@byee
Barry, thank you VERY much for the info, and your time and effort.
First off, regarding the thickness of new (715 miles) brake pads, er, um, I have an APPROXIMATE figure for you. That is, I don't feel comfortable removing them --
unless it's extremely easy, someone (or, say, the shop manual) can guide me through it, and I can't possibly screw up taking them out and putting them back in -- so I only have a rough number for you.
So I tried to align my caliper with the pads
in situ (and there's some parallax error in the pic, but not really, when I was doing this live a few minutes ago):
And then, turning my caliper around, without moving the measurement:
So I make the thickness of a new pad at
roughly 0.306" (7.77mm), or possibly, looking at the pic, maybe a tad more.
Let's move on to your question: "Would you happen to know if there are different length valve stems available which mount onto our C400GT wheels to increase the clearance?"
Funny you should ask about that. Just like the freakin oddball location that BMW employs for the valve stems, they, too, are oddballs, not your garden-variety stems.
I wanted to examine one up close and personal, without removing one from the bike, which would have let the air out, possibly breaking the tire bead, and possibly ruining some thread-locker. So in August 2022, less than a month after I took delivery of my first C 400 GT, I ordered one from Max (email screen grab):
And then I looked at it closely, and took a gob of measurements. For example, here's on pic from Aug. 2022:
So you can see that this is not an ordinary valve stem. The green-coated threads screw into the corresponding tapped area of the "spoke" (or whatever you want to call it), and there's no nut on the inside, etc. So you can't "get behind" that stem, so to speak. (And I'm pretty familiar with ordinary valve stems, because over 25 years I've had shops replace stems, when changing tires for me, with assorted angled or T-valve stems that I've provided.)
So, no, this is one-off territory, no non-Beemer variations would work, IMO.
(On one visit to Max for something, I actually asked the workshop manager if they would be willing to drill through the center of the front wheel rim, so I could add a regular valve stem, for TPMS purposes. He told me: nope (and I can understand their position). I have thought about asking an indie shop to do this, but even that idea is sort of a problem, because the center of the rim is angled, not flat, and I'm not sure that a good seal would be possible. Nevertheless, I bought a pair of new high quality straight valve stems, of the 8.3mm variety, in case I ever go this route. (Most bikes use an 11.3mm rim hole, but a good portion use the smaller size; I decided that if I'm going to have a hole drilled -- in the center of the rim, the way every other manufacturer does it -- I might as well keep it as small as possible.)
Back to the stock valve. I also peered inside, and took some more measurements. I was wondering whether I could dremel off some threads, in order to lessen the external height of the valve stem. The problem there is that the standard valve
core already takes up all the room in there, i.e., is essentially seated at the bottom of the area. So cutting a few threads off the external threads would also entail cutting through the valve core. And I'm not aware of any extra-short valve cores, although I haven't really looked.
It was about that point that I gave up, mounted the FOBO sensor on the rear wheel's valve stem, and put the other sensor on the shelf.
@mzflorida renewed my interest in this whole TPMS thing a week or two ago, when he showed me a TFT screenshot of TPMS readings, by someone who has apparently unlocked (hacked?) this capability. I have no idea how the sensors are mounted; they're apparently internal sensors, but they must have nothing at all to do with the stock valve stems, because, as I mentioned, there's no threads
behind those stock stems -- they just screw into the spoke. So they must be mounted in some fashion inside the rims. And the whole thing requires that this gentleman remotely update the bike's software. If this is legit, the whole thing is just too weird for me.
Now, to get really far afield, another -- expensive! -- possibility is to get new wheels. I think the front wheel on the Voge SR4 Max 350 -- like the C 400 GT, manufactured by Loncin -- is designed for the same size discs (265mm, per
https://www.1000ps.de/motorradvergleich-voge-sr4-max-350-abs-2023-vs-bmw-c-400-gt-2021-150107, vs. 10.4", per
https://www.bmwmotorcycles.com/en/m...gt/technicaldata.html#/section-technical-data ).
If you're unfamiliar with that scoot and have 12 minutes:
Most importantly for this discussion:
the Voge has normally placed valve stems (see the pic at
https://chinamotorworld.com/voge-sr4-max-proved-to-be-a-reliable-touring-scooter/ ). They're angled, but they could easily be replaced by my
all-time favorites, the T-valves from FOBO --
https://my-fobo.com/accessories -- which I used on my second Big Burgman (an '08 model, owned from '16 - '22):
But, yeah, I think I'm losing my tenuous grip on reality here. Probably just drilling into the center of the front rim would work best.
That's all I got.
www.chigee.com
