Shift Cam Technology

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Since I got back from the NEC I've been giving this BMW shift cam technology a bit of thought and for those who may be interested I've added a link showing the workings of it. The only stuff I can find is on the BMW R1250GS. I know it's not quite the same, but it shows the basic principle and similarly, how it shifts!
You may want to turn down the accompanying music though

https://www.youtube.com/watch?v=rT2S8zYGZ24

On the S1000RR the principle is the same, though the whole camshaft doesn't slide across as on the GS. The system differs in that the actual shaft stays in place, though turning of course. How it differs is that the cam lobes slide along the turning shaft, located on multiple splines that keeps the cam lobes correctly timed to the shaft. Stay with me please:untroubled:
The inlet cam lobes are set in pairs, that is 2 lobes for cylinders 1 and 2, and 2 lobes for cylinders 3 and 4. Mounted on top of the cylinder head are 2 electric? electronic? motors. Stepper motors, I suppose you'd call 'em. They are positioned over shift gate. when the ECU speaks to these stepper motors, the pins in these stepper motors pop into the grooves in the shift gate which slides the 2 pairs of cam lobes along the shaft to alter the valve lift and duration of lift.
Hopefully I've added a picture of the top of the new S1000RR cylinder head showing, I hope the shaft, pairs of lobes, shift gate and their stepper motors.
690c708f0e8e5ede34aaf874e9baf51f.jpg
 
So cylinders 1&2 are independent of 3&4? Which would make sense if as someone else spotted they also have split throttle control (1&2 + 3&4).

Is the system electronically activated as if it is it can't make it into a race engine...I'd have expected a passive system, but equally I can see it's of little bother to a race engine which is usually always screaming...
 
Yes Alex, cylinders 1 and 2 are indeed independent of the other two. I thought just the same as you about using the system in racing!
Just to throw another spanner in the works, when I looked at the sectioned engine at the show I'm sure the exhaust camshaft had high and low profiles side by side too, though the cam cover wasn't cut back enough to see if shift cam technology was used on this shaft.
I wish I could go back for another look🤔
 
So, to recap! The actual cams seem to be ground as one piece, hollow and internally splined to fit the shaft. First one pair of cams, high and low lift are positioned side by side.Then the bearing journal, longer than you would expect on a "normal" camshaft. This allows the whole cam assembly to move to the left or right, as required. Then we have the other pair of cams, high and low......or low and high? Then machined onto the end of this is the shift gate. This has helical grooves machined into it, one going to the left, one going to the right. So all that's needed to move the camshaft assembly, while it's turning, is for a pin to engage in one of the grooves for it to move the cams left or right.
That's how I see it working anyway. The only thing that puzzles me, is how the finger follower climbs? from one profile to the next without without subjecting the follower or cam to some form of trauma.
Any ideas guys🤔
 
Since I got back from the NEC I've been giving this BMW shift cam technology a bit of thought and for those who may be interested I've added a link showing the workings of it. The only stuff I can find is on the BMW R1250GS. I know it's not quite the same, but it shows the basic principle and similarly, how it shifts!
You may want to turn down the accompanying music though

https://www.youtube.com/watch?v=rT2S8zYGZ24

On the S1000RR the principle is the same, though the whole camshaft doesn't slide across as on the GS. The system differs in that the actual shaft stays in place, though turning of course. How it differs is that the cam lobes slide along the turning shaft, located on multiple splines that keeps the cam lobes correctly timed to the shaft. Stay with me please:untroubled:
The inlet cam lobes are set in pairs, that is 2 lobes for cylinders 1 and 2, and 2 lobes for cylinders 3 and 4. Mounted on top of the cylinder head are 2 electric? electronic? motors. Stepper motors, I suppose you'd call 'em. They are positioned over shift gate. when the ECU speaks to these stepper motors, the pins in these stepper motors pop into the grooves in the shift gate which slides the 2 pairs of cam lobes along the shaft to alter the valve lift and duration of lift.
Hopefully I've added a picture of the top of the new S1000RR cylinder head showing, I hope the shaft, pairs of lobes, shift gate and their stepper motors.
690c708f0e8e5ede34aaf874e9baf51f.jpg


Cheers for posting. I've been meaning to read up on how they were going about this. This is giving me a little understanding of it. Looks to me that there are a lot of moving parts, I hope it has been tested for a very long time, as I can't help but think it has the potential to have various different failures.

Is this similar to the system system used in BMW cars? I remember reading about the Vanos system the older cars had, that worked on vacuum ( if I remember correctly) that had no end of issues, if engine was revved hard from cold.
 
If it shifts on the flat part of the cam (closed valve) there's no wear

Probably why it's 2 and 2 cylinders
 
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Is this similar to the system system used in BMW cars? I remember reading about the Vanos system the older cars had, that worked on vacuum ( if I remember correctly) that had no end of issues, if engine was revved hard from cold.

Though I'm not conversant with this system Kenny, I would doubt it's similar in any way....
 
Cheers for posting. I've been meaning to read up on how they were going about this. This is giving me a little understanding of it. Looks to me that there are a lot of moving parts, I hope it has been tested for a very long time, as I can't help but think it has the potential to have various different failures.

Is this similar to the system system used in BMW cars? I remember reading about the Vanos system the older cars had, that worked on vacuum ( if I remember correctly) that had no end of issues, if engine was revved hard from cold.

As noted it looks to be servo/PWM motor controlled thus entirely at the mercy of the ECU. The ECU mapping will control the switch over. VANOS and VTEC etc all are load/RPM based.
 
If it shifts on the flat part of the cam (closed valve) there's no wear

Probably why it's 2 and 2 cylinders

Yes, I thought of that too......but for the cam to move across to the base circle (valves closed) at precisely the correct time seems almost impossible to me. Remember the camshaft turns at half engine speed. We don't know at what revs the shift will occur but if its say 8,000, the camshaft is spinning at 4'000 revs! And remember this......even if one pair of lobes are on the base circle, the other pair are not, so my question remains:rapture:
 
I vagually remember some talk about the Superbike or BSB rules where people were saying it needed to be mechanical like on the Suzuki system to be legal for the racing?? I guess they dont really need the < 8000rpm cams on a racebike anyhow but an interesting point.
 
I vagually remember some talk about the Superbike or BSB rules where people were saying it needed to be mechanical like on the Suzuki system to be legal for the racing?? I guess they dont really need the < 8000rpm cams on a racebike anyhow but an interesting point.

Yes any VVT system must be passive. Hence the GSXR centrifugal system is legal.
 
I know it's a less critical part but how does the exhaust system valves move fast enough for a first gear pull. Or the variable intakes move fast enough to be useful?
 
Just to clarify a point! In my photograph, the cams that are visible in the picture are for cylinders #2 and #3 only. The cams for cylinders # 1 and 4 are not visible and are, I assume fixed to the ends of the sliding cams and out of sight. Does that make sense?

690c708f0e8e5ede34aaf874e9baf51f.jpg
 
Sorry to be banging on and on about this topic but please take a look at this! it just goes to show that this technology isn't new. It also suggests that perhaps I'm wrong in my last post, surmising that cams # 1 and 4 are joined to to cams #2 and 3.
That would also answer my own question about possible damage to cams and followers when changing profiles.
So it looks like you are correct Corkgsxr.
I was confused because there are only 2 stepper motors. Perhaps these steppers each move 2 sets of cams?

https://www.youtube.com/watch?v=I5dy2Vnf95w

Really only the first part is relevant......
 
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