Fallen's Losi LMT

[Fallen]

My cheap roller ($280) arrived, and within a few days I got a body painted and mounted.

It's the Pro-Line 2021 Bronco body for shortcourse trucks.

The wheelbase and width are perfect, and it bolts right up to the LMT cage. The height is a bit short though. My LHS had it in stock, so I figured I'd give it a shot, and it worked.

I also bought the ESC & motor combo the RTR trucks come with. It's apparently pretty rad in the LMT. I haven't yet installed it, as my sons are napping with them.

The truck + body + ESC & motor and I'm right around $400 to get it running. I already had a servo and radio gear.

It should be alive within the next few days. It's my first real monster truck, so hopefully it's as fun as they look.

 

[Fallen]

No photos in this update, just a few findings:

Use the factory servo saver. One of my sons destroyed some steel servo gears in less than 5 minutes on 2S. The factory servo saver functions quite well, and has a lot of adjustability.

The stock shocks have a lot of sticktion, but not when held vertically and cycled. Try to get the shocks as vertical as possible to eliminate sticktion.

The tires track straighter when run in reverse. I have no idea why. I figured this out by having the wheels off of the truck, and rolling them back and forth on the floor with my 2 year old son. Rolling them forward, they'd go off towards the outer face of the wheel. Rolling them backwards, they'd go straight everytime.

I mounted my rears in reverse, as I consider the rear axle my "straight ahead" axle. My fronts are mounted normally.

 

[calcagno45]

Truck looks good! Interesting find with the tire directions.

I heavily considered the LMT kit while on sale. I ended up going with the SMT since it was only $100.

 

[Fallen]

Dang, $100 is pretty cheap. I've been eyeing the LMT for a while now, so I jumped on that.

They're a lot of fun. We drove it at the beach today. All of my sons were jumping it, because it's just so easy. I made a 6 inch jump in the sand with my feet, and my older son was getting like 1.5 feet of air off of it, on 2S.

They just love to get in the air!

And thanks. This is my bash body for this truck. I'll eventually do up a nice, scale body for it.

 

[Fallen]

I decided to add my FPV system to this truck. It's fun, but still not as fun as watching the truck. It's like going to a Monster Jam show, and only watching the driver's FPV footage. Boring!

My body's grill got chewed through by roof landings forcing g it downward over the chassis plates. I added these body posts to prevent that.

If only I'd thought of that before my grill was destroyed.

But about that, I probably won't be doing any nice bodies for this truck. Scale monster trucking is about really fun driving, which in monster truck terms means throwing caution to the wind.

Most monster trucks suffer failures during freestyle runs. But they almost always destroy their bodies, every single run. I think I'm just going to assume that trashing bodies is pretty much par for the course.

My 13 year old son destroyed another metal gear servo. This time on 3S, and with the servo saver installed. We're going to have to limit this truck to being driven in wide, open spaces.

It's still been a blast to drive. I'm figuring this monster truck thing out, and it's great fun. Everything is a jump for a monster truck. Oh, and the sticktion these shocks have doesn't seem to matter much. These big tires go a long way to soaking up big hits.

 

[Fallen]

We drove the LMT at the beach today and found a few weak points:

Somehow my center differential shifted a few MM forward in its carrier. The differential shredded the entire stock plastic carrier. We'd only gotten through 1/2 a battery.

I emailed Horizon about a warranty replacement for the carrier. It's a $22 part, so not too expensive but I have no idea what caused the shift. That means I'd likely burn another one if I replace the carrier. I'll probably upgrade that part to a Vitavon housing to try to prevent future differential movement.

The axle housings also let sand in unfortunately. I have no interest in buying $300 aluminum axle housings. I'll try to seal these housings up with a combination of CA glue between the pieces and E6000 on the outer seams. Hopefully that prevents sand from getting in, as beach driving is a must for my RC cars. So much so, that if aluminum housings are the only way to seal them, so be it.

She'll be down for parts for a few days or weeks. Fortunately it's a pretty easy truck to work on. My differential are all still solid and they don't leak. The shocks also don't leak, and the sticktion is going away with more running.

I suspect that once I get the center differential carrier squared away, and the axle housings sealed I'll have a truck we can run reliably in the sand all summer.

It's fun on 2S and jumps really easily. It's easy for my 3 year olds to drive and they love it.

I've come to expect these types of requirements with new trucks. I've had very few RC cars that didn't need something or other, to run reliably. So I'm not bothered by at least having to upgrade the center differential housing.

 

[meatmonkey]

The sale on lmt roller got me too. I'm a little annoyed that mine came with the gen 1 axle housings that are notoriously fragile, since the trucks been out for over a year I figured they would all have the updated housings.

Did yours come with the updated housings?

I pulled mine apart before running and the amount of slop in the transmission pinion shaft was atrocious, like I don't know how the gears survive at all with such little gear engagement. Took almost 1mm of 6mm ID shims to get it in the ballpark.

None of the diff housing bolts were tight, which I'm sure would have led to sheared bolts and ruined gears. Really wish it came as a kit as there looks to be about 0 quality control going on before shipping them out.

 

[jebster]

The sale on lmt roller got me too. I'm a little annoyed that mine came with the gen 1 axle housings that are notoriously fragile, since the trucks been out for over a year I figured they would all have the updated housings.

Did yours come with the updated housings?

I pulled mine apart before running and the amount of slop in the transmission pinion shaft was atrocious, like I don't know how the gears survive at all with such little gear engagement. Took almost 1mm of 6mm ID shims to get it in the ballpark.

None of the diff housing bolts were tight, which I'm sure would have led to sheared bolts and ruined gears. Really wish it came as a kit as there looks to be about 0 quality control going on before shipping them out.

I also broke down and bought one during the sale. Can you tell which generation of axle housing one has from the exterior? I've read about those issues a long time ago when I first considered getting an lmt. Mine is still sitting in the box in the basement right now.

 

[Fallen]

I don't know how to tell the difference between 1st and 2nd gen axle housings unfortunately. My LMT had several screws which were not Loc-Tited and were loose. I also had a few screws which had already stripped the holes due to over torquing.

There's a guy on YouTube who goes by Hetmanski Hobbies. He did a race prep video for the LMT, and I'm now going to follow most of his steps. For those who don't want to watch the video, I'll post some detail about what I do. It's basically CA gluing most of the axle housings together.

The housings themselves are comprised of 8 different pieces. That doesn't include the steering components for the front, or lockouts for the rear. With the CA glue method, you can turn 7 of those pieces into one solid piece.

After mine is rebuilt, I'll have my sons run it in the sand again, then I'll disassemble and reinspect the housings.

I think the glue method can help because the problem is flex in the housings. I learned with my Traxxas UDR that plastic, multipiece solid axle housings which flex too much allow gaps to momentarily exist between mating surfaces under loads. When the front tires are throwing back sand / dirt / rocks that's a problem.

The CA glue method should solve a lot of the flex that exists between these 7 pieces that can be made one. Hopefully the CA glue also gives some sealing between all these pieces.

I've already started gluing the housings up, but I'll still be down for parts until I have a new center differential carrier. I'm confident the carrier problem came about due to the sand in the axle housings, particularly the rear. I'm not sure how it caused it, but that's the likely culprit.

With how many beach days my family gets, I won't tolerate a vehicle that can't tolerate sand. I'll report back once I find out how effective this CA glue option is. If it doesn't work, I'll probably jump to AL housings.

 

[Fallen]

After gluing these up and letting the glue cure for a day, initial findings are pretty impressive. These glued housings are very stiff. I wish I'd tried flexing them prior to the gluing, but with my hands I'm unable to detect any visible / felt flex. My old Traxxas UDR housing was quite easy to flex by hand.

I added one more glued piece to each housing tonight, the upper link mounts. This makes for 8 pieces glued together, each housing. Gluing the upper link mounts makes the axle unchangeable from a steering axle to fixed and vice versa. If I wanted to add rear steer, I would now need to buy a whole new axle housing.

I'll eventually get some pictures up, but with these 8 pieces glued I can still disassemble the axle enough to service / replace all of the internals.

I look forward to getting these built back up, and back in the sand.

 

[Fallen]

Here is how far the axles can be glued together while still maintaining the ability to access the internals.

This takes 8 pieces and turns them into one. I brushed some plastic weld over the seams to hopefully add some sealing. Remember, my concern with these axles is keeping debris from entering the housing. I doubt I'd ever snap a housing.

Once you glue the upper link mount on you're stuck with that housing being a steer or fixed axle. Keeping the upper link mount removable maintains your ability to switch from steer to fixed or vice versa.

I also dipped my screws in CA glue before putting them in.

 

[Fallen]

I figured out what caused my center differential to shift forward in its carrier. It was related to the sand, but not the sand in the axles. The driveshafts locked up and wouldn't compress when the suspension compressed. So the rear driveshaft put the force into the rear side of the center differential.

So I'll have to find a good work-around for those. I don't need an AL differential carrier. I might need to remove and clean my driveshafts every few runs in the sand. Maybe they'll wear down a bit over time too, as there's a very tight fit between the inner and outer slider. I greased them a bit after cleaning them, but maybe that will hurt more than it helps...

I rebuilt the axles, and these housings just need some help. The pinions mesh way too tight if you even remotely tighten the carrier bolts. The bolts have to be loose enough to allow the pinion to slide back and forth about 3MM. This also leaves a gap between the housing and the carrier, allowing dirt and sand into the housing. It seems like AL housings might eventually be the way to go here.

On a positive note, Losi is sending me a new center differential carrier for free. The only question they had was "what's your address?" Again, Horizon's warranty service is excellent. Far better than Traxxas, whose warranty service is a sad joke.

Once my new differential carrier shows up, this LMT will be back in the sand / dirt. I'll probably need a bit of E6000 to seal these axle housings up unfortunately. It doesn't seem right to need to use goopy gunk to seal up "precision" drivetrain components on a hobby grade truck. That said, solid axles put a lot of forces into these plastic housings. If I want precision and durability, I'll probably just need aluminum.

 

[meatmonkey]

Externally the newer housings have two "extra" boots on the bottom half kinda below the sway bar brackets.

Didn't realize you could reduce the number of pieces and remain serviceable. I'm gluing mine as well now and we'll see how long they last.

 

[Fallen]

Thanks, mine look like version 1 housings too then. I guess these rollers are old stock.

Good luck on the gluing. I'm still down for parts, so you'll have a read on how these work before I do.

 

[Fallen]

I've finally made it through an entire battery (2S, 4000MAH) with no failures.

Replacing the center differential carrier was a big project. I had to almost disassemble the entire truck to access it. Fortunately, Horizon sent me the part for free, which lessened the pain of the project.

My center differential rear carrier bearing was also destroyed, which I didn't find until after I had put everything together and was testing it. I don't know if the bearing failed and took out the differential carrier, or vice versa. Hopefully it was actually the bearing, as that's not likely to fail again since I replaced it with a rubber sealed bearing.

If you have sticktion in your suspension, it's probably not the shocks. Having to disassemble everything allowed me to see how over-tightened most of the LMT's hardware was. The suspension link connections were all over-tightened along with the sway bar and shock connections. Loosening all of those up a tiny bit freed the suspension up a lot. No more sticktion. It's nice and plush now.

It's very fun to drive on 2S. Monster truck driving is probably the funnest type of driving, for driving's sake only. Scale trailing is fun because the trucks look realistic. Racing is fun because you're dancing on the line between perfection and disaster. Monster truck driving is just fun. Find some uneven terrain in an open space and it's a blast.

I haven't driven it on sand yet, so no read on how my CA glue + E6000 job has stiffened and sealed the axle housings.

If my axle repair doesn't do the trick, SSD has made some aluminum axle housing rear halves. They're pretty cheap and they should solve the problem if my fix doesn't.

 

[Fallen]

I've now put about 10ish batteries through this LMT. That's mostly been my sons driving, and we've been in dirt, sand & grass.

I only have one new failure to report. That is my passenger side front shock fell apart while my 13 year old son was completing a freestyle run. The e-clips holding the piston in place came loose. I replaced them with Traxxas e-clips as they're slightly larger. I cut the bladder out, and re-used the bladder ring that seals the shock cap. In the lower seal cartridge, I replaced the black plastic wiper with 2 Axial o-rings. And I greased the o-rings and re-filled with 30wt oil. I did both front shocks, and left the rears alone.

I have some KNK 100mm limit straps on the way to hopefully prevent future problems.

We've run about 5 batteries in sand, and no more problems so far. The drivetrain still sounds and feels smooth.

I had to apply some stickers though, as what monster truck is complete without sponsors?







And then I painted the roll cage with an unplanned combination of whatever left-over paints were in my garage. It's a weird mix of yellows and greens, but it stands out. That's what I was after.

It's been a ton of fun. My sons love driving it, and when I get a turn I'm pretty jazzed about it too.

 

[Fallen]

Several freestyle competitions between my oldest son and I, some practice driving from my daughter and 3 or 4 Beach trips later and...

The glue method to stiffen these axles housings just isn't doing the trick. I laid about a 1/2" wide bead of E6000 over the seams where the rear, center section meets the rest of the axle housing.

The axle still flexes too much for this bead to be an effective seal. I still ended up with a 1/4" gap where one section of the rear housing pieces moved apart underneath the E6000. The seams were all flush when built.

So I have decided to scrap the glue and gunk method. I bought new stock housings and the SSD aluminum rear case halves. These should provide the stiffness necessary to keep these axle housings properly sealed from debris.

While it would have been nice to have this problem solved from the factory, I don't put too much blame on Losi. These plastic, solid axle housings see a lot more stress than a crawler does. My UDR had the same problem, and it too was solved by an aluminum housing half. The aluminum part is stiff enough to strengthen the plastic pieces it attaches to, resulting in a stiff, sealed axle housing.

A few more days of tinkering, some new axle housings and my LMT should finally be "sandproofed."

 

[Fallen]

I've now installed the SSD axle case halves to both axle housings. If you want photos of those, find them elsewhere. SSD makes some really great, inexpensive parts.

In the below photo you can see how I'd used E6000 to seal the "third member" of the stock housings, as it was the only piece not CA glued on. This seal proved ineffective in light of the flexibility of the stock housing.

I installed 100mm KNK limit straps to each shock.

I then picked up and painted a new body:

This body fits the chassis like a glove. It mounts perfectly to the stock roll cage, so it will be very structurally supported.

So, long story short, here's my guide to a 2S bulletproof (and sandproof) LMT roller:

Parts needed:

1. SSD axle case halves.
2. KNK 100mm limit straps.
3. Find a body you like. Pro-Line's Slash bodies tend to fit nicely.

Maintenance needed:

1. Go through all of the hardware and loosen the parts that have been over-tightened.
2. Loc-Tite any metal to metal hardware.

Go do some rad jumps!

 

[ScaleLifeNewbie]

Good lookin bug Fallen! IMO, this body fits the LMT better than the Bronco, it was a little narrow to my eyes.

I’m glad to hear your have had good luck despite hearing all the horror stories on these trucks.

 

[svt923]

Maintenance needed:

1. Go through all of the hardware and loosen the parts that have been over-tightened.
2. Loc-Tite any metal to metal hardware.

Go do some rad jumps!

The next bit of maintenance that will likely be needed is replacing the rod ends on the links. They are quite soft and tend to stretch fairly quickly.

This was one of the upper link ends after about 10 packs: