What made it so unstable?🤨... AK-917 TOTAL fail!
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- čas přidán 12. 09. 2024
- I made some carbon side plates, a carbon splitter, changed the motor and esc and geared up, WHAT HAPPENED?🤯
Total fail every time at only about 60mph and it's quite hard to figure out what to tweak or modify🤔
Let the serious tuning begin!
All the carbon parts I made using a jigsaw, drill and file, not ideal but does the job.
Unboxing test and first impressions
• Rlaarlo AK-917 Alloy r...
Set-up
Turnigy XK3665 3190KV brushless motor
hobbyking.com/...
HPI Racing ELH-6s esc
www.frontlineh...
RRP 43t 48p 5mm bore pinion gear www.metrohobbi...
Arrma ADS-15M 15KG servo
www.arrma-rc.c...
ATS foam wheels 65mm tall 28mm wide, unknown shore rating.
Link is for bulk buy 6 x full sets but check sellers other listing's for some other options.
www.ebay.com.a...
Music made on the GroovePad phone app.
All editing done on my phone using the Kinemaster phone app.
Contact -
Email
saulaldridge@yahoo.com
Facebook
/ rc-crazy-110316407770980
I believe it has to do with either traction or alignment.
Do you have travel limiters? The downforce pushes hard around 70+ speeds. The front could be lifting because the rear is squatting.
Yes it was mainly stock alignment and geometry issues with the steering.
And it was actually the rear that was lifting or getting loose which was the strangest feeling, doesn't really make sense hey🤷😅
Working much better now👌
@@rccrazyWhat is the alignment process?
I eventually got 134mph so everything was much better👌
As you said it needs overdrive in the front maby 5-10 % and what a load of rubbish about the "research"🤣 i have always had problems with no centre diff on any on road cars like my old vaterras they have a fixed drive system and lose traction on acceleration and also are tail happy its just how they are it seems. Had the same problem with the arrma felloney when i had one and got rid of it after a few runs. Hope you can figure it out or they add some over drive gears or under drive for the rear
Yeah except I think I got it wrong when explaining it, to go faster the crown gear would have to be a tooth smaller not larger, oops😅
But yes with this set-up proper overdrive may actually have helped, the HSP Flying Fish is exactly because as you said, no centre diff to tune, there are ways to counteract or compensate for that though😁
Next video I'll try and explain what I THINK may have fixed this tail happy stuff on my car👍
@@rccrazy looking forward to seeing its mate just got back from my first run with my tto2 on 4s with a castle maba X system and holy is it fun to drive already through one set of tyres 😂
Not burning rubber your not having fun🤪🤘
Another amazing running 🤩👍
Thank you greatly Rene😁👍
I can fully understand your frustrations now watching how many attempts you did in this video. I remember you told me it just wouldn't stay straight after 100+kph, Maybe having the esc up on the top brace might be affecting the CG?
Yeah man I had a hard time keeping it straight just cruising at like 50kph🤔
The CG could be too high but it could only be because of not having enough weight down low, could very well have been the case though as this is a very light lipo and motor for this car👌
Thick I've fixed it enough to keep it straight now so 🤞 for the next run!
Correct me if I am wrong, but it looks like the little rear spoilers are missing, watching the crashes, it looks a little like the front end lifts slightly and then basically the cars on a bed of air, hence steering issues and grip rolling. I’m also wondering just how smooth the road you’re using is, it only takes a little bit of change in the surface to destabilise the car. I am wondering if the extra weight (and corner balancing) of 6s might have helped, but it might also have created a bigger crash, so I appreciate why you chose not to. Really hope you can get it stable again.
I don't believe the little wings were beneficial in any way, I have way less aerodynamic cars that are super stable, and it definitely felt like the rear was breaking loose before the front but that's purely off feeling and could be totally wrong!
Road is perfect, super smooth👌
But since filming this I have played around with layout, tinkered with the geometry and yes just running a larger heavier lipo has benefited massively with stability!
With a little luck the weather will be ok this weekend so I can re test🤞
Check that the avc is working the correct direction.
The little spiolers on the back are called Gurney Flaps.
Yes avc is going the correct way and yes could technically call them crude Gurney flaps being just flat bits of plastic, kind of useless in this case though just going in a straight line, reduce downforce and you go faster👌
It is strange that some AK917 are so unstable at 60 - 70 mph, others are running 90 - 100 + mph fairly stable. Check out John Linneman latest video where he is running 145mph with his AK917 on 4s with TP motor & Mamber Monster esc. Running straight as an arrow, I believe he is running rigid rear suspension by replacing the rear shocks with adjustable tie rods, he also used rigid tie rods on the front of his 160mpg Arrma Vendeta but with shocks on the rear, but with limited travel using fuel tubing on the rear shock shafts. I know that James Mccoy also on his speed cars uses very limited travel on his front & rear shocks using silicon fuel tubing, so he only has a few mm of movement on his shocks. On your AK917 I would try fitting the fuel tube mod on the rear shocks to limit travel.
Yeah the fact that some are stable and other not just seems odd but why is the question.
Yes I did see John's runs, very smooth and fast, yes I run solid fronts instead of shocks on some of my cars but this is literally my second run and I mean they did claim 200kph+ out of the box so for some not to even manage 100kph there is definitely some inconsistencies somewhere.
I've made some changes and I believe I've got it running better so I'll get out asap and give it another run👍
As of now, John is up to 153mph. For this car, I'm thinking the stability problems area related to the mods. The ESC is to high up (NEED to keep COG low), plus the plastic brace is top soft/flexible, and the ESC might be shifting slightly, which could be throwing the left/right balance off when the vehicle is running. Also, I don't think that front splitter is helping any...it could be creating a 'negative' effect. Truth is, I see several things that could be causing it. But, as for what's *actually* causing it, I couldn't say...I can only speculate.
I'm not participating in the challenge, but not because I don't want to. Right now, I can't afford to...don't have the funds for the necessary upgrades. 🤙🏼
Yes bad CG mainly.
But I had not done any proper modifications for this video, stock shock oil, stock diff oil, stock geometry.
The centre brace was solid though being half carbon, no flex!
My splitter work fine, it was doing its job possibly too well considering the nose was planted and the rear was getting super loose.
Yes many factors come into play that's why we test, mod, test, mod and test some more.
Saul maybe try splitting you batteries to one each side or move the esc to the opposite side, to keep the center of gravity down. 💪🏼👍🏼🚗
Yeah someone else just mentioned the esc being too high, it was well balanced with this set-up so I though it would track pretty straight but not at all!
I have changed the car quite a bit again so I'll get it out hopefully this weekend if it's good weather🤞
Dad may be working away though, he's not sure yet.
Hey mate is the gear meshing too tight between the pinion and the spur gears? Looks like liftoff oversteer unbalancing the car, maybe move the ESC to the one side instead of on the upperdeck carbon support - that's a big difference between this and your last run.
The mesh is good, a TINY bit closer to the spur would actually be fine having such small teeth on these gears.
And I would say balance could've been a issue if it was darting off in only one direction but it was all over the place😬
I think the stock geometry is the main issue, front wheels were toed in, shocks were super springy and definitely something a bit odd with the steering assembly.
I'll get it tuned hopefully👌
Not a bad unit for the early bird price.. but at the current asking money..well, tell them their dreaming.
Honestly even the sale price was too much in my opinion, the cheapest version (the alloy roller) cost me $220aud, that's a lot for a 1/10 roller especially from basically a brand new company🤔
idk. i have metal rtr version and i did 112km/h with it on 3s pretty much out of the box. Changed spur and pinion, dialed down toe out in front, almost neutral camber in the back, steering rate 45-50% on dumbo rc transmitter and gyro maybe 15-25%.Also maxed out pretension on back springs. It is twitchi on slow speeds, but after 50-60 km/h it goes like on rails.
I uploaded another video today, much better again now I've made some changes
exactly this, balance too. that heavy battery on one side. drop your electronics on the other side to get better balance.
Great video 👏
Hey Saul not sure what’s up with yours and a few others I’ve seen that just don’t track straight. I’ve only had mine up to 105kph but it’s been running straight fortunately.
Hope you sort it out 👍
Thanks mate👍
I honestly it was just bad CG with the esc mounted on top and possibly some small inconsistencies in geometry from car to car.
Played with the set-up a bit and it feels better but can only push to like 80kph in my street so 🤞 the weather is good on the weekend.
Those wheels are a nice color and style which ones are they brother? Great content by the way
Thanks mate!
These are ATS foamies, toughest foamies I've had so far.
I'm not sure what shore rating they are and honestly I don't know where to get them other than ebay Australia, not sure if the seller ships internationally if you are elsewhere but would definitely be worth it as he has bulk lots for VERY cheap!
www.ebay.com.au/itm/115054020282
I’m having the same issue with keeping the car straight. Even with dual rate turned way down, it gets squirrelly once I try to pick up the speed. I’m checking and rechecking. Hope theirs and answer out there.
All I have changed so far that has proved beneficial is basically just changed to very aggressive toe out angle on the front wheels and I'm now using MUCH heavier lipos, seems to be helping, properly test this weekend hopefully🤞
Props for trying to keep it straight 👍 Bummer yours isn’t tracking 🤔
Yeah man I tried so hard to keep it tracking straight, I think it's tuned better now so more stability and better tracking next run hopefully🤞
Thanks mate👍
Keep at it, you'll figure it out 🙏
I have made some changes, tested in my street, can only get upto about 80kph but it definitely seems much more stable at that speed.
I'll get it out ASAP and test it at higher speeds🤞
Thanks😁
Front one way diff is what's needed like in professional-grade touring cars in on road racing cars
I really don't think a one way would change anything unless your racing.
Can't see it benefiting a straight line run at all🤔
@@rccrazy it would allow this front wheels to spend freely while the rear wheels are pushing while you're skating out of control
That is the complete opposite of what I have experienced with basically any RC cars really.
I definitely prefer the rear diff to be quite free and the front a lot stiffer as it helps pull the rear of the car straight.
@@rccrazy I understand that but if you look in your video and watch what your car is actually doing soon as you go to the Accelerate from its top speed all the way transfers to the front end and the rear end of the car cannot slow as fast as the back end and it breaks free you also got to take into account your battery Waits all on one side of the car you're not running this thing in an oval and of course you're not trying to run it in a course even though he trying to go in a straight line but that weight can affect the directions a car goes when the rear end breaks free. Old school guys back in the 90s and 2000's had front one-way dips in all of our cars that we had go very fast this allows the front wheels to spin freely from the drivetrain when you're trying to slow down allowing the rear wheels to do most of the braking
@@rccrazy if you look at high-end 1/8 scale and 1/10 scale on road cars where they're touring or course road course cars they all have a one-way front diff. When you put the hammer down it's like the front end is posi track. When you go to break it slow the car down like the front wheels are not attached to the Driveline. And it still allows one wheel the inside wheel in a corner to spin slower then the outside wheel. You'll never get that result with a gear differential in the front end it just will not happen a ball differential in the front end will not allow it to happen. You may think I'm crazy but if you do some research you'll find out what I'm talkin about that crazy old guys right
I know the feeling, split mine in two at 138mph ...curb then tree,I probably won't be entering the challenge if I don't get the parts
138mph!🤯
If your getting this car upto those speeds I'd definitely be hassling the crap out of them to send your parts, that's definitely competitive speeds👌
Still patiently waiting for my car to arrive
Oh that's horrible☹️
Well I really hope you and many others that have be waiting quite a while now actually receive your order and soon!🤞
Good video. Bummer that you are having so much trouble with the car. Hopefully you are getting something figured out.
To say it was a handful to drive would be a under statement😅
I think I got it somewhere figured out some hopefully you'll be seeing better speed and less crashes next attempt🤞
Thanks Tim!
@RC crazy let's hope it's better. It would be a shame if you couldn't figure it out.
raz uses 1million diff oil. can help but think its the diffs slipping. or maybe the shocks are to soft and is rubbing the back wheels on the spoiler support bracket acting like a break when it squats. just a thought. side note someone 3d modeled some parts for printing
So my diffs are 100% not slipping, but technically if the front was slipping you may get some loss of power to the front wheels causing the rear to try and overtake but not if the rear was slipping, would probably be faster and more stable if anything.
The wheels definitely don't rub anything I made sure of that.
And in regards to diff oil and shock oil, you have to remember and I'm not having a go at you just facts but everyone has different preferences or set-up that just work for them.
Personally I would never run that thick oil in my speedrun diffs, I drive much better, find the cars much more reliable with a somewhat free spinning rear diff and maybe 500k max in the front.
Just changed the rear diff to 30k, tweaked the geometry and made some better carbon wings and its driving much better👌
Can only go speedrunning Sunday's at the moment so hopefully the weather is good!
woah nice vid and a very unstable car maybe try lowering your car and stiffening the shocks which was what i did for mine and its quite stable till i lost my grub screw for the central driveshaft which lead to an rwd ak917 :(
Thank you🙂
Yes the front of the car in this video was about 6mm from the ground so I don't have much more room to drop and the shocks were as stiff as possible without changing the springs🤷
But I have made a few changes since filming this, I think I got it driving a bit better.
Going out this weekend hopefully🤞
I got 83mph right out the box, minior suspension adjustment but for a £300 car pretty impressive.
From what I've seen these cars are hit and miss for some strange reason.
I have noticed watching others though, on average the carbon version seems to be doing better than the allay version🤔
But anyway, yes now I have played around with geometry and changed some stuff it's driving much better I've just not had the chance to take it out yet.
Soon hopefully🤞
@RC crazy yea, I understand why the carbon would be better. Even just getting it out of the box, it screamed quality to me, no slop in anything, better than my infraction build wise.
Really!
Yeah I'd throw this AK off a cliff before parting with my limitless🥰
Good looking setup brother… you get it straight it’s gonna be a rocket!!… mine is scary fast I’m 4 mph from 100…😳
Thanks, it may need a bit more weight I thing😅
VERY NICE 96mph! You'll be there in no time👌
I like your videos first… usually don’t give out free sauce 😬 but try 200k in your front diff 20k in the rear and the fastest servo you got. Also the shock oil is too lite so 80wt or higher your preference. Gt5 gyro seems smoother but not necessary I have a CF rtr version and I’m hitting 70 mph on 3s easy and still running stock esc and motor. My foams ain’t came yet but I did 82 on 3s rtr wheels….. video coming soon. I like drifting though Area52_rcs speed run videos coming soon😬😎 good luck 👍🏾
Thanks mate I appreciate it👍
Yes I have made many changes now just waiting to take it out for it's next test.
I have done basically what you suggested but small differences, changed the rear diff oil to 30k, front is super stiff already but not because of oil because the o-rings are WAY to tight around the drivecup shaft, should've put slightly thinner ones in but just left it as is for now, changed rear shock oil to 100wt and COMPLETELY changed the front toe angle to something I know will improve stability.
Pretty confident it'll now stay straight and get around 100mph on 4s, if all goes well then I'll be swapping to one of my monster motor and mod1 gears👌
@@rccrazy can’t wait to see the video 😎
Good Job Man! I think the CG may be the problem
Thanks👍
Yes only noticeable think is the CG at the moment, more weight and a little geometry tuning will help aswell I think🤞
It appears that you're running a tiny bit of toe out on your front wheels which is going to increase the sensitivity of the steering (and, I think, explains the twitchiness). Give it 0.5° of toe-in. That should settle the front end down a good bit.
I'm not disagreeing but it definitely felt like the front was planted but the rear was super loose, lack of weight and bad CG I'm really starting to lean towards.
And you may find this strange but I normally run quite aggressive toe out on the front because as soon as you throttle the wheels will toe in (negative force due to object mass or something like that) so after testing it with almost zero toe and then with about 0.2 toe in (was uncontrollable) I decided to go my usual way, SUPER AGGRESSIVE to out and it's driving much better.
I think it has something to do with the wheels basically fighting against each other but somehow creating the opposite effect and stabilising the car.
I'm probably 100% wrong but it seems to work for me every time😅
@@rccrazy Very interesting. To be fair, I've always been a big proponent of "whatever works for you" and everybody has their own taste as to what they want the car to feel like. Maybe you're right and it just needs some extra downforce over the rear axle (the original 917 design, incidentally, suffered from a complete lack of air moving across the ass of the car which led to the car literally swimming from one side of the track to the other which was why they lengthened the rear quarters by a good foot or more...I'm sure I'm not telling you anything new, just drawing some inferences from the original that may or may not be a factor here, I know it's not an exact replica and just inspired by).
You could make a little wing from some Lexan scraps to go between the two haunches of the rear quarter panels like you see on the 917k. Nothing crazy, just a dash.
Just for the record, I'm not trying to meddle in your work, I know we all have our own ideas and designs on possible remedies to teething issues we run across, so...this is just me spit balling a bit with you. 🙂
www.auto-motor-und-sport.de/oldtimer/porsche-917-026-031-1970-kh-gulf-le-mans/
Not sure why but the link keeps jumping to some strange site😬
But yes totally depends on everyone's style taste and personal preferences with well everything I guess.
You know what, even my 917 AFX car had a nasty habit of breaking loose much more than all my other style cars, very different scale but there could be something in it😅
As you said it's not a direct copy/replica but as I'm sure many people know by now a lot of the time scaling down in great detail rarely works as expected especially on-road race style RC cars.
And yes I think I recall the 917k having a funny short wing thing directly in the middle of the rear end, would definitely add downforce to the rear🤔
@@rccrazy Whatever the case may be, you got a new sub here and I look forward to your next outings. I speed run an Infraction GT and VTE GT myself and post my exploits up on CZcams. Nothing too crazy, I'm working my way through maxing out 2S, 3S and 4S before I move on to higher power envelopes.
Godspeed and good luck bro 👍
I really appreciate that mate👍
Yes I checked out a few of you vids and subs so I'll be watching closely at your runs also😉
Nice 131mph on 4s🤘
I need some Scorched centre shafts or something to push my limitless, so expensive though.
Its the driveline if its a 2 piece. Mine isnt getting power to the front and it acts just like that. Im going to try and make it a one piece.
No mine is the alloy roller that comes with a solid centre shaft.
In my case it was just the setup in general and too much top weight, CG was way off.
My latest video I got 203kph or 126mph so it's better but still a bit wobbly.
Also whats your controller / transmitter your using?
In this video I was using my Spektrum DX4C but I am getting range issues now for some reason, ended up using a DumboRC X6FG system.
balance. on decel it drove the opposite direction of the battery. also noticed you have some serious toe.
It was definitely more CG issues having so much weight up high, running a much larger lipo the car was much more stable because of the extra weight down low.
The car itself is very unstable in general compared to most other "speedrun" cars.
I have moved the esc down now though.
czcams.com/video/f2Hex-DwNWY/video.html
As for toe on the front wheels, I always have quite aggressive toe out on ALL my cars which helps prevent over steering.
Just put slightly taller tires on the front of the car it will equal out the front and rear gearing
I did try that in this video mate😅
No didn't help, if anything it made it worse which totally doesn't make sense🤔
It's all good now, just posted a new run of 129mph👌
When you let off the throttle you lost down force you have to let it slow down on its own
It was a centre of gravity issue, runs fine now even under heavy breaking.
I got 100 mph then crashed it. My fault. But what I had to do was turn my steering rate way down. So much that I can’t do a you turn on a double lane highway
Yes my rates were turned down.
It was just not tuned correctly for me, next test should be better hopefully now I done some tuning🤞
the weight been moved a lot higher with the esc up there ,and the battery making it off centre posibly?
The lipo is actually very close to the same weight as the servo and motor so having the esc in the centre is ok, up high is definitely a different story, 100% would change the CG centre of gravity🤔
Never had issues with top mounted esc in the past but you may be on to it.
We'll find out soon, made some changes so hopefully get out this Sunday🤞
@@rccrazy good luck, hoping shake mine down at some point, but wait for parts kind of made me lose interest at the moment
Rlaarlo have failed with this one, ive not seen one car hit 100mph without crashing 😂
Oh a few are getting higher speeds now but not without lots or dramatic changes I guess😅
Yeah not sure about the 12 months Research and Development they were bragging about though
This thing is a load of crap, the video is really cool tho, 😎 👌 very entertaining
I appreciate that thank you😅
Hopefully the craziness is in the set-up, as in hopefully the bad characteristics can be tuned out, done my best🤞
With a little luck we'll have some good weather this weekend and I'll have some better results to share with you guys😉
Check out john Linneman video's with 130mph & 145mph runs, running straight with no crash.
Reading comments on every video out their as lead me to believe i have the only good one, or i just know how to set up a bad car.( im not saying you cant)
Sorry but I can't agree with that😅
Having seen 130mph then 145mph already I know there are many sleepers still to show themselves, lots of people know what their doing including myself😉
@RC crazy yea I know their is many more good ones out their but comments are usually people complaining.
Yeah that's why I called them sleepers, the one not sharing their secrets yet.
I'm not sleeper but I know I can set-up a car, 116mph my PB so with 1/14 so that's pretty good I think🤷
@RC crazy I wasn't saying you can't set up a car. I feel like that's what you thought I was getting at.
I wouldn't care even if you were saying I couldn't build a car, but you did say it seems like you are the only person able to tune a crappy car which is obviously not true😅
Can I have the link to those foam tires? 🛞 Please !?!
Sorry they are no longer available as they were old stock from like 10 years ago
I have no clue buddy- honestly, it seems they overhyped this one- seems like it takes A LOT of time and money just to get it right- I'm like= what good is a $20k challenge if you end up spending $15k to win it!? ... whatever you decide, go get em brother‼️👍👍🦾🦾
Yes they pushed the challenge stuff way too much basically just to get more sales I'm assuming and forgot about their customers
But yeah first prize is what $5000us, if it cost even $1000 to get the car going nice or some that found it fine to drive but have spent upwards of $700 just for a motor and esc which is easy these days that's a lot of money to send down the road at 100mph+ if it's as unpredictable as mine😬
I'll give it my best hopefully without too many more crashes🤣