Didumos69

I'd scan this forum for examples or search rebrickable.com for MOCs with PFs. There are a lot of examples with free instructions. Searching this forum is limited to avoid overload, You can use Google and also type 'eurobricks'. And if you still don't find what your looking for, then simply post a new topic to the technic forum with your question.

I'm affraid I missed this sentence when I first read your last post. I'm a little curious about how you tweaked the gear rack. Would also be great to see some pictures of what you're actually building. Anyway, good luck with your build!

My experience is that when you build a gearbox you need to have a good understanding of how you make rotating axles and gears with clutch run smoothly. When you put the gears just a little too tight or the clutch gears don't have exactly the right amount of play, your setup won't operate as expected. This is something that can not be read from normal instructions. This is why I will base my choices on the reviews from Sariel and Jim.

I took the same question in another topic as a challenge and made a front axles concept with knob gears. I thought it would be nice to post about it here too. I tried to make something sturdy with substantial ground clearance. The wheel hubs are supported above and beneath the horizontal knob gear. The gear rack has been stabilized with an extra slider. Opposed to what the incorporated pivot offset would suggest, the gear rack side should be seen as the back side of the module. The small Ackermann effect is mainly the result of the gear rack moving along a straight line and two tie rods (composed from pin-axle connectors) linking the gear rack to the pivot points. The overall Ackermann effect is quite small, although it still suprised me after building this concept. You should be able to tweak the Ackermann effect by changing the pivot points or the points where the tie rods connect to the gear rack, but the options are limited in this compact setup with 6 knob gears eating up a lot of space . The upper input axle is for drive and the lower input axle is for steering. It would probably have been more convenient if these operated the other way arround. I don't have the knob gears, so I built this concept using 12 tooth bevel gears instead of knob gears, which also works just fine. This concept has been inspired by the only image that is still alive on this MOCpage. LXF-file here.

CV-joints are constant velocity joints, so they don't suffer from the sine-wave. The knob gear arrangement also boils down to a constant-velocity joint. Standard CV-joints indeed allow for a small steering angle only. U-joints are not so bad in that regard, but they suffer from a gradually increasing sine wave as the steering angle increases. Btw, I have been able to extend my design with an extra slider attached to the gear rack. It adds more stability to the gear rack. I updated the video and the LXF-file accordingly.

Now the question is, do the tumbler tyres fit?

Unimog wheels fit perfectly. Indeed for Ackermann steering there is a relation between the wheel base and the pivot offset; a longer wheel base asks for a SMALLER pivot offset. However this relation assumes a straight connection between the left and right pivot points. In my setup the gear rack moves along a straight line and two tie rods link the gear rack to the pivot points. This also affects the steering angle difference between left and right. In my design the latter effect is stronger than the pivot offset effect and works in the opposite direction. That's why the overall Ackermann effect is quite small, although it still suprised me after building these axles. You can tweak the Ackermann effect by changing the pivot points or the points where the tie rods connect to the gear rack, but the options are limited in this compact setup with 6 knob gears eating up a lot of space One off-topic hint: Better remove video's and images in quotes. Moderators don't like that

I still have two copies of the earlier posted images. They seemt to subscribe your clear statement.

:thumbup: You're welcome! I just build my design and it operates as expected. I don't have the knob gears so I used the 12 tooth bevel gears instead, but there is space enough for the knob gears, also in turns. In my build the upper input axle is for drive and the lower input axle is for steering. I used the 5.5L axle with end-stop as vertical steering axle and as wheel axle to prevent these axles from falling out.

Turns out that Ackermann steering is almost negligible. It actually has the opposite effect of what I expected, So you would have to tweak the wheel hub - gear rack connection a little or use the module the other way around, with the gear rack at the back side of the module that is. You can move the gears at the front to the other side of the module, which would make the upper axle the drive axle and the lower axle the steering axle. The operation and sturdiness of the wheel hubs and knob gears should be just fine.

I took this as a challenge too (no offence LXF). Something sturdy with the wheel hubs being supported above and beneath the horizontal knob wheel. Hopefully this will help you getting started. It includes Ackermann steering. The gear rack side should be seen as the front side of the module. EDIT: Actually it is the other way around; the gear rack side should be regarded as the back side of the module. See reply number 11. I updated the images and the LXF-file below accordingly. LXF-file here.

At the same time it hints the next ultimate set having this part: a Peugeot 106 (Maxi)

Not quite . The Porsche has even newer axle connectors without ridges to make peddle shifting more smooth (snapshot from official video):

I actually made this manual mixer for this thread. The mixers rotate in opposite direction. LXF-file here.

Thanks! I recently built the tractor and my kids love it. My son (6) likes to explain to everybody that it has a real 'fake' engine

I see it this way too. And I would like to add that it would be preferable if the vehicle represents a real supercar, or an imaginary car that meets real-life supercar requirements.

Steering angle doesn't seem that disappointing... The video shows an overall gear rack travel that seems to be slightly more than the supposed 1.0 stud (from left to right), probably because of some slack in the gear rack stoppers, which would be perfectly normal.

Designed myself a manual mixer. The mixers rotate in opposite direction otherwise they would collide. LXF-file here.

which is required since you have to drive home backwards because the steering angle won't let you turn around the car... :wink:

I have ever read - in the magazine Psyche - that it makes sense to make a rational decision about what color of socks you should buy. For anything more advanced it's an illusion to think you can make a rational decision. We make many subconscious considerations we cannot rationalize. Better trust your gut feeling...

...But seriously. Ever since I was a child I have been fascinated by the idea of building the most simple machine that can reproduce itself. We already have a machine that can print its parts, except for its electronics. But I want a machine that can put an instance of itself together. And I want it to build - and be build - from Lego pieces only. Or maybe we should look better at biology and build two machines; one that can put together the other and vice versa. Or maybe a number of machines that can be placed in different arrangements to reproduce each of the individual machines. That should be doable. Maybe we'll find the key to life itself.

Statler: The question is, will MRP_ saw off his own legs? Waldorf: The question is, who cares?

Sticker 3B represents Weissach (Porsche test track). http://www.diecastselect.com/collections/weissach

Nice progress, it's really starting to look like something! Good to read that the front suspension turns out fine. It's one of the best angled steering setups I've seen in supercars :thumbup: .

Impressive work and the looks are great too! And your writings are always a pleasure to read .