Exhausts and Engine » Correct orientation of GSAP unit

Got a bit of a cheeky request. Would someone who has a workshop manual or similar be willing to look up some information and share it with me on the re-attaching the Gear Shift Assist Pro unit on the splined Gearbox selection shaft (2015/16 R1200RS).

I’d like to know:
1. if there is a specific orientation for when re-mounting the GSAP unit on the gearbox selection shaft,
2. what torque is required for the ‘small’ bolt that holds the assembly to the shaft and
3. finally is there a ‘dealer’ only plug-in and reset the system that has to happen after the GSAP is disconnected and refitted

There are four pieces in the GSAP unit assembly
The main GSAP unit which (has an electrical connection on it, yes it is connected correctly) and three ‘mounting’ parts, a hex-head screw, a washer and a ‘snow flake’ shaped cap, the latter is splined inside to fit on the gearbox selection shaft and ‘fluted’ externally to fit inside the GSAP unit
GSAP_Pats.JPG - Bild entfernt (keine Rechte)

The piece that interests me the most is the snow flake cap at first glance it looks symmetrical with six ‘legs’ that spiral out, but, looking carefully at the inside. Each leg has three slots to accept the splines of the section shaft, all that is bar one, which has the central spline slot 'missing' i.e. not machine/cast (blue leg).
SnowFlakeInside.JPG - Bild entfernt (keine Rechte)

The selection shaft has a horizontal line on it, and at these two point on the shaft it appears one spline is missing from each side, you can’t see it in photo and I can’t capture as it is behind the frame rail, the parts fiche appears to show a missing spline too, but I just might be imagining it.
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SelectionShaftFiche.JPG - Bild entfernt (keine Rechte)

If the selection shaft has two missing splines, this tells me the Snow Flake cap has 2 possible orientations on the selection shaft. When I took it off I don't think it was aligned with either, you can 'force' the snow flake onto the shaft if you are not subtle.

Now looking at the outside of the Snow Flake. Again at first glance symmetrical, but two of the legs (red arrow) have deeper circular indentations and different leading and trailing edges to each other, and to the other four legs (I have also blue arrowed the missing slot leg). I cannot see any markings on the GSAP unit, but trying to offer up the snow flake to the GSAP unit it feels like there is only ‘one’ way it slots in, but this really is a subtle ‘feeling’, again you can mount it in it, one of six ways if you 'force' it.
SnowFlakeOutside.JPG - Bild entfernt (keine Rechte)

All this combined means, I think, there is only one way the GSAP unit, Snow Flake and selection shaft should go together. I wasn't aware of any of this alignment stuff when took it apart, but it was not easy getting it off, not as easy as it is now to 'trial assembly' and disassemble again. I haven’t put it back together and tried it on the bike for real since discovering the alignment stuff - and yes, why would this cause a previously working GSAP to stop if it hasn't been apart - but I’d like confirmation if possible of how it goes together.

Cheers

JayQ

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Torque for securing fastener: 10 Nm

Huh.

Here's what the gear assist unit looks like before re-installation. Looks like your snowflake - also known as the sleeve - fits inside the recess with orientation as noted before re-installation. I did not see that the shaft required specific orientation to the unit, but a good manual always leaves a few things out.....
Picture1.jpg - Bild entfernt (keine Rechte)

Cheers guys, that is very helpful. In that orientation the missing spline slot lines up with the missing spline on the forward facing side of the selection shaft. I will get it back together and see if it makes any difference,

Thanks again
Jay.

Good news, my GSAP is working again, however what’s not clear is what actually fixed it.

I put it back together ensuring the correct alignment as discussed above. Went for a ride, GSAP not working, same as before, changing gear on the clutch no problem, but try for a clutchless shift up or down and the gear lever would feel like it was locked solid (after taking up the slack in the lever).

Took the GSAP unit off the selector shaft again, double checked everything, put it back together, still binding up. Took it off again.

Looked at the on-line prices of a GSAP unit, on the US microfiche site, $702, decided I had nothing to lose and took the GSAP apart (mostly). Unfortunately I have no photos, the SD card has toasted itself. So I’ll try to describe as best I can.

There is an electrical connector held on with two screws, I removed these, to discover that there was no wiring from the connector to the inside of the GSAP body, the connector is in fact a sensor. In addition to the two screws it was held on along one edge with a what turned out to be a sealant, so I eased the sensor off the GSAP body.

I then undid four screws that hold on a cover, the cover is also held on with what initially looks like a gasket, but is sealant. I eased the cover off. What is inside is fascinating for its complexity to achieve something quite simple. Inside is mechanical, nothing electronic.

Basically there is a magnet mounted on a sleeve which surrounds where the gearbox selection shaft goes into the GSAP, that sleeve can rotate through a few degrees (in both directions) independent of the selection shaft. The rest of the inside is a very strong coil spring around what looks like a tiny shock absorber, about an inch and a quarter long, and this stops the sleeve (that the magnet is on) rotating until quite a large force is applied, I couldn’t induce movement by hand, it needed a good length lever to get any movement in the spring.

I’m guessing that as you move the gear lever, both the GSAP and gear selection shaft start to rotate, during this initial phase the ‘mini-shock absorber’ and spring keeps the magnet in a fixed position (relative to the selection shaft), but when the selection shaft starts to experiences the resistance of the gear selection mechanism (inside the gearbox), that resistance is greater than the force the spring and mini-shock are exserting on the magnet and its sleeve, so the spring and shock ‘give’ and the magnet then rotates relative to the selection shaft, but that movement isn’t much before the shock mechanically binds and the force on the gear lever and GSAP continue to rotate the selection shaft again. The relative movement of the magnet will induce a current in the exterior sensor at which point the brain inside the bike does its gearless shift work (if the clutch hasn’t been activate).

Since the inside was purely mechanical I gave it a bit of a wipe out with a cloth and a light spray of ACF50 (anti-corrosion fluid) but nothing much else. I then put the cover back on using some silicon sealant. Just before I put the sensor on I gave it a rub with the cloth, only to find the surface that sits on the GSAP body had a compacted layer of road grit and grim ‘baked’ on. I cleaned this off with some WD40. When I mounted the sensor and did up the mounting screws, I could see that it stood proud of the GSAP by a small fraction, less than a 1mm, which why the crud gets in there.

Anyhow put it back on the bike and rode, and GSAP was working really sweetly again. The other things I cleaned, regreased and adjusted on the last assembly, were the ball joints on the ‘selector rod’ between the gear lever and the GSAP unit. Both the ball joints felt very stiff but loosened up after cleaning and regreasing.

So I can’t say with any confidence what the problem was, but the things I changed were:
the thin layer of crud, between the sensor and the magnet,
clean the inside of the GSAP and a light coat of ACF50
cleaned and lubricated the ball joints
double checking the GSAP / selection shaft alignment (but I do doubt it was ever wrong).

Jay