Didumos69

Even if we would revert to 9L links, which I think would be a pity, the main problem I see is that the shift lever would be more or less behind the seats. I think the shift lever and the control axle should somehow be split. The lever nicely in-between the seats and the control axle behind the seats.

The ratios of the primary gearbox are: 1:1, 5:4, 5:3, 25:12 and the ratios of the secondary (low-high) gearbox are: 1:1, 25:9. Together that makes: 1:1, 5:4, 5:3, 25:12, 25:9, 125:36, 125:27, 625:108, or 1, 1.25, 1.67, 2.08, 2.78, 3.47, 4.63 and 5.79. The overal in-out ratios can be easily changed though. The primary gearbox and the secondary gearbox are connected with a 16-16 gear mesh in the center of the gearbox. This could be changed to a 20-12 or 12-20 mesh, which would multiply all speed ratios by 20:12 or 12:20 respectively.

I fully agree @Attika. The rotary catch is designed for running through 4 90 degree positions. This is also why I don't think the rotary catch is as much of a game changer as has been suggested. That being said, I do see some possibilities, for instance using the rotary catch to engage or disengage secondary control axles with rotary catches to control the gearbox. Also, when it comes to making a 5+R or a 7+R, I think an approach that could work is to have two parallel gearboxes (not serial as in the Bugatti and in my tunnel transmission) and combine it with a gearbox selector. That way you could first run through the gears of a 4-speed and than through the gears of a 1+R or 3+R. It will be big though.

You could do that, but I fear you would run into double engaged clutch gears during shifts. 30 degrees (a half shift) won't be enough to disengage the driving ring.

Here's my centered sequential 3+R version. Ratios are 1:2(R), 1:2, 1:1 and 2:1. LXF-file here.

I will use 2 of these dog bone pieces. I'll look into that, but I fear it won't be as small as that 4-speed gearbox.

That is where the new yellow extension rings go. You can see them in the video. They are not available in LDD and I forgot to add placeholders.

Here are the LDD-files I have. Btw, I refer to a gearbox as heavy-duty when the output-axle is sandwiched by the auxiliary output axles. This will reduce the chances of slipping. Simple sequential 4-speed gearbox with single rotary catch, video: https://youtu.be/kqlaKH_oLsc Centered heavy-duty sequential 4-speed gearbox with single rotary catch, video: https://youtu.be/vCwiEUTxCrg Centered heavy-duty sequential 4-speed AWD transmission with single rotary catch, video: https://youtu.be/OSuf6UZWp7k Sequential 8-speed transmission tunnel with rotary catches and 8-to-1 gearblock, video: https://youtu.be/b5zdYGAGlec I'm still working on a centered sequential 3+R gearbox with single rotary catch.

I'll share LDD files tomorrow. All my 4-speed sequential gearboxes without reverse - and the ones from many other designers too - follow the same approach. The input is split into two input axles - typically rotating in the same direction - with different gear ratios, giving them different RPM. The driving rings are attached to these two input axles. The clutch gears at the front and back side of the driving rings make a second gear ratio with the output axle, either directly or via auxiliary output axles - also rotating in the same direction - that are joined into the main output axle. In the centered gearboxes I showed in this thread, the left-right RPM ratio of the two input axles is 2, one turns twice as fast as the other. Regardless of how the driving rings are controlled, with links and the old catches, or with the new rotary catch, sequential shifting always follows the same pattern over subsequent shifts: left side engaged, right side engaged, left side engaged, right side engaged etc. So with one shift, the engaged side always switches from left to right or from right to left. At the same time it follows this front-side-engaged/back-side-engaged pattern: front, front, back, back, front, front, back, back, etc. So every two subsequent shifts it switches from front-side-engaged to back-side-engaged or vice versa. Now to obtain 4 speeds in the right order, you have to make sure the left-right jumps, which occur every subsequent shift, make a smaller gear ratio difference than the front-back jumps, which occur every two up-shifts. In other words, left-right has to make the minor ratio difference and front-back has to make the major ratio difference. This way, the minor ratio difference makes the difference between 1st and 2nd gear (one up-shift), the major ratio difference makes the difference between 1st and 3rd gear (two shifts) and combined they make the difference between 1st and 4th gear (two + one shifts). The major ratio difference being bigger than the minor ratio difference ensures that when you switch from 2nd to 3rd gear, you drop less RPM by switching between the left and right driving rings than you gain by switching between front and back clutch gears. So for the front-back jumps in the centered gearboxes I showed in this thread, I use a front-back RPM ratio that is bigger than 2. In the AWD transmission it is in fact 3.52. I hope this makes sense.

So in my line of gearboxes with rotary catches, here is my centered heavy-duty 4-speed AWD transmission with single rotary catch. It's not small, but it can handle a lot of torque and runs extremely smooth. Thanks @Attika for the info about the old driving rings. They insert a lot deeper, so no slipping occurs this time. Ratios are 4:15, 8:15, 15:16, 15:8 (0.27, 0.53, 0.94, 1.88).

Thanks @Attika! Then I will use the old driving ring and old clutch gear. I might even be able to shorten the setup so I won't need the extension ring.

But how does this connect to the gearbox? The control axle was moved to the back as much as possible - and tied to the gearbox with 6l links - to create space for the seats.

Thank you @Sariel! Could you also check if this has consequences as to how deep the 3L driving ring inserts into this side of the differential?

Nice attempt! I hope I did not contaminate you with the symmetry-virus . I tried this layout for a AWD with one rotary catch, but ran into the problem that the auxiliary driving ring inserts into the differential too deep, causing the driving ring to slip in the 16t clutch gear at the other end. Does anybody know whether the new red 4L differential is different from the old one? Do the new 3L driving rings insert into the red differential as deep as in the red clutch gears, or deeper? In the old DBG version they insert deeper.

Excellent replica! Nice trick with the frictionless pins to make the panels curve.

I strongly advice to do this: https://rebrickable.com/mocs/MOC-5236/Didumos/42056-porsche-911-gt3-rs-unofficial-errata/#info

Thanks! Al though I feel flattered if someone wants to build my ultimately playable version, I would first like to suggest building @jb70's version. It has all the necessary fixes, quite some feature of my ultimate version and some more things like working doorlocks. And it has full-blown instructions. It even has the essentials of my improved paddle shifter unit in it. https://rebrickable.com/mocs/MOC-8003/jb70/42056-pimp-up-my-porsche/#info About gathering the necessary parts. I honestly don't know the answer, but maybe you could use Rebrickable to see which sets would more or less cover the extra parts you need. I know Rebrickable has some nice functions for that, but I don't know the details.

Great story and the best model I have ever seen at this scale! HoF-worthy imo.

Cool! I'm looking forward to seeing how you did that. I might even try it myself. Nice buggy! I'm glad to have provided some inspiration. I think my next RC model will be small too.

I guess you're right. But I don't mind. I love this puzzling with gears.

Nice work and thanks for sharing @Attika! The clutch gear used for torque transfer could also sit on the control axle, then at least it won't affect the axles in the gearbox. I remember we once came up with two very similar AWD gearboxes. One direct and one sequential. When I recall the simplicity and compactness, even symmetry, of those gearboxes and I compare that with what can be done with the rotary catch, I don't get the feeling that this new piece is the holy grail. Okay, it makes controlling driving rings more easy, but to come up with an elegant or symmetrical 4-speed AWD gearbox has not become more easy. Only with 2 rotary catches you can use existing 4-speed setups, like what @Sariel did, but then the control setup is not really more compact than with links. But perhaps we simply didn't discover the ultimate usage of the rotary catch yet.

That's great! I thinks it can have some play. Thanks!

I have my Hammerhead still assembled and both the return-to-center for the shift lever and the 90-degree limiter of the shifter still work fine. Also, my experience is that these silicon bands last for many years. When I first got out of my dark age, my kids received some boxes with LEGO from family. There were several white silicon bands in them that are at least 10 years old and they're still in perfect shape.

I'm working on two variations of this centered 4-speed gearbox with a single rotary catch: A 3+R version: And a 4-speed AWD version: However, for the AWD version, I need to know whether this is going to fit (and if I need the new red differential for it). Does anybody know?

That's indeed a nice idea for controlling existing gearbox layouts, even though I'm not a fan of using clutch gears to transfer control (or drive) over rotating axles. The 2 control axles are not aligned at 90 degree perfectly, but good enough. I used the same approach in my 8-speed transmission tunnel. Yes that's something that was bothering me too. Not only because one rotary catch should be sufficient to control 4 speeds, but also because you have to somehow split the control over 2 control axles, what you did with 16t gears, which takes a lot of space too. This is why I started focusing on using only one control axle for 4-speed gearboxes. Looking forward to seeing it! Please post it here when you're done.