Didumos69

Ultimately playable and realistic, I love it. Great job!

oo if you use a half pin to avoid the silicon bands from sliding off. I've also seen someone using o+ with a 2L axle running through the + to keep the silicon bands in place. Its important that the 2L liftarms can rotate freely. You should also not squeeze them too tight beteen the 3L perpendicular connectors, otherwise they won't fall back easily. The silicon band(s) should keep the liftarms in position.

I understand, but without any images showing the details it's hard to help diagnose what the problem is. This could be an alternative spot for supertechnicman's 4th to 1st gear block. I needed this to combine this feature with HoG shifting.

Without pictures it's hard for us to tell. The output axle underneath should indeed be rotating 90 degrees with each switch and should have a 45 degree offset. Btw, the whole paddle shifter unit only operates well when there is some kind of resistance on the output axle. Out of the box the two 8T gears down the line (one on a pin with friction) are used for friction. When following my 5-step procedure the 90 degree indexer takes over this role.

Nice idea! I think the silicon bands and ball joints can move to the inside of the shifter unit, there should be space for those somewhere in the lower part. This gives one stud of space to use between the unit and the speedometers. I made a daylight video:

Okay, it has gotten late, but I got what I wanted: "HoG shifting:" Now that the gearbox has its own indexer and the selecter axle rotates with little friction, the road has been paved for something new. Add to that the fact that the Porsche is actually a gearbox on wheels, so why not make shifting gears easy. I decided to go for playability rather than authenticity with my MOD, so I opted to sacrifice MaxSupercars' reverse gear blocking MOD and go for HoG shifting instead. However, I did hold on to supertechnicmans 4th->1st gear block. The HoG will stick out of one of the big panels that is beneath the rear window.

This is done to mimic pushing the car and see if the gearbox can drive the engine. Apparently not in 2nd gear, in this build. One a side note, I see you used the 5 step procedure to make the gearbox work. It appears to me that the shifting mechanism works just fine or isn't that the case? Just being curious, I didn't try with a motor myself.

This last red clutch gear you are testing appears to be completely stuck! Is the 13L liftarm correctly mounted? The 3L pin with pin hole to which the liftarm is connected might be slightly rotated. Can't think of anything else.

This evening I made an LDD-file and some renders showing the changes I made to the drive train axle scheme to reduce friction. I followed nerdsforprez' pointers and used a different axle and axle connector scheme right from the start. Up until now my drivetrain operates without problems. Of course there is friction, but nothing drastic. I have put the wheels on the chassis (finished Box 1) and have been able to push the car in all gears without any problems. I even thought of gearing up the engine, but let's not get too enthousiastic yet. I decided to leave the connectors behind the diff completely out. Even when using 2L connectors, the gears at the back - the ones that needed to be swapped to get the 1-2-3-4 sequence right - might get squeezed against the 11L liftarms they're sitting next to. EDIT (2016/06/26): I also removed the 2L connector inside the gearbox and thus dropped the 5.5L axle connected to it. Now the gearbox - engine axle is completely place on a half stud offset, but this works out fine; the axle is still supported by half a stud at the rear of the engine. I updated the images and LXF-file acoordingly. EDIT (2016/07/06): Based on a review by Blakbird of the Minimally playable Porsche, I minimized these changes a liitle bit further. I dropped the extra support of the toggle joint in the D+N+R gearbox. It didn't seem be really necessary and it did require the replacement of a 13L liftarm with an 11L liftarm, so it was relatively expensive. And instead of using a 5x7 frame, I now use a simple support for the axle running form D+N+R gearbox to the differential. The 4th-to-1st gear block is now integrated in this support. Here you see the original axle scheme in the back and my axle scheme in fornt. First of all I made sure all axles running through an open space never have an axle connector on each end of that space. I also better secured the toggle joint, replaced the pin with pin hole under the dashboard and added extra support for the 15L bridge from D+N+R-console to differential casing. Finally I replaced the 24t clutch gear and auxiliary gears with a gearless friction clutch, which doesn't cause any friction when it's not slipping. Here you see the added parts (transparent green), the reused parts (original color) and the dropped parts (transparent red). It should be easy to locate these axles in your build by viewing this in 3D. The LXF-file can be found here. I defined two groups, one with the original scheme and one with the one I used.

Also in my case 2nd gear has more friction when driven by differential than when driven by engine axle. Still nothing drastic, but there is a difference. I can't explain why. Yet...

So this is propably why it doesn'r run smooth in second gear. All individual axles should have some play and also - especially - the red clutch gears should rotate freely. I always agitate each axle and clutch gear a little to give it some play. I will be posting an alternative axle scheme for the drivetrain in the MODs and Improvements thread later tonight. That should also help reducing friction.

Nice trick! In fact the 7L rack only has about 3L of actual teeth, so will get you nowhere. The longer one is 13L and has a 9L span of teeth if I'm not mistaken. As has already been pointed out, getting a worm gear in the right height would be the same as bringing an 8 tooth gear in position. In general you can state that for every extra stud you need to bridge, you need 16 extra teeth in your mesh. Given that the 12 tooth bevel gear alignes perfectly with the 7L rack, you would have to bring the gear rack up .25 of a stud (<=> 4 teeth) to mesh with a 8 tooth gear or worm gear. Apparently a studded beam placed up-side-down does just that. :wink;

Thanks! When the number of MODs grows bigger I think it would be nice to have 3 MOD-categories: MODs that are essential, MODs that add to playability and MODs that add to authenticity. But that's for later. I will suggest this to the thread starter when it becomes opportune

Yes, I'm affraid I have been contaminated (I even believed I would build it and take it apart immediately, so it would never see daylight, somehow the idea appealed to me, but I,m affraid I have to admit it's already on display while still under construction )

Indeed funny how these things can change. I personally would never have believed I would actually fall for a supercar set. I'm much more into rough cars than into supercars, but I have been dragged into the speculation thread and the Porsche got a hold on me. So I ended up buying this set with the idea to build it once, make my own judgement and then use it as a parts donor for another project. But now I find myself dedicated to making this set ultimately playable. I simply can't resist the urge to make it right. Speaking of playability, for those that do not usually modify their sets it might still be worthwhile to take a look at a short list of essential and simple modifications that is being maintained (by Kumbbl)) in the OP of the Mods and Improvements thread. As for the gear shifting mechanism I would also like to mention a simple 5-step procedure I put together to make the mechanism backlash proof and avoid multiple engaged gears. This might go a little further, but it cetainly adds to playability .

Thanks! The least I will do is deliver an LXF-file of Box 1 showing all the differences, but that will be after I finish buidling. I'm also rearranging most axle connections to reduce friction.

It's a bit of a one-man-show in this thread lately. So I'm sorry to bother you again, but I'm utterly excited about how I got the gearbox to work properly. It operates smooth (backlash proof), more pleasant (no upper silicon bands), much lighter (less friction) and you don't need to pull the paddles to the extreme . This is the recipe for succes: 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). You won't believe how this feels compared to the original, I promise, you won't regret this . You only need 15 additional - commonly used, small - parts and you can drop 7. Flip the change-over-catches in paddle-shifter-unit by 180 degrees: Add the simple 90° limiter; give the bevel gear with pin hole max play: Remove the 8 tooth gears used to add friction; minimize friction instead: Use only one silicon band for each paddle shifter: Extend both change-over-catches in the gearbox using 2L axles and 2L levers:

I made a short video showing the adjustment I made to the gear shifters to avoid friction. Btw, while building I try to eliminate most of the friction risks, also by following the pointers provided by nerdsforprez earlier in this thread. I also want to keep out the 24t clutch gear for dealing with halting and the 8t gear that is used to avoid backlash. IMO these are fallbacks that introduce too much friction in drive train and gear selection mechanism. I'm gonna make this baby rock! The gear shifter adjustment:

This evening I started building my Porsche and I think I found another friction issue within the gearbox. I also integrated my simple 90° limiter to get the orange paddles in perfect 90° positions. This turns out to work very well. The driving rings are being operated very effectively; there is clearly only one red gear engaged at a time and the engagement is full. However, when one of the two red gears at the back of the gearbox is engaged, it gets clamped between the driving ring and the 13L LGB liftarm to the back of the gears. My impression is that the gear shifter (or change-over-catch) has too much travel, or at least more than the half stud that is needed to engage one of the red gears. With the new 3L axle connector allowing the driving ring to move beyond its ideal position, the result is that the engaged gear gets clamped and suffers from substantial friction. To solve this I used a 2L axle and a 2L lever on each gear shifter to increase the distance between the gear shifter's pivot point and the ball joint. This slightly reduces the gear shifter's travel. Now the red gears are no longer clamped and are still sufficiently engaged. I'm not sure whether this will fit with the body, but I will find out later and let you know. Or maybe someone can check? Also without the 90° limiter the orange paddles may accidently arrive in a perfect 90° position. So I reken the red gear getting clamped could also occur without the 90° limiter.

I always admire people who make small builds with looks and functions. Nice work!

Positive caster - as in your front axles - means that the steering axis is tilted slightly backwards. This causes the tyre to touch the ground behind the point where the imaginary line following the steering axis touches the ground. The effect is that the wheel wants to trail the steering axis, just like a wheel of a shopping trolley wants to trail its steering axis. This gives a car straight-line stability. Unsteered rear axles don't have a steering axis, so they don't need this kind of effect. However when rear axles are steered as much as the front axles, then there would be as much reason to apply caster angle to the rear axles. In that case you also need a steering axis that is tilted backwards, just like the front steering axis (so not mirrored). If it's only a few degrees steering angle, then I wouldn't bother. EDIT, when axles are driven, caster, camber and kingpin inclination need a fine balance. This is an easy to read article about proper angles.http://www.motoiq.co...-and-Scrub.aspx

Indeed interesting. As far as I can see you're not using the standard wheel hubs. How are you going to deal with the new rims not having axle holes? Apart from that, I like the concept. You could secure the perpendicular axle-pin connector holding the pivot ball-joint a little better by using a 4L axle with end-stop. In your second picture you can see it sliding off a little bit.

Thanks! Feel free to build it, no problem. It was actually meant to serve as a starting point for others. The LXF-file you found is part of a building directions page on my bricksafe, a link to this page can also be found in the original post of this thread. Building won't be easy but it should be doable. And if you have questions you can always ask them here

These are very fine and useful observations, thanks for this thorough investigation! Covering axles running through open spaces completely with axle connectors or bushes is asking for friction. I'm planning on working out an LDD of Box 1 with all these kind of adjustments. This is once again an example of an easy to solve problem. They have given us a puzzle. I bet the original designers have made themselves a list of mistakes and are betting on when we solved all of them

Thanks! Interesting idea! I wasn't really looking for a limited slip diff or a friction clutch. I just thought of another application of the simple 90° indexer I built as a possible improvement of the Porsche gearbox. It would be nice to built a clutch that is only engaged when an axle starts slipping someday, but I'm affraid my focus will be the Porsche untiI I have actually built it