Get rid of the worm drive?

[mwe-maxxowner]

I have toyed with the idea of turning my mrc into a mini monster truck. Limit the suspension travel a little. Different tires, speed it up some, monster truck body. Something that reacts and handles more scale than something like the mini summit or mini revo. I don't find myself crawling the mrc much any more since I have a larger vehicle to crawl.

Is there a way to do away with the worm drive tranny, so that I did not have drag brake on if I didn't want it? Full on drag brake and speed don't mix very well. Lol. If I ever wanted to go back to crawling I could add drag brake with my ESC (mmp or sidewinder).

[89redranger]

There are no worm gears in the trans OR axles of the Minis. Yes, they are VERY low geared but the drag brake is all in the ESC programming. Regardless, without a trans swap or stupid high KV brushless, you're not going to get the kind of speed you're looking for. Many have pondered the idea (myself included), many have tried, and I have yet to see a running example. Not to say it can't be done, there are just a LOT of hurdles to jump to get there.

[mwe-maxxowner]

Ahh thanks! I thought I'd read it was worm drive. Perhaps that was the micro?

I'm assuming the speed issue is just because of the ratio inside the tranny and the axles? I'm only looking for 20mph or so. Would a 4000kv on 2 or 3s not do it?

[EeePee]

We have a whole forum of/for Losi Micros, it would take three seconds to look.

[winnerone23]

Originally Posted by mwe-maxxowner

Ahh thanks! I thought I'd read it was worm drive. Perhaps that was the micro?

I'm assuming the speed issue is just because of the ratio inside the tranny and the axles? I'm only looking for 20mph or so. Would a 4000kv on 2 or 3s not do it?

Lol.. 20mph in a mrc.. I want to watch!

Don't get me wrong.. It would be cool! But the drive train most likely wouldn't hold up to the torque of a motor, that would make it go 20mph..

I guess, I had a mini ofna, that got some speed to it. It was running a mini brushless motor.. So maybe.. But it wasn't a monster truck and didn't go over rocks or thru the woods..

There was a thread around here and video, of a scale mini Toyota pickup. It had open diff's and everything.. It was a cool ride.. No monster truck but maybe it will give you some ideas

[mwe-maxxowner]

Thanks for the info and advice guys. Bear with me. I have an mrc, but I've never torn into it much. Never needed to. I moved the upper shock positions, lowered the ESC, installed a 1/10 servo, put the battery over the front axle, installed aluminum spools, and called it a day. So forgive me if some of these questions seem absurd.

Has anyone ever modified the tranny ratio, eliminated the tranny, or shoe horned a different tranny in?

Are there other axles that can be made to work on this, that perhaps have open diffs?

Does anyone know the tranny and diff ratios on the mrc, or know where to point me to find them?

When I first thought the idea up, I was considering the mini vxl 4000kv 380 motor. I know it to be tough, and seems like it would fit well. I'm willing to run 4s through it and torque limit the daylights out of it. Lol.

Am I to take it that the gearing can't be changed much with pinions and spurs like the vehicles I'm accustomed to? (Mostly traxxas stuff)

I just really like the idea of a solid axle this size to tool around with. I imagine it taking off and twisting and behaving like Bigfoot . But, if it's a hopeless endeavor, maybe I should just satisfy my urge to tinker with it by making it an even better crawler. (I'm quite pleased with it as is though)

Below is the truck in question:

Originally Posted by mwe-maxxowner

Here's my truck, in all its glory! (Or lack thereof)

Since then the body posts on the side were removed, and the upper shock mounts installed in the holes that are there.

[mwe-maxxowner]

https://youtu.be/7Dxptm5aqRM

The truck in this video would be plenty fast. Is there any way to combat the chassis twist? Some is desired, adds to the realism, buy not that much. I'm guessing stiffer springs, maybe with some creative preload, but is there something else that can be done?

[JBcustoms]

You could play with pinion/spur combos to get the wheelspeed you desire. Not sure about how well the drivetrain would hold up to abuse though. I am currently in the process of buildi g a semi-scaler out of a losi mini and added a trazzas summit trans as a transfer case. The summit trans has a ratio of almost 2:1 so I needed to double the output speed of the losi mini trans. Went for a 50t spur gear from a mini lst and planning on using a 22t pinion to achieve the ratio I need.

[mwe-maxxowner]

The mini summit trans? Do you have a build thread?

What are weak links in the drive train of this thing, and are there upgrades to help with them?

[T_Tank]

If your looking to use a traxxas 1/16 VXL trans 71074 which has the 380 motor mount there is another version that uses larger 540/550 (use one of these in a tlt-1 mt)

To overdrive the axles use traxxas 7079 ring an pinion (only use the pinion gear)

Finally to unlock the diffs (which you will want to at least in the front) use duratrax vendatta DTXC7448 diff gears you might need to make some shafts for the spiders to ride on and also need to shave the larger gears to be thinner. A sorta guide on how to get the vendetta gears in to the mrc diff case can be found here Im2talls MMT - Page 2

As for tires I'd extremely recommend tlt-1 tires as they are about spot on for scale an then look at losi mini LST bodies to get close to the scale even more.

If you order a castlelink for your mmp should be able to set the drag on it I'd think.

Look forward to seeing someone make a mt out of one of these little trucks I think you could get a spot on 1/18 scaler monster going that least hits 20-30mph (yes the ring an pinion can handle that mini lst shares ring an pinion, the vendetta diff insides will handle the power aswell and the traxxas trans is darn near bomb proof)

[mwe-maxxowner]

Originally Posted by T_Tank

If your looking to use a traxxas 1/16 VXL trans 71074 which has the 380 motor mount there is another version that uses larger 540/550 (use one of these in a tlt-1 mt)

To overdrive the axles use traxxas 7079 ring an pinion (only use the pinion gear)

Finally to unlock the diffs (which you will want to at least in the front) use duratrax vendatta DTXC7448 diff gears you might need to make some shafts for the spiders to ride on and also need to shave the larger gears to be thinner. A sorta guide on how to get the vendetta gears in to the mrc diff case can be found here Im2talls MMT - Page 2

As for tires I'd extremely recommend tlt-1 tires as they are about spot on for scale an then look at losi mini LST bodies to get close to the scale even more.

If you order a castlelink for your mmp should be able to set the drag on it I'd think.

Look forward to seeing someone make a mt out of one of these little trucks I think you could get a spot on 1/18 scaler monster going that least hits 20-30mph (yes the ring an pinion can handle that mini lst shares ring an pinion, the vendetta diff insides will handle the power aswell and the traxxas trans is darn near bomb proof)

This is exactly what I needed! I already have castle link and such. I add drag to my telly with it. Are you saying the 1/16 traxxas tranny can indeed be used? In addition to the stock, or in place of?

I will start amassing parts. Any suggestions on limiting the torque twist?

[T_Tank]

You would use the Traxxas trans as a replacement for the losi transmission. Would need to make a custom upper tray for electronics as the motor would sit differently. Also the Traxxas r
Trans has options for a high or low Internal gearing after the spur.

As to fight torque twist most of the folks that make shafty monster trucks use a sway bar to reduce torque twist.

[mwe-maxxowner]

I'll research the sway bar. I was figuring something like that, just not sure how to implement that on this platform.

When I look at it in person, it may be obvious, but the mini transmission from traxxas bolts right up? For ESC and rx mounting I've got that covered.

I'm aware of the option to run it stock, or in the under drive configuration. Partly why I like the idea. I can flip the gears later if I want and still have a crawler .

[T_Tank]

Doesn't bolt right up to the chassis plate but here is a reference you can use for making a custom chassis plate.
https://tinkercad.com/things/7bRZMPZwtdF

As for everything else aslong as you make sure you get the VXL model transmission (has the 380 motor mount) the stock mrc motor will mount up.

The trans has the same sized output shafts as the mrc so no fuss there aswell!

I've seen some folks literally zip tie the sway bars to the lower links to stiffen things up not sure if thats what you want exactly but is a super cheap option.

[JBcustoms]

My build thread, work in progress. Post #19 has the gear ratios for the trans, axles, pinion/spur, and summit vxl trans.

Thrift shopping at its best, a MRC build...

[JBcustoms]

The MRC trans is something like 7.5:1, and the summit trans is 2:1, or close enough. I would recommend keeping the losi trans and playing with pinion/spur combos to achieve the wheelspeed you want, but possibly doing the underdrive mod to the summit trans and running that? Anyways, keep us posted!

[mwe-maxxowner]

I will most likely try keeping the losi tranny, and shoe horn the mini revo in if it becomes necessary. I happen to have one in the parts bin though . Thanks for all the held, ideas, and advice guys. Truly.

[mwe-maxxowner]

Anyone have experience with the hot racing shocks for the mrc? I like that they have adjustable preload. That may help me dial out some torque twist. And I'd see if there are some stiffer springs.

I'm not looking to spend much that is too unnecessary to make it work and be what I have in mind, but if I take this on, it needs to have SOME upgrades. Haha. I hope the velineon 380 motor fits in there. The stock motor is tight, and I fear the vxl is a hair larger in diameter.

It seems there is a problem getting the diff outputs of the vendetta diff parts to work with the mrc shafts. I'll be honest I'm a little overwhelmed while reading through that thread, but it'd be nice if I can figure it out. It sounded like he had to make a mold for pins to ride on inside the case out of what sounded like jb weld.

There was also mention of adding the traxxas mini slipper to the mrc tranny. I think that sounds like a great idea. That gives me a reliable slipper, and spur options.

[T_Tank]

To clear things up with the diff gears the mini lst diff gears need pins to hold to the mrc axle shafts while the vendetta ones just need the backs shaved down as they are slotted they don't need any modification to hold the mrc shafts.

I'll have to look at my mrc and mini T to see what I had to do again to use the mini vxl slippers.

Shocks I'd look at 3 racing Shocks of similar length as the mrc ones.

[mwe-maxxowner]

Alright, I recall seeing some 3 racing shocks while browsing ebay that said they would fit. They were cheaper than the hr shocks too.

I have vendetta gears on the way, everything else I might need (merv parts) I already have. Then, once I have a working rig, I'll go for the body and tires.

I'm also hoping to find some track wideners for it. I was looking at the merv tranny and the mrc, and it doesn't appear that it would be that difficult to custom mount it into the mrc.

Do the mini t and the mrc use the same tranny with different gearing? I'm guessing if it were that simple, I'd already know haha.

I ran stock mrc specs through a gearing calculator at 4000kv and 12 volts and got 6.something mph...so the diffs will most definitely get overdriven, and the tranny will probably get a swap too.

Anyone know the ratio of the diffs with the traxxas pinion gear to overdrive it? If so, I can find out what my largest available pinion is and see what that calculates too.

I have a 5700kv motor, but it is 540 can, I'd like to keep a smaller motor in.

Then again, there is a leopard 5460 kv 4 pole 380 motor, and I hear the leopard motors are pretty great...
Though I definitely don't want a motor that's too hot that will give me overheating issues. Maybe sticking around 4000kv would be best, especially with the tranny swap.