Jerold's Limitless Build

[dk10438]

If you use shorter batteries you can use the standard receiver box with the XLX2. This is in Raz Shifrims Speed Run Secrets. The difference is he used gensacearespammers Basher Batteries and cut the trays, used dual lock on the bottom with a side straps. I'm sure this was the inspiration for Arrma doing the V2. You can probably just use the V2 battery trays and the receiver box as well.
View attachment 257933

thanks
I was watching that last night but you need shims on the bottom of the battery box cuz there's a bolt that sticks up at the back of the car that needs clearance. It's only like 158mm in total length. I think the 6200 CHNL's are 160mm and the 9500's are 172mm so a smaller receiver box would give it a little more space....

 

[Diem Turner]

thanks
I was watching that last night but you need shims on the bottom of the battery box cuz there's a bolt that sticks up at the back of the car that needs clearance. It's only like 158mm in total length. I think the 6200 CHNL's are 160mm and the 9500's are 172mm so a smaller receiver box would give it a little more space....

You can separate the receiver box and servo mount and then stand the receiver box upright to save space.

 

[Jerold]

thanks
I was watching that last night but you need shims on the bottom of the battery box cuz there's a bolt that sticks up at the back of the car that needs clearance. It's only like 158mm in total length. I think the 6200 CHNL's are 160mm and the 9500's are 172mm so a smaller receiver box would give it a little more space....

I think the Dual Lock works for him? It's been a while since I watched the full video. Also if you have a Tap Plastics near by, they sell ABS scraps for $1. It's very durable and super easy to work with. A table saw works great, but if you don't have that a jig saw or a coping saw work too. Even a box knife if you have enough patients.

 

[Jerold]

New PB and Some Video
Short story is I broke 120MPH today!

Turn up the sound really loud, your neighbors will ask if you are watching the F1 race. I love the sound.

The Setup
The same setup as before with the exception of finally trying out the batteries picked up in post #38 and installed in post #46. They were on close out from SMC and $50 each and I figured what the heck. The are an odd size and I had to shim them up a bit to get them secure, but what do you want of for 1/2 price batteries.

They are 4S SMC Graphine Extreme V2, 7700mAh. The difference is they are 2P4S, which means 2-4S cells in parallel and the odd size makes me think they are drone batteries. The 2P4S should give more current than 1P4S. Over all they are solid. I got several runs up to 117MPH, at which time they had dropped to about 4V, then I switched to my CNHL batteries. Next time out I will start with the CNHL and end with the SMCs.

With the CNHLs I hit 120mph.

I shot the video with an old Iphone 4 and a small tripod. It's not great video but the setup was free. I will be adding an action cam to my Christmas list. Not a GoPro or DJI. Something much less expensive, since I don't extreme sports anymore and this is probably the only thing I will use it for.

The Data
The full data log is attached. My 2 cents on the data. Looking at just the log for last runs, I'm in the throttle for about 3s.The current peaks and voltage droops the most right at the point I'm at 100%, from there it stabilizes. Which means more space more speed. Unfortunately (according to my GPS) I'm using 1400 of the 1600ft I have for the road. Which means I need to get in the throttle sooner.

Also looking at my temps, my motor his 185C, which isn't ideal. I'm looking into better cooling solutions. I'm thinking a couple of 40mm fans mounted flat to the pan next to the motor maybe powered by an adjustable BEC or switcher.

Something strange is I'm not getting 100% output, just 95.7%. I'm not sure what that could be, maybe ESC calibration?

Getting More Comfortable and Learning to Drive
I noticed today that I'm getting more comfortable with the car and driving it. My warm ups were 75 mph, 98 mph, 109mph. The D/R steering helps tremendously, but so does practice and knowing when it's too wonky and it's time to abort and shut it down.

Just getting to 120 is a fair amount of work and I really appreciate how good of a driver the really fast guys are. Especially James McCoy on that that country road.

Burnouts
Yeah, I know it's no bueno for the tire, but instant smoke is impressive. . . and it's fun.

 

[Diem Turner]

New PB and Some Video
Short story is I broke 120MPH today!
View attachment 258710
Turn up the sound really loud, your neighbors will ask if you are watching the F1 race. I love the sound.

The Setup
The same setup as before with the exception of finally trying out the batteries picked up in post #38 and installed in post #46. They were on close out from SMC and $50 each and I figured what the heck. The are an odd size and I had to shim them up a bit to get them secure, but what do you want of for 1/2 price batteries.

They are 4S SMC Graphine Extreme V2, 7700mAh. The difference is they are 2P4S, which means 2-4S cells in parallel and the odd size makes me think they are drone batteries. The 2P4S should give more current than 1P4S. Over all they are solid. I got several runs up to 117MPH, at which time they had dropped to about 4V, then I switched to my CNHL batteries. Next time out I will start with the CNHL and end with the SMCs.

With the CNHLs I hit 120mph.

I shot the video with an old Iphone 4 and a small tripod. It's not great video but the setup was free. I will be adding an action cam to my Christmas list. Not a GoPro or DJI. Something much less expensive, since I don't extreme sports anymore and this is probably the only thing I will use it for.

The Data
The full data log is attached. My 2 cents on the data. Looking at just the log for last runs, I'm in the throttle for about 3s.The current peaks and voltage droops the most right at the point I'm at 100%, from there it stabilizes. Which means more space more speed. Unfortunately (according to my GPS) I'm using 1400 of the 1600ft I have for the road. Which means I need to get in the throttle sooner.
View attachment 258711

Also looking at my temps, my motor his 185C, which isn't ideal. I'm looking into better cooling solutions. I'm thinking a couple of 40mm fans mounted flat to the pan next to the motor maybe powered by an adjustable BEC or switcher.

Something strange is I'm not getting 100% output, just 95.7%. I'm not sure what that could be, maybe ESC calibration?
View attachment 258721
Getting More Comfortable and Learning to Drive
I noticed today that I'm getting more comfortable with the car and driving it. My warm ups were 75 mph, 98 mph, 109mph. The D/R steering helps tremendously, but so does practice and knowing when it's too wonky and it's time to abort and shut it down.

Just getting to 120 is a fair amount of work and I really appreciate how good of a driver the really fast guys are. Especially James McCoy on that that country road.

Burnouts
Yeah, I know it's no bueno for the tire, but instant smoke is impressive. . . and it's fun.

Congrats man, well done! The sound of the GP4 diffs is way better than the GP5. Much more of an F1 sound.

You're definitely right about getting into the throttle sooner. You want the last 10-15% of your pull to take the longest as the voltage sag increases towards to end of the pull.

You want your curve to look more like this

And less like this

Unfortunately we can't see the burnout video.

 

[Jerold]

Congrats man, well done! The sound of the GP4 diffs is way better than the GP5. Much more of an F1 sound.

You're definitely right about getting into the throttle sooner. You want the last 10-15% of your pull to take the longest as the voltage sag increases towards to end of the pull.

You want your curve to look more like this

And less like this

Unfortunately we can't see the burnout video.
View attachment 258722

My bad, the burn out video was marked as no embeddding. Try it now.

 

[Diem Turner]

My bad, the burn out video was marked as no embeddding. Try it now.

Cheers, working now. Instant smoke indeed. If you want it to take off straighter, add some pre-load to your right rear shock.

Don't forget to post this in "How Fast Did You Go Today?". Nice work bro

 

[Jerold]

Cheers, working now. Instant smoke indeed. If you want it to take off straighter, add some pre-load to your right rear shock.

Don't forget to post this in "How Fast Did You Go Today?". Nice work bro

Thank you. I've got a long way to go to run with the big dogs, but I wouldn't have gotten here if weren't for this forum and guys like you helping out!

I was thinking to try and get a 0-60 time, but it turned to smoke. Which is way more fun. You thing the the turn from torque twist?

 

[Diem Turner]

Thank you. I've got a long way to go to run with the big dogs, but I wouldn't have gotten here if weren't for this forum and guys like you helping out!

I was thinking to try and get a 0-60 time, but it turned to smoke. Which is way more fun. You thing the the turn from torque twist?

This forum is such an amazing resource. We're all learning together and I'm always happy to share what (I think) I know. I'm not worried about running with the big guys, I'm just looking to improve and, maybe, someday I'll catch up to them. I kinda doubt it because the costs begin to get a little prohibitive beyond 170mph. I don't think I can afford trashing a set of foams on every run like vwturbowolf.

You can correct the left turn with suspension tuning. Next time you're out, increase pre-load on your right rear shock. This will increase traction on the right side. Go in full or half turn increments. Keep doing this until the car launches straight.

 

[K-BASH]

New PB and Some Video
Short story is I broke 120MPH today!
View attachment 258710
Turn up the sound really loud, your neighbors will ask if you are watching the F1 race. I love the sound.

The Setup
The same setup as before with the exception of finally trying out the batteries picked up in post #38 and installed in post #46. They were on close out from SMC and $50 each and I figured what the heck. The are an odd size and I had to shim them up a bit to get them secure, but what do you want of for 1/2 price batteries.

They are 4S SMC Graphine Extreme V2, 7700mAh. The difference is they are 2P4S, which means 2-4S cells in parallel and the odd size makes me think they are drone batteries. The 2P4S should give more current than 1P4S. Over all they are solid. I got several runs up to 117MPH, at which time they had dropped to about 4V, then I switched to my CNHL batteries. Next time out I will start with the CNHL and end with the SMCs.

With the CNHLs I hit 120mph.

I shot the video with an old Iphone 4 and a small tripod. It's not great video but the setup was free. I will be adding an action cam to my Christmas list. Not a GoPro or DJI. Something much less expensive, since I don't extreme sports anymore and this is probably the only thing I will use it for.

The Data
The full data log is attached. My 2 cents on the data. Looking at just the log for last runs, I'm in the throttle for about 3s.The current peaks and voltage droops the most right at the point I'm at 100%, from there it stabilizes. Which means more space more speed. Unfortunately (according to my GPS) I'm using 1400 of the 1600ft I have for the road. Which means I need to get in the throttle sooner.
View attachment 258711

Also looking at my temps, my motor his 185C, which isn't ideal. I'm looking into better cooling solutions. I'm thinking a couple of 40mm fans mounted flat to the pan next to the motor maybe powered by an adjustable BEC or switcher.

Something strange is I'm not getting 100% output, just 95.7%. I'm not sure what that could be, maybe ESC calibration?
View attachment 258721
Getting More Comfortable and Learning to Drive
I noticed today that I'm getting more comfortable with the car and driving it. My warm ups were 75 mph, 98 mph, 109mph. The D/R steering helps tremendously, but so does practice and knowing when it's too wonky and it's time to abort and shut it down.

Just getting to 120 is a fair amount of work and I really appreciate how good of a driver the really fast guys are. Especially James McCoy on that that country road.

Burnouts
Yeah, I know it's no bueno for the tire, but instant smoke is impressive. . . and it's fun.

Looks like something let go at end of pull,huge rpm spike an A&W dropped at the same time...odd

 

[Diem Turner]

Looks like something let go at end of pull,huge rpm spike an A&W dropped at the same time...odd

Might have hit a bump and the wheels momentarily lifted.

 

[Jerold]

Looks like something let go at end of pull,huge rpm spike an A&W dropped at the same time...odd

Yeah, I saw that but didn't think about a bump.

If figured it was a sample error. If the motor is turning 60K RPMs, you need to sample 2x that (120 ksps) to avoid aliasing. Since the sample rate is 1/5 of a second (200ms), which is about 600 times too slow to be accurate enough to recreate the curve. Which means it's really a single point and not a slope or a trend. It could have been much higher or wider for all I know. Basically the data logging is crude.

But I think @Diem Turner is right. For some reason,which I can figure out there is a high spot I can't see right next to where I put the camera. Maybe next time I will post a slow motion camera there and see what happens. It definitely seems to hop in that area once in a while.

 

[K-BASH]

Not sure if ya messed with the steering speed on radiolink or not.but instead of messing with D/R everytime I run my speed at 1% an return at 100%.works great for me elevates adjusting to turn around an imo much better control....I'd also advise setting up failsafe...not sure if your having overloading beeps still,if you are ya most likely have a week connection somewhere..inspect for hot wiring after run..reading your logs with everything on the screen would help us help you diagnose issues.things like ripple,mah can show problems with your setup..the most important is voltage drop,rpms an triggerpull.try an keep runs consistent far as time an distance so comparing an learning logs on setup easier..to me the log above has high #'s for a 120mph 8s run,even with a fast 5 second buildup.volts dropped lower than they should have,474a is high,an also almost 12000w on a 120 pass is insane...if ya had ripple an mah on it would help also...on run like this I'd guess xlx2/1717 to be well under 1v...0.7v tops an I bet it was well over 1v on this run..I suspect you got resistence somewhere..either excessive vibrations in drivtrain,bindage or bearing somewhere.you should do a video of you pushing car lightly on ground so we can hear it's roll resistence.on 8s with log #'s this high I'd expect 140mph..aim temp gun throughout drivetrain,diffs,spool an look for hot spots after run..hot high friction areas are problem areas that's holding car back..I'd also consider going gt for more room,higher speeds an more stability...awsome build thread

 

[K-BASH]

Here's a 155mph 7s log...on 8s watts would be much higher. Smooth rolling car on 8s 120 run an packs should be above 25.5v minimum an under 10000w,under 1v ripple an 800-1000mah used on a 3300ft pass..I'd imagine lower amps even with fast triggerpull..70%-100% throttle is the most important part on starts...you where very aggressive there an that hurts v-drop the most.

 

[dk10438]

Not sure if ya messed with the steering speed on radiolink or not.but instead of messing with D/R everytime I run my speed at 1% an return at 100%.works great for me elevates adjusting to turn around an imo much better control....I'd also advise setting up failsafe...not sure if your having overloading beeps still,if you are ya most likely have a week connection somewhere..inspect for hot wiring after run..reading your logs with everything on the screen would help us help you diagnose issues.things like ripple,mah can show problems with your setup..the most important is voltage drop,rpms an triggerpull.try an keep runs consistent far as time an distance so comparing an learning logs on setup easier..to me the log above has high #'s for a 120mph 8s run,even with a fast 5 second buildup.volts dropped lower than they should have,474a is high,an also almost 12000w on a 120 pass is insane...if ya had ripple an mah on it would help also...on run like this I'd guess xlx2/1717 to be well under 1v...0.7v tops an I bet it was well over 1v on this run..I suspect you got resistence somewhere..either excessive vibrations in drivtrain,bindage or bearing somewhere.you should do a video of you pushing car lightly on ground so we can hear it's roll resistence.on 8s with log #'s this high I'd expect 140mph..aim temp gun throughout drivetrain,diffs,spool an look for hot spots after run..hot high friction areas are problem areas that's holding car back..I'd also consider going gt for more room,higher speeds an more stability...awsome build thread

I'm curious to know what you mean by "I run my speed at 1% an return at 100%.works great for me elevates adjusting to turn around an imo much better control'
I set conditions and adjust the D/R for speed runs and it seems to work great.

 

[K-BASH]

Radiolink steering speed,slow steering speed works way better for me than adjusting D/R every single time to turn around..

I like mine slow like this

 

[Jerold]

Radiolink steering speed,slow steering speed works way better for me than adjusting D/R every single time to turn around..

View attachment 258829
I like mine slow like this

I thought about the steering speed, but wanted more precise control with limits, which is why I went with the D/R. It might freak me out a bit to turn the wheel and see nothing happen.

The Throttle speed is something I did mess with and didn't have very good results. But then again my my entire setup was a bit whacked. Although looking @Diem Turner comment about throttle control, maybe the throttle curve might be more appropriate.

 

[Jerold]

Going through more physical data today. Here is a capture from one of the runs, pardon the crappy image.

It looks like I'm slammed on the ground. This is confirmed by some fresh scratches on the bottom, from the splitter to the diffuser. The good news is that it's evenly scarred.

Normally I have about 1/2" of clearance at the splitter,which is a bunch too much, but I don't have perfect roads either and the extra clearance helps. I have full aero as well.

What I think is happening is the aero is creating way too much down force for the suspension and it's compressing. I'm hesateant to stiffen the suspension to much, because it will just bounce around and be hard to drive. So maybe do this in steps.

To remedy this my thought process is

1. First reduce the aero. Cut the front by 1/3 and the back by 1/2.
2. Add more preload to the springs and Reset the right height lower
3. Thicker shock fluid and/or stiffer springs

Reducing the areo and stop dragging the chassis should be good for a few MPH.

 

[Diem Turner]

I thought about the steering speed, but wanted more precise control with limits, which is why I went with the D/R. It might freak me out a bit to turn the wheel and see nothing happen.

The Throttle speed is something I did mess with and didn't have very good results. But then again my my entire setup was a bit whacked. Although looking @Diem Turner comment about throttle control, maybe the throttle curve might be more appropriate.

I programmed a bit of positive throttle expo in my ESC. I found that this helps a bit with speeding the acceleration up in the beginning and slowing down towards the end of the pull.

Going through more physical data today. Here is a capture from one of the runs, pardon the crappy image.
View attachment 258840
It looks like I'm slammed on the ground. This is confirmed by some fresh scratches on the bottom, from the splitter to the diffuser. The good news is that it's evenly scarred.
View attachment 258842
View attachment 258843

View attachment 258841
Normally I have about 1/2" of clearance at the splitter,which is a bunch too much, but I don't have perfect roads either and the extra clearance helps. I have full aero as well.

What I think is happening is the aero is creating way too much down force for the suspension and it's compressing. I'm hesateant to stiffen the suspension to much, because it will just bounce around and be hard to drive. So maybe do this in steps.

To remedy this my thought process is

1. First reduce the aero. Cut the front by 1/3 and the back by 1/2.
2. Add more preload to the springs and Reset the right height lower
3. Thicker shock fluid and/or stiffer springs

Reducing the areo and stop dragging the chassis should be good for a few MPH.

What you should probably do is add some shock limiting to your front and rear shocks so that you don't bottom out in the front and limit squatting in the rear to reduce the risk of blow overs. What you want to do is restrict the rear suspension to the point that it is impossible for the chassis to go past level no matter how hard you press down on the rear.

There are two methods that I've seen to accomplish this. One is to put fuel tubing on the shock shaft. The other (the one I prefer because it doesn't require disassembly of the shocks to add or remove limiting) is to use plastic c-clips that you clip onto the shock shaft. I made mine myself from some 3mm plastic bits I had laying around (don't ask me what they are or where they came from but I reckon you could probably find something similar at your local hardware store).

Stiffer springs can help but they can introduce a new problem. If they're too stiff, the composite material of the lower arms is too soft and the droop screws will become non-functional because it will just push the droop screw back through the arm. You can work around this by putting some silicone tubing on the shock shaft inside the shock to shorten the fully extended shock (I hope this makes sense). The only other option at that point is to move to aluminum lower arms (that's the route I took because the idea of having to disassemble, drain, shorten or lengthen tubing, re-fill and assemble my shocks whenever I want to adjust my ride height was a proposition I wasn't willing to live with).

Hope this helps

 

[Jerold]

I programmed a bit of positive throttle expo in my ESC. I found that this helps a bit with speeding the acceleration up in the beginning and slowing down towards the end of the pull.
View attachment 258854

What you should probably do is add some shock limiting to your front and rear shocks so that you don't bottom out in the front and limit squatting in the rear to reduce the risk of blow overs. What you want to do is restrict the rear suspension to the point that it is impossible for the chassis to go past level no matter how hard you press down on the rear.

There are two methods that I've seen to accomplish this. One is to put fuel tubing on the shock shaft. The other (the one I prefer because it doesn't require disassembly of the shocks to add or remove limiting) is to use plastic c-clips that you clip onto the shock shaft. I made mine myself from some 3mm plastic bits I had laying around (don't ask me what they are or where they came from but I reckon you could probably find something similar at your local hardware store).
View attachment 258855

Stiffer springs can help but they can introduce a new problem. If they're too stiff, the composite material of the lower arms is too soft and the droop screws will become non-functional because it will just push the droop screw back through the arm. You can work around this by putting some silicone tubing on the shock shaft inside the shock to shorten the fully extended shock (I hope this makes sense). The only other option at that point is to move to aluminum lower arms (that's the route I took because the idea of having to disassemble, drain, shorten or lengthen tubing, re-fill and assemble my shocks whenever I want to adjust my ride height was a proposition I wasn't willing to live with).

Hope this helps

Good point, messing with the ESC throttle curve is more accurate and easier than trying it on the RadioLink. I can add just a touch of negative exponential curve, ... I think that is negative? Either way make it look like that. Got it.

You're describing a bump stop. Which, on a real car, prevents you from smashing your axle/control arm/whatever into the frame, which is bad. Riding on the bump stops (done that before) does stiffen the suspension but effectively makes an infinite spring rate and makes the ride super choppy and uncontrollable on a rough road. Small bumps under throttle or braking causes the car to skip and dart.

The nitro tubing is installed in the rear, which ash you described, is a PITA to install. Raz made it look so easy. But I either didn't use enough of it or it's too soft for the amount of down force I have.

I have a lot of ABS plastic and can try the discs like you have. Or I might be able to just buy some plastic washers and split them and wedge them on to the shaft. What do they look like installed? Do they sit under the spring above the spring cup or inside the spring stacked up?