The detachable faceplate on my 3T Motus stem cracked. I did not tighten it unduly; it is clearly a bad design. The photographic evidence:




I came across vredstein's post about his 3T Motus cracking whilst doing a search of the forum. To wit:

I received a replacement faceplate from 3T just today. I really like how the stem looks. Questions for vredstein: are you still riding yours? How's it doing?

The front insert between the faceplate and the body is a solid piece of metal, while the back insert is rubber. I wonder if I overtightened (according to 3T specs) the front bolt on the hard insert, causing it to crack, where I should have tightened the back bolt on the soft insert?

I also wonder: having received the replacement, do you think putting the rubber insert in the front and discarding the hard insert would be a good idea?

It happened to me, too.

What did you have to do to get the new faceplate?

Wow, the stories just keep coming out of the woodwork. Search this forum for "3T Motus" and you'll come up with more threads, one of them mine. I first contacted 3T, who sent me to the old 3T distributor at www.gruppospa.com. I sent my story about the stem and photos to the first contact person at this page: https://www.columbustubi.com/EN/contatta.html.

I honestly wonder at this point if 3T shouldn't put out a recall. I mean, somebody could get seriously hurt.

time to use another stem, no?

I agree. I wouldn't trust that stem.

I got a replacement stem from the original EXCELLENT Ebay seller
https://stores.shop.ebay.com/The-New-...__W0QQ_armrsZ1.
I used this stem on a Cinelli Eubios handlebar. This handlebar is 26.0mm in diameter. The Motus stem is supposed to work with both 26.0 and 25.4. The stem's clamp radius seem to fit a 26.0 perfectly, but just like yours, the spacers don't completely fill in the space.
When I clamp this onto my handlebars, both the front triangular metal spacer and the rear rubber spacer have plenty of wiggle room. Like you, I debated on whether to clamp it so the front spacer was tight, leaving the rear rubber spacer with wiggle room, or clamp it so the rear was tight, and the front has wiggle room. I even tried making an additional spaceer cut from an old inner tube. But since it's still rubber, once you tighten the bolt, any faulty stress is still going to manifest itself.
I finally decided to clamp it even, making sure there was an equal amount of space front and rear. The spacers might as well not even be there. Hopefully, this equal clamping pressure will be the safest. Since my original post, I've been keeping any eye on it and there are no signs of cracks.
I'd be interested so see how this fits on a 25.4 bar.
I was trying to get ahold of a Salsa SUL quill stem with the removable faceplate, but that too is a problem unit and I believe it has been recalled. Weird because the SUL stand for Stiff Upper Lip. Instead of a flat mating surface or spacers, it has a lip which was specifically designed to strengthen it.
In the end, I think the smartest thing to do is just bite the bullet and get a Nitto stem and live without a detachable faceplate.

I have a Nitto Noodle 26.0 bar on mine. Actually, I'm currently using a nice silver ITM quill stem with "Bianchi" pantographed on it, which better suits my Bianchi both in terms of said pantographing and the fact that it's silver. But the Motus is a cool-looking mofo of a stem, though. I kinda wouldn't mind putting it on again. Shrug.

Now that I think about it, I'm quite sure mine cracked for two reasons: 1) the bad design, of course; and 2) a 10 km-section of really rough chipseal-like road that had been redone without my knowing it (and without my knowing where it would end). That damn section of road was harsh enough to loosen my headset, and I do recall hearing some creaking in the bar after that. Lesson learned: stay away from chipseal!