Didumos69

The short answer is: No and that's why I wouldn't regard it as essential MOD. The frame on top of the gearbox mainly serves to support the axle running from the D+N+R selecter to the diff. That one originally had a 15L long unsupported span. This helps reducing friction. The long answer is: It depends on what you want with your build. There is a very bendy part in the chassis between the D+N+R-console and the gearbox. If you want all your gears to rattle happily also after playing without body and pressing the suspension a few times and want to be able to gear up your engine and push along your Porsche in 1st gear without a constantly slipping clutch, then you can't do without a more rigid chassis.

In the essentials-MOD the 90 degree limiter could move from the right to the left side, or actually switch sides with my version of the 4th to 1st block. In my ultimately playable build I need the limiter to be like this or else it would collide with my left rear HoG that can only be routed to the front along the left side of the console. Still, I think the better way to fix the reverse gear shifting would be to actually bypass the gearbox in reverse. But that would be an advanced MOD and as it adds to realism it should IMO also make sure the gearbox is not engaged when in neutral. That would require the order to be engine->D+N+R->gearbox. Right now it is engine->gearbox->D+N+R. Btw the essentials-MOD does not have my rigid chassis MOD, although it has a 7x5 frame on top of the gearbox, but this frame only spans the gearbox. It's the poor man's solution

That's good news! I think it would be nice to make a difference between 'must-have'-MODs and 'nice-to-have'-MODs. I have an LDD-file of Box 1. available in my Ultimately playable thread with all MODs I regard as 'must-have'. It contains groups showing all the differences: In each group there is a subgroup representing the old structure and the new structure. All new structures are embedded in the chassis and all old structures placed to the side of the chassis. By clicking on a subgroup you select all parts in a group. That way you can inspect the differences. Maybe this could also be of use to you. (Original designer of this file was JunkstyleGio, but I made quite some fixes.) Besides the must-haves that I list in my Ultimately playable thread it contains HoG steering and a 4th to 1st gear block. I deliberately left out the reverse gear shifting block because it takes up a lot of space and still allows to shift from 4th gear to neutral and back.

For all MODs that I regard as essential (see OP of this thread) I made a LXF-file of Box 1. showing the differences in terms of groups: In each group there is a subgroup representing the old structure and the new structure. All new structures are embedded in the chassis and all old structures placed to the side of the chassis. By clicking on a subgroup you select all parts in a group. That way you can inspect the differences. (Original designer of this file was JunkstyleGio, but I made quite some fixes.) Besides the must-haves that I listed in the OP of this thread it contains HoG steering and a 4th to 1st gear block. I deliberately left out the reverse gear shifting block because it takes up a lot of space and still allows to shift from 4th gear to neutral and back.

About Attika's fix to turn around the change-over-catches in the paddle-shifting-unit: I found out it is better to actually replace the change-over-catches with (+0)-liftarms. When you simply turn the catches around, the levers attached to the paddles may bump into the square backside of the catches when returning. This troubles the returning of the paddles. When you replace the catches with 2L (+0)-liftarms the paddles return easier. I updated my 5-step procedure to get the shifting mechanism working properly.

I fully agree. And I would like to add one more thing: Lego is all about making 'models'. And to me (sorry, I have an engineering background) 'model' means: Simplification of a system (or thing) that brings about one or more aspects of that system's (or thing's) nature. Models allow us to zoom in on certain aspects while leaving other aspects out. So it's all about what exactly do you want to tell with your model. Even when something isn't really noticable when playing with a vehicle you can still have a good reason to implement it. This small design sort of has it all .

I'd rather speak of urge, but thanks!

I managed to do what I planned to do. I routed the second HoG in the back to the front and I made the chassis somewhat sturdier by building a little more structure inside the mid-console. Part of this structure are a few lengthwise liftarms that run over the gearbox. I had to swap 1st and 3rd gear and 2nd and 4th gear to make room for the liftarms. All worked out fine. The whole mid section of the chassis is very rigid now. Also the gear sequence and gear ratios have not changed, even though they switched positions. The most difficult part has been to get all axles and clutch gears to run smoothly again. That took me at least 2 hours. This remains to be the problem with this gearbox. I hope I don't need to take appart the whole chassis again . As a side note: I think the time consuming finetuning is an issue with most Lego gearboxes, or at least the ones I have seen. IMO there is something inherently wrong with the Lego clutch gears and driving rings: They need to be enclosed by liftarms or another stop, otherwise the driving ring will simply push the red clutch gear out of place and it won't get engaged. At the same time they need some play, otherwise they won't rotate freely when not engaged. These two condition are hard to unify, especially when you take into account that a red clutch gear measures exactly one stud. But the result is there. The gears run more smooth as ever and the chassis is substantially sturdier . Here are some pics of the work in progress. I will upload two short videos later, as my wifi won't let me right now. Liftarms and HoG routing: Reduced engine braking (geared up by 300%): Taking the chassis apart, so far no good . Inserting the 5x3 frames: I also moved the DGB 4x2 liftarm that serves as 4th to 1st gear block to this side of the 11x5 frame. This way it can also support a pin with pin hole that is used for routing the second HoG.. Routing the second HoG from the back to the front: Rearranging all gears And finally putting the liftarms in place: EDIT (2016/06/29): I have been able to add another 7L liftarm to compensate for the 15L liftarm that had to be split into a 5L and a 7L liftarm;

Perhaps a good idea to read some easy background info: http://www.motoiq.com/MagazineArticles/ID/1982/The-Ultimate-Handling-Guide-Part-8-Understanding-Your-Caster-King-Pin-Inclination-and-Scrub.aspx If you want all angles to be proper, then this could also be a source of inspiration: http://www.eurobricks.com/forum/index.php?showtopic=92099&st=150#entry2503499

Thank you guys! Today I plan to wire the second HoG underneath the rear window from the back to the front and at the same time I want to place some lengthwise liftarms on top of the gearbox. That should make the chassis a little stiffer and avoid the gears from being squeezed when playing with the chassis only. I want this build to be playable without body too . I wanted to add two 15L liftarms, but unfortunately the 90 degree limiter won't let me. I have to divide one of them into a 5L and a 7L liftarm. To add the liftarms I will first insert two 5x3 frames between the D+N+R-console and the gearbox. These frames will also serve to carry the HoG axle to the front. To place the frames I will have to take the whole front section apart. However, the most important issue to tackle is the 24t gear that is in the center of the gearbox. It will collide with the liftarms I have in mind. Btw, the blue 2L axle-pin connectors sticking out of the liftarms will insert into a black panel when the body is added. EDIT (2016/06/29): I have been able to add another 7L liftarm to compensate for the 15L liftarm that had to be split into a 5L and a 7L liftarm; So what I will do first is rearrange the gears in the gearbox: I will swap 1st and 3rd gear and I will swap 2nd and 4th gear. If I'm not mistaken this won't effect the gear sequence, as long as I also rotate the orange paddles by 180 degrees. Or actually this isn't even necessary when I swap both 1st with 3rd and 2nd with 4th, but then I would have to change my 1st to 4th gear block . Before: After: I checked with LDD and the only parts that will collide with the 24t gear is the dummy red 3L pin with axle hole that was only needed to avoid mistakes with placing the diff. Time to remove it . Here are two images showing the whole structure and the dropped structure in the background: All this should fit the out-of-the-box body.

It seems like you can dream in flex axles Very nice light weight bodywork. I love to see how you can bring forward the essence of a car with just a few lines.

Thank you Blakbird. I understand your concern, but I checked that of course. My goal is to make the MODs fit the body as is, so I built the closest parts of Box 2 in LDD to verify. It comes close to the seats but will turn out fine I think. I added some screenshots. But it could still be that I get to deal with something unforeseen when building the body. I indeed plan to make the body removable too.

Thanks! I will indeed probably copy the door handles from the other thread. I won't be reluctant to take over the MODs from others - and refer to the original designer - unless I think it should be done better. I like the suggestion to move the steering HoG to the back as well, just like you did. It would create the opportunity to have a gear indicator stick out of the hole in the dashboard

Ultimately playable Porsche 911 GT3 RS Now that I have finished Box 1. and got the shifting mechanism and drive train working properly, I thought I might start my own thread about this project. I plan to submit the result to the Porsche of Your Dreams contest. With this project I aim for playability rather than authenticity. So McPherson strut suspension and rear wheel steering? Probably not. But HoG steering and HoG shifting? Yes. I'm actually working on 2 versions, the minimal version and the ultimate version. The minimal version includes all 'must-have' modifications - or fixes - that I listed in the minimal sections below. The ultimate version will include rear HoG steering, rear HoG shifting, a more sturdy chassis, a dashboard gear indicator, Ackermann steering and a stabilized gear rack. The ultimate version also includes all essential fixes, but sometimes implemented in a different way to fit the more advanced modifications. I will keep an index here on the OP of this thread of all the modifications I implemented or plan to implement. Ultimate version - Planned features Lockable doors Ultimate version - Implemented features 4th to 1st gear block Hand of God steering Hand of God shifting Sturdy without body Geared up engine Dash gear indicator Ackermann steering Stabilized gear rack Secured wishbones Improved clearance Improved shifters Removable body Ultimate version - Building directions (link) I do not plan for full-blown instructions. For now I can only offer this thread with reports on all MODs and a LXF-file showing the differences in terms of groups: In each group there is a subgroup representing the old structure and the new structure. Both new structures and old structures are embedded in a version of the chassis. By clicking on a group or subgroup in the group tab you select all parts in that group. Now when you invert the selection and then delete the selection you see a cutaway of the group, which allows you to inspect the group thoroughly. Use Ctrl-Z to undo the delete after inspection. This way you can inspect the differences group by group. I also have a parts list available with the extra parts needed for this version. If you want to build this using the LXF-file for the 'ultimate version' you should take into account the following pointers: You need to make sure each individual axle that is part of the shift or drive train runs smoothly, with the least of friction. Make sure gears don't rub against liftarms, especially the red clutch gears need some play. When you replace the knob gears inside the PDK-unit with bevel gears, make sure the axles keep their original orientation. A knob gear mesh implies a 45 degree orientation difference. Note that the 3L pins with 1L axle inside the PDK-unit need to be inserted half a stud deeper than what the LXF-file shows. LDD does not allow a full insertion. Also check the changes to Box 2; for instance the way the vertically placed black panel in front of the rear suspension module has been secured to adequately lock up the 20t bevel gears used for the rear HoGs. Also check the changes to Box 3 and 4, which are needed to make the body removable. Minimal version - Gear shifting MODs (link) I applied Paul Boratko's gear sequence fix as described in Jim's review. I flipped the change-over-catches in paddle-shifter-unit by 180 degrees (as suggested by Attika). I added the simple 90° limiter to the gear selector axle; used two of the four white silicon bands. I removed the 8 tooth gears used to add friction; minimized friction in the selector axle instead. I used only one silicon band for each paddle shifter; wrapped it around the neck of the ball joint once. I extended both change-over-catches in the gearbox with half a stud (more info here). Minimal version - Friction reducing MODs (link) I removed the pin-joiner in the D+N+R-gearbox. Original idea suggested by Blakbird, see his detailed build report. I avoided red gears from transferring torque on axles rotating at different speed, see eliminate friction in gearbox. I added an extra support for the 15L axle running from D+N+R gearbox to differential, see alternative axle scheme. I avoided axle connectors from rubbing against lift-arms as suggested by nerdsforprez, see alternative axle scheme. I replaced the white clutch gear with a gearless friction clutch, see alternative axle scheme and white gear replacement. Now I could gear up the engine: Replaced the 2 16t gears with a pair of 24t-8t gears, see eliminate friction in gearbox. Minimal version - Building instructions (link) For the minimal version I made building instructions in terms of errata. The errata will help you implement the necessary fixes while building the model from scratch. It provides a list of extra parts you need (only 30 small and commonly used parts) and a sequence of steps that serve as a replacement of the corresponding steps in the original building instructions. All can be found in this PDF. and on Rebrickable. The errata include a 4th-to-1st gear block, but do not provide instructions for additional features like HoG steering or a removable body. I was a little bit in doubt whether to include all changes to the axle scheme or not. Blakbird - who has test-driven this set of modifications, thanks for that! - was already satisfied without applying all changes to avoid connectors from rubbing against liftarms. I decided to include them anhyway, beacuse I think it's simply a matter of good practice and since these errata are specifically useful when you build the model from scratch, it's an easy gain. For all MODs that are included in the errata I also made a LDD-file of Box 1. showing the differences in terms of groups: In each group there is a subgroup containing the old structure and a subgroup containing the new structure. All new structures are embedded in the complete chassis and all old structures are placed to the side of the chassis. By clicking on a subgroup you select all parts in that group. That way you can inspect the differences. Besides the modifications listed above the LDD-file contains HoG steering.

These are some very cool and handy MODs. I will certainly apply some of them. Luckily, I still have to start with the body, haha. Thanks for sharing!

Now that all gears rattle happily I actually start to enjoy my build. Here's a short video of the chassis being pushed along in first gear with the engine being geared up by 300%. I thought it would be nice to summarize all friction reducing modifications I made to the drive train, just like I did with my 5-step procedure to get the shifting mechanism to work a few days ago. Here we go: I removed the pin-joiner in the D+N+R-gearbox. Original idea suggested by Blakbird, see his detailed build report. I avoided red gears from transferring torque on axles rotating at different speed, see eliminate friction in gearbox. I added an extra support for the 15L axle running from D+N+R gearbox to differential, see alternative axle scheme. I avoided axle connectors from rubbing against lift-arms as suggested by nerdsforprez, see alternative axle scheme. I replaced the white clutch gear with a gearless friction clutch, see alternative axle scheme and white gear replacement. Now I could gear up the engine: Replaced the 2 16t gears with a pair of 24t-8t gears, see eliminate friction in gearbox. And don't forget to ensure all axles and clutch gears have some play. Enjoy!

Would it resemble the real Porsche better?

Now that I managed to let all gears rattle happily instead of moaning I did some extensive test drives with my son yesterday evening. With the HoG shifting that I added it's easy to shift gears while pushing the vehicle. While doing so, I still experienced very short double engagements while shifting. A very short moment of grinding gears that occurs only occasionaly and only while shifting. Luckily the double engagement disappears immediately after shifting because of the 90 degree limiter doing its job. My conclusion is that this behaviour is inherent to this type of sequential gearboxes; while shifting there is always a moment that two gears are 'semi'-engaged. So I can live with that. However, as part of an earlier MOD I removed the white clutch gear. But to save my gears I thought I might have to reintroduce it to handle the short double engegements. But using the white clutch gear means adding 4 extra gears to the drive train and I'd rather don't go there. It would add friction even when it is not slipping. So I inserted another friction clutch with similar resistance. It's actually better because it has constant friction whereas the white clutch gear has a toggling resistance. But the biggest advantage is that I could insert this without any extra gears. Funny side note: This a nice reintroduction of the pin joiner that was removed from the D+N+R-console as suggested by Blakbird. Here's a video showing the clutch slipping:

That's good news! I'm glad it worked out fine. Also nice to see how the gearbox behaves when being motorized. Thanks for sharing!

Thank you Appie! I don't get it either. Sometimes I think they gave us a puzzle on purpose, just to generate buzz and hopefully increased sales. But that would be too much of a gamble. I did indeed not yet build the rest of the vehicle, haha. I simply can't build something that doesn't feel right, or in this case, feels wrong. I actually had some restless nights because of this. This is the first set I bought since I'm out of my dark age and I want it to live up to the euros I spent on it.

You're right, but that was not what I meant. In fact all clutch gears rotate all the time, or even better, all gears rotate all the time. What I meant to say was that the 4 red gears sitting next to the change-over-catches - when not engaged - simply make dummy rotations, without transferring torque of any kind. Not even to drive another unengaged axle. So even though they have different RPM compared to their axles, they will encounter only little friction, simply because of the absence of the lever effect that the red gears in front of the gearbox are subject to. Hope this helps clarify. Join the club . The same happened to me when I was dragged into the speculation topic. I'm actually not into supercars

Maybe, but I think supporting gears with 2L frictionless pins is not a good idea in a gearbox. Especially not in a situation where there is a lot of up - or down force on the gear, which is the case in this setup. It's better to have an axle that is supported at both ends. So I would not advice doing that, but you could try of course EDIT: Another reason why I would not advice using frictionless pins in this situation: When placed on a 2L pin, the up - and down force will make the gear and pin tilt slightly. Given the fact that the gear is enclosed by a liftarm on one side and a frame on the other side, this tilting will again cause unncessary friction. Especially when you take into account that the red gears measure exactly one stud whereas the normal 16t gears measure a little less than 1 stud, which gives them some play by default. So I wouldn't even bother trying.

I think so too. My observation was that in 4th gear the RPM of the involved red gear is equal to the RPM of its axle (gear / axle RPM ratio is 1:1). However, in 2nd gear the gear / axle RPM ratio is 1:3, which confirms 2nd gear being the most problematic. In 1st and 3rd gear the other red gear is involved. In 1st gear it has a gear / axle RPM ratio of 1:1 and in 3rd gear a gear / axle RPM ratio of 9:25, which is actually almost as severe as with 2nd gear. This aslo explains why 1st gear suffered from less friction than 2nd gear. Please do!

I think I fixed yet another friction generating issue with the gearbox: http://www.eurobricks.com/forum/index.php?showtopic=133743&st=275#entry2591636

I think I solved yet another - probably the last - severe friction problem in the Porsche gearbox. After getting the gear switching mechanism to work smoothly, there was still one thing bothering me, especially after seeing schraubedrin's video's: The friction inside the gearbox. Just like in schraubedrin's case my build appeared to be especially sensitive to friction in 2nd gear. Even though I could push my build along without any grinding in all 4 gears, the amount of friction kept bothering me. So yesterday - while I was out road cycling - I tried to get my head around it. I started analyzing and got to the following hypothesis: Btw, before I got to the actual problem I arrived at a few basic conclusions, just to take away some confusion: 1. In each gear all axles rotate and all gears rotate. 2. In each gear the same number of gears is involved in transferring torque from input to output. Hypothesis The two red clutch gears that are not actually involved in one of the two clutches - the ones lined up between the other 16t gears just in front of the actual gearbox (left in the image below) - serve a completely different goal as compared to the 4 red clutch gears that are directly involved in a clutch. The latter ones - when not engaged - simply make dummy rotations, but without transferring drive. Not even to drive another unengaged axle. So even though they have different RPM compared to their axles, they will encounter only little friction. And when these clutch gears are engaged, they get forced to rotate along with the axle in order to transfer torque. So whether engaged or not, there will be hardly any, or even zero friction between the red clutch gear and its axle. This is not the case for the two red gears lined up in front of the gearbox: There is always one of them involved in transferring drive, while its axle is rotating with different RPM. Now given the way these red gears are lined up between normal gears, the one that needs to transfer drive actually works as a kind of lever and will push itself up or down against its axle. Now taking into account the axle rotating at different RPM, it's easy to understand that this will cause friction. Some observations: In 4th gear the RPM of the involved red gear is equal to the RPM of its axle (gear / axle RPM ratio is 1:1). However, in 2nd gear the gear / axle RPM ratio is 1:3, which confirms 2nd gear being the most troubled by friction. In 1st and 3rd gear the other red gear is involved. In 1st gear it has a gear / axle RPM ratio of 1:1 and in 3rd gear a gear / axle RPM ratio of 25:9, which is actually almost as severe as with 2nd gear. This aslo explains why 1st gear suffers from less friction than 2nd gear. Resolution The two red clutch gears not directly involved in one of the two clutches can actually be omitted quite easily. So that's what I did and guess what? It solves the issue completely!!! I don't know if you know how gears sound when they don't suffer from unintended friction. They make this light rattling sound. You can almost hear them being happy with their job. Well this is what I hear now. I even geared up the engine by 300% and it still operates fine. I summarized what I did with a short photo sequence below. On a side note: As part of earlier modifications (90° limiter and drive train axle scheme) which eliminated double engaged gears I also removed the white clutch gear and surronding gears in front of the gearbox. The white clutch gear served to deal with a halting gearbox and was no longer needed. Due to that removal I had a spare 24t gear and a spare 8t gear left, which I used to gear up the engine. And I used the two 16t gears that came off the back of the engine in the fix below. Photo sequence Remove the 16t gears from the back of the engine: Collect the extra parts needed (include the two 16t gears from the back of the engine). Also add a 24t gear and a 8t gear: Take the back of the chassis off (remove two liftarms alongside the bottom of the rear axles) and take the mid-section out of the gearbox: Refactor the mid-section of the gearbox as follows: Put the 16t gears in place (make sure they are nicely centered along the 2L axles) and push the mid-section back in place: Put the back of the chassis on again. Make sure each individual axle rotates with minimal friction and the clutch gears have enough play: Gear up the engine: These should be your left overs: And you're Porsche is ready to rock!