42083 Bugatti Chiron - MODs and Improvements

[Bartybum]

Does anyone know what the turning radius is like when you remove the front axle CV joints?

[Rikus]

44 minutes ago, Kumbbl said:

With reasonable geometry and not too much friction 2 hard shocks per wheel are in each and every case enough for such a car... if not then there is a design fault 

I fully second this...

I made some very simple test using the 5 different shocks I own and a digital wight scale...

Long shock absorbers (9.5L) have a stiffness, at almost full compression, of of 550g (Soft), 1000g (Hard) and 1200g (Extra Hard - Unimog type)

Short shock absorbers (6.5L) have a stiffness of 500g (Soft) and 1100g (Hard - the same used in the Chiron).

So, by using 2 of them on same wheel means thay can stand easily up to 2000g for each wheel, without being fully compressed...

Considering to have them halfway compressed (that’s the correct setup for a car), the weight on the front axle should have to be 2000-2200g maximum...

[Didumos69]

38 minutes ago, Musikfreak said:

@Didumos69: If I'm also allowed to answer:

It's to prevent gears breaking due to the friction of the engine. It's actually located directly before the engine.

The gearbox is always running in the selected gear, but it's output is only connected to the W16 when drive is selected. If Reverse is selected the whole box is circumevented and a constant ratio is going to the engine.

The thing I found so far (currently I have a "rolling chassis" shortly after the marriage) in my build:

The gear change works nicely most of the time. When the engine is disconnected the gearbox has very little resistance. When the engine is connected however, the resistance can get so high, that the slip gear actually engages and the engine does not move. There is also a huge backlash in a few gears. You would have to push the car almost a meter after a gear change to get the engine to move.

The sequence actually looks ok to me. I have not measured it precisely, but I see a constant change in speed until you reach the big jump from first to last gear.

 

I'm currently trying to optimise the performance. The engine itself is running smoothly but I guess the sheer amount of gears and clutches (the power has to go through both clutches at any time) is causing this behaviour. I have to say that I'm very diligent when building my models and check every bit while building for minimum friction and so on (e.g. my porsche was running completely smooth after build) but still have problems here. The marriage process, while cool considering how the real car is made, is not helping this. Because the way it's build it's hard to actually check all the functions beforehand and then once it's all together it's already hard to reach the parts in the center. However even with these limitations I'm quite impressed with gearbox and it's density.

Thanks! Also a very valuable report to me.

In the end I think having an 8-speed gearbox with always 2 clutches engaged, a DNR and a W16 with 3 crankshafts, is simply too much to ask for a smooth running drive train. In isolation, the engine, gearbox and DNR are impressive and my run smooth, but all together the drivetrain is never going to be really playable. I don't think I will be buying this set.

Edited June 2, 2018 by Didumos69

[Kumbbl]

@DugaldIC, @Musikfreak: best infos so far - thanks a lot - now I am sure and will buy the beast... and have a slight thrill of anticipation to apply some MODs ... ;)

 

[Ngoc Nguyen]

Who will lead the way and earn the title Chiron Consummationist this time 

[Appie]

29 minutes ago, Didumos69 said:

Thanks! Also a very valuable report to me.

In the end I think having an 8-speed gearbox with always 2 clutches engaged, a DNR and a W16 with 3 crankshafts, is simply too much to ask for a smooth running drive train. In isolation, the engine, gearbox and DNR are impressive and my run smooth, but all together the drivetrain is never going to be really playable. I don't think I will be buying this set.

As the DB11 from Jeroen Ottens also has 2 clutches always engaged and a DNR stick, the only difference is a V12 and this W16. The DB11 runs smooth, so mainly fixing the friction issue in the W16 (from 3 to 1 crankshaft?) and perhaps a few gearbox tweaks (is this free from idler gears on axles turning the other way?) might be enough to make it smooth?

[Kumbbl]

29 minutes ago, Appie said:

so mainly fixing the friction issue in the W16 (from 3 to 1 crankshaft?

I could imagine that a W16 with only one crankshaft build with current available parts would even run less smooth than the 3-crank-monster.... but of course this is just an assumption... the only way to find out would be a comparison build with real bricks.... 

[Didumos69]

1 hour ago, Appie said:

is this free from idler gears on axles turning the other way?

No, it has a similar row of clutch gears on axles turning at different speed .

Edited June 2, 2018 by Didumos69

[DugaldIC]

@Kumbbl enjoy the build once you pick it up. It's definitely worth it, even if it's just for the pieces.

@Didumos69 I'm guessing the white slip gear is just a built in fail-safe just in case there's built up tension in the gearbox or something jams in the gearing. Although unlike the Porsche this shifting mechanism is flawless, it shifts fast reliably everytime.

@technic_addict the front suspension doesn't have very good geometry at all, if it was set up properly it would work much better. Unfortunately the way they've set it up doesn't really leave any room for adjustments and or tweaking. 

[nerdsforprez]

5 hours ago, ShowsOn said:

If the W16 engine was made on a smaller scale, e.g. like the Mack Anthem engine, could it have more realistic details, only a single crank shaft, and save space that could be used to add other functions?

This has been done.  Problem is, it is too small for this scale.  

@Didumos69's version is closer to scale....

Edited June 2, 2018 by nerdsforprez
Correct link

[Didumos69]

Here is the complete drivetrain, including the selector axles. I might have some colors or axle lengths wrong (please let me know). Next step will be to figure out how drive flows in each subesquent gear.

Edited June 2, 2018 by Didumos69

[Aventador2004]

10 minutes ago, Didumos69 said:

Here is the complete drivetrain, including the selector axles

I assume you got this set?

[Didumos69]

3 minutes ago, Aventador2004 said:

I assume you got this set?

No, I don't .

[Johnny1360]

Wonder how it would be if you simply swapped those two gears, the clutch gear and 8 tooth going to the engine. The engine would turn slower thus reducing friction, am I thinking right? 

[Rudivdk]

57 minutes ago, Didumos69 said:

Here is the complete drivetrain, including the selector axles. I might have some colors or axle lengths wrong (please let me know). Next step will be to figure out how drive flows in each subesquent gear.

I can't see it because of the density, but do you have the axle with the 24t gear that is meshing with the blue 20t on the D-N-R selector connected to the main driveshaft somewhere? Otherwise nothing will be driven when the blue 20t is engaged...

 

Edit: oh wait... the red 16t on the D-N-R must be reverse (since it connects directly to engine, it is a single speed), so then the 24t-20t mesh is the gearbox output for 8x forward

Edited June 2, 2018 by Rudivdk

[Didumos69]

40 minutes ago, Rudivdk said:

I can't see it because of the density, but do you have the axle with the 24t gear that is meshing with the blue 20t on the D-N-R selector connected to the main driveshaft somewhere? Otherwise nothing will be driven when the blue 20t is engaged...

 

Edit: oh wait... the red 16t on the D-N-R must be reverse (since it connects directly to engine, it is a single speed), so then the 24t-20t mesh is the gearbox output for 8x forward

The 20t blue gear of the DNR flows to the gearbox and in the back of the gearbox it flows back (with a 24t-8t mesh visible in first image) to the main driveshaft, which connects the front and rear diffs. Reverse flows directly to this main driveshaft via the 16t gear.

Edited June 2, 2018 by Didumos69

[Didumos69]

1 hour ago, Johnny1360 said:

Wonder how it would be if you simply swapped those two gears, the clutch gear and 8 tooth going to the engine. The engine would turn slower thus reducing friction, am I thinking right? 

I would first try swapping the 20/12 mesh right in front of the engine. I reckon it would fit without other adjustments.

But first I would want to know what the exact cause of the friction is.

I didn't analyze the gearbox yet, but in the engine I think it's not optimal to have the center crankshaft drive the other two crankshafts via the back side of the engine. It would be more elegant to have the 3 24t gears at the other ends of the crankshafts, so all crankshafts are in fact dead ends of the drivetrain.

Edited June 2, 2018 by Didumos69

[Permo]

Especially with these kind of complex setups, the amount of friction very much depends on "the hands of the builder" would be my guess.

Build with care things should run smoothly if the design is correct, if not, there's always silicone spray.

I think with the introduction yesterday many builds were done in a rush, wich would explain friction in the drivetrain.

Edited June 2, 2018 by Permo

[Rudivdk]

1 hour ago, Didumos69 said:

 in the engine I think it's not optimal to have the center crankshaft drive the other two crankshafts via the back side of the engine. It would be more elegant to have the 3 24t gears at the other ends of the crankshafts, so all crankshafts are in fact dead ends of the drivetrain.

Noticed that as well, crankshafts are wobly as h*ll so transferring power through them seems at least suboptimal... But seeing the density of the entire build, I think it would require loads of changes to accomodate 3x 24t on the other side of the engine. Especially since 24t are slightly wider than 3studs, you would need 5studs room or bushes in correct allignment to make that fit. 

[Didumos69]

25 minutes ago, Permo said:

Especially with these kind of complex setups, the amount of friction very much depends on "the hands of the builder" would be my guess.

Build with care things should run smoothly if the design is correct, if not, there's always silicone spray.

Yes, but like @Musikfreak said, the marriage step, where the two halfs of the chassis are combined, might easily ruin your carefully assembled build. Personally I would never lubricate things in a manual model.

25 minutes ago, Permo said:

I think with the introduction yesterday many builds were done in a rush, wich would explain friction in the drivetrain.

I think so too. Many reviews have been rushed too. It's a good thing @Jim has some more time.

Btw, I'm simply in the process of trying to understand everything and seeing whether there are some obvious improvements. This doesn't mean I assume there is too much friction in this model. @DugaldIC for instance, seemed to be quite content with it.

Edited June 2, 2018 by Didumos69

[Aventador2004]

2 hours ago, Didumos69 said:

No, I don't .

How did you LDD it then? Online manual?

[Didumos69]

4 minutes ago, Aventador2004 said:

How did you LDD it then? Online manual?

From available images. I started with @ibessonov's attempt to model the gearbox from a few days ago and checked it with the available photos (his attempt was actually very accurate ). Also @Meatman gave some pointers that I could verify with photos. And after the shortly leaked product reveal video I could reproduce the DNR shifter.

 

[Aventador2004]

Just now, Didumos69 said:

From available images. I started with @ibessonov's attempt to model the gearbox from a few days ago and checked it with the available photos (his attempt was actually very accurate ). Also @Meatman gave some pointers that I could verify with photos. And after the shortly leaked product reveal video I could reproduce the DNR shifter.

 

OK.

[Pvdb]

2 hours ago, Didumos69 said:

From available images. I started with @ibessonov's attempt to model the gearbox from a few days ago and checked it with the available photos (his attempt was actually very accurate ). Also @Meatman gave some pointers that I could verify with photos. And after the shortly leaked product reveal video I could reproduce the DNR shifter.

 

You are on a mission Didumos69.  I am impressed.  The drive train in totality looks pretty immense!!    I see that you have also worked out all of the ratio's,  The step ratio between each gear is pretty even wheras I would have expected a larger step between 1st and 2nd, and smaller difference in ratios as we go through the gears, but this is hard to do in a Lego 8 speed gearbox. 

Edited June 2, 2018 by Pvdb

[Didumos69]

35 minutes ago, Pvdb said:

You are on a mission Didumos69.  I am impressed.  The drive train in totality looks pretty immense!!    I see that you have also worked out all of the ratio's,  The step ratio between each gear is pretty even wheras I would have expected a larger step between 1st and 2nd, and smaller difference in ratios as we go through the gears, but this is hard to do in a Lego 8 speed gearbox. 

Maybe on a mission, but I'm still not buying .

I actually wanted to post the ratios here. Funny thing is that the second gearbox in the Bugatti has ratios that are practically equal - when normalized - to my first ever gearbox attempt with the new parts. Ratios of that gearbox are: 4:5, 1:1, 4:3, 5:3.

• Green is input
• Yellow is control
• Red is output

 

In the figures below minus means the rotation direction flips, this was to check if reverse is actually reverse. The first gearbox in the chain has 4 positions, but toggles between 2 speeds. The second gearbox has 4 positions and 4 speeds.

 

Engine to DNR

(Always) -3:5 x -1:3 = 1:5

 

DNR gearbox

(1st-8th) -5:6 = -5:6

(Reverse) -1:1 = -1:1

 

D - 1st gearbox (R)

(1st-4th) -1:1 = -1:1

(5th-8th) -5:3 x -5:3 x -1:1 = -25:9

 

D - 1st to 2nd gearbox

(1st-8th) -1:1 x -1:1 x -1:1 x -1:1 = 1:1

 

D - 2nd gearbox (L)

(1st,5th) -3:5 = -3:5

(2nd,6th) -1:1 x -1:1 x -4:5 x -1:1 x -1:1 = -4:5

(3rd,7th) -1:1 = -1:1

(4th,8th) -1:1 x -1:1 x -5:4 x -1:1 x -1:1 = -5:4

 

D - 2nd gearbox to main

(1st-8th) -3:1 = -3:1

 

Main to diffs

(Always) 5:7 = 5:7

 

Combined

(Rev) 1:5 x -1:1 x 5:7 = -1:7 = -0.143

(1st) 1:5 x -5:6 x -1:1 x -3:5 x 1:1 x -3:1 x 5:7 = 9:42 = 0.214

(2nd) 1:5 x -5:6 x -1:1 x -4:5 x 1:1 x -3:1 x 5:7 = 2:7 = 0.286

(3rd) 1:5 x -5:6 x -1:1 x -1:1 x 1:1 x -3:1 x 5:7 = 5:14 = 0.357

(4th) 1:5 x -5:6 x -1:1 x -5:4 x 1:1 x -3:1 x 5:7 = 25:56 = 0.446

(5th) 1:5 x -5:6 x -25:9 x -3:5 x 1:1 x -3:1 x 5:7 = 25:42 = 0.595

(6th) 1:5 x -5:6 x -25:9 x -4:5 x 1:1 x -3:1 x 5:7 = 50:63 = 0.794

(7th) 1:5 x -5:6 x -25:9 x -1:1 x 1:1 x -3:1 x 5:7 = 125:126 = 0.992

(8th) 1:5 x -5:6 x -25:9 x -5:4 x 1:1 x -3:1 x 5:7 = 625:504 = 1.240