.png.94a0d1c33952e15a35e0b13d13e1c498.png)
Didumos69
-
Posts
3,045 -
Joined
-
Last visited
Content Type
Profiles
Forums
Gallery
Everything posted by Didumos69
-
.thumb.png.116032e930e483fb4ebbfdc62183bd34.png)
Good to see some progress here! I like the idea of being able to use the tractor tires and wider mudguards as an option. Curious how that will look. I'm also curious if the wheels will still stand straight when you use tires that don't have a flat surface. It will be a nice test of the suspension. -
If the clutch only slips on very short, rare and infrequent occasions, then yes. I integrated this in the Porsche in june and it preserved its friction over time. But I wouldn't advise using this in a motorized function or in a function that relies primarily on the slipping of the clutch.
-
That's a nice one indeed! Does require some bracing to avoid the stud from popping out though. I know there are more ideas out there that give more resistance. For instance: And my version is similar to one from Sariel: http://sariel.pl/2009/01/linear-clutch/
-
I suppose that was a motorized build. It's probably better to not use this at all in a motorized function. I use this for a push-along model and only to deal with a halting gearbox during shifting if that happens at all. The drive train itself is smooth enough to not cause the clutches to slip.
-
@charlesw, thanks for your report! You must be able to build the Porsche out of your head by now . It has also been reported that correcting the gear sequence only introduces more friction. Can you confirm that from your experience? @polda, the friction clutch should actually never slip, its only purpose is to protect all gears when the gearbox halts, something that should only occasionally occur during shifts. So you have to make sure everything runs smoothly. It's hard to tell when you're at the right friction level, but you should be able to hear the difference between happily rattling gears and gears that are having trouble rotating.
-
That sounds really cool! A whole lot of things packed under the hood, must be a car with a noteworthy front . I used the linear clutch as a replacement of the white clutch gear in the Porsche to remove some unnecessary gear meshes. Thanks! I wasn't near my LEGO the last few days, so I had to make do with LDD, but I'm eager to continue the real life build. The gear inside idea comes from @Paul Boratko's Scorpion CK-R.
-
Great that you're using the stepper principle. I'm curious how exactly, but I will be patient ... Here are some close-ups of the gearbox and a cutaway showing the entire drive train (LXF-file of the drive train cutaway can be downloaded here). I don't think it will be suitable for motorizing though, because the subsequent gear ratios are quite far apart (1:4.2, 1:2.52, 1:1.4 and 1:0.84). I also incorporated 2 linear clutches between the central diff and the other 2 diffs. Just to be sure nothing gets damaged when the gearbox halts. Chances of double engaged gears are minimal, but during shifting there is always a short moment of having two clutch gears being 'half engaged' so there is always a small risk. I don't think much is going to change about this drive train. EDIT: I just noticed that the #2 connector above the central diff collides with the diff. This could be easily resolved by replacing the connected axles with a single 10L axle. I updated the cutaway-LXF accordingly. I'v also been working on the gearbox casing in LDD a little. To leave enough space for the seats I had to downsize the engine from V10 to V8 and had to move the gearbox 2 studs backwards. To make room for the gearbox I also had to change the rear suspension module slightly. And I figured out how the shifting mechanism is going to work. Essentially the shifting mechanism will be the same as in my compact stepper, only this time I separated the shift lever from the knob gears. The 90 degree limiter is wrapped around the shift axle itself. The movement of the shift lever is translated to the knob gears using liftarms. I still have to work on the bracing of the mid section, but a 5 stud distance between the seats still seems feasible. This is the current state:
-
Thanks! Unfortunately I'm having more trouble setting up the shifting mechanism.... I used two half pins with a 1x1 flat round tile attached to them to avoid the CV-joints from getting stressed. It gives just a little more gear rack travel than half bushes. The max steering is now slightly better that the max steering angle of the stock Porsche.
-
Thanks! I guess I will have to put half bushings too. I did some work on the drive train. Even though I've only planned for a 4-speed sequential gearbox, I do want to cover a wide range of ratios. So not something like 1:2.5 upto 1:1, but rather something like 1:3:5 upto 1:0.8. Another requirement is that I don't want red clutch gears to transfer drive on axles rotating at different RPM. This is a common practice, but from modding the Porsche I know it induces a lot of friction on the axles involved. When not engaged, red clutch gear should only make dummy rotations and not transfer drive. And finally it all has to fit underneath the engine and I don't want the gearbox to be wired through the entire chassis. After some playing around in LDD I came up with a quite simple setup that takes full advantage of the integrated center differential. Taking into account the gearing around the front and rear diffs, the overall gear ratios will vary from 1:4.2 (first gear) upto 1:0.84 (4th gear). This means that in 4th gear the wheels rotate 5 times faster than in 1st gear. This is quite a lot, but it's equal to what the Porsche has and I like to see a clear difference between the 4 gears. Because the engine is placed right on top of the gearbox, I had to skip 16t gears inbetween the clutch gears and driving rings. Now I have to design the casing and the gear shifting mechanism and test it in real life. Like always, comments and feedback are welcome! Here's the LXF-file of the gear layout.
-
Lengendary build alltogether ! Great to see the car moving in 1st gear with minimal friction. Would love to see more details of the drive train and gearbox.
-
And it won't be a suprise that I don't want red clutch gears to transfer drive on axles rotating at different RPM .
-
I agree it's a different challenge to build a manual car, even though I never build a motorized vehicle, but at this stage I think it can still go either way. The mid section is indeed temporary and the mid console will be smaller, 5 studs wide, but will remain to be part of the main structure running along the length of the car. I'm currently working on the full drive train with 4-speed sequential gearbox and V8/V10-engine. My objective is to have a gearbox that is not wired through the entire car as we often see, but is more of an independent module. But this will be quite hard to achieve, because it needs to sit behind the seats and half underneath the engine, so it has to be flat. Along the way I will make the midsection of the chassis.
-
Thank you guys! The frames connecting the suspension modules are temporary, I only wanted to get an impression of the combined suspension modules. Evwmtually, I want to have no more than 5 studs between the seats. For now motorizing is not planned, I don't even have a singlenmotor, but it's certainly something in the back of my mind.
-
It's 1:8.
-
For those interested here are two cutaways showing the essence of the suspension setups. At the heart of the setup is the middle suspension arm just beneath the CV-joints to which the springs are attached. This arm could only be placed there because the suspension travel is limited to two studs. In the back side you see the yellow catches that secure the torsion bars (axles holding the upper wishbones). At the front side you see the anti-roll bars. Front suspension: Rear suspension:
-
Thanks! @Meatman, I just checked again and when I make the sharpest possible turns the wheel making the inner curve makes a slight wobble and gives a little resistance. So it does occur a little. When I push the suspension to make horizontal suspension arms, the effect disappears, which is a little encouraging. So it's caused by the combination of the steering angle and the suspension angle. The idea is that eventually - when the model is finished - the suspension is somewhat compressed and the front suspension arms will be close to horizontal, so under normal circumstances the CV-joints won't get damaged. It's a little disappointing though, but for this model I decided to accept the limitations of LEGO CV-joints and LEGO wheel hubs.
-
The anti-roll bars indeed have some effect, but part of what you see also happens when I unmount the yellow anti-roll bar catches. But I guess real anti-roll bars also have a limited effect judging by the fact that they are generally quite modest in appearance (they are thin). I guess that eventually the independence of the suspension should prevail over the anti-roll effect. As for the tweaking of the ride height, the idea is that the torsion bars help lift the car, they should mitigate the compression of the suspension. But that will only work when there is some default compression, which should eventually come from the cars weight. I know what you mean, the CV-joint can only handle a limited angle. The effect you are referring to does not occur in this build, not even on the inner wheel. The chances of the effect also depend on the angle made by the suspension arms. I tried to find a setup that keeps this angle within similar positive and negative margins. Actually the steering is not that sharp, it is comparable with the steering of the Porsche after removing the gearrack blockers. It's about 20 degree max angle I guess. The Ackermann steering gives a nice feel though. No tire scrub. And another advantage of the outer wheel not steering very sharp, is that it gives room for the ant-rooll bar track rods at the front side of the suspension arms.
-
Thanks! This is exactly what I had in mind too. I used the axles holding the upper wishbones as torsion bars. For the front suspension I secured these axles slightly more relaxed than for the rear suspension. At this stage the suspension doesn't compress under the vehicles own weight, but the idea is that when all is finished it does. That gives the opportunity to tweak the suspension height by playing with the way the torsion bars are secured. I ordered 8 red normal springs, for it might be that eventually 8 hard springs turn out too hard, but we'll see. I tried to simplify the rear suspension by leaving out the black side arms, but they turn out to reduce sloppyness significantly. That was also the idea; they actually serve as stabilizing links. I made a temporary frame connecting the front and rear modules to get an impression. I'm quite content at this stage. Next step will be the gearbox and shifting mechanism. Here are a few images and a quick video of the current state: LXF-file (with placeholders for the Porsche wheel hubs!) can be found here for the front axles and here for the rear axles. Comments and (suggestions for) improvements are welcome.
-
Hennessey Venom GT Spyder
Didumos69 replied to Lox Lego's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Insane! Truely amazing replica! You guys rock! -
Now I get it. Looks very nice and in my opinion a very original approach to HoG shifting . Does this mean you will also have a shifter or paddles close to the driver seat, in addition to the HoG shifters?
-
Good to know! And thanks for saying thanks! (On behalf of everybody who contributed.)
-
Thanks! Part of picking a fantasy car is that it leaves some room for interpretation . I actually ment to ask whether it would be an option to have two sway bars for the rear axles only, one at the back and one at the front of the rear axles. But I have another idea for the backside of the rear axle, something I've spoken about with... ...@DugaldIC before. The axle holding the upper wishbone rotates along with the suspension arm and can be used as a torsion bar. What I plan to do is replacing all springs with softer springs. That should serve two goals: 1) It should give some default compression which gives a more natural feel and reduces the ground clearance slightly and 2) it gives the opportunity to finetune the suspension by playing with different ways to secure the torsion bars. That way I can also realize a realistic rake angle. Good to know that you're also working on sway bars, I'm getting more and more curious what you're working on . I'm aware of the volnurability of the catches with cross holes. I was also afraid that the ball joint would pop out of the catch, but apparently that doesn't happen. The sway bar is 15 studs long and the amount of resistance when twisted is not that big. But I will keep an eye on them as I will probably stress the sway bar about 10000 times before I finish this build . You are right of course, the wheel hubs are the bottle neck. It's true that I aim for rigidity, but in this case I also seek for a rugged appearance. I don't think the front axles can be simplified a lot though, given that I want the springs to sit between the suspension arms. But I agree the rear axles seem a bit over-complicated and 5 stud wide A-arms are maybe a bit overkill. Still, reinforcing the standard LEGO suspension arms to say 3 studs and mounting them rigidly at both ends certainly reduces sloppynes of the whole setup. The way the front suspension arms are mounted in the Porsche for instance - with a single liftarm inside the suspension arm - is really sloppy and could be easily improved this way.
-
I've been working on this a little more. I added an anti-roll bar to the front suspension (LXF-file here). There was just enough space to mount a track rod to the lower suspension arms. I also lowered the lengthwise liftarms by 2 studs. They are part of the main structure of the chassis that runs all the way from the front to the back. Otherwise that structure would rise far too high compared to the rest of the car. I guess I still have to get used to building this close to the ground . However, there is still 2.5 stud ground clearance and 2 stud suspension travel, all well for an AWD supercar. I didn't have time for a video, but here are some images of the front suspension at this stage: I also designed the rear suspension (LXF-file here). I wanted it to have the same signature as the front suspension, so also 4 stud between the lower and upper wishbone (heart to heart). And also the shocks between the wishbones instead of on top of the upper wishbone. It also has 5 stud wide A-arms, an aniti-roll bar and fake brake calipers. There is place for another anti-roll bar at the backside, but I don't know whether that would be very realistic. Does anybody know? This is what it looks like at this stage (I still have to build it):
-
Okay, I get it. No problem to use this thread for this discussion, on the contrary. It's a good thing to share ideas thisway . I hope someday a shifter emerges that does not rely on any kind of elastic resistance .
-
Also interesting. What happens when you make only half a shift? Same question for @Timewhatistime. In my case that's where the limiter comes into play to make sure the shift axle either moves back or completes the shift. Just out of curiosity, what is the center knob gear for? To drive a gear indicator? HoG shifting? Btw, your LDD-file seems to differ from your images.