42056 - Porsche 911 GT3 RS - MODs and Improvements

[DayWalker]

I saw that somebody was trying to get a numeric build of the porsche with the original build and the different "options". Maybe we should draw a kind of table for compatibility on the ultimately playable thread (I have just discovered your "very impressive" thread with your ultimate version ^^) ?

... so that people can choose the combination they want.

Edited June 30, 2016 by DayWalker

[Didumos69]

I saw that somebody was trying to get a numeric build of the porsche with the original build and the different "options". Maybe we should draw a kind of table for compatibility on the ultimately playable thread (I have just discovered your "very impressive" thread with your ultimate version ^^) ?

... so that people can choose the combination they want.

Thanks!

It would indeed be nice to have a MOD compatibility table. However, some MODs - for instance the 4th-to-1st-gear-block - can be changed very easily to fit various other MODs so I'm affraid it will be a lot of work to maintain. I already have that problem for the 'minimal' and 'playable' versions that I'm maintaining in my ultimately playable thread. I wouldn't want to be responsible for the complete overview as the number and diversity of MODs will only grow.

[Ngoc Nguyen]

@DayWalker: can you provide more picture of the gear indicator integration from different angles? I'd much appreciate!

[Didumos69]

I just posted a photo report about my dashboard gear indicator, rear HoG steering and stabilized gear rack in my ultimately playable thread. Btw, I have a better looking indicator in mind, the one used here is just a placeholder.

I just realized I could easily route my approach to the DayWalker gear indicator, but coming from the dashboard side instead of from the gearbox side. A marriage with the HoG shifting might be possible after all .

Edited July 1, 2016 by Didumos69

[DayWalker]

@DayWalker: can you provide more picture of the gear indicator integration from different angles? I'd much appreciate!

Here are some aditional photos :

To adjust the angular position of the indicator, I suggest you finish by the vertical 7L axis, and ajust the position of the top big gear (20 teeths). When OK, push the axis, til the bottom of the chassis.

@Didumos69 : your chassis is impressive !

Edited June 30, 2016 by DayWalker

[Ngoc Nguyen]

@DayWalker: Thanks a lot! I much prefer your solution to Didumos' one.

[DayWalker]

Hi guys !

Today, I will present you a solution to change the steering geometry into a Ackermann one. With the body on the car, the change is invisible ^^.

Here are few photos to explain how to do

1-Fixation of the suspension

It is very close to the original solution : I have added a vertical 7L gray bar to make the solution more rigid, since 2 bars of the original lego's build must be removed, and few elements in the gray 5x7 L rectangles

2-changes on the fake brakes

We need to add a flat 2L black element like this :

3-The heart of the solution

... and we need a narrower system between the two arms, and the body of the car does not help. After different tries, I made this :

As you see, there is no toothed bar, since apparently, it does not exist in the right length (from LDD). Consequently, I used another mechanical solution with a kind of gutter. The rotation of the gear is transmitted to the orange 2L studless part, and then moves the dark 11L gray with 2 balls at the ends.

4-On the front of the car

If the HOG is already present, just use a 5L axis with Z=12. This axis should penetrate into the central hole of the gray 5L bar of the previous photo.

5-Assembling

This is how the elements should be assembled. For those who look carefully, I have exchanged the right and left suspensions on this photo...

... but is ok on this following step :

... and when finished :

Of course, it is fully compatible with the removable body ^^

Edited July 2, 2016 by DayWalker

[Saberwing40k]

Have you had any fouling, or does it fit? Also, does it limit steering angle/increase turning radius, or not? Finally, do you notice any difference in how well the car turns, versus without the mod?

[DayWalker]

Well, on the initial building, the translation of the toothed bar seems to be a little bit less than +/- 1 stud. Here, 1 stud is possible. But, ok, the radius should be measured to be sure since the geometry is a little bit different ^ ^.

... and yes, everything fits in the body ! (my first tries were too wide... but here, it is ok, no issue at all).

EDIT : apparently, without the body, I get a radius of 67 cm (half turn with 134 cm from center to center of the chassis). Could you measure the radius without the body to get the enhancement if any ?

EDIT2 : I believe we can reduce the number of gears : it will be next step.

Edited July 2, 2016 by DayWalker

[Didumos69]

Hi guys !

Today, I will present you a solution to change the steering geometry into a Ackermann one. With the body on the car, the change is invisible ^^.

Here are few photos to explain how to do

This is a very nice solution DayWalker! Very inspiring too. One question: Could you post a picture showing the wheel in max steering position, so we can see the different angles?

Different from many other advanced steering characteristics, Ackermann steering is very noticeable in a playable model like this, you can feel it. Simply put: It adds to playability. So I will have a go at this too for my ultimately playable version. I have to mary it with my rear HoG steering though. I would also slightly improve the way the balljoint is attached to the wheel hub. I checked this with the real model and it's not more limiting than other parts. Btw, this is not meant to compete with your solution. I'm just trying to translate it to my playable version:

And here are a few shots of what I have in mind to mary this idea with rear HoG steering. I replace the removed 7L liftarms with 9L liftarms a little further to the back. I reused the gear rack and did some plumbing to move the ball joint one stud inwards. I also added a gear rack stabilizer..

Edited July 2, 2016 by Didumos69

[DayWalker]

Thank you !

Here is a top view of the chassis at maximum position. Apparently, the inner part of the right rim (they are very wide !) is touching the arm.

EDIT @Didumos : I believe you have a problem with the body (its fixation and the two 5x7 rectangles behind the front wheels) and the axis parallel to the toothed bar.

Edited July 2, 2016 by DayWalker

[Didumos69]

Thank you !

Here is a top view of the chassis at maximum position. Apparently, the inner part of the right rim (they are very wide !) is touching the arm.

EDIT @Didumos : I believe you have a problem with the body (its fixation and the two 5x7 rectangles behind the front wheels) and the axis parallel to the toothed bar.

Thanks for the photo. Is there enough angle difference between the left and right wheel? I can't tell much difference from the photo, but a small difference will probably be sufficient.

You're right, my gear rack stabilizer collides with the body. I will have to study a little further. EDIT: I might be able to move it underneath the gear rack with one stud space between the gear rack and the stabilizer.

Edited July 2, 2016 by Didumos69

[DayWalker]

You are welcome !

I agree, the difference of the angles is not very obvious...

Edited July 2, 2016 by DayWalker

[efferman]

This is a nearly invisible modification, but after years on the shelf it coud be worth to pay the money for it. The stickers are directly printed on the Parts by steindrucker.com and actually not for sale

Edited July 2, 2016 by efferman

[Ngoc Nguyen]

I attempted some MODs at the paddle handler. The aim is twofold:

- Make the paddle handler closer to the steering wheel

- Increase the distance from the center axle, so that shifting requires less force.

I don't have a smartphone, so please excuse me for the low quality. However, the mods achieve both aims above.

http://www.mediafire...703_022224.JPG#

http://www.mediafire...703_022318.JPG#

The 3L connector I use is this: http://brickset.com/parts/4121667. Since shifting with these handlers require much less force, the rubber bands can be discarded. If you wanted to use them, you can add two pins with tow balls to the middle holes of the 3L connectors, and hook the bands to them.

Edited July 2, 2016 by nguyengiangoc

[Didumos69]

Here is a top view of the chassis at maximum position. Apparently, the inner part of the right rim (they are very wide !) is touching the arm.

I agree, the difference of the angles is not very obvious...

(Sorry for quoting this image, but it's subject to this post.)

@DayWalker, as the angle difference wasn't really visible in this photo, I wanted to try this first before putting in the effort of implementing something comparable in my ultimately playable build. Just for testing purposes I replicated your setup - or at least your exact geometry - at the front site of the front suspension. This gives of course the opposite of the desired effect, but it's only to investigate what the effect is. And just like in your photo, the Ackermann-effect didn't really show. But I also found what the issue is with this - and probably with your - setup: The ball-joint with axle that is used to connect the track rod to the wheel hub, does not fully insert into an axle hole. Now in your setup - and in mine - the ball-joint with axle is placed upside-down compared to the original setup. This causes the ball-joint with axle to move 0.2 stud more upwards than the ball-joint with pin at the other end of the track rod. As a consequence, the track rods are flattened out a little compared to the original situation, which in turn results in a slight toe-in-effect in your setup - toe-out in my setup. This means that the Ackermann-effect first needs to compensate for this toe-in before it actually takes effect. This explains the more or less parallel wheels in your photo.

Here you can see the toe-out in my test setup. Your setup will probably suffer from a comparable amount of toe-in.

Once again the solution can be found in silicon bands, but you could of course also change your setup to get the track rods similarly angled as in the out-of-the-box situation. This is an old image, in our setups both ball-joints point into the same direction.

This is what it looks like with the silicon bands. This also significantly reduces slack in the whole steering setup. I don;t have a picture of the Ackermann-effect in this situation, but I can gaurantee it is much better visible than in your photo:

Edited July 3, 2016 by Didumos69

[DayWalker]

Nice study ^ ^

And you are right. In fact, I had to make a choice of the vertical position of the 11L bar on which balls are attached, because :

• the arms of the suspensions have a pivot almost at the middle ; the distance between the wheel and the pivot is 3 L
  
• the length of the tracks rods are 6L
  

Consequently, depending on the hight of the chassis, the parallelism of the front wheels is not maintained (it is also an issue in the original setup). For a perfect design, I assume that we would need 4 L track rods. If it is not clear, have a look to the position of the tracks rods when the suspension is used ^ ^

EDIT : Here is a phot for which the arms and the track rods are parallel. For this position, the two front wheels must be also parallel.

On this photo, (the other extrem position), we see that arms and track rod are not parellel, so front wheels are not parallel.

I believe there is no perfect solution except using 4L long track rods (but it does not exist ?). So the only thing we can do is to tune the vertical position of the two balls per suspension system so that wheels are parallel for the default position of the suspension (and apparently, your solution is better than mine without the body ^^)

Edited July 3, 2016 by DayWalker

[Appie]

Isn't this called bump steer? As far as I know to fix it, the steering rods and the wishbones have to be the same length. Which they are, but it isn't utilized as you pointed out (distance in your image is 4L btw, not 3). This would also mean the original model has issues with bump steering (yet another flaw ). Modifying the suspension (without touching the wheelarch) and using the full length of the wisbones should fix it.

Edited July 3, 2016 by Appie

[DayWalker]

Yes another issue of the original version...

Just to mention : with the body, wishbones are almost horizontal, so bumping is quite limited (situation close to the first photo of my previous post). I really hesitate in modifying the suspension, but it would also change the behavior of the front height VS vertical forces... Not sure it is necessary, and I begin to be limited with my stock parts (I bought a 42038 set, only for parts, since lego technics are very different from what I used to play when I was a teenager... with studfull).

.

Edited July 3, 2016 by DayWalker

[Didumos69]

Nice study ^ ^

And you are right. In fact, I had to make a choice of the vertical position of the 11L bar on which balls are attached, because :

• the arms of the suspensions have a pivot almost at the middle ; the distance between the wheel and the pivot is 3 L
  
• the length of the tracks rods are 6L
  

Consequently, depending on the hight of the chassis, the parallelism of the front wheels is not maintained (it is also an issue in the original setup). For a perfect design, I assume that we would need 4 L track rods. If it is not clear, have a look to the position of the tracks rods when the suspension is used ^ ^

I believe there is no perfect solution except using 4L long track rods (but it does not exist ?). So the only thing we can do is to tune the vertical position of the two balls per suspension system so that wheels are parallel for the default position of the suspension (and apparently, your solution is better than mine without the body ^^)

Isn't this called bump steer? As far as I know to fix it, the steering rods and the wishbones have to be the same length. Which they are, but it isn't utilized as you pointed out (distance in your image is 4L btw, not 3). This would also mean the original model has issues with bump steering (yet another flaw ). Modifying the suspension (without touching the wheelarch) and using the full length of the wisbones should fix it.

Yes another issue of the original version...

Just to mention : with the body, wishbones are almost horizontal, so bumping is quite limited (situation close to the first photo of my previous post). I really hesitate in modifying the suspension, but it would also change the behavior of the front height VS vertical forces... Not sure it is necessary, and I begin to be limited with my stock parts (I bought a 42038 set, only for parts, since lego technics are very different from what I used to play when I was a teenager... with studfull).

.

@DayWalker, I understand your considerations, thanks. Given that the wishbones are almost horizontal under the weight of the body - and thus the wheels almost parallel - you should see a better angle difference (Ackermann-effect) when steering than without the body. Can you confirm that?

The steering rods should indeed be the same length as the wishbones to avoid bump steer. Btw, I think it's better to speak of heart-to-heart distances in this context, that is 5L for the rods and 3L for the used part of the wishbones. The current suspension setup can do with a single shockabsorber, because both ends of the suspension arm serve as moment arm. So if the full length of the suspension arm was used, you would need two shocks or one shock and a longitudinal torsion bar attached to one of the wishbones. I don't think I will go that far.

This will be my shot at Ackermann steering in my playable build. I completely turned aroud the widthwise setup of liftarms an frames. I will be using a 7L rack with an additional slider. The yellow levers hollding the calipers - so not the calipers themselves - can actually be lowered - I checked - by half a stud, so a 2L (+0)-liftarm can be attached to the wheel hub. This way I could also preserve the exact angle of the steering rod as compared to the original build. I had to take into account my rear HoG steering, but where the rear HoG axle (with the U-joints) enters, the dashboard HoG axle could also enter. All fits within the boundaries defined by the body.

LXF-file here. This might of course change while building.

Edited July 3, 2016 by Didumos69

[Richard Dower]

Based on this thread...is the Porsche the most flawed Technic model ever?

[DayWalker]

@DayWalker, I understand your considerations, thanks. Given that the wishbones are almost horizontal under the weight of the body - and thus the wheels almost parallel - you should see a better angle difference (Ackermann-effect) when steering than without the body. Can you confirm that?

Yes, I assume, but I am not an expert in mechanics !

[syclone]

I have a question :

How this car would look with Power Puller wheels?

[Blakbird]

Based on this thread...is the Porsche the most flawed Technic model ever?

Not even close. With nothing but the Step 5 (which requires no extra parts) my model works completely fine. Most of the things in this thread are improvements to make it better. Any set could be made better, I suppose.

Rather than the most flawed, I would say it may be the furthest from the expectations of AFOLs, but that is at least as much due to high expectations as low quality.

[DayWalker]

@Didumos : Aren't your fake brakes touching inside the rims ?

Nice mod to get an Ackermann geometry too !

Not even close. With nothing but the Step 5 (which requires no extra parts) my model works completely fine. Most of the things in this thread are improvements to make it better. Any set could be made better, I suppose.

Rather than the most flawed, I would say it may be the furthest from the expectations of AFOLs, but that is at least as much due to high expectations as low quality.

I agree with you. It is maybe the first time that a Technic set is really impressive for its look and close to the real car... but a non functionnal sequential gear system is a pity. The minimum thing that we expect from a supercar is an operationnal (ie, rotating) fake engine (and a HOG if the steering wheel is not easily accessed). To me, the 8880 (my previous super car) had a perfect mechanical system, and my only mod was "adjustable seats". Here, the porsche is a nice set, but "details" are quite a pity (wrong sequence of speeds, fake engine issue, no HOG, no inclined drinving wheel, no removable body, while it can be very easily done : even for the Ackermann geometry, I am almost sure that the difference is less than 150 parts, excepts for the Didumos Ultimate version ^ ^). The good point is that we can make a lot of improvements.

The body is very nice, and except few details, certainly one of the nicest official reduction of a real car ^^

Edited July 3, 2016 by DayWalker