell.

Features of the chassis
56mm inboard distance like stock aswell as mrc style hole pattern so can use other transmissions
Cabin cage can flip up after removing two screws to access battery and esc
front nose section setup to fit spektrum SR300WP or OrangeRx GR300
Tube thickness is 4.5mm with screw areas 5mm to 6mm

Fun fact on axles is the ring gear can be flipped either way you choose and modular link/shock mounts!

So have any questions or concerns I need some folks that know go fast to bounce thoughts off of!
 

T_Tank

Well-Known Member
Small update on the frame finally figured out a battery box accepts battery packs that are 69mm X 46mm x 18.25 about the size of some 2 cell and 3 cell losi mini lipo packs.




Now brain scratching goes into figuring out what kind of ecs would be a good option that doesn't make people break the bank that can handle 540 brushless motors in sensored or sensorless.
 

Manfjourde

Contributor
This looks cool, will the axles hold up to a 540 setup and the bigger tires?

Maybe a 380 size motor in a 540 can for a bit less power yet plenty for something this small. I love minis and in encrypts to see where this goes.
 

T_Tank

Well-Known Member
Well the tires are are about 3.5" so they are actually smaller diameter then the stock losi crawler tires might even weigh a little less compared to the stock or close to the same.

Now the question if the diffs can hold out I'm sure the ring an pinon in the axles will handle it fine in such a light weight setup. Now as for the vendetta diff gears... they "should" survive compared to a mini lst's stock diff internals, unlocking the merv trans with a center diff should provide better health for the axles to.

I don't have a 380 vxl mount handy for my merv trans to figure out the distance between the underside of the motor mount distance to the chassis mount on the axle though don't think that changes between them could be wrong though down the line it be nice to figure out.

I'm debating on redesiging the frame to use 3mm thick tubing throughout but increase in size for where screws go in but that might make the chassis a little more frail at 4mm the printed stuff stiffens right up and does have minor flex. Chassis rocking 4.5mm thinking how i drive and how I jump doubles this thing needs more beef!

Here is a idea how the stance width with a mrc with tlt-1 wheels looks
 

T_Tank

Well-Known Member
Update on the axles shown in the cad model 2nd revision came out fitting just a smidgen tight on the bearings but everything turns over freely and holes line up and fit the stock mrc plastic parts like the stock axles!

Just need to grab some losi end links so I can rebuild the upper 4 link on the test rig!






Ignore the ball stud on the axle that was for a panhard bar but it was causing a few to many issues on the test rig and even stock axle needed a few mods

Servo in the picture is also shown in the pushed back configuration which happens to clear the chassis brace on the 3D printed wild willy chassis I have.
 

highroller

Well-Known Member
This looks super cool, I think you should post it up in the general section. Not many people check this section.
 

T_Tank

Well-Known Member
Figured this be the more correct place for a long winded concept to built product.

I'm very happy with how the axle turned out just need some adjustments so the front cover fits flush with the back half without to much tension!
 

im2tall

Well-Known Member
I've Been Gone 2 Long !!!!

Well Da^n,you've been busy!!!:cool:) You know my MMT is sitting right here on my desk in a box,with the all new electronics,and my lazy ***** stll didn't assemble it,and rebuilt the Ground Pounder last week!SMH! Atleast I have something to post later!:eek:! LOL!!
 

T_Tank

Well-Known Member
Finally able to order some prototypes of the chassis with the exception of the right chassis section and batter holder. All should be in at the end of the month! Wish me luck!
 

T_Tank

Well-Known Member
Well to my surprise some parts have shown up early!

Only the L side chassis "frame" and trans adapter came in this order but gave me some good viewing of stuff I should fix of simplify.

I'll show off it all "assembled" with a stock losi mini crawler side plate on the opposite side which lined up with the trans mount flawlessly



Then on the other side you see the chassis itself feels rather rigid for not having the center parts an the other chassis section. Pretty good for nylon!



shot showing the width of the chassis between the trans mount, as you can see this chassis will accept a stock losi mrc transmission!



Here is a pic of my mini lst body sitting over the chassis what you guys think?



Finally in this shot its a closer look at the body mount solution I went with. Its using stock mini lst body posts but if you want something tougher I think we can still find gpm alum ones or even make some body mounts of our own.



According to shapeways I should to another pleasant surprise get the front center, rear center and roll cage parts in tomorrow!

I haven't ordered the right side or battery box yet as I'm gonna check some eyeballing with the transmission now in to make sure I brained right on the angle I gave the battery box to fit as low as I could in the truck.
 

im2tall

Well-Known Member
I rounded out the rear diff twice,did contact somebody about the issue,but struck out,I think I'm just gonna put a locker in the rear,and keep the front unlocked for now!!
 

T_Tank

Well-Known Member
You mean stripping the internal gears in the differential or the ring and pinion? Do wish there was a way to get metal gears for the diff..
 

T_Tank

Well-Known Member
double post sorry but more parts came in!

cage, front, rear center cross members are installed finally!



side by side with a slick rock cage



lot of clearance for the cage part wonder how it will look with other bodies

 

im2tall

Well-Known Member
You mean stripping the internal gears in the differential or the ring and pinion? Do wish there was a way to get metal gears for the diff..
Yup the internal output gear,only on 1 side too,I think the green gears may be the HD ones,I'm gonna buy a few this week and see what happens,I have the blue,which I assume is the stock ones,I'm not sure but I'm gonna give that a shot before I pop a locker in there.
 

im2tall

Well-Known Member
I just noticed that body is short,and your chassis shock mounts are gonna be at an angle with a decent wheelbase for that wheel size,and if you use the MRC shocks,it more than likely gonna be squatted like a race truck. You're gonna need a mini revo body,and way to straighten out your shocks to be more 90deg as opposed to 45deg. Basically it's gonna sit like my MMT in the 1st couple post in my thread you'll see what I'm saying!
 

T_Tank

Well-Known Member
part of the issue with the body shots is the perspective the inner most holes on the chassis would have a steeper angle middle is slight angle an outermost holes would be just about straight.

The mounts on the chassis have 3 holes so I can move them back an forth if needed also not using wideners with my mmt with the tlt-1 wheels so I should... in theory have a wheel base almost the same as wide as the truck. If need be the forward most shock mount holes should get me to 80 to 90o. MRC shocks are the right length.. just need to get a rebuild kit for them and get mini T ball studs so the shocks will be closer to the chassis

Body in the pictures is a mock up but was what I tried to use as a reference for size but was aiming at using a different mini lst body but goal is to be able to use most 1/18-1/16 scale bodies.
 

T_Tank

Well-Known Member
update got it kinda setup as a roller right now may need to re think the rear link lengths for some clearance fixes for the 540 mount this "shouldn't" be a issue with smaller motors or the losi trans.

I think I need to eyeball some wider traxxas wheel hexes to get about... another 8mm out on the wheels to get them to the desired width

also need to go buy some correct length turnbuckles using a large mix of different ones its all "kinda" where it needs to be

anyways less talk more pictures







and now with body!



 
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