Didumos69

It was indeed Appie's response that answered that question. And the 5L liftarm that you are referring to is indeed the one you need. Together with the 2x4L liftarm it will eventually replace the 9L liftarm Appie is referring to. Placing the 9L liftarm was originally done in step 275 if I'm not mistaken.

I have been reasoning about this approach a little more and have come to the understanding that when a setup like this - with a simple friction clutch between the output axles - gets confronted with one of the output axles spinning, it will never be able to transfer more torque to the non-spinning wheel than the amount of torque created by the friction clutch. Given that a light slip - or low friction - clutch will never live up to the torque needed to get a car moving, a setup like this will never resolve a spinning wheel. In that sense my approach is indeed not realy diferent from inserting 2 2L axles between the tan gears in the differential. I know about Torsen diffs and active diffs and I know my simple clutch is absolutely not an advanced principle, but I thought it would qualify for LSD. But I've learned my lesson about LSD now, also after seeing this video: https://youtu.be/WeLm7wHvdxQ. And to come back to my approach, the practical value of my type of differential (locked by default, but opened when turning/slipping) could be that it avoids windup in turns (diff open) and adds to straight line-stability when driving straight (diff closed). So lets call it a straight-line-stability-diff .

Thanks Victor, appreciate it. I would like to get out of this more competent than I was, so let me try to summarize what some of you are trying to tell me: The part that I call clutch is actually behaving as a lock until it starts slipping, from that point on it will no longer create resisting torque between the two output axles, until it no longer slips. Is that what you mean? So this is also not a LSD, or is it?: I intended to see the rattling clutch (it's not a ratchet because it allows motion in two directions) as something that also creates resisting torque while slipping. When I deliberately rotate the output axles in opposite direction, it also feels like it still provides substantial resistance. Would it make any difference when two smooth rubber surfaces created the resistance, or would that still not count as LSD?

Max, I don't understand what you mean, could you pleae clarify? It could very well be that I'm not completely correct with the terms that I use, but after some googling around I arrive at the conclusion that the essence of a LSD boils down to "some sort of mechanism that applies a torque (internal to the differential) that resists the relative motion of the output shafts. In simple terms, this means they have some mechanism which resists a speed difference between the outputs, by creating a resisting torque between either the two outputs, or the outputs and the differential housing" (source Wikipedia). You could argue that the mechanism is not internal to the diff, but applying a torque that resists the relative motion of the output shafts is exactly what my solution does. Or am I missing something?

I turned my simple 90° indexer into a light slip clutch and to me it seemed very suitable for application in a limited slip differential. I replaced the angle element with square mid-section with a 2L axle connector so it has 8 preferred positions (45° steps) instead of the 4 in the 90° indexer. I played a little with it and even in a small light-weight push-along car you can sense the straight-line-stability and the clutch actually starts slipping when pushing the car through turns. The white silicon band can be replaced with a red one wrapped around the limiters (2L liftarms) twice to make the clutch tighter. I think this approach gives a very realistic effect, or at least an effect that is realisticly proportional to Lego vehicles, also motorized vehicles. But you will have to find out that for yourself. EDIT: As has been pointed out below this does not really qualify as LSD. The friction clutch is always engaged and for it to be a LSD the clutch should only be engaged when one of the output axles slips. LXF-file here.

I couldn't agree more. It all relates to your own knowledge. When you're into engines then you'll be fully aware of the pistons moving up and down while pushing the car. And when you're into suspension and steering stuff you'll be fully aware of the caster doing it's job while moving your car around, etc, etc. However, for Ackermann steering I do notice the difference. I have to admit I'm more into suspension and steering than into engines and gear boxes - so it could be imagination - but IMO slack is the precise reason that when you push your car through turns without Ackermann steering you will get a lot of unintended camber; negative camber when pushing backwards and positive camber when pushing forward. In fact your car suffers from toe-in in turns without Ackermann. So for me Ackermann is a must-have

It's all about realism. When it's about proper angles, caster angle, camber angle, kingpin inclination, etc, then this is a very easy to read article: http://www.motoiq.com/MagazineArticles/ID/1982/PageID/3202/The-Ultimate-Handling-Guide-Part-8-Understanding-Your-Caster-King-Pin-Inclination-and-Scrub.aspx And the videos of nicjasno are very informative, for instance and

Very nice work so far! I finally took the time to look at your design. It looks great how you melted together the shcok with the wheel hub. You already mentioned negative caster, but there is another thing that triggered me. As far as I can judge the calipers are mounted one stud too low. In the new hubs the two axle holes are at the same level as the upper pin hole. I also wonder whether changing angles (caster) won't make the wheels collide with the body of the car more easily. But I can't test that for you, because I don't have the set yet (it has been shipped though :sweet: ).

That's also what I understood. I think you can leave all as is and continue. I also tested whether it makes any difference how the CV-joints are aligned with the angles that are used, but it doesn't. The whole thing operates in 90 degree steps so it doesn't really matter how you eventually connect this CV-joint with the one attached to the paddle shifter unit. EDIT: didn't see the above answer, but boils down to the same... Btw, did you apply the essential improvements listed in the original post? A few of them are mission-critical.

Yess!!! (It has been shipped!!!)

Ingenious paddle gear selecter! I love the idea of using belt wheels to obtain 6 positions. I'm looking forward to see how you are going to translate the 30 degree rotation steps to discrete shifting steps to engage the appropriate gears. And how are you going to make that compact? Guess I'll have to be patient...

Thanks! I made an LXF-file. Without the bevel gears this is all there is to it:

Looking really good! Not using flex axles makes this build breathe the 90s. Love it!

Thanks! I also tried with a red silicon band wrapped around the indexer twice and then you really need to apply a lot of torque to make it switch. If you would use an unangled shockabsorber I'm affraid it will behave as a lock and not toggle at all.

Thanks! I hope it's useful! I had this idea already, but when I read your response to Lipko today about 'a second limiter in the back of the car' it reminded me to really start checking if this would work I would be honoured if anything like this would show up in the DB11!

I just posted about this in the Porsche MODs and improvements thread, but I think this might be worth sharing with everybody. In an attempt to further improve the definite character of the selecter axle in the Porsche gearbox I found a very easy way to limit an axle to 90° positions. I think this video tells the whole story (don't bother the bevel gears if you're not interested in the Porsche gearbox). (Actually I don't really know what the name is of this kind of mechanism. ) Without the bevel gears this is all there is to it: LXF-file here.

I think I have found a way to add a second limiter that directly applies to the selecter axle that operates the driving rings. This should make the positions of that axle more definite. In other words, it will help limiting the axle to 90° positions only. Perhaps this could improve the way the gearbox operates, avoid halting and reduce backlash in the switching mechanism even further. And hopefully this will make the 8-tooth gear on axle-pin with friction unnecessary, which was also meant to reduce backlash (the right one of the two 8 tooth gears at the upper left corner of the first image below). The limiter has been integrated in the section close to the gearbox where the gear selecter axle crosses the drive axle. I tested it and it works very well and does not generate friction on the drive axles. I also checked whether this fits in the chassis and it does. I don't have the bevel gear with pin hole so you have to imagine that part. This video tells the rest of the story: EDIT: The 8 tooth gears used to add friction have indeed become unnecessary when this limiter is used. Or actually, they should be ommitted for the gear selection to work flawlessly, see this post. I also swapped the limiter to the left, so it doesn't collide with the reverse gear blocking mechanism from MaxSupercars and Appie. The white silicon band could be replaced with a red one wrapped around the limiter twice. I don't know exactly how much torque the paddle selecter generates, so you will have to try what works better. Maybe using a red silicon band works better if you drop the friction-generating 8-tooth gear. EDIT: Wrapping two white silicon bands around the two limiters turns out to do the job. These can be taken from the paddle shifters. With this mod the whole operation becomes lighter, so the paddle shifters can do with one silicon band each. Simply wrap it completely around the ball joint once to obtain the desired tension. See this post. Now the question is, can somebody test this on the real model? If you would then here are some considerations to take into account: - It's advisable to combine this with Blakbird's pin joiner fix and Attika's change-over-catches-fix. - Try if the whole setup can do without the 8-tooth gear attached that was meant to reduce backlash. - Make sure the bevel gear with pin hole has enough play. - Make sure the angle element and the two added bushes sit tight - not too tight - against the frame so the selecter axle won't be tempted to push the angle element against the bevel gear with pin hole. The original and modified construction: The added (transparent green), reused (original color) and dropped (transparent red) parts: LXF-file here.

Thank you Blakbird for testing the HoG-MOD. I will add the 3x3 liftarm and the extra pins you used to the LXF-file and drop the bush . Then I will update my final post about it accordingly. EDIT: Done, LXF-file here (also contains variations for removable HoG and for a gear rack at the back of the front axles).

This makes perfect sense to me! Thanks for clarifying! Leaves me with one other question. Would it make any difference whether the two CV-joints are aligned with their splits having the same orientation or with perpendicular splits? It wouldn't suprise me if it did. Like I said CV-joints start behaving odd when angled more than 11 degrees. In LDD this pin joiner actually touches one of the drive axles. Besides that the pin joiner may have some friction with the adjacent bevel gear with pin hole. Nobody tried whether removing the pin joiner reduces friction even further?

Looking good! One question about the front suspension: Are you sure the vertical liftarms between the upper and lower wishbone still fit with the wheel hubs leaning backwards (caster)? The ball joints of the wheel hub won't make a height difference of 4 studs (heart to heart). Or did you insert ball joints with axle instead of ball joints with pin to gain a little height (with axle stick a little further out of the pin hole)? I'm curious how you did that.

I think someone mentioned it before, but there is something strange with step 121 and step 173 of the BI, which might cause differences. In step 121 one of the CV-joints is inserted in a 2L axle connector. However the CV-joint is oriented perfectly horizontally, while the 2L axle connector is rotated by 45 degrees, just like the knob gear attached to it at the other end. In fact step 121 shows something impossible. Most of us will leave the knob gear in 45 degree position and will end up having the CV-joint in rotated position too. However you can rotate the CV-joint clockwise or counterclockwise. This is where the first difference might occur. Further on in step 173 the CV-joint coming out of the paddle selecter - which is oriented perfectly vertically - is connected to the CV-joint that was put in place in step 121. Step 173 shows how the vertically oriented CV-joint is connected to the horizontally oriented CV-joint. In practice this might turn out differently, because of the first CV-joint being rotated by 45 degrees. So you could end up with the CV-joints having the same orientation or different orientation. I've been playing with CV-joints and when they are angled more that 11 degrees they start grinding. So I don't trust them and therefore I wouldn't be surprised when their relative orientation matters in the whole gear selection setup. So I'm very curious whether the CV-joints in your builds have the same orientation or different orientation. EDIT: Now that I'm looking into this I'm wondering, how can tthe whole gear selection mechanism operate properly if somewhere down the road a 90 degree oriented axle connects to a 45 degree oriented axle? Where have these 45 degrees gone? What am I missing? Or is this 45 degree difference what's needed to avoid backlash? But then the above possibilities might make the difference between adding backlash and reducing backlash. Could somebody clarify? Remarkable side note; Step 173 is the last step showing the CV-joints. In the remaining 683 steps you don't see them again...

There is one more thing that I can't get out of my head. In the section where the drive axle crosses the gear selecter axle there is also a pin joiner placed. Not that I think pin joiners are generally bad after the Blakbird fix, but I thought it would be worth trying without. I don't think the pin joiner is needed for keeping the bevel gear with pin hole in place and it does cause some unnecessary friction. Did anybody try? This won't fix the backlash problem but maybe it reduces friction even further.

Great idea! You mean something like this? Maybe the removable HoG can be stored under the hood together with the luggage bag (Sorry I used my HoG)

Thanks, appreciate it! Great initiative to keep track of the essential or 'must have' MODs and separate them from the more advanced 'nice to have' MODs. It will give a first hand to people who simply want to enjoy their Porsche.

Thanks! I think it would be a good thing if there are several options to choose from, so I would also like to encourage Appie to continue his effort to realize a HoG in the rear of the car, that would be awesome! Good news, I took the LXF-file of Box 1 (from Tommy Styrkovy's McPherson post, great thanks to the original designer!) to verify whether all will fit and it does. It would of course still be great if someone tested it with real bricks. I updated my LXF-file to contain the steering train with and without dashboard HoG. So to wrap things up: This is a simple dashboard HoG, secure and with a minimal set of extra parts. The HoG is positioned right above the 1x1 hole in the dashboard. The steering ratio of the steering wheel is the same as in the original build, the HoG is more direct. The second image shows the added parts (transparent green), what has been reused (original color) and the dropped parts (transparent red). The red axle connector is a substitute for the new axle connector that was used in the original gearing above the gear rack. I also reused the 5L yellow axle and several other parts. The last image shows the extra parts needed. I edited my first post about this solution to reflect the changes. Thanks! EDIT: - Updated the LXF-file with the 3x3 liftarm to keep the gear rack in place as was suggested by Blakbird. - Added a variation with removable HoG to the LXF-file (see third image), an idea from Attika. - Added a variation prepared for placing the gear rack at the back of the front suspension (might be needed for Ackermann steering). With and without standard HoG: What has been added (transparent green), what has been reused (original color) and what has been dropped (transparent red)? Variations for Ackermann steering and with removable HoG Parts needed for standard HoG: LXF-file here.