12GS - VSS or tapping ABS?

Discussion in 'GS Boxers' started by bonox, Oct 23, 2006.

  1. dede

    dede Lefty

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    Thanks Crilly, I had considered, since my bike is non ABS mounting a prox to the front wheel in the bracket cast for the front ABS pick-up and doing something like you are talking about if I can't get a pulse from the bike. Are you using the Rostra CC, where did you mount the box? I already modified throttle housing to twin cable before reading about the Bowden Box mods.
    #81
  2. Crilly

    Crilly Been here awhile

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    :norton If you mount it on the front wheel and the rear looses traction the cruise will open the throttle and spin the wheel real fast. If mounted to the rear it will just try to keep the wheel at the same speed. I mounted it below the seat on the left side. I use big wire ties. And yes I use the rostra electric cruise control. It works better in the mountains (at Altitude) then vacuum ones. I now use the stick switches with a balloon over it to water proof it. Use a color balloon that matches the bike.
    #82
  3. Crilly

    Crilly Been here awhile

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    :norton One other thing. Make sure you cut off any excess cable housing inside the splitter box. It caused mechanical problems (stuck throttle) that I thought for the longest time was electrical.
    #83
  4. Poolside

    Poolside Syndicated

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    <BR>
    Do you have experience with this? I mean, I realize it sounds like that's what would happen.

    Cruise control authority has a Rate Of Change limit, and other conditional tests built into its control loop that prevent such operation.

    I see that you used an aftermarket sensor and that it works well for you. That's a good solution, especially if the factory-equipped wheel speed sensor can't be sorted.

    <BR>
    #84
  5. Crilly

    Crilly Been here awhile

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    :norton Posted by Poolside.
    Do you have experience with this? I mean, I realize it sounds like that's what would happen.


    Lost traction with a throttle lock in the rain once, spun the rear wheel up pretty fast before I caught it.

    I donot use the tack wire. All the hook-ups are to the battery threw a relay fuse bloc, except the relay hooked up to the brake light.
    #85
  6. Poolside

    Poolside Syndicated

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    :lol3 That must have been a fun moment or two!

    Mostly when using a throttle lock I'm riding with no hands, but in the rain? You are definitely a thrillseeker! Cheers!

    <BR>
    #86
  7. dede

    dede Lefty

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    Good point, thanks I'll reconsider my mounting ideas. Hey can you save me some more fishing around and tell me where you tapped in the clutch and brake light safety kill wires? I have mounted this unit to another bike but not to a GS.
    #87
  8. Crilly

    Crilly Been here awhile

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    :norton I do not use any other wires but a relay to the brake light. Kill switches, and rev limiters will have to suffice. You run the brake light wire to ground (N/C) through a relay and operate the relay from the brake light on the bike.
    #88
  9. BluByU

    BluByU Been here awhile

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    Anyone worked out the bowden box for an 1150GSA?

    I have a CCS100 in the box, will most likely pick up a Rostra so as to cut out the vacuum hoses. I have installed the CCS100 kit on several bikes and a few cars. My older GSA throttle cables have me puzzled.
    #89
  10. dede

    dede Lefty

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    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.

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    #90
  11. daGeeeze

    daGeeeze Geeezed lightning

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    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.
    #91
  12. dede

    dede Lefty

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    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.
    #92
  13. daGeeeze

    daGeeeze Geeezed lightning

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    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. :lol3
    #93
  14. dede

    dede Lefty

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    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.
    #94
  15. kpavey

    kpavey K12Sman

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    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:
    &#8226; At 100km/h you cover 27.8 metres/second &#8232;
    &#8226; At 100km/h, in top gear, the K1200S engine is running at about 3500rpm &#8232;
    &#8226; 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 &#8232;
    &#8226; So in 1 metre, the bike would have 29.2/27.8 = 1.05 pulses. &#8232;
    &#8226; So pulses per mile (PPM) would be = 1.05*1612 .14 = 1691 PPM &#8232;
    &#8226; Pulses per km (PPK) = 1050 PPK (for the metric lovers out there)
    &#8226; 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
    #95
  16. dede

    dede Lefty

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  17. Crilly

    Crilly Been here awhile

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    :norton 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
    #97
  18. kpavey

    kpavey K12Sman

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    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
    #98
  19. kpavey

    kpavey K12Sman

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    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
    #99
  20. kpavey

    kpavey K12Sman

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    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

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