Jerold's Rlaarlo Build

[Jerold]

TMI on the mod-1 explanation. Enough to scare anybody away from doing the swap!
But seriously man, great information.
Just curious, what 48p spurs will go in there, I mean by brand/type, not size? I’m sure your RR pinion is so much better than the Rlaarlo ones it’s crazy, was wondering if a quality 48p spur was available from RR, Tekno, Saga, etc.

I figured it might b a bit much, but when I go back a year later this is my reference.

The simpler explanation is to find a Mod 1 gear set that
- Has a Center Distance between 52 and 65 mm, which is the same as the TTC.
- The spur gear has to be less than 42mm Outside Diameter.
- The pinion has to be less than 36mm Outside Diameter.

I'm using a 5mm motor shaft, and the 48P choices are a bit limited, but I found some on Amain. RR goes up to 45T and Maclan goes up to 35T.
https://www.amainhobbies.com/robinson-racing-48p-machined-pinion-gear-5mm-bore-17t-rrp2017/p454470
https://www.amainhobbies.com/maclan-drk-48p-steel-pinion-gear-w-5mm-bore-25t-mcl4307/p1456254

There are more 3mm shaft options, up to 47T.

There might be eBay options too, but I wouldn't use them.

I also pulled the cover off the car and the nylon gear looks OK. I think the motor moved a bit, which is my fault. The first replacement screws I used were counter sunk and I should have used cap screws. The counter sunk screws don't have enough bite on the mount. Those are in and I will see if I can get better than 48mph in a straight line. The straight line puzzles me.... a lot.

 

[Dan B.]

Those are in and I will see if I can get better than 48mph in a straight line. The straight line puzzles me.... a lot.

Did you ever get vertical stabilizers on the rear? Everybody speed running these seems to think it’s a must for straight line stability, and once speeds approach 80-100 the aero of the body kicks in and keeps it planted better. That’s what I’ve heard anyway. I’m really looking forward to building this thing.

 

[Jerold]

Did you ever get vertical stabilizers on the rear? Everybody speed running these seems to think it’s a must for straight line stability, and once speeds approach 80-100 the aero of the body kicks in and keeps it planted better. That’s what I’ve heard anyway. I’m really looking forward to building this thing.

Not yet, I have the material (ABS) and just need to cut them out and bolt them on. I also have a chunk of aluminum to relocate my servo. Unfortunately, I've had too many other things that pushed this down the list.

 

[Jerold]

I got a box of parts, minus some axles that are out of stock. They like to take flight when you crash. Included in that is the Rlaarlo "Bat Wings". I will need to make a splitter which shouldn't be too hard.

Right now life is getting in the way and I haven't had any time to work on it.

 

[Gman18]

The Build List
Rlaarlo 1/10 Carbon Fiber On-Road Cars 200km/h Roller
TP POWER 3640
CONTACT J13773 26mm
Castle Creations Mamba Monster 8S
4S Battery & QS8 Connectors

Why are You Building This?
Some say I'm smart, others say I'm stupid or it maybe it's just poor life choices? In reality this build started from a video I saw from Tomely RC, called "Rlaarlo's NEW 100mph RC Car is So Cheap on Pre sale!"

I had never took Rlaarlo seriously, but it looked interesting and fairly inexpensive too. Spoiler - I didn't do all the math. Eventually, I saw a few more videos then my speed running buddies on Arrama Forums got into the game, so I purchased the Rlaarlo AK-917 CF roller. I was second on that thread to buy one and I was the first to get it.
View attachment 164933
This is a bit of adventure to do something brand new. As a side note, even though this started in the Arrma Forums, @WoodiE runs both forums and is very cool to let us play in the Arrma sandbox with other brands; I thought it would be appropriate to do the Rlaarlo build here.

What Will You Do To It?
Being brand new and from a small company is a bit of a challenge to get a plan. No one has built one before and none of the specs for the motor size, gear pitch, wheel hex, etc were published and it was an adventure to find the information. The good news is if you have questions and email them, the do get back to you the next day. Which is better than most US manufacturers.

Through several other videos and hours of research, I managed to figure out the max diameter of the motor was 36mm, thanks to Francis at RC Review. He had a good angle that I could see the 36mm can was flat on the chassis. Bars&Tones RC swapped the wheels for foam and I was able to see the hex size. The gear pitch appeared somewhere in the website at some point. Also Rlaarlo started to give a few more details on their website.

The Mock Up
To get some ideas I took the pic from the Rlaarlo website and scaled it in Visio to full size. Then started placing scale blocks of different components.

I went through a few iterations. Other's are stuffing the XLX2 in there which is an awesome ESC, but I did some back flips on the limitless to make everything fit gracefully and took the easy path on this one. It gets the MMX 8S ESC with a 4S battery and TP 36xx series motor. The basic layout I decided on is below.
View attachment 164936
When the shipping notice arrived, I made an order to Island Hobby, Amain and Amazon. THIS is the math I didn't do. So my $200 roller is now about $1K. Don't tell my wife, or she will get another Louis Vuitton.
View attachment 164940View attachment 164941View attachment 164942

Out of the box
It looks like good quality. The CF is smooth and fairly ridged. The pit fall is the HW. It looks like some of the hexes are buggered, but they just made that way. Maybe the manufacture has a crappy swage or they are the 2nds for batches. I don't know but I will eventually be replacing the HW with better stuff as I go through it. I use good tools but stuff happens and better quality HW makes a huge difference on the frustration scale and it's worth $20 and a it of effort.
View attachment 164943

When I pulled it apart there was thread lock on the metal-metal screws, which a bit of heat fixed. I used a soldering iron on the head which seems to work. You can use a torch, which is normally my preferred method, but you need to be careful of the carbon fiber.

The shocks feel decent but the springs are way too soft. The book that comes with it says they are 28mm x 65mm, so I'm hopping to find something that will fit. They will be getting some sort of limiter, otherwise it will just chassis slap on everything.

An added bonus is it comes with the lights and body fan. I don't care about the blinkers or exhaust, but just having head and tail lights make it easier to see at a distance.

The center spool shaft is 5mm and @LibertyMKiii and confirmed you can put a Mod 1 gear set in there. I'll be running the 48P gears for now, but will eventually move to Mod 1. If you are thinking about it, do the math to make sure they fit.

The Real Layout
This is the first pass at the fit and I've got plenty of room. Just pulled the battery tray. Unfortunately, the servo is right where I want to put the ESC. Since I don't want to drill holes and move the servo it's getting this layout for now.
View attachment 164937

I delayed putting it together because I thought I was missing a piece.
View attachment 164938

However, it turns out I wasn't paying attention and it's a different mount.... which is the one that is a total pain in the butt to get mounted with the correct mesh. I have the sliding mount ordered.
View attachment 164939


Mounting the Motor and Adjusting the Pinion
To get the gear mesh correct it's a bit tricky. This is how I did it. First thing is I pulled center brace. Then remove the back cage and wing support. Two screws on the shock tower and two in the back. The longer screws go in the back.

Leave the pinion off for now. With the back removed you can get a driver to the front of the motor mount between the control arms. It's not exactly aligned so be careful. Also the mount has recesses for the screw heads and they are M3x(shorter than I thought). Make sure your screws aren't too long and get into the motor. I snugged them up to keep it in place but could still move the motor a bit. Then slipped the pinion on the front and nudge the motor until the mesh was correct. Then re-tighten the screws. Then added thread lock, by removing them one at a time without moving the motor. The last step is to slide the pinion on from the front. Like I said it's a pain in the butt.

Another note on this is the shaft of the TP motors touches the gear cover, which you will probably want to keep, and I had to create some space on the plastic cover. The reason I decided to keep it is that it's next to the battery and would make a nice saw if there was a crash where the battery moved.

More to come. . .

Can you explain what exactly is the mod 1 upgrade? I ordered the carbon fiber roller and it’s on the way and ordered the adjustable motor mount but don’t see a mod 1 upgrade in the list of upgrades on the RLAARLO website. I would really appreciate your help as I order more and more parts. I plan on using a Castle motor and ESC but not sure which one yet. Raz Shifrin obtained 8S ESC and 6200 KV motor - not sure why he went 8S when the max battery that can fit is 4S. Any help or advice would be great, man. I have a few nitro cars and this is my first step into electric motors. I don’t plan on ever going 150 MPH but would not like to buy cheaper parts and have to upgrade if I ever want to go faster. 120 or 130 MPH would probably be my max. Thanks, buddy!

 

[Jerold]

Can you explain what exactly is the mod 1 upgrade? I ordered the carbon fiber roller and it’s on the way and ordered the adjustable motor mount but don’t see a mod 1 upgrade in the list of upgrades on the RLAARLO website. I would really appreciate your help as I order more and more parts. I plan on using a Castle motor and ESC but not sure which one yet. Raz Shifrin obtained 8S ESC and 6200 KV motor - not sure why he went 8S when the max battery that can fit is 4S. Any help or advice would be great, man. I have a few nitro cars and this is my first step into electric motors. I don’t plan on ever going 150 MPH but would not like to buy cheaper parts and have to upgrade if I ever want to go faster. 120 or 130 MPH would probably be my max. Thanks, buddy!

The Mod 1 upgrade is swapping the 48P gears for Mod 1.

It's a chunkier pitch of gears, stronger and seems to run smoother. It's something you can buy from Rlaarlo, you will need to figure out what gears you want and swap the pinion and spur both.

If your interested, all the math is shown in #59. I based it off of Total Teeth Count, which determines the center to center distance and the amount of space you need. I've include a tool (MS XLS) as well.
https://www.rctalk.com/forum/threads/jerolds-rlaarlo-build.138240/page-3#post-1385590
@Gman18 - @LibertyMKiii did a bit of a tutorial on the Mod 1 conversion.

 

[Gman18]

Hah, you over estimate my driving skills, but thank you just the same. I'm sure it a squirrelly little ballistic nightmare at speed.

I figured go with the the biggest I can get and I can always dial it back. That's what I did with the Limitless, started with 4S then dialed back the power in the ESC on 8S. It will be interesting to see what tweaks I need to do the the electronics, throttle curve, braking %, DR, etc..

Do you have any regrets for putting the ESC on the same side as the battery? I am curious because I am considering the same layout for my build. I really don’t want to put the Servo on the top brace as some have done! Congrats on posting this series and sharing with all of us.

 

[Jerold]

Do you have any regrets for putting the ESC on the same side as the battery? I am curious because I am considering the same layout for my build. I really don’t want to put the Servo on the top brace as some have done! Congrats on posting this series and sharing with all of us.

Not really, it's fits just fine that way and I didn't really have many other options. The downside is I'm space limited on the battery. The other option I thought of was to move the servo to the other side, which I didn't really play with.

Eventually (probably in the new year) my plan is to move the servo to the upper brace. It saves a ton of space and allows for full size batteries.

To do this I did a bunch of layouts in Visio with different electronics and batteries. I did this pre-release, before anyone got a car, by using a picture from their website and scaled it off the wheelbase. Then made blocks of different components.

This one seemed the most optimal. I even played with using 6 smaller 4S batteries nestled around the car (lower left), but the wiring would be a nightmare.

 

[Gman18]

Not really, it's fits just fine that way and I didn't really have many other options. The downside is I'm space limited on the battery. The other option I thought of was to move the servo to the other side, which I didn't really play with.

Eventually (probably in the new year) my plan is to move the servo to the upper brace. It saves a ton of space and allows for full size batteries.

To do this I did a bunch of layouts in Visio with different electronics and batteries. I did this pre-release, before anyone got a car, by using a picture from their website and scaled it off the wheelbase. Then made blocks of different components.

This one seemed the most optimal. I even played with using 6 smaller 4S batteries nestled around the car (lower left), but the wiring would be a nightmare.

View attachment 171459

I appreciate your response! I might go to the top brace for the servo as it will give me options with both batteries as well as a longer motor. Rlaarlo is revealing a dual motor 1:10 and while the idea is very cool I would likely stick with one bigger motor than two motors abs two ESCs. The car is going to be pretty heavy for the suspension design they use?

 

[Jerold]

I appreciate your response! I might go to the top brace for the servo as it will give me options with both batteries as well as a longer motor. Rlaarlo is revealing a dual motor 1:10 and while the idea is very cool I would likely stick with one bigger motor than two motors abs two ESCs. The car is going to be pretty heavy for the suspension design they use?

Yes, the springs are super soft. I use a coaxial (front) and triaxial (rear) setup and it was too stiff. I 'think" I went back the stock setup because it was too stiff for the lower speeds I was running. If I as getting to 150mph it would probably be OK.

 

[Gman18]

Yes, the springs are super soft. I use a coaxial (front) and triaxial (rear) setup and it was too stiff. I 'think" I went back the stock setup because it was too stiff for the lower speeds I was running. If I as getting to 150mph it would probably be OK.

I can’t decide if I want to use a Castle 1412 or TP 4040 SCM. Do you know what KV is needed to run 160-170mph on 4s with a TP 4040 SCM? I will likely not run over 130 but I would like the potential to be faster if Ilmy setup is super stable.

 

[Jerold]

I can’t decide if I want to use a Castle 1412 or TP 4040 SCM. Do you know what KV is needed to run 160-170mph on 4s with a TP 4040 SCM? I will likely not run over 130 but I would like the potential to be faster if Ilmy setup is super stable.

The factory Rlaarlo AK 917 mount can only accommodate a 36mm motor. Which means the TP 4040 won't fit unless you do the Habao motor mount mod (See the video from LibertyMKiii) or slot your chassis pan. I haven't seen anyone slot the pan yet, but in theory it will work.

I'm running a TP 3640 motor and Castle MMX 8S ESC on 4S. I "should" be able to hit 130 mph with a fair margin, but the car is so twitchy I have yet to break 80 mph. In my case it's not gearing that's holding me back, it's talent. Either driving or building.

There are gear/speed calculators our there, but it's more complex than just math. On paper a 5400 KV motor on 3S (68,000 RPM) over driven (1.10:1) could hit 150 mph. But you have a bunch of friction and voltage droop. So it's more like a 4S number on a good day.

https://www.radiocontrolinfo.com/information/rc-calculators/rc-car-calculator/

Some of the smaller motors max out around 30K - 60K RPM. If you use the TP SCM they can max around 100K RPM. But you loose torque on the higher Kv motors and it may not be able to actually get to that speed. Higher torque means more acceleration but less RPM (Lower KV). Higher KV means more RPM and less torque. So you need to find the right combination.

It's a light car so I'm thinking higher KV should be OK. But I'm not even in the 100 mph range yet so take that with a grain of salt.

The easy choice is the Castle Combo. Raz Shifrin got to something like 150+ on that combo. Then he switched to a TP and got to 170. But who knows what else he did. You can see his pinion is pretty larger but I can't see the spur. I would assume he is over driven.

I will start with a conservative gearing, then run it and look at the max amps pulled. If they are OK them bump the gearing. If they amps call come in one spot (spike) that a driver issue and there is still more left in that gearing. If it's over amps at full throttle for a few seconds then it's over geared. It's something to play with.

You will also want to consider Mod 1 gears. The swap is pretty straight forwards and is much stronger than the 48P gears that come with it.

 

[Gman18]

The factory Rlaarlo AK 917 mount can only accommodate a 36mm motor. Which means the TP 4040 won't fit unless you do the Habao motor mount mod (See the video from LibertyMKiii) or slot your chassis pan. I haven't seen anyone slot the pan yet, but in theory it will work.
View attachment 171460


I'm running a TP 3640 motor and Castle MMX 8S ESC on 4S. I "should" be able to hit 130 mph with a fair margin, but the car is so twitchy I have yet to break 80 mph. In my case it's not gearing that's holding me back, it's talent. Either driving or building.

There are gear/speed calculators our there, but it's more complex than just math. On paper a 5400 KV motor on 3S (68,000 RPM) over driven (1.10:1) could hit 150 mph. But you have a bunch of friction and voltage droop. So it's more like a 4S number on a good day.

View attachment 171461
https://www.radiocontrolinfo.com/information/rc-calculators/rc-car-calculator/

Some of the smaller motors max out around 30K - 60K RPM. If you use the TP SCM they can max around 100K RPM. But you loose torque on the higher Kv motors and it may not be able to actually get to that speed. Higher torque means more acceleration but less RPM (Lower KV). Higher KV means more RPM and less torque. So you need to find the right combination.

It's a light car so I'm thinking higher KV should be OK. But I'm not even in the 100 mph range yet so take that with a grain of salt.

The easy choice is the Castle Combo. Raz Shifrin got to something like 150+ on that combo. Then he switched to a TP and got to 170. But who knows what else he did. You can see his pinion is pretty larger but I can't see the spur. I would assume he is over driven.

I will start with a conservative gearing, then run it and look at the max amps pulled. If they are OK them bump the gearing. If they amps call come in one spot (spike) that a driver issue and there is still more left in that gearing. If it's over amps at full throttle for a few seconds then it's over geared. It's something to play with.

You will also want to consider Mod 1 gears. The swap is pretty straight forwards and is much stronger than the 48P gears that come with it.

Are you using a PP launch control? Would that not tame part of the twitchiness? Also, I saw the link for the mod 1 pinion gear but I’m not sure where to buy the spur gears? I woud think if one uses launch control, the gears would not be stressed enough to need MOD 1 strength. I suppose they could break when trying to stop the car as well as accelerate.

 

[Jerold]

Are you using a PP launch control? Would that not tame part of the twitchiness? Also, I saw the link for the mod 1 pinion gear but I’m not sure where to buy the spur gears? I woud think if one uses launch control, the gears would not be stressed enough to need MOD 1 strength. I suppose they could break when trying to stop the car as well as accelerate.

I don't have PP launch control; however, I am using the throttle delay on the Radio Link and some throttle curve on Castle ESC.

The Throttle delay ramps the throttle slowly over a few second and the throttle curve allows the throttle to ramp less at the top end, which I have yet to even get close to on that car. My tendancy is to get it stable them pin the throttle which creates a current spike. The throttle curve helps slow that down.

I'm also running a little bit Gyro. If you turn that on make sure the orientation is correct otherwise it's like super power steering and turns the car away from the slide.

Even with the driving aids I think there is too much power to the tiny wheels and when they get the slightest bit of traction loss, it just gets all crazy.

 

[Gman18]

I don't have PP launch control; however, I am using the throttle delay on the Radio Link and some throttle curve on Castle ESC.

The Throttle delay ramps the throttle slowly over a few second and the throttle curve allows the throttle to ramp less at the top end, which I have yet to even get close to on that car. My tendancy is to get it stable them pin the throttle which creates a current spike. The throttle curve helps slow that down.

I'm also running a little bit Gyro. If you turn that on make sure the orientation is correct otherwise it's like super power steering and turns the car away from the I don't have PP launch control; however, I am using the throttle delay on the Radio Link and some throttle curve on Castle ESC.

The Throttle delay ramps the throttle slowly over a few second and the throttle curve allows the throttle to ramp less at the top end, which I have yet to even get close to on that car. My tendancy is to get it stable them pin the throttle which creates a current spike. The throttle curve helps slow that down.

I'm also running a little bit Gyro. If you turn that on make sure the orientation is correct otherwise it's like super power steering and turns the car away from the slide.

Even with the driving aids I think there is too much power to the tiny wheels and when they get the slightest bit of traction loss, it just gets all crazy.

I meant to ask if you’re also running with a gyroscopic receiver and you answered that. You’re probably right it is an over power issue. Having said that, I don’t understand how guys like Raz are running dual motors and quad motors and expect to get transaction. Nice chatting with you!

I don't have PP launch control; however, I am using the throttle delay on the Radio Link and some throttle curve on Castle ESC.

The Throttle delay ramps the throttle slowly over a few second and the throttle curve allows the throttle to ramp less at the top end, which I have yet to even get close to on that car. My tendancy is to get it stable them pin the throttle which creates a current spike. The throttle curve helps slow that down.

I'm also running a little bit Gyro. If you turn that on make sure the orientation is correct otherwise it's like super power steering and turns the car away from the slide.

Even with the driving aids I think there is too much power to the tiny wheels and when they get the slightest bit of traction loss, it just gets all crazy.

Nice talking to you! Thanks for sharing your build.

 

[Jerold]

Nice talking to you! Thanks for sharing your build.

You're very welcome.

BTW I didn't answer the were to buy gears questions. I had an Arrma pinion and a Saga pinion that seemed to be a good ratio. The Spur gear shaft is 5mm, just make sure it's not too wide.

Island Hobby Nut sells Saga gears and they are very stout (overkill). There website is difficult to navigate and it might be easier to call them. They should be familiar with the 917.
https://islandhobbynut.com/

Also you can look on Amain. They usually have pretty good stuff.

You could try just about anything that fits in there, but you get what you pay for. I would stick to a known brand.

 

[Gman18]

The factory Rlaarlo AK 917 mount can only accommodate a 36mm motor. Which means the TP 4040 won't fit unless you do the Habao motor mount mod (See the video from LibertyMKiii) or slot your chassis pan. I haven't seen anyone slot the pan yet, but in theory it will work.
View attachment 171460


I'm running a TP 3640 motor and Castle MMX 8S ESC on 4S. I "should" be able to hit 130 mph with a fair margin, but the car is so twitchy I have yet to break 80 mph. In my case it's not gearing that's holding me back, it's talent. Either driving or building.

There are gear/speed calculators our there, but it's more complex than just math. On paper a 5400 KV motor on 3S (68,000 RPM) over driven (1.10:1) could hit 150 mph. But you have a bunch of friction and voltage droop. So it's more like a 4S number on a good day.

View attachment 171461
https://www.radiocontrolinfo.com/information/rc-calculators/rc-car-calculator/

Some of the smaller motors max out around 30K - 60K RPM. If you use the TP SCM they can max around 100K RPM. But you loose torque on the higher Kv motors and it may not be able to actually get to that speed. Higher torque means more acceleration but less RPM (Lower KV). Higher KV means more RPM and less torque. So you need to find the right combination.

It's a light car so I'm thinking higher KV should be OK. But I'm not even in the 100 mph range yet so take that with a grain of salt.

The easy choice is the Castle Combo. Raz Shifrin got to something like 150+ on that combo. Then he switched to a TP and got to 170. But who knows what else he did. You can see his pinion is pretty larger but I can't see the spur. I would assume he is over driven.

I will start with a conservative gearing, then run it and look at the max amps pulled. If they are OK them bump the gearing. If they amps call come in one spot (spike) that a driver issue and there is still more left in that gearing. If it's over amps at full throttle for a few seconds then it's over geared. It's something to play with.

You will also want to consider Mod 1 gears. The swap is pretty straight forwards and is much stronger than the 48P gears that come with it.

Thanks, friend! I will post pictures when I complete my car.

 

[Dan B.]

What a great thread, thanks again @Jerold

 

[Gman18]

Great start on a cool build thread! After reading, I’m glad I ordered the sliding motor mount when I ordered the car. What a PITA to adjust mesh!
I think you nailed it on the electronics as well, with room to go up to a bigger KV 36xx motor if you want.
I“m going to try really hard to not give in to temptation and buy a MMX8S. You’re brave. And probably a better driver than me. This is one small, light car. I’ll probably go HobbyWing and keep it to 3 or 4S.
Can’t wait to see your runs, man!

Who makes good hardware? I’ve looked and can’t tell good from garbage!!!

 

[Dan B.]

Who makes good hardware? I’ve looked and can’t tell good from garbage!!!

Which hardware? I ordered the motor mount from Rlaarlo. Like @Jerold mentioned above, some guys are using a Hobao motor mount and that one allows a 40xx sized can.
If you’re talking screws and nuts kind of hardware, my only advice is to stay away from stainless, as it’s much softer than plain steel screws. The factory Arrma screws are pretty good. You can also order really good ones, 12.9 hardness and above, from McMaster Carr. I usually just buy take-off bags from Jenny’s RC, like these.
https://jennysrc.com/collections/ar...4-3s-blx-screws-tools-nuts-hardware-ara4319v3