Chiron gearbox problems

[BaaaaL]

Hi!

After having assembled the complete model once, I was not satisfied with the shifting mechanism (it kept cracking and getting stuck in certain gears), so I disassembled it and now trying to rebuild. Only today, I have rebuilt the entire gearbox from scratch 5 times, but I get the same problem every time: In certain gears, there is insane friction, and the gears are not turning properly, only skipping and cracking. I can still turn the wheels of course, but I have a feeling that this is not how a 400$ model should work if built properly.

https://imgur.com/a/2WIeaxO

Upon further experimentation, I came to the conclusion that the noises and friction originate from the part with the two tan and two small black gears extremely close together (lower right corner) as they seem to be literally rubbing against each other. Also, when I remove the axel engaging these gears, the entire mechanism is very fluid. Can someone please tell me what I'm doing wrong? I have tried to leave some space between the gears in question, but as soon as I build the housing for the gearbox and insert it into the chassis, everything snaps into place under the pressure.

Any help appreciated, this is driving me crazy

[aeh5040]

The 20t double bevel gears (the tan ones here) are not good, unfortunately.  They are really too wide, and in addition there seem to be further problems with the more recent molds.  It's certainly not a good design to have two of them touching like this. I suggest swapping them over, trying different orientations, and seeing if you can give them a bit more space by playing with the surrounding support structures.  And yes, it's sad that this is necessary.

Edited June 22, 2020 by aeh5040

[BaaaaL]

1 minute ago, aeh5040 said:

The 20t double bevel gears (the tan ones here) are not good, unfortunately.  They are really too wide, and in addition there seem to be further problems with the more recent molds.  It's certainly not a good design to have two of them touching like this. I suggest swapping them over, trying different orientations, and seeing if you can give them a bit more space by playing with the surrounding support structures.  And yes, it's sad that this is necessary.

Thanks, that was my thought as well. The biggest issue seems to be the part where the tan ones and the black ones mesh together. I will try and see what I can do......hopefully I can find a combination which actually works.

[aeh5040]

Just now, BaaaaL said:

Thanks, that was my thought as well. The biggest issue seems to be the part where the tan ones and the black ones mesh together. I will try and see what I can do......hopefully I can find a combination which actually works.

Yeah, it's very disappointing.  Even rotating the gears on their axles by 90 degrees can sometimes help IME.

[Didumos69]

@BaaaaL, read this. And then move on to https://rebrickable.com/mocs/MOC-16181/jb70/42083-pimp-up-my-bugatti/. The stock Bugatti gearbox was a total flaw and has been improved by MOC-ers dramastically.

Courtesy of @jb70.

Edited June 22, 2020 by Didumos69

[BaaaaL]

50 minutes ago, Didumos69 said:

@BaaaaL, read this. And then move on to https://rebrickable.com/mocs/MOC-16181/jb70/42083-pimp-up-my-bugatti/.

Thanks man, I actually wanted to contact you after reading about your gearbox midifcations on the same forum. The problem is, I don't really want to do the "pimped up" version, as I would need loads of extra pieces which are a pain to get hold of here. Is there perhaps a way to build a modified gearbox with the stock components, and attach it to the chassis in such a way that it does not require other modifications to the assembly down the line?
 

Edited June 22, 2020 by BaaaaL

[Maaboo the Witch]

8 minutes ago, Didumos69 said:

dramastically.

Both dramatically and drastically. You know they're serious...

[Didumos69]

15 minutes ago, BaaaaL said:

Thanks man, I actually wanted to contact you after reading about your gearbox midifcations on the same forum. The problem is, I don't really want to do the "pimped up" version, as I would need loads of extra pieces which are a pain to get hold of here. Is there perhaps a way to build a modified gearbox with the stock components, and attach it to the chassis in such a way that it does not require other modifications to the assembly down the line?

Thanks a lot!

I don't think such a thing has been documented. You could make it an exercise trying to get the basics of the pimped Bugatti gearbox, without the center differential, using the stock parts.

EDIT: Or use the images in this post as a source of inspiration:

9 minutes ago, Maaboo35 said:

Both dramatically and drastically. You know they're serious...

I wanted to add a touch of drama to the whole flawed gearbox thing.

Edited June 22, 2020 by Didumos69

[doug72]

I read somewhere about lightly sanding both sides of new 20T double bevel gears as they see slightly thicker than original ones.

[BaaaaL]

30 minutes ago, Didumos69 said:

I don't think such a thing has been documented. You could make it an exercise trying to get the basics of the pimped Bugatti gearbox, without the center differential, using the stock parts.

EDIT: Or use the images in this post as a source of inspiration:

I wanted to add a touch of drama to the whole flawed gearbox thing.

Thanks!

If I may, I have one more question concerning the gearbox: On the rebrickable forum, you told someone to align the towball to the upper left, otherwise the sequence of gears will be incorrect. However, the manual clearly shows the ball aligned to the lower left multiple times, and even makes a point by magnifying it before the marriage step. How should I align it?

[Didumos69]

1 hour ago, Doug72 said:

I read somewhere about lightly sanding both sides of new 20T double bevel gears as they see slightly thicker than original ones.

This is about the Bugatti.

1 hour ago, BaaaaL said:

If I may, I have one more question concerning the gearbox: On the rebrickable forum, you told someone to align the towball to the upper left, otherwise the sequence of gears will be incorrect. However, the manual clearly shows the ball aligned to the lower left multiple times, and even makes a point by magnifying it before the marriage step. How should I align it?

I need more context. Where did I post this exactly?

EDIT: It was here. I guess what they did wrong is putting it in second gear before adding the tow ball assembly. You should stick to the instructions, just make sure it remains in 1st gear until you add the tow ball.

 

Edited June 22, 2020 by Didumos69

[BaaaaL]

4 hours ago, Didumos69 said:

This is about the Bugatti.

I need more context. Where did I post this exactly?

EDIT: It was here. I guess what they did wrong is putting it in second gear before adding the tow ball assembly. You should stick to the instructions, just make sure it remains in 1st gear until you add the tow ball.

 

Thanks, that's a huge help, at least I know I can marry the two parts safely. I will probably rebuild using the modified version at some point in the future, provided I can find a local store that stocks all needed components....

[Didumos69]

10 hours ago, BaaaaL said:

provided I can find a local store that stocks all needed components...

Bricklink.

[BaaaaL]

8 hours ago, Didumos69 said:

Bricklink.

Thanks, I finally managed to figure out how it works with the Rebrickable lists, and I have ordered everything, although it cost a huge load of money for the amount :( The third assembly is going to be the pimped version :)

[NathanR]

Sorry to hijack this thread, but I've run into the same problem. I'm on Step 86 of the Chiron, and already the tan and black bevel gears (20t and 12t) are clicking loudly as they move, It takes quite a bit of effort to force them to turn. The gears look ok, and have enough space between them that they should be moving freely. 

On 6/22/2020 at 4:00 PM, Doug72 said:

I read somewhere about lightly sanding both sides of new 20T double bevel gears as they see slightly thicker than original ones.

Do you mean to sand down the circular sides of the gears, or the rectangular blocks on each tooth? It seems to me that the problem is that the rectangular blocks on the teeth of tan and black bevel gears are catching on each other as they turn, with the blocks making the teeth almost snap into position.

 

I'd like to build the standard Chiron (it's only my first build through), any suggestions for a simple fix? I read that the older 20t gears work better, but bricklink doesn't distinguish them - any tips for tracking down the right version of the gears? 

Our could I get away with swapping the 20t and 12t pairs for 24t and 8t? Would that be buildable? Would it dramatically change the apparent gear speeds in the assembled car?

[myvideo000]

you can order light blueish grey gears instead of the current ones in tan and black. 

[NathanR]

On 7/4/2020 at 6:26 AM, myvideo000 said:

you can order light blueish grey gears instead of the current ones in tan and black. 

Thanks! Actually, I managed to find a seller on brickowl who differentiated between the old-style unreinforced and new-style reinforced axle hole variants. The old style gears run amazingly smoothly! I've finished the main gear box and I'm now understanding why so many builders have complained about the amount of friction in the whole drive train, it makes me really glad I got the old gears.