12GS - VSS or tapping ABS?

[daGeeeze]

Originally Posted by dede

I finally got it all buttoned up and the Rostra unit works great. I rode on the interstate a couple of times, the only odd thing was in gusty head winds the unit speeds up and if the wind drops before reaching the set speed then the speed is not very constant but only varies about 3-5 mph. At 75 mph in fairly calm conditions it is smooth up and down hills and when I push the ACCELL button it speeds up 1-2 mph and when I hit the COAST button it slows about the same amount, all in all worth the work. As you can see in the pics I converted my 2009 GSA throttle to a twin cable system using two stock GS cables and the throttle drum from a 1300GT. The unit can be overpowered by pulling the throttle closed. My bike is non ABS and the Rostra unit bolted in the place of the ABS unit on a bracket I made. I ditched the factory cable from the Rostra and made an Aluminum adapter to go from the CC unit to the factory GS cable, I then cut the Bowden box end off the factory cable and welded my own on to achieve the desired inner cable length and fit the Rostra unit. Someone on this thread stated that the three pin plug under the beak contained a VSS signal and they were correct, the blue w/ green stripe worked for the 6400 pulses per mile setting. I did not use the clutch disconnect as I would have needed to add another relay besides the rear brake relay.

That's some good work right there. I've got all the same lack of features on my '06 so I'll have to mirror your work. I already have the Rostra unit but it's sat forever. Thanks for this help. I really love switching the throttle to dual cable. I would want that without all the other stuff.

[dede]

Originally Posted by daGeeeze

That's some good work right there. I've got all the same lack of features on my '06 so I'll have to mirror your work. I already have the Rostra unit but it's sat forever. Thanks for this help. I really love switching the throttle to dual cable. I would want that without all the other stuff.

thanks. I own a machine shop so the fabricated parts were easy. I had considered developing a twin throttle conversion kit strictly for cruise control before taking the factory unit apart. If I built a clamp on unit the factory heated grips would be lost or I would need to purchase complete throttle drums and housings from BMW at about $100.00 each. My next project will be installing one on an ABS model.

[daGeeeze]

Originally Posted by dede

thanks. I own a machine shop so the fabricated parts were easy. I had considered developing a twin throttle conversion kit strictly for cruise control before taking the factory unit apart. If I built a clamp on unit the factory heated grips would be lost or I would need to purchase complete throttle drums and housings from BMW at about $100.00 each. My next project will be installing one on an ABS model.

Forgive me if this is absurd. It's been a long time since I looked at my Rostra unit but I thought it had a shaft that rotated to pull the cable. I was thinking it would be kinda neat to create your own bowden box on the end of it and set it up so that you eliminated one cable from the cruise. My thoughts were to use a peg on one pully to engage the one beside it. The cables to the carbs would be on a middle pulley, the cable(s) from the throttle would be on one side of that with a peg to engage it, and a disk with a peg would be on the other side to engage it. That latter would be mounted to the shaft while the other two could spin.

Having the double cable setup would mean the carb wheel and the throttle wheel could be connected firmly since the throttle grip would turn and keep cables from slacking and popping out. With just the single throttle cable I thought a small spring would keep tension against the cable and it would not turn with the cruise applying throttle. I did have a problem on cruise with my old GL1800 in that it wanted to turn the throttle and I wanted to hang onto that.

[dede]

Originally Posted by daGeeeze

Forgive me if this is absurd. It's been a long time since I looked at my Rostra unit but I thought it had a shaft that rotated to pull the cable. I was thinking it would be kinda neat to create your own bowden box on the end of it and set it up so that you eliminated one cable from the cruise. My thoughts were to use a peg on one pully to engage the one beside it. The cables to the carbs would be on a middle pulley, the cable(s) from the throttle would be on one side of that with a peg to engage it, and a disk with a peg would be on the other side to engage it. That latter would be mounted to the shaft while the other two could spin.

Having the double cable setup would mean the carb wheel and the throttle wheel could be connected firmly since the throttle grip would turn and keep cables from slacking and popping out. With just the single throttle cable I thought a small spring would keep tension against the cable and it would not turn with the cruise applying throttle. I did have a problem on cruise with my old GL1800 in that it wanted to turn the throttle and I wanted to hang onto that.

The Rostra unit does have a plastic tube sticking out of it but if you pop the cover off you will find that the end of the tube is attached to a metal washer and that is held by an electro magnet mounted to an encoder that is moved in and out by a ball screw with a small gear belt and pully setup driven by a servo motor. So in other words the motion is linear and not rotating.

[kpavey]

Guys greetings again - has anyone thought to use a coil (primary side) as a VSS pulse pickup? I've been told by BMW that the K1200S (sorry don't have a GS!) despite having the same GPS connector on it as the GS's (with TTA on Pin 2), it doesn't work. I've measured it and could only read about 11mV at 100km/h. I doubt this is enough to reliably trigger the VSS

I propose using a primary ignition coil lead which pulses with firing frequency. As the K1200S has coil on plugs the primary lead is low voltage suitable (I assume pulsed 14.5VDC).
We need to know how many pulses per mile (PPM) or kilometre this method will provide. Here's the calculations:
• At 100km/h you cover 27.8 metres/second 

• At 100km/h, in top gear, the K1200S engine is running at about 3500rpm 

• The ignition coil fire frequency will be half that at 1750rpm for a four stroke engine which divided by 60 is 29.2 pulses/sec 

• So in 1 metre, the bike would have 29.2/27.8 = 1.05 pulses. 

• So pulses per mile (PPM) would be = 1.05*1612 .14 = 1691 PPM 

• Pulses per km (PPK) = 1050 PPK (for the metric lovers out there)
• So we set the Rostra switches 3-6 into the OFF position which is a 2000 PPM setting. The Rostra setting needs to above the max PPM calculated so this looks fine.

Would be interested in knowing if anyone has done this before successfully, or found issues with this approach.

Cheers Kendrick

[dede]

[QUOTE=kpavey;16584939]Guys greetings again - has anyone thought to use a coil (primary side) as a VSS pulse pickup? I've been told by BMW that the K1200S (sorry don't have a GS!) despite having the same GPS connector on it as the GS's (with TTA on Pin 2), it doesn't work. I've measured it and could only read about 11mV at 100km/h. I doubt this is enough to reliably trigger the VSS


I can tell you for sure it works great on my GS. If the plug on the K bikes serves the same GPS function as the R bikes it should work for them as well. I am NOT an electrical garoo. I hooked my Rostra up to a power supply along side the bike with only a ground hooked to the bike itself and tested it first with the 3 prong plug under the beak. Set the dip switches to the lowest gain setting and 6000 pulses per mile, the VSS signal I believe is square wave. That said read the McCruise instructions, if I remember right it uses pulses off the stick coils.

[Crilly]

I go to WW Granger and buy a NPN prox sensor and mount it on the rear wheel. I count the 6 brake rotor bolts. Works great on the rostra. The big advantage is you can shift and still hold the same speed. The rostra electric one works better than vacuum at altitude. I just buy the RT cover, spring, and cruise wheel for the splitter box. I just drill a hole in the box for the ball end. Make sure to shorten the cable housing on the rostra, or you will end up with all kinds of problems that look a lot like electrical, instead of mechanical.

For the switches, I use the lever looking one. I but a ballon over it to water proof it. This is the easy way to do it.

For the brake light wire you have to use a relay, if you have an LED tail light.

I do not use a switch on the clutch lever. That back up is the rev limiter and kill switch. Just use the brake lever first.

Good luck, I love cruises on my bikes. Crilly

[kpavey]

When I measured the VSS signal (TAA pin 2 on the K12S GPS connector) with my CRO I got a noisy sinusoid, not a square wave. Beats me why BMW would offer up the plug and the pin but make it near useless...I can try to post an image later perhaps as I took a photo. I asked for a software update to make it functional but BMW said it couldn't be done...go figure!

The VSS pin 2 signal comes from the ZFE module. At idle it still reads around 6mV (same noisy sinusoid) and it does change with road speed in amplitude, not sure if in frequency (CRO is a bit large to have sitting on the tank!). So perhaps you are right, it's a coil based signal. I think for it to work the frequency would have to increase with roadspeed, not amplitude.

I wouldn't mind using a working VSS also for the PC-V I have fitted, but I digress.

I'm against adding additional hardware if I can help it, just the potential for more failure modes and ugliness on what is otherwise a beautiful bike. YMMV.

Perhaps the GS and K12S have different GPS connector functionality. Would be great if you could read/capture with a digital portable scope what the GS puts out on pin 2 wrt ground.

FYI, there's also a wire called "WL" between the instrument cluster and the ZFE - anyone know what this wire is/does? Refer https://files.me.com/kpavey/f4skft:

Cheers KP

[kpavey]

OK

A contact through work suggested the "WL" is the Wake Line, when high wakes up the module. I'd have thought that would be done via CAN but anyway, would seem there's no magical VSS available there.

The only other thought I had about using the COP primary lead is that going down hills, if steep enough, the injectors might cut off as some ECUs do, and this might cause the cruise to cancel. In the big picture on average roads this probably isn't a deal breaker and you might be grabbing brakes anyway to avoid overspeeding.

Cheers, KP

[kpavey]

Well started thinking about other sources of a signal and the camshaft sensor (inlet cam I'm assuming given it's position on the rear face of the head) isn't such a bad candidate. Appears to be a 6VPP sinusoidal signal with varying dwell of course with engine speed. Pins are easily accessible near the BMSK (twisted Blue/White and White pair) so this seems like a better solution that using the COP feeds IMO - no cutout going down hills. Obviously it isn't really a VSS because it only samples engine speed not road speed, but most of my cruising will be in top cog so good enough for me. See pic below, timebase is 1ms/div and 1V/div vertically. Cheers KP

[Mad Kaw]

Well after reading this thread it appears there is no useable "VSS" signal available on a 1200GS. Sad because on other bikes I've installed the Rostra and the VSS signal was so slick! (ie Concours 14). However on my R1150RT I had to implement magnetic coil pick-up and put small neodym magnets in the bolts heads of the brake rotor attachment bolts. Works very well. Just a bit of a pain but well worth it.

I have gotten so spoiled to using an electronic cruise over the past several years of riding that a recent trip on the CDT (the return trip was all SLAB) I went nutz having to hold that throttle with nothing more than a Kaoke for 1700 miles back to the house. I gotta get some relief so I am going through the PITA of installing a cruise on my GS.

If any of your tech whiz types figure out a way to tap the ABS wheel ring pulse such that the Rostra brain can decipher it please post it here. I don't THINK I saw any solution in this thread. But if I missed it please point it out.

Thanks

MOO!

[BuilderBob]

Check this out: http://www.murphskits.com/catalog/do...200S_Final.pdf

Cruise fitted to a K1200S, but I checked my 800GS while I still had it and all of ingredients to make it work were there. Don't write this one off yet.

Page 10 is where you want to look.

[Poolside]

Originally Posted by Mad Kaw

Well after reading this thread it appears there is no useable "VSS" signal available on a 1200GS.

If any of your tech whiz types figure out a way...please post it here. I don't THINK I saw any solution in this thread. But if I missed it please point it out.

The link posted by BuilderBob covers the procedure. Based on the information on page 10 of that link, the VSS signal on the R12 is apparently an 'active low' signal. And needs a 'pull up resistor' in order to be a useable signal. That all sounds perfectly normal. Except I would try using a 1/4 watt 1K or 2.2K resistor. A 300 ohm resistor seems like too low a value for a typical pull up resistor. Send me a PM if you would like to discuss it more detail. This post here is probably the best post in the thread: http://www.advrider.com/forums/showt...2#post15868552 Summary of the above post. Mounting the Rostra Cruise on a R12GS: 1. Convert R12GS throttle grip to a 'twin throttle cable system' using two stock R12GS cables and the throttle drum from a 1300GT. One throttle cable connects to the Bowden box as it normally would. The new 'second' throttle cable connects to the Rostra unit. 2. The Rostra unit is equipped with has a throttle cable sticking out the side. Remove that cable and make an aluminum adapter to go from the Rostra unit to the new 'second' GS throttle cable. 3. Cut the 'cable ferrule' off the new 'second' GS throttle cable and solder on a new cable ferrule in order to achieve the desired inner cable length, and fit the cable to the Rostra unit. 4. The three pin plug under the beak contains a VSS signal. The blue w/green stripe works on the Rostra Cruise with the 6400 pulses per mile setting. Presumably the pull up resistor mentioned above is required in step 4.

[rdcyclist]

Originally Posted by Poolside

Yes, all of this information is excellent. Thanks for the pull-up resistor info Jim. I spent quite a bit of time trying to get that signal to work and ended up throwing up my hands and going with the coil signal. The required 12v is right there on the same connector...

About the other post, it looks to me like Dede used way more than just a K13 throttle drum. He's got a dual cable throttle housing that looks like it's from a K13 but the interface to the right side switch assembly needs quite a bit of modification to work on the R12GS bars. Looking at the pic he's got in his post, there's an intermediate aluminum part to make the GS switch bracket mate up. I'll send him a PM for more detail. Being able to run a dual cable throttle assembly is HUGE...

[dede]

I DID NOT add any extra electrical components to my setup! This is on a 2009 R1200GSA non ABS.