42056 - Porsche 911 GT3 RS - MODs and Improvements

[Tommy Styrvoky]

I think I am nearing a finished design for the Macpherson suspension for the front. There is only one area that may cause issues with the trunk structure, but everything should fit on the stock body, and work with the "marriage" of the body and chassis. I think another issue that could arise with the current shock mounts is collisions with the upper part of the shock and the shock mount, say if the model's wheels are being turned, and the suspension gets fully depressed, but I think this is unlikely to happen. If there is issues with the trunk colliding with the upper shock mount, I will need to flip it around. Could someone please test the clearance between the trunk and the front? Or a picture from the side of the model, near the wheel arches looking at the space between the suspension and the front of the trunk would be nice, as I lack the parts to build a mockup of it.

It is also a rather easy drop in part, you just have to remove the upper A arms of the suspension, and the pieces connecting the upper and lower arms, and a couple parts that are in the center. A few of the parts get reused in the suspension too.

LDD file for just the suspension http://www.bricksafe... macpherson.lxf

Edit... I accidently changed this version to negitive caster angle.... well I guess it isn't a final version yet. I will fix it tomorrow.

Lego GT3 RS macpherson.lxf by Tommy Styrvoky, on Flickr

Lego GT3 RS GT3 RS macpherson strut.lxf by Tommy Styrvoky, on Flickr

Lego GT3 RS macpherson colored.lxf by Tommy Styrvoky, on Flickr

Edited June 10, 2016 by Tommy Styrvoky

[Didumos69]

I think I am nearing a finished design for the Macpherson suspension for the front. There is only one area that may cause issues with the trunk structure, but everything should fit on the stock body, and work with the "marriage" of the body and chassis. I think another issue that could arise with the current shock mounts is collisions with the upper part of the shock and the shock mount, say if the model's wheels are being turned, and the suspension gets fully depressed, but I think this is unlikely to happen. If there is issues with the trunk colliding with the upper shock mount, I will need to flip it around. Could someone please test the clearance between the trunk and the front? Or a picture from the side of the model, near the wheel arches looking at the space between the suspension and the front of the trunk would be nice, as I lack the parts to build a mockup of it.

It is also a rather easy drop in part, you just have to remove the upper A arms of the suspension, and the pieces connecting the upper and lower arms, and a couple parts that are in the center. A few of the parts get reused in the suspension too.

Edit... I accidently changed this version to negitive caster angle.... well I guess it isn't a final version yet. I will fix it tomorrow.

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: ).

Edited June 10, 2016 by Didumos69

[Kumbbl]

Sure thing, more testing is always good. I tested this mod of Max in my mockup. There's a reason the 2L axle with axle connector is in front of the model: in case it needs extra bracing on top (there's a 3L pin with stopbush there anyway on the actual model), but I don't think it is needed, but perhaps your experience will be different.

Here's the file.

Thank you - looks good and works well in my mockup...

[ddeklerk]

Sorry if this is a little off-topic, but I gotta ask. When reading all these post about modifications to the model, I come across a lot of technical terms that I have not heard before. A few of them I could figure out with a quick Google search, but others are still somewhat of a mystery to me.

For instance, caster angle. I get that it is the angle of the suspension of the front wheels (I think), but what is it's significance. Is a positive angle preferred over a negative angle? What kind of effect does it have.

Some other terms that are foreign to me are 'Macpherson suspension' and 'Ackermann steering' just to name a few.

My guess is that these are not specific terms to Lego, but rather to cars and other vehicles. But where can I find out more about these sort of things, or does it just come over time?

This set may be the first set that I buy (ordered from the online Lego shop, still no further info) in a very long time, my last one being 8297. And it has sparked an interest in Lego Technic in me that I have not had before. I am looking forward to expanding my modest collection of parts and making my Technic MOCs, something that I have not done before.

[Didumos69]

...

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

Edited June 10, 2016 by Didumos69

[ddeklerk]

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.co...-and-Scrub.aspx

And the videos of nicjasno are very informative, for instance

and

I understand that it is about realism. I can't imagine it having much of an effect on the actual driving of Lego models, but I could be wrong.

Thanks for those links. I took a look at the first one, the written article, but if I'm honest I can't say I understood much of what was talked about. Although that may be because your link sent me to page 3 of 6. When I have the time I'd like to read the rest as well.

I've got a feeling that this will grow to be an obsessive hobby of mine. And I intend to learn as much as possible when it comes to making my own models. If only I did not already have two expensive hobbies (computers and mechanical keyboards). I cannot wait to get my hands on the Lego Porsche and to apply all the essential mods to it. Then I will further modify it to my liking, or make something different out of its parts.

[scooper22]

Having a correct steering and suspension is very important, best seen on the Unimog:

[nerdsforprez]

I understand that it is about realism. I can't imagine it having much of an effect on the actual driving of Lego models, but I could be wrong.

I've got a feeling that this will grow to be an obsessive hobby of mine. And I intend to learn as much as possible when it comes to making my own models. If only I did not already have two expensive hobbies (computers and mechanical keyboards). I cannot wait to get my hands on the Lego Porsche and to apply all the essential mods to it. Then I will further modify it to my liking, or make something different out of its parts.

It really is about realism. Many of these really don't make a different regarding driving the models. Lego PF is too slow to really make most models (not all) need these mechanical advantages, but it is still fun to try and mimic such real-life applications. The Porsche, technically, doesn't even drive as is out of the box.

As for the concern this might be a growing obsession..... well, welcome to the club

[Kumbbl]

It really is about realism. Many of these really don't make a different regarding driving the models. Lego PF is too slow to really make most models (not all) need these mechanical advantages, but it is still fun to try and mimic such real-life applications.

fully agree... and it is ONLY about realism and ONLY about your own knowledge that your lego car is build realistic... in daily practice (ie. ushing your Porsche around) you will hardly notice any difference between the original front axle layout and a modified MacPherson strut suspension with Ackermann.

And to learn for yourself how such sophisticated front suspension works and to see its advantages the lego parts are somehow unsuitable cause of the inherent slack etc, the unsuitable geometry and also the scale of the model is too small... and to notice a difference between Ackermann and non-ackermann during pushing the car the max steering lock of the Porsche is way too small...

The only aspect which IMHO really influences playablity is bump steer because with a huge bump steer front suspension will hardly work even when driving over a piece of paper ;-) So a front suspension layout with as much as possible reduced bump steer gives IMHO the greatest practice value to the owner...

To make a long story short: with better suitable parts (ie. less slack, better geometry etc.) for sophisticated front-suspension layouts i would highly appreciate authentic and realistic layouts in supercars but with current available parts it is more or less worth- and useless (exception: reducing bump-steer if possible - but based on my own experience with building a lot of the well known supercar MOCs out there: there is always too much bump-steer regardless how sophisticated the suspension layout is....) - apart from the fun of a MOCer during the designphase...

- just my 2 ct...and no offending to all the front-suspension lovers out there! ;-)

[Didumos69]

... and it is ONLY about realism and ONLY about your own knowledge that your lego car is build realistic...

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

Edited June 10, 2016 by Didumos69

[Nmapladem]

Evolution shift down with it works pretty well, stops the engine sound was me and not a problem of the mechanism.

I like to remove all the central gears and direct implementation with central control

There are more than all implement

See Video:

Edited June 12, 2016 by CopMike

[Attika]

I don't think it should cause any problems to place the parts in either orientation, CV= Constant velocity joint, so it is designed to function correctly, until it reaches it's maximum travel, then it can have problems locking. With the error in the instructions, it will align itself when you shift the gearbox.

It is ok. that cv must be in 45 degree, so you good to go. Sorry coming back late...

oops I quoted you Tommy instead of Trace 17, but it is in the same subjet.

[Tommy Styrvoky]

Well I fixed the flaw I missed yesterday when I was configuring the suspension to fit around the bodywork... It was late at night (actually morning). It now has proper caster angle, and I removed the points where it had collision issues. Now I noticed something else, the shock absorber sometimes will bend, this is because of the hard suspension. I think the front suspension needs to be replaced with soft suspension, and it functions fine. I think this will work with the current model, as the shock absorber is in a more vertical position, so it has more leverage on the lower arm. So to fix this problem, either a new upper spring mount, or softer springs used. Though I am unsure if soft springs can support the model?

I took a look at Appie's rear steering design, and I think I see some possible methods of moving the spring mount of my current macpherson suspension to function with the rear wheel hubs and allow for a driven axle. I will see about configuring it around the rear axle. Another though for the rear suspension, is a method of switching between crab steering and traditional steering, as the rear car uses this at different speeds. I was thinking something to the main shifting console, but the middle position= no rear wheel steering. Though any good thoughts for where to mount the changeover catch for toggling it? I was thinking making a linkage that would route up to the center console, and maybe a switch could be mounted there.

LDD file http://www.bricksafe...cpherson V2.lxf

GT3 RS macpherson V2.lxf by Tommy Styrvoky, on Flickr

GT3 RS macpherson.lxf by Tommy Styrvoky, on Flickr

GT3 RS macpherson colored.lxf by Tommy Styrvoky, on Flickr

Edited June 10, 2016 by Tommy Styrvoky

[nerdsforprez]

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

also.... I don't want to distract from the real intent of this post which I am following with much interest....but I will quickly add this..... I think that so much of the time those that follow threads like this and perhaps technic-heads in general we focus so much on correct engineering, physics, etc. that we forget about the science of materials. I went to school with a metallurgist and when I initially met him I was like.... oh yea, I guess there is a whole science dedicated to the study of metals, alloys and similar compounds. That makes sense. Engineering, physics and the like aside, we can never really reproduce anything even remotely close to the real thing because we are working with entirely different materials.....

[Appie]

I took a look at Appie's rear steering design, and I think I see some possible methods of moving the spring mount of my current macpherson suspension to function with the rear wheel hubs and allow for a driven axle. I will see about configuring it around the rear axle. Another though for the rear suspension, is a method of switching between crab steering and traditional steering, as the rear car uses this at different speeds. I was thinking something to the main shifting console, but the middle position= no rear wheel steering. Though any good thoughts for where to mount the changeover catch for toggling it? I was thinking making a linkage that would route up to the center console, and maybe a switch could be mounted there.

See, there's something I forgot to say. Ideally, I was personally thinking about using Jeroen Ottens' DB11 gearbox, but instead of using it for 4 more gear shifts it shifts from counter steering in gear 1-2 to crab steering in gear 3-4. This would of course require a redesign of the gearbox area as well. Which is well over my head. So I'd leave that to the pro's and just kept my very basic concept around counter steering and if I saw a possibility, I wanted to put the switch for counter/crab besides my HOG.

Great work on the McPherson, soft springs might work, the front doesn't look heavy.

[deathman20]

Oh boy great idea's all around. Really eager to dig into this more this weekend.

Since I'm enjoying my model so much I'm also building it on LDD with all the tweaks I'm implementing as I go along.

One of the first mod's I've done to any of my models and this seems to be well worth it in the end.

[Tommy Styrvoky]

See, there's something I forgot to say. Ideally, I was personally thinking about using Jeroen Ottens' DB11 gearbox, but instead of using it for 4 more gear shifts it shifts from counter steering in gear 1-2 to crab steering in gear 3-4. This would of course require a redesign of the gearbox area as well. Which is well over my head. So I'd leave that to the pro's and just kept my very basic concept around counter steering and if I saw a possibility, I wanted to put the switch for counter/crab besides HOG.

I think it would be possible with the current gearbox to toggle a changeover catch like you mentioned.

[Trace17]

I don't think it should cause any problems to place the parts in either orientation, CV= Constant velocity joint, so it is designed to function correctly, until it reaches it's maximum travel, then it can have problems locking. With the error in the instructions, it will align itself when you shift the gearbox.

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.

Thank you both, I will proceed then and hopefully all will be fine.

Didumos, Yes thanks to all the wonderful people here I have been keeping tabs on the mods and what I will implement. I don't post much, but rest assured I read things quite often. Of the list of 7 mods in the OP, I've already done number 1, (I used a later suggestion to use "half bushing", not sure on the exact term but 4 smaller ones instead of 2 standard ones).

I will also be doing 2 and 4 for sure, and I will also be removing the pins that will add a tiny bit more to the steering. I'm not sure if I have the parts for some of the other mods like HOG. so I may not implement.

For #3, was it ever posted how that affected the body and the final build. There's a post by Appie here: http://www.eurobricks.com/forum/index.php?showtopic=133743&st=25#entry2577539 and talks about how it affects it but I couldn't find any picture of what needs to be done (in what Appie refers to), and since I'm no technic expert and a visual person, I'm not sure to what exactly you mean. Is this the additional part needed (with 2x4 liftarm supertechnicmans put in video) http://www.bricklink.com/v2/catalog/catalogitem.pageP=32316#T=S&C=11&O={"color":11} and is there a picture of this anywhere?

[Didumos69]

For #3, was it ever posted how that affected the body and the final build. There's a post by Appie here: http://www.eurobricks.com/forum/index.php?showtopic=133743&st=25#entry2577539 and talks about how it affects it but I couldn't find any picture of what needs to be done (in what Appie refers to), and since I'm no technic expert and a visual person, I'm not sure to what exactly you mean. Is this the additional part needed (with 2x4 liftarm supertechnicmans put in video) http://www.bricklink.com/v2/catalog/catalogitem.pageP=32316#T=S&C=11&O={"color":11} and is there a picture of this anywhere?

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.

Edited June 11, 2016 by Didumos69

[nerdsforprez]

So I have been following this for a while, here are a few observations regarding friction. Although it sounds like a lot of the friction issues have been worked out with Blakbird's fix and others..... I see a couple things that can add very minute, but still important, unnecessary places of friction......

on step 111

I think the use of the 3L connector is unnecessary. It rubs against the the two points circled. Anywhere axles are flush against connectors you will have additional friction. why not increase the length of the of the axle that joins all parts, gears, etc. and use a 7 instead of 4L axle? For bracing, perhaps one 1/2 bush can be use to make sure there is no movement. But the 3L connector to ensure no movement is overkill.... and likely causes too much friction.

In the same step....(111) it appears that the toggle joint pin connector (white arrow):

has only one point of connection (other than the gears). I am not sure.... but this seems insufficient. Under torque, could not this piece turn slightly to increase friction in the mechanism? I would like to try it out myself, but out away from any LEGO at the moment. It appears it could easily be braced with a perpendicular connector:

---- this may require the liftarm that accompanies that space (13L; light bluish gray) be changed from 13 to 11.... but I don't think that will cause really any problems. Not sure if it would be that much of an improvement but it just seems that the toggle joint pin connector is too poorly braced.

Lastly.....again with the 3L connectors. Great part... to be sure, but IMO too often used in this set and add to the friction in the gears unnecessarily. on step 269....

these are three points of contact that do not have to be there. I get that you dont want the gears sliding around, but each of the following gears are either backed or have out in front a bush so I don''t see them going anywhere (and two of the three are axles with pins... they are not going anywhere). Why not change the axles from 4L (w/pin), 3L, 4L (with pin) to 5L (w/pin), 4L, 5L (w/pin) respectively followed by a 2L connector (they would not touch the 13L gray liftarms.

[Didumos69]

...

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

Edited June 11, 2016 by Didumos69

[efferman]

this time only a small mod on the Dashboard. to place it more close to the steering wheel

[Tommy Styrvoky]

this time only a small mod on the Dashboard. to place it more close to the steering wheel

looks great, how much space is taken up in the front for the moved shifting mechanism?

[efferman]

it is nearly fully inside of the frame, only a lever collides with a 5x7 frame of the body, so i dont have the option to remove the body.

[M_longer]

10 pages so far, probably few more are coming. It is nice to see that in two days all flaws of the set were fixed. It is also interesting where this modding will end, because (thanks to your effort guys) at some point this set will have only two things in common with final modded version: name and colour :)