RCS19, clutch master cylinder switch?

[pswiatki]

I just found out the RCS clutch master cylinder (Brembo PR16x16-18) does not have the place for the switch to be mounted. As far as I can tell the switch signal is used for some safety logic to shut off the engine in a potentially dangerous situation (in gear and - say - side stand is extended, etc).
The suggestion was to use a hydraulic switch to get the signal in the onboard computer.
However, I understand it must be a different one from the brake switch because unlike the brake switch,
it shall react ofter certain pressure level is reached - not when the pressure just started rising. Is my thinking correct? Do such clutch pressure switches even exist? If yes, do you have any recommendations for such a switch for Breva 1200 (MY 2008)?

 

[V700Steve]

You could put a pressure switch in front of bleed line.

 

[pswiatki]

OK, that would probably be very convenient. But please let me know one thing: how does such a switch work - I mean: for the clutch, the computer expects the trigger when the clutch is fully depressed, right? I would welcome any pointers to the actual switches I could use here. In Todd's store, I can see this: https://gtmotocycles.com/collections/brakes/products/16-cast-clutch
and the picture suggests there is a build-in switch. Maybe it's because that particular master in not from RCS line....

By the way: is there anything limiting the movement of the clutch [ehmm.... English word... let's say:] actuator? I mean: if the master is different from the original it may be that before the lever on the handle bar ends its move the actuator would move farther than with the OEM master. I imagine it is different than in the brake system, because the movement of the pistons in brake calipers is naturally limited by the hard surface of the actual brake disc, right?

 

[pswiatki]

One more thing: the OEM clutch lever has the adjustable pushrod. Is it also the case with Brembo RCS clutch master cylinder? Can the pushrod be adjusted in RCS as well?

 

[V700Steve]

That master will work fine, all set up. Ask Todd about the adj on rod but outta work great.
You'll be wanting a matching one for the front brake.

 

[GTM®]

I can see this: https://gtmotocycles.com/collections/brakes/products/16-cast-clutch
and the picture suggests there is a build-in switch. Maybe it's because that particular master in not from RCS line

That is correct. The cast version is an OEM (Ducati) spec. I got a reply from Brembo this morning, and the RCS does not have any accommodations for one. They are talking about it internally now. I will post again if I hear back, which likely won't be for a few months, after EICMA.

 

[GuzziMoto]

The switch is used for safety "logic". How critical that is would be up to you.
When the engine is not in neutral and the side stand is down the clutch switch would trigger the system to kill the engine should you let the clutch out in that situation. Without the switch the system could not do that, and while you could jump the switch out it would then make it possible to ride off with the side stand down. That has been known to cause issues.
I don't think I have that system fully functioning on any of my Guzzi's, but two of the four have that retarded side stand that springs up on its own as soon as you pick the bike up off it. The other two have had issues with the switch at the side stand, and it that doesn't work the system doesn't work just as much as it would not work without the clutch switch.
So, it would be a personal choice on whether or not to run it with that system non-functional. But perhaps Brembo will come out with a solution. Or, as mentioned, you could use a hydraulic switch in place of the mechanical switch. They cost around $10 - $20.

 

[pswiatki]

Thank you so much for the confirmation of what I thought how that logic worked. The good thing is there's a yellow warning light when the side stand is down, so one shall just pay a bit more attention and stay safe (which is a general rule, applicable not only to that clutch/side-stand/engine-kill logic).

Not fully convinced I could actually use a hydraulic switch. I understand its application on the brake line where it should close the circuit as soon as fluid pressure starts increasing - after all one wants the stoplight to indicate the rider just started braking and the bike is slowing down. However, for the clutch, I think, the switch should close the circuit when the clutch is fully disengaged. Actually, with my original switch, I can hear it click when the clutch lever is fully pulled to the handlebar, so... I wonder how a pressure switch would work in place of the original switch.
Unless of course there are different switches of such kind and one could pick the switch which activated at a "proper" (higher) pressure level - then it could be a good replacement, I think.

 

[pswiatki]

That master will work fine, all set up. Ask Todd about the adj on rod but outta work great.
You'll be wanting a matching one for the front brake.

Thanks a lot for your answer. Fully agree - I am soooo wanting already. Except it is the other way round in my case. The current front brake master cylinder is probably really nearing the end of its life and I cannot easily get the OEM master (lead time of 8 weeks possibly means no more riding this season - I live in Central Europe and the weather is quite nasty at the end of October or early November). I hear all the good things about RCS masters and read really enthusiastic reviews, too. My buddy just got a KTM bike with a similar radial master from Brembo (probably not the RCS, though) and said it worked perfectly for him. Sooo... I would go for RCS 19mm for the brake and... oh well.... double that with the proper, matching master for the clutch, too. Have to check the brake lines, I guess I will replace the OEM ones with custom-built for the RCS masters. Don't know about the clutch line - have no length info for it, but perhaps I can find that info here. Must check.
Thanks again!

 

[GuzziMoto]

Thank you so much for the confirmation of what I thought how that logic worked. The good thing is there's a yellow warning light when the side stand is down, so one shall just pay a bit more attention and stay safe (which is a general rule, applicable not only to that clutch/side-stand/engine-kill logic).

Not fully convinced I could actually use a hydraulic switch. I understand its application on the brake line where it should close the circuit as soon as fluid pressure starts increasing - after all one wants the stoplight to indicate the rider just started braking and the bike is slowing down. However, for the clutch, I think, the switch should close the circuit when the clutch is fully disengaged. Actually, with my original switch, I can hear it click when the clutch lever is fully pulled to the handlebar, so... I wonder how a pressure switch would work in place of the original switch.
Unless of course there are different switches of such kind and one could pick the switch which activated at a "proper" (higher) pressure level - then it could be a good replacement, I think.

You could measure which way your stock clutch switch works. I don't have a Breva, but on the Guzzi's I do have the clutch switch is closed when you pull the clutch in. The switch closing triggers a relay. In fact, the whole freaking logic is done with relays. The current to run or not run the motorcycle goes through relays, not through that dinky little switch. As I recall (without looking at it) with the bike in gear and the side stand down the clutch switch must be closed (pulling in) which keeps a relay in position to allow the bike to run. If you let the clutch out while the side stand is down that relay changes position and current no longer goes through to allow the bike to run. If you put the side stand up the relay that the clutch switch controls is no longer required to keep current flowing to run the bike, as the relay the side stand controls short cuts the clutch relay.
In the end, a switch is either normally open or normally closed. Some switches have both normally open and normally closed terminals. It is easy to measure with a meter to see if the existing switch is functioning as normally open or normally closed. A typical brake or clutch switch in my experience is normally open and when you pull the clutch or brake lever the switch closes. But either way can be made to work. Worse case scenario if you need to reverse a normally open switch to normally closed you can do it with a relay.

 

[GTM®]

I guess I will replace the OEM ones with custom-built for the RCS masters. Don't know about the clutch line - have no length info for it, but perhaps I can find that info here. Must check.

I offer these for adapting stock lines; https://gtmotocycles.com/products/oem-line-adapter - or I can supply new lines including clutch; https://gtmotocycles.com/products/spiegler-brake-lines

 

[pswiatki]

You could measure which way your stock clutch switch works. I don't have a Breva, but on the Guzzi's I do have the clutch switch is closed when you pull the clutch in. The switch closing triggers a relay. In fact, the whole freaking logic is done with relays. The current to run or not run the motorcycle goes through relays, not through that dinky little switch. As I recall (without looking at it) with the bike in gear and the side stand down the clutch switch must be closed (pulling in) which keeps a relay in position to allow the bike to run. If you let the clutch out while the side stand is down that relay changes position and current no longer goes through to allow the bike to run. If you put the side stand up the relay that the clutch switch controls is no longer required to keep current flowing to run the bike, as the relay the side stand controls short cuts the clutch relay.
In the end, a switch is either normally open or normally closed. Some switches have both normally open and normally closed terminals. It is easy to measure with a meter to see if the existing switch is functioning as normally open or normally closed. A typical brake or clutch switch in my experience is normally open and when you pull the clutch or brake lever the switch closes. But either way can be made to work. Worse case scenario if you need to reverse a normally open switch to normally closed you can do it with a relay.

Well, being a hardware (and embedded software, too) guy, I know I could easily find out if the clutch switch is a normally opened/closed type. That is not my concern, though. My point was that the moment the switch shall be triggered is fundamentally different for the brake as opposed to the clutch. For the former it should get triggered as soon as any braking action starts, so when the lever just started moving. For the latter, though, it should only get triggered when the clutch fully disconnected the gearbox from the engine. It is therefore safe to assume the suitable clutch lever position for such a trigger is at the end of its movement (closest to the handgrip). So, I am not entirely sure when the pressure switch would get triggered if put of the clutch hydraulic line.