Thanks! It has been the most frustrating part about the mod, but it is the most rewarding both in handling characteristics and working out the puzzle of which variables to tweak how much and whether the instability is due to the wheel or the tire itself.
I can imagine how frustrating it must be, nobody ever wants to work on tires because there are too many values, everyone always copies vanilla values but you obviously can't do it because there are no such tires in vanilla game.
Yeah, I have been working on tiny tires since I made the joke mod last summer. The hardest part by far has been trying to keep the wheels from collapsing in on themselves without using spring values that cause instability. What I really need to be able to do is use fewer rays since that will increase the angle and distance between the nodes, but it is too bumpy at from 1 to 5-ish mph as it is. I initially did try for 6 rays, but the stability improvements beam-wise was not worth the loss of stability due to so few contacts. It was so bad that the wheels would skip under hard braking, so I had to settle for 8. It is much better than the 10 I was using before, but the wheels can still collapse under the right conditions.
I finally got the tires feeling like real tires! There is very little unexpected bounce to them now and they handle how I expect a kart to handle based on my experience with indoor karts: very responsive turning, a bit of slide on the rear during hard cornering with throttle applied, and generally high g force corners. The steering angle will need to be tuned for the course you plan on driving as the sweet spot is at different points at different speeds. For instance: On the new map I am making (pictured below) The steering angle NEEDS to be 100% on the indoor courses in order to be able to turn sharp enough, but somewhere around 50-70% for the outdoor courses in order to allow more wiggle room with inputs. I also adjusted the position of the rear wing to be more centered over the rear wheels. Previously, the wing would push down behind the rear wheels and lever up the front wheels, which meant that the front downforce needed to be unrealistically high in order to get grip on the front end. I only just set up the changes, but the handling is significantly better now with aero now that the two wings are not fighting eachother and the additional weight is not trying to lift the front end. The new map is coming along nicely. I have the base of the bottom course done (collisions and course deco), the left course is about 50% done, and the indoor courses on the right are 80% done. The remaining three I am still waiting on approval before I start to work on them. I made a forum post for the map here Map Overview(positioning is final, but terrain details are not):
This weekend was primarily spent on testing, so I didn't get too many changes in place. Most of my attention was on the tires, of course, but I also put effort into other areas. I worked on the sound for the 600cc engine, fixed the vibrating headlight, and tweaked the tuning for the 350cc config. Having dedicated courses for the kart has made tuning it for realistic settings a whole lot easier. Instead of using just two courses on two separate maps, I can move between different types really quickly to see how the changes affect different situations.
So uh, I discovered an important beam was missing from the welded front suspension. Due to how many support beams I have in the area, I did not notice it was gone until now. Since this issue does affect handling when turning right vs left, I will be pushing this update out sooner than expected. A note about the performance: With the dummy, I can get up to 8 of them before seeing fps drop. Without the dummy, I can get the usual 12. The reason is that the dummy is constantly scanning the gforces to see how it should react. Below is the list of changes I need to make/finish before the release: Finish realistic kart tires I am feeling like they are almost perfect. There are a few things I need to iron out Make unrealistic kart tires stable As of now, they are not stable in the least Since they are a part of one of the default configs, I want it to be stable before the update. Redo welded front configs As with each update, I tweaked the precompression on the front end as well as changed the tires Surprisingly, the tire changes alone significantly changed the alignment. Test each part related to the welded front suspension This is due to the addition of the missing beam. It shouldn't be that big of a deal since I mirrored the rest of the beams left to right and the missing beam was only on one side, but I want to be sure. Items I hope to have finished by the time I am finished with this update: The kart wheels are not compatible with vanilla vehicles although they share the 3 lug slot The headlight is angled too high up to see things that are nearby Items that will not be finished by the time I am finished with this update, but will be present: The I4 engine sounds The I4 engine mesh The V4 engine mesh
If any of you have used the backyard kart since the update this morning, you will have noticed a few things. I have not posted an update as of yet, but the 350cc sound is significantly different than before the update, the performance of the tires should be dramatically different, and overall, it should drive better. The sound change I will need to add to my to-do list before the next update, but the rest was a nice surprise. As to the status of the update: I have almost completed the changes to the suspension and it is significantly more stable now. It no longer relies so much on the wheels themselves to lever the hub and instead I added a node to the center of where the wheels are, which helps a ton since the hub nodes are significantly more stable than the wheels and it gives more lateral support to the wheels since the node is directly in their center. It also helps out the rear end in much the same way and both allow me to reduce the tension on the wheel rigidity torsion beams. This will only be on the welded front suspension for now so I can get the suspension fix out ASAP. The biggest benefit of this change is that braking is much more stable now since the wheels do not completely take the burden of the hub at such a bad angle. Where it used to skip under braking, it now (mostly) smoothly comes to a stop or slides. The tires are also nearly done and just need a few tweaks now that they no longer have to support the rotation of the hub by themselves. The configs are coming along, but I need to start over due to the major change I made today. That shouldn't take too long since The values are not too different from before. The sound might actually need an entire rerecording... There is a ton of buzzing in the audio that I could not hear before the 0.28 update. I will begin working on that ASAP, but I will not be pushing back the update to accomodate it since it is more of a preference thing instead of actual annoyance. The buzzing makes the engines that use the 350cc files sound more like motocross engines than the smoother sounding street bike engines they are intended to mimic. Edit: Just wanted to add that this is probably the most satisfying unintentional fit in this mod so far Edit Edit: The change to the rear wing position SIGNIFICANTLY changes the aero balance. Instead of nearly needing double the lift coefficient on the front, it now needs roughly 4% more lift coefficient. This is a huge boon since with the reduced drag, the kart can go even faster without sacrificing the handling. The update I am releasing is going to be heavily biased toward the realistic variants of the welded front configuration and the next will fine-tune the rest.
Okay, I am nearing completion and expect to have this version uploaded tonight. One issue that will require more research is that the electric crazy config absolutely shreds the rear wheels when accelerating at full from a stop. This does not occur with any other setup, so it likely has to do with the axle. This is a very niche issue, so I will not be postponing the upload since the other issues/fixes are much more impactful. The full list of changes: Frames: All: slight tweaks to the precompression with beams connecting the front subframe Engines: Corrected weights for all engines Added a new 600cc sport engine Based on the Suzuki Gsxr600 The torque curve is based on a dyno run I found on youtube The power with the high-end exhaust is based on the power ratings FSAE teams managed to get Currently uses a mix of vanilla sounds as I really dislike recording the audio for new types of engines, but I will be getting a custom sound together eventually Fuel: Added new fuel tank parts Separated twin tanks into left and right. Can mix and match lower and upper configurations and choose to only have a fuel tank on the right or only on the left Raised Rear: Changed engine mount beams Exhaust: Updated weathered exhaust texture Suspension: Welded Front: Adjusted precompression values further The caster no longer affects the toe angle, but it heavily affects the camber. It can be compensated for by adjusting the camber for now. Added a missing beam on the left arms This beam was one of the primary arm beams, which meant that turning right caused the left arm to bend more than the right would, causing right turns to be more sensitive than left turns Added an additional node to the center of the wheel location This adds additional stability to the front wheels since there is now support directly at the wheel instead of hanging the wheel off of the hub. Standard and IRS: Reworked the bypass shocks so they now perform much better Raised Rear Axle 3 Lug: Added the same support node to the rear axle Added new suspension geometry Referred to as "Alt" Wheels: Significantly reduced the weight of the 8x6, 4x6, and 4x4 wheels Added new models for the 4x6 and 4x4 wheels Added new larger kart wheels 5x6 rear and 5x5 front Tires: Significantly reduced the weight of the kart tires Added a new mesh to the Kart Soft tires. Added new 10-inch tires for the 5-inch wheels Aero Moved the rear wing over the rear axle Adjusted lift coefficient of the front wing Configs: Retuned all configs that use the welded front suspension or the kart tires Retuned the short course configs with the new bypass shock values Misc: Animated rear axle and brake meshes for the raised rear axle
Oof. So a couple of testing values leaked through. The wheels for the standard configs are attached using loose bits of yarn. I will have an update to fix this up as soon as possible. This will also include further improvements to the rear 8x6 kart soft tires as well as some mismatched diffs fixed on some of the awd variants.
So I was unable to get the changes stable before the weekend, so I will be posting an update this weekend. I had some major breakthroughs on the performance of the rear tires. So much so, that the ultra tires are almost not needed anymore. They cannot handle the 1000cc engine on the drag strip, so the ultra tires will still be in place until I can fix that without destabilizing the tires. I am starting to believe that most of the vibration in the tires below 40 mph is from the small number of rays causing a more abrupt hit when the nodes touch the ground since the tires become significantly more stable the faster you go until around 150 mph. I am basing my assessment of the stability of the tires on the node forces debug tool, which has helped a lot with determining which variables need to be changed. Basically, my goal is to keep the forces from going full red at all at any reasonable speed and I am getting pretty close. However, I need to balance this with the wheels collapsing on themselves. The values I need to use to keep them truly stable can result in collapse under the right circumstances, such as: Too much acceleration, putting all of the weight on one tire, and hitting a wall with just the tire. The tires can correct themselves in most cases, but there are instances where they will collapse too far for the beams to right themselves. TL;DR: Didn't get the tire changes stable in time for the weekend, but the changes will be worth the additional wait.
With the update in place, I am looking at the suspension and the frame to find ways to reduce the beam complexity. I have so far made one change that has significantly improved the front end: torsion bars. Instead of using 20 or so beams to keep the front arms steady, I instead used only 8 torsion beams. This had a huge impact on the stability of the front end and allowed me to remove dozens of the precompression settings I had in place. This has reduced the bounciness in the front end noticeably as well as allows more flex in the front arms. The flex is important for racing karts because it emphasizes the leverage on the rear wheels and actually helps keep them more stable during a hard turn. Where before, the kart would lift the inner front wheel off the ground, now it holds more firmly to the ground while still levering up the inner rear wheel. When the next update hits, you can watch the wheels debug and see that the inner wheels will start to lose weight, then the rear wheel will begin to lift before the front and return in reverse order. The next update should be another significant improvement in handling. I am so used to how the kart handled before and the quirks of the front end, that I have a hard time driving it at the limit now. It has much more grip in the rear without changing anything about the rear end or the tires and this is without sacrificing the turning angle. I am able to get the same level of performance out of it with half the caster angle and now camber has a noticeable effect on grip. I have a preliminary variant of the 350cc config that peaks at around 2.15Gs before sliding. I tried to record the ortho view to show the difference in the amount of shaking in the front arms, but the fps drops to 9 whenever I use that view for some reason. One other benefit to this change is that I should be able to further reduce the weight in the front end since I no longer have to use insanely high beam spring to keep it steady. The current version uses a spring value of 2500800 whereas I get the same effect with much less complexity with only 300 using the torsion bars. The front end needed to use weights 2-3x the rest of the frame in order to get the result I was looking for, so I hope to be able to shave off another 40-60 lbs now that I can use a weaker spring value. Of course, I will be looking to reduce the weight of the rear axle as well since it currently weighs over 50 lbs where the irl axle weighed something like 9 lbs and I do not believe that I need it to be nearly as strong as it is. TL;DR: I am improving the front suspension and frame and have made significant improvements so far.
I managed to get the weights down and still maintained the stability of the structure! I wish I had thought to use torsion beams sooner to rigidify the front arms. The weight of the 350cc welded front race config has been reduced from 672 to 612 lbs! This is just with reducing the weight of the front end and the weight reduction has made the steering much more responsive. The kart still weighs more than twice what a standard racing kart weighs, but it's made from thick steel tubing, so I don't think that targeting that weight would be realistic. The changes have also made the driver camera much more stable. There is still a little bit of jiggle to it, but the nausea levels are much lower now. Here is a quick video to show the first-person camera as well as how sensitive the steering is now.
I am still working on getting the new front end setup stable as the torsion beams do not like to be in a crash, but the handling is much more responsive now. The funniest thing I noticed now is that due to the caster angle, if you are understeering, turning more should solve it since the greater steering angle will lift the inner rear wheel more. The new rear axle is stable, so it's just down to tweaking the front end so it doesn't explode with the smallest force on the front end.
I am also looking at ways to improve the sound of the i4 engines. After watching a ton of videos and comparing the sound of the relevant bikes to the vanilla sounds or what I can get from automation, I realized that they are super similar. The automation sounds seem the closest for the I4's that rev below 10k, but the vanilla sounds work really well for the ones that go over that. To get the sounds to be closer, I just need to get idling samples from the relevant bikes. The reason for this is that an idling bike seems to sound very different from a car, even with the same kind of engine setup. The I4's currently in the mod are the 500, 600, 750, and 900cc engines. The other engine types are: I1 (250, 450cc, Predator), I2 180 degree(350cc), and V4(1000cc). The I1 and I2 engine sounds are passable enough, but the v4 definitely needs a rework. I will have to try to find better samples or do a better job of recording audio from engine sim. The engine sim sounds are really close to the Ducati Streetfighter v4 engine I based the torque curve and engine model on, but getting the settings right for recording is a bit hard. AngetheGreat recently uploaded a video on how the sim works in more detail and spent some time explaining the audio simulation and I think I can get much better samples than I have in the past. However, it is a bit of a pain to get the samples as there are somewhere around 30 samples I need to get and then I need to edit each one to remove any clicking when the sample repeats. This is not hard work, but it is monotonous, both in how boring it is to do and the fact that I will be listening to a single tone for however long it takes to get the cycling right. As far as the new front end: For now I will be including it as optional as I have with the alternate front suspension geometry. Mostly because it significantly changes the handling of the kart and takes time to get used to, but also because it isn't 100% stable and is prone to exploding. The new handling is very different from a standard car. Usually, you want to keep the tires in the optimal angle for grip and the grip curve is parabolic. The kart's grip curve start's out parabolic, but as you increase the steering angle past the optimal grip angle, the rear inner wheel gets levered up more and more. This causes the turning circle to shrink even though the front tires are in a state that would normally mean understeer. This phenomenon is significantly more pronounced with the new geometry since the front and rear are both much better planted despite being much lighter. Both the pre and post-lift states have much more grip than the previous setup. So much so that flipping the kart is a common occurrence with the current tires when oversteering. I am still working out the best tunes for the front end to make the grip curve much less sharp as currently, the difference between understeering and severe oversteering is a few degrees of steering angle. Also, since the front end is much lighter now, the imbalance of weight is even more noticeable. Where the front spoiler used to be optional, it is almost mandatory for every engine more powerful than the 350cc. This is due to the more powerful engines being able to almost completely lift the front end at almost any speed. Adding the front realistic spoiler helps in most cases, but using the unrealistic front spoilers allows you to fine-tune the lift coefficient so it doesn't cause oversteer. The next update will still have its primary focus on the kart tires, but these other changes significantly improve the driving experience and make it more immersive and predictable.
I haven't made much progress on the engine sounds, however, I did make a bunch of progress on the front end. The torsion beams were too unstable during a crash, so I reverted back to the old beam framework while reducing the weight. I was hoping that I could reduce the complexity, but it just didn't work out. However, since I am using the existing framework, tuning the handling is much easier. The front end is still really light and is really sensitive to weight transfer, but the improvement to overall stability by using much more sane beam values more than compensates for this quirk. I will be spending the next bit fine-tuning the tires for the new weight and working on the engine sounds. I am revisiting the original engines (250 and 350cc) and realized I dealt you all the greatest injustice: I forgot to compensate the torque curves for the friction values, thus reducing the power compared to IRL values. In the case of the 350cc, it had 8 hp less than it should have had. I used an irl torque curve and used automation to generate friction and inertia values, but neglected to correct the curve for the values. The vast majority of my focus over the past few updates has been on the welded front configs. I have been tweaking the others here and there, but as soon as I finish this new reduced-weight setup, I will be putting my focus first on the IRL configs, then the independent rear configs. The IRL configs mostly will require a bit of attention to the tires and the frame stiffness. The bubble tires are way too springy and lose traction way too easily and the frame has absolutely no flex to it. The independent rear configs are at least 200 lbs too heavy and have the same unrealistically stiff frame. Since I am working with the existing beam structure, the update should be coming sooner than later. There are a few things I need to work out before I post the update, though: Critical items (affect handling and stability of the kart and will be addressed in the next update) Finish fine-tuning beam values to accommodate the new weight Finish tire tweaks Body Kits Some body kits cause instability All body kits interfere with the alignment of the welded front config Things that bug me, but don't affect the performance of the kart and may be addressed with the next update: engine sounds: All I do not know if this is across all hardware, but on my setup, there is a bit of choppiness to the engine sounds that only seems to affect this vehicle 350cc The recording quality was meh to begin with and has a ton of post processing I4 and v4 I am still working on tuning the engines in engine sim before I can get recordings Body Kits The body kits are not compatible with the alternate front suspension The body kits are not compatible with the new I4 exhaust Engine meshes The I4 and Ducati engine meshes still need simplifying Mesh density There are a few meshes that I can get rid of since they are duplicates in slightly different positions. For example the raised suspension engines and the independent rear engines. Things that do affect the handling and performance of the kart, but are fairly nitpicky and are not likely to be addressed in the next update: The frame is way too stiff There is almost no flex in the frame, which is super unrealistic This was done solely to isolate other variables in the instability of the handling in the early days, but it stuck around because I was afraid to change too much This change will be coming sooner or later, but not before I finish the new front-end setup. To put it in perspective, the frame has the same stiffness as the frame from the pigeon despite being made of smaller tubing and essentially being a convertible. The dummy lean needs some tweaking Right now, it likes to lean far too early in some cases This is due to vibrations becoming more severe as speed increases and the turning circle gets smaller I do not want to make the dummy less responsive, but now the dummy directly upsets the kart along long sweeping corners due to it oscillating slightly. This is a slight effect, but still noticeable with the lower weight of the kart. All of the frame nodes are the same weight While the frame weight is accurate for the materials, all of the nodes are the exact same weight regardless of the lengths of the pipes that connect at the point of the node. ( I placed a node at all but two intersecting points in the frame) This makes for a really well balanced frame, but it does not make for a realistically balanced kart. The front end is quite a lot more dense than the rear, but the rear weighs just as much as the front. How I am going to do this is I am going to take a node and get the sum of half of the lengths of each pipe connected to that node and multiply it by a per foot weight of steel pipe of the diameter used. This will result in the right being heavier than the left due to the longer pipe on that side, but it will at least be more realistically balanced. Since it is (for lack of a better word) canon, I will also be including a symmetrical frame.
In the interest of realism, I am going to be redoing the setup for the rear mounted 250cc engines. I used a placeholder model from a Honda CRF205R before I managed to get a scooter engine with the attached cvt together and now that I have such a model, I will be changing the engine specs to match the bike the model came from: a Honda CRF205R. The reason I am not going to use the scooter engines for the rear mounts is that the rear arm will stick out much too far to be reasonable while still having room for the rider. Since I already have the engine models made, this will be a really quick change. The longest part of this change will be to record a 1-cylinder sound up to 13k rpm and update the blend file. I am thinking about doing all of the recordings up through the 20k's just to be 100% sure I will never have to do the recordings again lol. I managed to get engines in engine sim that sound similar to the real life counterparts to the engine types in this mod as well as perform similarly, so I am almost ready to get the recordings started. However, I will probably be putting this off as much as I can because it is a huge time sink to do the recordings. Getting them for the V4 took over half an hour just to get the recordings and another hour or so to make sure they loop properly without any popping and that the idle loops are synchronized. My goal with the engine sounds is that they are a high enough quality that people will steal them for their own mods lol.
I managed to get the soft and hard kart tires performing well with the lower weight. Now I just need to fine-tune how much flex there is in the front arms and fix the bubble tires. This weekend is going to be really busy for me, so I will not be able to get it finished then. However, the hard part is done, so expect an update sometime next week. With the reduced weight, the choice of body kit is critical to the handling o. They now weigh 10% of the total weight and depending on which you choose, the center of gravity could be as much as 10% lower and 50% higher. The covet bodykit has a higher center of gravity and can cause the kart to flip during hard cornering. The SBR bodykit lowers that center of gravity and significantly improves handling despite the greater weight. The 350cc engine is also a whole lot more aggressive now that it has a proper torque curve. It can reach top speed at lentola less than halfway down the main straight.
I finished the raised rear axle and was able to port those changes to the standard rear axle. I was also able to reweight the frame and front suspension as well as loosen up the frame a bit. The frame now flexes during hard cornering and especially when hitting the frame from underneath. My initial reasoning for tightening up the frame as much as possible was to try to make it more stable, but having the flex in the frame makes it a whole lot more stable since it doesn't try to bounce when cornering hard. Now the kart slides a lot more readily than it skips or flips. Changing the frame weights actual;ly reduced the total weight by about 20 or so lbs and finally brings the kart in line with the real IRL weights! The tires also contribute to the improvement as they no longer suddenly dig into the pavement when sliding and are a lot more forgiving in general. With all of these recent changes, I stress-tested my pc with how many karts can run simultaneously. I haven't really tried this since well before I implemented lua to make the dummy lean, but I can still get 17 before framerates get unstable. The update primarily focuses on the welded front configurations, but some of the changes leaked over to the IRL configs. The frames now deform and the weight balance is now realistic. I also adjusted the weight of the standard rear end, so the 350cc config now handles more realistically. It was not designed to go over 20-30 and nor was it ever driven faster than that, so the bubble tires have been changed to perform optimally below 30. They absorb bumps a lot better, but cannot handle high speed turning or high speed bumps without causing the kart to spin. I know I say this every update, but the changes I made this time around have a massive impact on the handling. You can still throw it around corners, but it requires some throttle control, even with the bottom-tier engines. You can get away with flooring it non-stop, but it will be a lot more difficult. The steering is now significantly more sensitive, so having the full steering angle is only necessary for the tightest courses and the caster can be set to neutral without too much understeer. I am currently working on packaging the mod for upload, so expect an update to be approved soon! --- Post updated --- So, um. The beamng packer decided to nuke the backyard kart. Luckily I hadn't closed notepad++ for the some of the files, so I was easily able to recover those changes. Some of the files were corrupted beyond recovery, such as the jbeam files and most of the textures, so I essentially need to make the changes all over again. Luckily, the tire changes were not nuked, so the hard part doesn't need to be redone, but this is still going to push the update back quite a bit while I redo the changes to the suspension and the frame
