Jerold's Limitless Build

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Ok I missed a few posts I guess lol 😂
Totally understandable. I tend to put a lot of details in there, mostly for me and about 1% of the people actually care about. Then there is the other 1% that just look at the pictures. For the rest of the 98% it's crap shoot if it's read or not.
 
Front Wing Screw Mod

I ran into a minor problem right after I got the Limitless roller. The front wing wasn't very well attached and would pop off with just about anything. It turns out hole for the screw had been stripped out. The wing, with screw attached went flying up in the air. This was temporally fixed by adding a bit of electrical tape on the screw to take up some extra space but that didn't last long.

Eventually I replaced the front bumper (ARA320515) and that fixed it for a little bit until the screw pulled through the Lexan wing. Which left me front wingless.
Front_Wing.jpg


Not wanting to spend $30 on wings, I was thinking to add a washer on the top. However, looking through my stash of stuff found a set of 1/8" Hillman screw covers #881025.

This not only fixed the problem but makes it look more finished too.
IMG_4626.jpg


Don't tell Hillman though, because the get rebranded to Arrama Screw Covers and cost $8.95.
 
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ESC End Swap, Rewire, Drive Shafts, Bent Center Brace and Batteries
During the last run I spun the grub screw out of the spool and had to take it all apart. This seemed like a good time to clean up the wiring and put in some drive shafts that were not bent. Of course we had a little adventure along the way.

I also had to make some shims for my weird batteries.

ESC End Swap and cleaning up the wires
When I originally mounted the ESC I had the three motor wires forwards. This kept the motor wires and power wires short but made a mess of the control wiring. It was zip tied to the center brace and deemed "good enough".

This is the original wiring and setup. It's not tidy but is functional. Also the power wires at the rear made it a tight fit for the body and I have to make sure they are away from the wheels.
1656992040597.png


This is the new setup. The control wires run straight down and then into the receiver box. The sensor wire is routed underneath the mess and held down with some servo tape. The On/Off switch was stuck to the center brace with more servo tape. Then some 1/4" wire split loom to dress it up.
thumbnail_IMG_4653.jpg

The blue thing is my antenna tubes, they are just hot glued together for now. You can ignore it (or make fun of it); it's more stuff to fix later.

One of the problems I had with mounting the ESC is the sketch they give you. It's technically accurate but using that as an template is not a good idea. This is what I did for the original mounting, just taped the diagram to the metal and punch the holes. Needless to say the holes weren't straight and needed a little "adjustment".

This time around I laid out the pattern on a scrape piece of Masonite. Masonite is also very smooth on one side and allows you center punch a hole without moving around from the grain of wood. This also made it much easier because I wasn't dealing with a floppy piece of paper that wouldn't lye flat and also allowed me to test fit it. I placed the template on my plate, drilled one hole, then bolted it down. repeat.
IMG_4628.jpg

You may also notice, in the new setup is the Perfect Pass Carbon Fiber V2 drive shafts. They are super light and dead straight. I did have to do some Dremel work on the center diagonal supports. This was in the product description before I bought them and it was not a surprise.

Bent Center Brace
When I was reinstalling the center brace, it seemed a bit shot for some reason. After looking at it, I noticed that it wasn't straight. The 90 degree bend from the flat to the vertical was a bit less than 90 degrees and made the entire thing about 10mm too short. To correct this, I "gently" adjusted in the vice.

This is an inexpensive Ebay purchase and I'm not surprised. I also heated it pretty good to braze on my side plates, but I don't know that aluminum looses hardness with heat? Either way it bent.

At some point, I will need to find a better solution. I'm thinking a few vertical layers of carbon fiber, in the same shape, bonded/bolted together or maybe figuring out some way to tie it to the motor mount. Although, I'm a bit leery of stressing the motor mount because it's a critical piece of equipment.

Send your ideas and comments.

New Batteries
In post #38 I picked up some new batteries that were sort of an odd size. They are SMC batteries on sale for $50 each, figured I would give them a try. When they arrived I found out that they were indeed a very odd shape for the Limitless platform. Taller than wider, much taller.
1656991174027.png

Since they are taller than wider they are a bit wobbly (engineering term) from side to side. The Velcro straps would probably be fine, until they are not. I'm also a believer of when in doubt make it stout. This has to be fixed.

I needed to fill about 3/4" total, between the two sides. A trip to Tap Plastic bargain bin solved the problem and $8 later I has several sheets of 1/8" and 1/4" ABS plastic. Then cut* it to size.

* Normally I would pull out the table saw and get better cuts, but I was being lazy today and they look like crap.

The ESC on the center brace can interfere with the batteries. The blue thing is my antenna tubes, they are just hot glued together for now. You can ignore it and it's more stuff to fix later.The inner shims were trimmed to still give support and make sure the battery doesn't lean against the ESC.

This is the new 1/8" ABS floor plate with 1/4" one plate on the inboard, ESC clearanced side.
thumbnail_IMG_4655.jpg


With the battery and the other 2 shims it looks like this. I was thinking to glue all the parts together for each side but realized I probably don't want to. If they separate, then I can adjust them forwards or back depending on where the wires exit.
thumbnail_IMG_4657.jpg

For now the battery power leads are exiting the back of the tray. It fits nicely, is very secure, the wire route easily; although, the wires are a bit long to get to the ESC. It's not ideal from a power perspective.

I can flip the batteries 180 and the wire can exit on the outboard front end of the tray. The leads are shorter, but I also need to carefully watch the clearance on pinion.

In the end is about .25 mΩ (300 mV @4S) per lead difference. That can be significant, but looking at my previous logs I don't think it will make any difference until I start nearing 150 mph? . . . Which will be a long time.
thumbnail_IMG_4656.jpg


When/if I start getting to 150 MPH, I can flip the motor and put to batteries on one side. That will allow the shortest possible leads. Or maybe CNHL will have my 9500 4S back in stock.
 
Control-Z
A new solution for a stock body Limitless V1 with and XLX2. The body lower and fits better and the XLX2 is on the pan!
IMG_4822.jpg

End swapping the ESC
I started this a while back and I've been getting busy with other stuff and some travel. However when I finally got it done I found out that the wires didn't really fit under the stock Limitless body. That combined with a few other annoyances made me scrap that idea. Control-Z

Custom Double Wide
My first thought was to double up the battery tray, side by side, and create a custom battery tray. Then I can just put the XLX2 on the other side. My plan was perfect but a bit daunting. I prototyped the tray created from 3/8" ABS and it fit both of the monster batteries. Securing it to the pan and the weird angles was a bit much but doable. Also I have to figure out some way to secure them, which was getting a bit weird. Then get an aluminum tray made but no one makes M3 Nutserts that don't require a special tool and a 5 ton press. Ok to I hit too many walls . . Control-Z, again
1663905547471.png


New Servo Mount
I started looking at the gigantic electronics box and servo mount. Then I started thinking there must be a way to save some space. The solution is to mount the servo the down brace.

My mock up looks good and plenty of space. Then use my XLX2 center brace to hold the electronics. Less weight up top, the body sits lower and shorter wires.
1663906116274.png

With a bunch of time and CAD work I had a design, then went to Send Cut Send to get an estimate, which is pretty cheap.

1663905225466.png

However, they have a $29 min and I didn't want to drop $30 on a part that may not fit nor work. So it's off to Home Depot for some bar stock. Good thing too my holes were just a bit off and I had to give them a bit of love with the drill.

I cut off a chunk of bar stock and drilled my holes screwed it in and everything work. But I didn't get the fancy shape, but it's a prototype. I used an electronics box from a Mojave and made a dual antenna mount (ignore the crappy tubes). The antenna sit inside the body and are higher than stock.








This is with everything in there. Ignore the messy wiring, that will get cleaned up. It turns out my Mojave box is too small for the Castle link and all my wires, so I'm probably going to chop up Limitless box and use that. Also trim down the center tray a bit or more likely I will get a better one that is stronger, that POS tends to bend because of the right angles. I swear it bent sitting on my bench.
IMG_4820.jpg


What Left
Loctite everything
Clean up my wiring with Limitless box
Properly mount the XLX2
New chassis brace?
Who makes this/Where can I get one?​

1663907524024.png
 
Happy Happy Joy Joy!
HHJJ.gif

OK not 100% success but pretty close. It runs and just needs a few minor tweaks.

For those that are too young to remember, that's Ren and Stimpy. So stupid it's funny or at least it was when I was younger.

New Servo Mount
There are two mysterious holes on the top edge of the forward down brace. I have no idea what they are for (please comment if you know) and I figured they needed to be used. So the servo is now mounted to the downward front tower to chassis brace.
1664935274924.png


The mount is pretty simple. I made it from from 1/4" Aluminum and puts some screws to it. It fits perfect, the servo/steering geometry looks pretty good. The servo is level, the arm is parallel to the bell crank arm. It's the original linkage too. The only downside is the brace has a bit of flex under load. I'm not really relying on turning much, at least I hope I don't need to, so I'm not too concerned about it, yet.

I did some clearancing on the brace for the RS Carbon Fiber Drive Shafts which might have (I'm sure) weakened it a bit. There are Aluminum options if it's a problem. Or mount it to the chassis with the 4-post mounts I see everywhere; although, that requires drilling some holes.

Super Power Steering
The only real problem I found (and band-aided) was the steering. It was like super power steering. If I turn right it would totally hook a right or the same on the left. Basically it was undriveable. I couldn't find anything mechanically wrong, then I remembered that I turned on the gryo right before the tear down. I bench tested it and it was correct. But when I put it back together the receiver location is different which swapped the gyro. Which means if I turn right it "thinks" I skidding left and turns into (right) the skid. - Super Power Steering.

I have to go back to RadioLink Docs and figure out how to get the right mode or calibrate it or whatever. For now I put it at 0% assist and it cleaned it up.

The Pics
If your like me and skip the drivel, the pics are below. Pardon the extra messy work bench. Oh... one last thing, ignore the blue tape. :unsure:
1664934740341.jpeg
IMG_4832.jpg
IMG_4833.jpg
IMG_4834.jpg
IMG_4835.jpg


1664936160860.png
 
Gryo Jitter?
I'm not sure what this is and maybe someone can help me. Maybe I'm wasting my time?

In the last installment my Gryo phase was backwards. I would turn right, it detected a right side skid and corrected by turning right. It's interesting but not very useful.

I pulled out my RadioLink manual and it says to change the phase.

1665553356029.png


As soon as I did that and the front wheel just shook while sitting on the bench. It stopped when I picked it up. The phase is correct. Back moves right and it steers right. As soon as I drove it down the drive way the front wheels started wobbling.

This first video is just me moving the wheel. The first 10 sec have the Gryo on at ~80%. Note that it's not responsive and very chunky. It's almost like the sample rate (assuming it's digital) is too low. The next few seconds is after I turned the Gryo down. Notice the servo is nice and smooth now.

The second video of the car driving and you can see the front wheels "hunting".

Any thoughts are helpful.
 
Gryo Jitter?
I'm not sure what this is and maybe someone can help me. Maybe I'm wasting my time?

In the last installment my Gryo phase was backwards. I would turn right, it detected a right side skid and corrected by turning right. It's interesting but not very useful.

I pulled out my RadioLink manual and it says to change the phase.

View attachment 249632

As soon as I did that and the front wheel just shook while sitting on the bench. It stopped when I picked it up. The phase is correct. Back moves right and it steers right. As soon as I drove it down the drive way the front wheels started wobbling.

This first video is just me moving the wheel. The first 10 sec have the Gryo on at ~80%. Note that it's not responsive and very chunky. It's almost like the sample rate (assuming it's digital) is too low. The next few seconds is after I turned the Gryo down. Notice the servo is nice and smooth now.

The second video of the car driving and you can see the front wheels "hunting".

Any thoughts are helpful.
I think you have the gain turned up way too high. I'd try recalibrating and then turn the gain down to 15-30% and see how she does.
 
I think you have the gain turned up way too high. I'd try recalibrating and then turn the gain down to 15-30% and see how she does.
Too much gain makes sense but it didn't occur to me that too much gain was an option.

Recalibrate the Gyro? I believe it calibrates/initializes when the power is turned on. I just need to make sure it's level and not moving.
 
Too much gain makes sense but it didn't occur to me that too much gain was an option.

Recalibrate the Gyro? I believe it calibrates/initializes when the power is turned on. I just need to make sure it's level and not moving.
When you turn the gain up to high it starts reacting to everything. You can tell when the gain is turned up too high when the car starts oscillating.
 
Fall Colors and an PB
I finally got out to do some more runs.

The short story is I got a new PB of 113 MPH on 8S with a D/R set at 90%. More importantly NO CRASHES! Yah!! But I did get some audible codes from the ESC.

It's only +2MPH, I'm trying to take baby steps until I figure out what's what.

IMG_4870.PNG


Leaf Collection
When I lived on the east coast and when the weather turned, so did the leaves. You could count on piles and piles of leaves, with bright orange, yellow and red colors. There is nothing like the fall colors on the east coast. I guessing my Limitless feels the same way because it brought me a present. No it's not staged, it collected the leaves and kept them through a 100mph run.
IMG_4869.jpg


Car Setup
Arrma Limitless OG (aka not V2). Changes are in bold
Stock Body​
8S - (CNHL 9500 4S) X 2​
Servo Relocation Mod/ RX relocation
Stock D-Boots and GRPs​
BEC Voltage 7.0V
Throttle D/R 50-90%
Steering D/R 50%
Gryo enabled @0%
GRP Tire Balanced (added)
Cut the body near the rear tires to avoid rubbing (added)
The servo relocation works well for this application. I wouldn't use it for bashing, racing or crawling, but here it's fine.
IMG_4834.jpg


I didn't see any rubbing or binding; although, I need to go through the car and will update if I find anything. The mounting surface is the front down brace and it is a bit flexy under load; however, I shouldn't "need" to make any quick turns. I'm hoping the solve the flex problem with an aluminum brace, the question is will my center drive shafts clear? I have the Raz Shifrin CF drive shafts and they are amazing, but also a bit stout so I had to clearance the factory plastic braces... which doesn't help the brace with lateral force. Please let me know if you have any ideas which front aluminum braces work with RS CF drive shafts.

Using the Throttle and Steering Dual Rate is very useful. The throttle is good for a few warm up passes where I can practice the throttle control without the speed. The steering really helps me keep it going straight. I will definitely being adding this as part of my regular setup.

I did enable the Gryo, but found it to be a bit too much. When I was testing it I noticed a wobble from too much gain, which limited me to something like 15%. However, when I got to my spot I tried it out and even at 30MPH, 15% was too much. So I dialed it back to a big-old 0%. Maybe it's because I increased the BEC voltage to 7V and the servo is more responsive. Which makes the control loop is smaller and needs less gain?

Practice Time
A while back is was short a battery and limited to 4S only and pretty much maxed out at 75MPH. I actually learned something from the limitation, there is a lot more to this than a fast car and pinning the throttle. There is some skill and experience to driving a 15lb car at 100,110. 120...MPH. Being limited on speed allowed me to just drive the car and not worry about going fast.

Basically I learned it's important to get more low speed passes. This time I started with 8S but turned down the Throttle D/R to 50% and started working my way up. Just like last time the speed was ~75MPH. Back down the D/R and made more passes. Eventually swapped to the GRP tires and had 2 passes at 100+. There was probably a 3rd but my GPS wasn't on - Doh!

ESC Codes
I managed to get this to happen twice. I made a run then staged for another one. The car cut slightly at first acceleration and then continued then continued to perform as expected. The code sounds like "o - - " which would be Excessive Load.
1668384731726.png
I'm not sure what the load would be, it was very easy acceleration from about 2 mph? The video is below.


Data Log
My log is attached in the ZIP file.

I'm still going through them, but I can immediately see a few things. the first is I had much more time at or near 100% throttle (relative to the D/R setting). The last run I had over 2 Secs of full throttle. The acceleration is looking much less jagged.

This is my last 113MPH run. You can see a plateau for the throttle followed by the braking. The throttle ramp is a bit exponential; however, I also figured out that if I get it rolling and straightened out, then give it the beans, I can get to get max speed in less space.
1668391563527.png


Another thing is the Voltage droop and Watts. My Watts went way up, like to 11K and my Voltage Droop was very high and dropped to 23V. That seems a bit much to me - Comments?
1668391738987.png


Edit: I forgot a few of the mods and updated my changes list marked with (added)
 

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Last edited:
Fall Colors and an PB
I finally got out to do some more runs.

The short story is I got a new PB of 113 MPH on 8S with a D/R set at 90%. More importantly NO CRASHES! Yah!! But I did get some audible codes from the ESC.

It's only +2MPH, I'm trying to take baby steps until I figure out what's what.

View attachment 256163

Leaf Collection
When I lived on the east coast and when the weather turned, so did the leaves. You could count on piles and piles of leaves, with bright orange, yellow and red colors. There is nothing like the fall colors on the east coast. I guessing my Limitless feels the same way because it brought me a present. No it's not staged, it collected the leaves and kept them through a 100mph run.
View attachment 256130

Car Setup
Arrma Limitless OG (aka not V2). Changes are in bold
Stock Body​
8S - (CNHL 9500 4S) X 2​
Servo Relocation Mod/ RX relocation
Stock D-Boots and GRPs​
BEC Voltage 7.0V
Throttle D/R 50-90%
Steering D/R 50%
Gryo enabled @0%
The servo relocation works well for this application. I wouldn't use it for bashing, racing or crawling, but here it's fine.
View attachment 256156

I didn't see any rubbing or binding; although, I need to go through the car and will update if I find anything. The mounting surface is the front down brace and it is a bit flexy under load; however, I shouldn't "need" to make any quick turns. I'm hoping the solve the flex problem with an aluminum brace, the question is will my center drive shafts clear? I have the Raz Shifrin CF drive shafts and they are amazing, but also a bit stout so I had to clearance the factory plastic braces... which doesn't help the brace with lateral force. Please let me know if you have any ideas which front aluminum braces work with RS CF drive shafts.

Using the Throttle and Steering Dual Rate is very useful. The throttle is good for a few warm up passes where I can practice the throttle control without the speed. The steering really helps me keep it going straight. I will definitely being adding this as part of my regular setup.

I did enable the Gryo, but found it to be a bit too much. When I was testing it I noticed a wobble from too much gain, which limited me to something like 15%. However, when I got to my spot I tried it out and even at 30MPH, 15% was too much. So I dialed it back to a big-old 0%. Maybe it's because I increased the BEC voltage to 7V and the servo is more responsive. Which makes the control loop is smaller and needs less gain?

Practice Time
A while back is was short a battery and limited to 4S only and pretty much maxed out at 75MPH. I actually learned something from the limitation, there is a lot more to this than a fast car and pinning the throttle. There is some skill and experience to driving a 15lb car at 100,110. 120...MPH. Being limited on speed allowed me to just drive the car and not worry about going fast.

Basically I learned it's important to get more low speed passes. This time I started with 8S but turned down the Throttle D/R to 50% and started working my way up. Just like last time the speed was ~75MPH. Back down the D/R and made more passes. Eventually swapped to the GRP tires and had 2 passes at 100+. There was probably a 3rd but my GPS wasn't on - Doh!

ESC Codes
I managed to get this to happen twice. I made a run then staged for another one. The car cut slightly at first acceleration and then continued then continued to perform as expected. The code sounds like "o - - " which would be Excessive Load.
I'm not sure what the load would be, it was very easy acceleration from about 2 mph? The video is below.


Data Log
My log is attached in the ZIP file.

I'm still going through them, but I can immediately see a few things. the first is I had much more time at or near 100% throttle (relative to the D/R setting). The last run I had over 2 Secs of full throttle. The acceleration is looking much less jagged.

This is my last 113MPH run. You can see a plateau for the throttle followed by the braking. The throttle ramp is a bit exponential; however, I also figured out that if I get it rolling and straightened out, then give it the beans, I can get to get max speed in less space.
View attachment 256171

Another thing is the Voltage droop and Watts. My Watts went way up, like to 11K and my Voltage Droop was very high and dropped to 23V. That seems a bit much to me - Comments?
View attachment 256173

Other than finding the perfect road, the next hardest thing is getting the throttle pull just right. That is the cause for you amperage spike here. You will need to attempt to get on the throttle really aggressively initially and then slow it down towards the end.

I have drawn over your screen shot the black chisel line is about what your throttle line was.
The Red is more of what I would like to see you do instead:

1668394343478.png
 
Front Wing Screw Mod

I ran into a minor problem right after I got the Limitless roller. The front wing wasn't very well attached and would pop off with just about anything. It turns out hole for the screw had been stripped out. The wing, with screw attached went flying up in the air. This was temporally fixed by adding a bit of electrical tape on the screw to take up some extra space but that didn't last long.

Eventually I replaced the front bumper (ARA320515) and that fixed it for a little bit until the screw pulled through the Lexan wing. Which left me front wingless.
View attachment 226989

Not wanting to spend $30 on wings, I was thinking to add a washer on the top. However, looking through my stash of stuff found a set of 1/8" Hillman screw covers #881025.

This not only fixed the problem but makes it look more finished too.
View attachment 226990

Don't tell Hillman though, because the get rebranded to Arrama Screw Covers and cost $8.95.
Carnage got the best of my Front wing. Same as yours, stripped. Shoogoo worked for a brief while. But then I just used a 3 mm oversized screw.
 
Another thing @Jerold is that driving on 8s is very hard.
Most of us found learning this side of the hobby is considerably better on 3s and 4s.
I was able to reach 127 mph on parallel 3s packs and now shooting for 150 as a goal for parallel 4s. Might be worth trying 4s for a bit. Happy to coach you on it if you would like some pointers.
 
Other than finding the perfect road, the next hardest thing is getting the throttle pull just right. That is the cause for you amperage spike here. You will need to attempt to get on the throttle really aggressively initially and then slow it down towards the end.

I have drawn over your screen shot the black chisel line is about what your throttle line was.
The Red is more of what I would like to see you do instead:

View attachment 256178
Yup that makes sense. I'm asking it to do more work when it's working the hardest. But is 11KW excessive? I mean it's only like eight toasters. :unsure:

Another thing @Jerold is that driving on 8s is very hard.
Most of us found learning this side of the hobby is considerably better on 3s and 4s.
I was able to reach 127 mph on parallel 3s packs and now shooting for 150 as a goal for parallel 4s. Might be worth trying 4s for a bit. Happy to coach you on it if you would like some pointers.
I saw your Hobao @127. It's impressive. Pointers, yes please. My goal is 130, given my space constraints I think it's a reasonable goal and running 4S or less is considerably less stress on my wallet, my car and my brain.

Maybe someday I will find a better road with less liability to it.
 
Yup that makes sense. I'm asking it to do more work when it's working the hardest. But is 11KW excessive? I mean it's only like eight toasters. :unsure:


I saw your Hobao @127. It's impressive. Pointers, yes please. My goal is 130, given my space constraints I think it's a reasonable goal and running 4S or less is considerably less stress on my wallet, my car and my brain.

Maybe someday I will find a better road with less liability to it.

I was up around 7kW on 3s so 11kW on 8s is not bad. The esc just throws a fit if you apply the throttle like that. It can handle more...

Try a parallel 4s run and post some logs and we can go from there. With the lower voltage you will find the car to be less jumpy/overly sensitive at the start so that you can apply the throttle in the way I had mentioned.
 
Yup that makes sense. I'm asking it to do more work when it's working the hardest. But is 11KW excessive? I mean it's only like eight toasters. :unsure:


I saw your Hobao @127. It's impressive. Pointers, yes please. My goal is 130, given my space constraints I think it's a reasonable goal and running 4S or less is considerably less stress on my wallet, my car and my brain.

Maybe someday I will find a better road with less liability to it.
FWIW, 130mph on 4S is well with the realm of possibility. You don't need 8S for that. That just increases the likelihood of accidents. I just got back from a 4S pass and set a new PB at 131mph.
 
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