Liberty's Kraton V4 speed project

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Knowing the HR spool has a design flaw I thought I'd risk it. Sure enough the rubber o-ring allowed the pin out and resulted in a RWD Kraton.

Result was 76 mph, when on the brakes the rear fish tailed and sent the rig over the curb where it began to cartwheel.
Yep it's not worth risking as you now know. ;)
So glad your Kraton survived the crash better than my Typhon did though when it went the same way.
 
Yep it's not worth risking as you now know. ;)
So glad your Kraton survived the crash better than my Typhon did though when it went the same way.
Thanks brother! I am also happy nothing bad happened. Kind of beside myself that you can not even pull off one run with that HR spool as it comes from HR. Crazy that they released a product like that, yet at least it is something where I don't have to build it from scratch. The solution is easy enough... I found a bronze bushing that will fit perfectly.
 
I used the whole bearing. 2 of them. I can't remember the size or number, but I think it's one of the wheel axle bearings. Fit perfectly. If you have a bearing kit, just start checking. No need to destroy the bearings, plenty of room. Easy peezy!;) I think I have a 34 tooth in there. I am going to go up a few teeth, to ease the heat issue.
 
Tested out the new diff repair utilizing the bearing method (thanks @cootertwo and @GMballistic). I figured it would be a good idea to test it out at lower power levels so I did a run on 4s. It was getting dark (about 8:30pm) and my SMC LiPo was not 100% charged, but wanted to get out before dark. Cells were ranging between 4.16 and 4.18.
It ran solid 73mph on 2 passes, drove perfectly straight and stable. It should be good to go for a 6s run next time we have a cool evening with no rain!

What size pinion were you running ..??
37t
Just a reminder that the Kraton has a different ratio for the front and rear differentials. This same 37/34 setup would be overkill on a Typhon.
Could possibly be too much gear on this one also. Not sure that I'll play with gearing too much on this one since I will be getting a Limitless once available.
If I can push this thing into the 90-105 range on 6s I'd be content.

-Liberty
 
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Do you have an idea of how much road you have to work with there distance wise? I’m wondering if I can find a nice clean patch of road like that near me and wondering if a 1/4 mile is needed. 1/8 mile. 500ft. Etc
 
Do you have an idea of how much road you have to work with there distance wise? I’m wondering if I can find a nice clean patch of road like that near me and wondering if a 1/4 mile is needed. 1/8 mile. 500ft. Etc
I actually took my Garmin Forerunner and tested this road on my mountain bike right around 1/4 mile.
Once you are pushing over 100mph the car will eat up road very fast!

Without getting too technical, these are the key points for a speed run on distance:
1. You need around 3-4 seconds at peak speed for the GPS to register that speed. (GoPro Hero's would only need around 1 second due to higher GPS sample rate frequency)
2. At 100 mph you are eating up 146 feet per second (4 seconds at 100mph is 584 feet)
3. 1/4 mile is 1320 feet. You will be utilizing most of that distance to get up to speed and slow down smoothly.
4. Typical radio range is around 700-1300 feet
5. For me good visibility is only about 600 feet (slowing down and making a U-turn at distance is tricky if you are not sure it has slowed down enough) This is why we stand in the middle of the run.

Helpful notes:
1. Walk the road and clear away rocks/debris.
2. Watch for traffic, people, and animals.
3. Futaba radios have best range (around 1200 ft on my 3PV and is also affordable, but higher models with FASST protocol have longer range)
4. Carbon fiber blocks/limits radio signals.
5. Setup the car with some rake in the suspension where the rear is higher than the front. Under acceleration the rear will squat. This will help avoid the front end lifting and resulting in a "blow over" Some guys resort to using lead weights in the front bumper also, but this comes with obvious penalties.
6. Wings create significant drag since our RC wings are just for looks and not shaped as true airfoils. At the least they should be trimmed down and flat as possible. The vertical side plates do help keep the car straight acting as a rudder. (assuming its not moving around in the 100mph wind)

-Liberty
 
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I actually took my Garmin Forerunner and tested this road on my mountain bike right around 1/4 mile.
Once you are pushing over 100mph the car will eat up road very fast!

Without getting too technical, these are the key points for a speed run on distance:
1. You need around 3-4 seconds at peak speed for the GPS to register that speed. (GoPro Hero's would only need around 1 second due to higher GPS sample rate frequency)
2. At 100 mph you are eating up 146 feet per second (4 seconds at 100mph is 584 feet)
3. 1/4 mile is 1320 feet. You will be utilizing most of that distance to get up to speed and slow down smoothly.
4. Typical radio range is around 700-1300 feet
5. For me good visibility is only about 600 feet (slowing down and making a U-turn at distance is tricky if you are not sure it has slowed down enough) This is why we stand in the middle of the run.

Helpful notes:
1. Walk the road and clear away rocks/debris.
2. Watch for traffic, people, and animals.
3. Futaba radios have best range (around 1200 ft on my 3PV and is also affordable)
4. Carbon fiber blocks/limits radio signals.
5. Setup the car with some rake in the suspension where the rear is higher than the front. Under acceleration the rear will squat. This will help avoid the front end lifting and resulting in a "blow over" Some guys resort to using lead weights in the front bumper also, but this come with obvious penalties.
6. Wings create significant drag since our RC wings are just for looks and not shaped as true airfoils. At the least they should be trimmed down and flat as possible. The vertical side plates do help keep the car straight acting as a rudder. (assuming its not moving around in the 100mph wind)

-Liberty
Freaking masters class right there! Thank you so much for the time it took to type all of that. Very useful and logical info.

My Typhon 3S is only at 56mph on 4S just yesterday for the first time, so I’m not in the ballpark of 100mph. I also don’t think I have an area that large that I know of. Other than behind a strip mall situation.

But I would have to hit something like that at a perfect hour when no one is there. Most places that don’t have traffic are also poor quality tarmacs. ??‍♂️

To be honest, I would be happy to hit 60 with my truggified Typhon 3S. I say that now but I’m sure I will want 70 then ??
 
Freaking masters class right there! Thank you so much for the time it took to type all of that. Very useful and logical info.

My Typhon 3S is only at 56mph on 4S just yesterday for the first time, so I’m not in the ballpark of 100mph. I also don’t think I have an area that large that I know of. Other than behind a strip mall situation.

But I would have to hit something like that at a perfect hour when no one is there. Most places that don’t have traffic are also poor quality tarmacs. ??‍♂️

To be honest, I would be happy to hit 60 with my truggified Typhon 3S. I say that now but I’m sure I will want 70 then ??

Location is everything. This spot I am using will be gone within 2-3 months since they have started framing out foundations for the new homes going in. I have to drive way out into the farming areas after this spot is gone. This means I will be doing significantly less speed runs. Large parking lots are great if you have them. Shipping distribution centers, High schools, large sporting event parking lots, or malls may be options IF they don't have too many trees and light poles. I have spent countless hours searching on Google satellite view for good spots. I wish I lived in Florida they seem to have perfect roads everywhere!
 
I guess while I'm sharing tips on speed runs here is another that I really like.
Weather Underground's 10 forecast allows you to hover over the day at different hours (orange line in the below image) and get wind speeds, temps, and precip percentage for that specific time. So for example I'm planning on running tonight around 8pm I can see winds are from the south at 7mph and temps in the ball park of 86 deg F.

I have found running with winds over 10mph is playing with fire to the tune of $$$$
So the next 7 days are out for me due to wind, time availability, and other factors.

41144
 
Do you have an idea of how much road you have to work with there distance wise? I’m wondering if I can find a nice clean patch of road like that near me and wondering if a 1/4 mile is needed. 1/8 mile. 500ft. Etc
If you can lay down the power hard but progressively (avoiding wheel spin) then you don't necessarily need that long of a road. These cars can accelerate very, very quickly. Set up is key though to whether you'll be able to put that power to the road.

Here's a video of my Typhon 6S doing a speed run on a local road I use just to give you an idea of usable road length: https://www.arrmaforum.com/media/arrma-typhon-6s-speed-run-pass-94mph.6153/
(y)
 
If you can lay down the power hard but progressively (avoiding wheel spin) then you don't necessarily need that long of a road. These cars can accelerate very, very quickly. Set up is key though to whether you'll be able to put that power to the road.

Here's a video of my Typhon 6S doing a speed run on a local road I use just to give you an idea of usable road length: https://www.arrmaforum.com/media/arrma-typhon-6s-speed-run-pass-94mph.6153/
(y)
Agreed, I tend to be overly cautious after a few crash scenarios.
I could accelerate much harder but only have a few runs with the car so I don't fully know its abilities yet.

-Liberty
 
Agreed, I tend to be overly cautious after a few crash scenarios.
I could accelerate much harder but only have a few runs with the car so I don't fully know its abilities yet.

-Liberty
Caution is a good thing though. ;)
Have you seen some of Philip's latest speed run videos that he's done using a new Go-Pro/FPV with GPS/speed meter on it?

Check out the acceleration on this as well as how quickly things can change.

 
Caution is a good thing though. ;)
Have you seen some of Philip's latest speed run videos that he's done using a new Go-Pro/FPV with GPS/speed meter on it?

Check out the acceleration on this as well as how quickly things can change.


Oh yeah Phill has set the bar. Can't wait to see what he can do with the Limitless!
I did some GoPro videos like this before everyone was doing it with my XMaxx (check out my youtube channel)
I passed along some of my basic video tricks to him about utilizing race render software. (makes GoPro videos easy)

I have not done any videos like that on the Kraton because the aerodynamics and the speed of it are very risky and GoPro Hero's are not cheap... Also have struggled to find a good mounting spot for it on the Kraton.

-Liberty
 
No changes from my 4s run above, but swapped in the 6s Turnigy Panther 5000mAh. I can tell the BLX185 esc is starting to choke at these speeds, but very satisfied with the results!!!

41188


Video or it didn't happen right?

 
Caution is a good thing though. ;)
Have you seen some of Philip's latest speed run videos that he's done using a new Go-Pro/FPV with GPS/speed meter on it?

Check out the acceleration on this as well as how quickly things can change.


HOLY ???? that's insane acceleration and top speed..!!!
 
Breaking 100

Having hit 94.5 mph on 6s the question is can I squeeze out 5.6 more mph out of this thing with the stock electronics? (no add on's like cap packs)

I have a few ideas like removing the TBR wheelie bar. Gearing is always something to play with, but it doesn't seem too far off from ideal. After 2 passes motor temps were right around 137 F. and it was around 87 F ambient temp. I also have not modified any of the ESC settings so I will likely do that next also.

Even if this rig won't go any faster with this ESC I have been very impressed with this BLX 185 system!

-Liberty
 
Taller wheels?
There really are only 2 good options GRP and BSR forms(that can handle over 100mph reliably). This location construction site would eat up BSR foams pretty bad. (I have several in the garage but wont use them on this car & road)
Gears can compensate for tires, but my issue is power against aerodynamic drag. Removing the wing along with the wheelie bar may be a good start for reducing drag. Could be just enough to get that extra 5+mph.

-Liberty
 
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