wtcc5 4688 Posted May 13, 2022 This one should be a short fun project of a Yokomo YR-F2- fan (me). The initial idea was to do a close copy build with available parts... A little research then showed that a korean guy did an awesome job here already: Shortly before I also thought about implementing a direct drive and also became unhappy with some design solutions of the YR-F2. So this will maybe take another route. This is the actual state (no direct drive yet): 10 Share this post Link to post Share on other sites
Honza 914 Posted May 17, 2022 Looking forward, it sounds like an interesting project. Direct drive with an independent suspension is quite challenging to design, I played with that idea, too. Have you considered different lengths of the driveshafts, like the real cars have? I was wondering, if there would be any adverse effects. 1 Share this post Link to post Share on other sites
wtcc5 4688 Posted May 17, 2022 Thanks for the positive feedback! @Honza: No, I haven't so far. The shafts will be very short in my actual concept, but I would like to keep them equal long. Are there any insights you would like to share regarding your direct drive FF? Today the parts, that can make the direct drive dream come true arrived: These are hop-up parts for the MST-TCR. A very simple and clever designed car. This shaft has the differential integrated and allows to use standard double joint cardans. What is a huge design plus for me, is that with this package the motor can be moved very close to the center of the front axle (22mm motor center to axle center). This makes the front motor layout attractive again (compared to the middle motor layout of actual competition fwd chassis) --> No front weight needed and short overhang. Also the direct drive should be an advantage regarding straight line speed and battery condition over a heat. I drew the shaft and worked on the motor position. I really like it. At the moment the concept consists of collision only , but I am positive to solve them in the coming weeks. I should even be able to add ultra long lower arms in front. 1 Share this post Link to post Share on other sites
Honza 914 Posted May 18, 2022 10 hours ago, wtcc5 said: Are there any insights you would like to share regarding your direct drive FF? Unfortunately, it didn't get past early CAD. My requirement to make it rally-capable (i.e. - long suspension travel and wide steering angle) further complicated things. But I might try it again my idea was using an FF03 ball diff, which is fairly narrow, and mount it between motor mount and spur cover (which also acted as a bearing holder and top link mount). That created free space behind the motor, so it could be slightly off-centre, which allows for slightly longer arms and right-hand drive shaft (I wanted to use a 30mm M0x shaft) I think that I scraped the concept, because suspension arm mounts ended up being pretty far from the bulkheads, held only by chassis bottom plate (which was planned to be 2mm GF composite, so quite flexible) . Otherwise, it was doable. 1 Share this post Link to post Share on other sites
Tizer 604 Posted May 18, 2022 Woo, this will be an amazing build! Any chance you would want to make a couple extra? 1 1 Share this post Link to post Share on other sites
wtcc5 4688 Posted May 18, 2022 @Honza: That sounds very cool! Maybe some day you will find the energy and ideas to make it happen! @Tizer: I hope it will continue to work out like it does right now. Because then I will be happy to share the fun with you and others. Today, I made good progress and solved a lot of smaller problems in my layout. Most of these solutions will change shape in the future, but show, that the package has potential: I am very happy that I could integrate the long lower arms, with the steering placement, bulkheads and servo position. The shown damper position would be my favorite, but I have no clue how to direct the forces over the spur gear keeping this compact package... I can imagine using TC-01 rocker arms somewhere there, but have no idea how, yet. 3 Share this post Link to post Share on other sites
Pylon80 2436 Posted May 18, 2022 6 hours ago, wtcc5 said: @Honza: That sounds very cool! Maybe some day you will find the energy and ideas to make it happen! @Tizer: I hope it will continue to work out like it does right now. Because then I will be happy to share the fun with you and others. Today, I made good progress and solved a lot of smaller problems in my layout. Most of these solutions will change shape in the future, but show, that the package has potential: I am very happy that I could integrate the long lower arms, with the steering placement, bulkheads and servo position. The shown damper position would be my favorite, but I have no clue how to direct the forces over the spur gear keeping this compact package... I can imagine using TC-01 rocker arms somewhere there, but have no idea how, yet. I could see 3D printed part attached to the upper arm. It would extend inboard of the upper arm pivots and apply a down force directly onto the shocks when the arms deflect upwards. Kind of like on a RWD mini-Z. I'll be watching your design with interest as usual. 2 Share this post Link to post Share on other sites
Honza 914 Posted May 19, 2022 Very interesting. It is great to see a FWD that's not just a TC with removed rear belt what driveshafts do you use? 1 Share this post Link to post Share on other sites
ruebiracer 1024 Posted May 19, 2022 Again, a Mega cool project Kevin, and already yet a very clever thought out concept! I´ll be watching with interest for sure! I´ve a feeling this will be the most unusual, clever compact package seen yet on front motor FWD. 1 Share this post Link to post Share on other sites
wtcc5 4688 Posted May 19, 2022 6 hours ago, Honza said: Very interesting. It is great to see a FWD that's not just a TC with removed rear belt what driveshafts do you use? Thanks! I plan to use Tamiya 42300. @Pylon80: Yeah, that seems to be the only way. I was a bit against this solution at first, because I prefer having a bit more travel for the shockshaft. After reviewing it shows, that the travel stays sufficient, so that seems to be a good design Good thinking! Yesterday evening I continued with the drawing of the super tight front package and everything comes together much better than first expected. Right now it is collision free and I am satisfied with nearly every detail. The lower arms are a bit ugly, but because they won't have to carry out the dampening, they could become slimmer. I also rearranged the electronics and will have the servo low in the chassis. Because of the upper shock arms it looks like a bull, so I am thinking about naming it that way 5 Share this post Link to post Share on other sites
Honza 914 Posted May 19, 2022 2 hours ago, wtcc5 said: Thanks! I plan to use Tamiya 42300. Wouldn't that make the car around 200mm wide? The TCR has 5mm shorter driveshafts. I can see potential issue with the damping solution - it created a lever, which multiplies force that goes into the arm's pivot ball. 1 Share this post Link to post Share on other sites
wtcc5 4688 Posted May 19, 2022 @Honza: I understand your concern regarding the stress on the upper arm mount. From my experience with these Awesomatix lower arm mounts on my KRv4.1, I am pretty confident, that it can take the load. On the Awesomatix and KRv4 a-arm these mounts have to widthstand a similar lifting load by the droop screw. I never experienced a pop-off myself in all races and trainings, yet. Thanks for this suggestion. I will definitely watch this area. Right now this design is attractive, because of its simplicity. In my drawing the car is setup for a 190mm width. MST says their car is 184mm wide. I will recheck if I made a mistake. 2 Share this post Link to post Share on other sites
Pylon80 2436 Posted May 19, 2022 One other idea that would both reduce the axial/vertical load on the ball link AND increase shock travel would be to have the left arm push on the right shock and the right arm push on the left shock, with long staggered 3d printed parts. But it's easy to have ideas Really excited about how it's looking so far! Share this post Link to post Share on other sites
ruebiracer 1024 Posted May 20, 2022 Also intesting is the camber gain in front, but I think Kevin has his plan. With the relative short uppper arm in relation to the lower one, negative camber would get relatively more negative compared to what many TC´s use nowadays, which all run relatively long upper arms. MAy you share your thoughts on your intentions Kevin? Curious about it! 1 Share this post Link to post Share on other sites
Honza 914 Posted May 20, 2022 12 hours ago, wtcc5 said: On the Awesomatix and KRv4 a-arm these mounts have to widthstand a similar lifting load by the droop screw. I never experienced a pop-off myself in all races and trainings, yet. Load from the droop screw is just load from the spring + some inertia of wheel, but here it acts against the damper, which means significantly greater force and it'll be moving at the same time. Although the onrad chassis won't experience large bumps that often and YR-F's original solution is quite similar and works, too. Share this post Link to post Share on other sites
wtcc5 4688 Posted May 21, 2022 Again several hours spend to shape this chassis concept... In front a lot of parts got reshaped. The gearing is now optimized for ETS 4.5 (outdoor) and 5.0 (indoor) rules and easily allows to go down to 3.0. The front arms got more details and more compact as the motor sits now closer to the drive axle. The rear came into existence also. At first wanted to integrate a pullrod type damping arrangement, but it took so much space and extra parts, that I will avoid it here. The compact design from the front just went into the rear also, just with better location of the damper and of course without all the motor-steering-units it became much simpler. The shape of the rear upper arms is functional, but a bit odd This compact unit allows a lot possibilities for battery placement/size and weight distribution. Regarding the question of my cambergain setup: With the KRv4 I ended up using 2.5 degree camber and found that it had not enough cambergain under load. The upper arm by the way is still 4mm longer than that of a standard competition touring car, even though it looks shorter. Fwd cars like and/or need less camber for straight line traction and then at least the "normal" camber for the corner. My friends often use 6° caster and 1° camber to get the best of both worlds. Awesomatix uses ultra long arms and "short" upper arms for some years now. So these were my thoughts behind this. I would have liked to make the upper arms some millimeters longer, but it wasn't possible with this package. 2 1 Share this post Link to post Share on other sites
Pylon80 2436 Posted May 21, 2022 I see you have included active toe or at least the possibility of it at the rear. What's your thought? Do FWD car benefit from it like TC cars do? Share this post Link to post Share on other sites
wtcc5 4688 Posted May 22, 2022 @Pylon80: I personally don't like too much effect of active toe on my racecars. It sometimes feels as if it makes the car nervous/inconsistent (even with toe gain). Most of the times I set it up being nearly neutral. What I like most of it, is that you can set up the toe without inserts on the fly between two practice runs Again another full evening was spend drawing. Again a lot of smaller and some large changes. It starts to look like a car. I had an headache finding attachment points for the upper deck with that tight package in front. I found them by extending the upper bulkhead clamps. The rear bulkheads were changed according. The lower plate was straight forward to design in front. Everything behind the steering assembly could undergo major changes in the coming days. This is mainly because of the battery- and servo- mount- package with its adjustability. I would like to have a tweak free, flexible arrangement, that allows to move the battery over the full length. Some ideas are in my head already, but it will take more nights until I have a suitable concept. From below it is visible how I try to achieve a low centre of gravity. 5 Share this post Link to post Share on other sites
Honza 914 Posted May 22, 2022 1 hour ago, wtcc5 said: From below it is visible how I try to achieve a low centre of gravity. It looks like an F1 from this angle maybe you could move the battery a bit rearwards and lay the servo flat in front of it to further lower cog? It looks like it'd have enough weight on front. 2 Share this post Link to post Share on other sites
Tizer 604 Posted May 23, 2022 I'm a bit sad that the design now doesn't have the long rear trailing arms like the YRF2 has. It's visually such a unique design, but it might be a bit outdated by now Either way the progress looks great and I'm looking forward to seeing this go into prototype/production phase. 1 Share this post Link to post Share on other sites
RichieRich 660 Posted May 23, 2022 Mentally, I cannot wrap my head around how the suspension/shocks function. Can someone explain it to me? Amazing design, though. Share this post Link to post Share on other sites
Pylon80 2436 Posted May 23, 2022 On 5/22/2022 at 12:01 PM, wtcc5 said: @Pylon80: I personally don't like too much effect of active toe on my racecars. It sometimes feels as if it makes the car nervous/inconsistent (even with toe gain). Most of the times I set it up being nearly neutral. What I like most of it, is that you can set up the toe without inserts on the fly between two practice runs Again another full evening was spend drawing. Again a lot of smaller and some large changes. It starts to look like a car. I had an headache finding attachment points for the upper deck with that tight package in front. I found them by extending the upper bulkhead clamps. The rear bulkheads were changed according. The lower plate was straight forward to design in front. Everything behind the steering assembly could undergo major changes in the coming days. This is mainly because of the battery- and servo- mount- package with its adjustability. I would like to have a tweak free, flexible arrangement, that allows to move the battery over the full length. Some ideas are in my head already, but it will take more nights until I have a suitable concept. From below it is visible how I try to achieve a low centre of gravity. I just saw it, the servo cut-out You could also have the servo flat and overhanging off the side. But then if you hit a pebble that would not be good. Still, not a problem on carpet. Like others here I just can't wait to see this beast come together! Share this post Link to post Share on other sites
wtcc5 4688 Posted May 24, 2022 @Tizer: Yeah, that is a bit sad, but the concept went its own way. At first I really planned to use the true parts geometry of the YR-F2. I need to find a real one @RichieRich: It is like the upper arm is a seesaw with the hub on one side and the damper on the other. The upper inner arm mounts are the joint. If the hub moves up, the other end of the upper arm moves down, compressing the spring. It is practically 70s F1 front suspension: @Pylon80: Thanks to you I got really unhappy with the electronics location and tried 8 or 9 different layouts. In the end I decided for a pretty conventional one in T-form. I really need the LiPo in the center line to allow for an easy weight distribution change. Also putting the servo on the center line would cause a collision with the topdeck. These and other collisions then brought me to this layout: The servo floats on a center line mount. With the receiver free to move (for example behind the servo), it is possible to have space for large esc. A standard shorty LiPo can move step-less 32mm front to rear. A lot of other things changed like the shape of all arms, of the lower chassis plate, I added the battery mounts and some other minor stuff, I already forgot Still on my todo list are: - hubs (I want aluminum ones and need to find a nice shape the manufacturing process) - rear active toe system - steering posts - fan mount - bumper - body posts 5 Share this post Link to post Share on other sites
Pylon80 2436 Posted May 25, 2022 If the folks in Shizuoka are reading this they will say: "We need to hire this wtcc5 guy!" 2 Share this post Link to post Share on other sites