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!
Check this out: http://www.murphskits.com/catalog/docs/Rostra_Cruise_Fitment_Guide_BMW_K1200S_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.
<table border="0" cellpadding="5" width="650"><tr><td>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/showthread.php?p=15868552#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. </td></tr></table> <BR>
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...
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...[/QUOTE] You are correct, I used the GT drum and the drum housing, I machined the throttle side off of the GS and the switch box side off the GT until both were flat and then screwed them together with very small flat head screws. The heated grip for the GT was a direct plug in to the GS and works fine.
Thanks for the clarification! It might be that the Rostra has a built-in pull up resistor. Or maybe the pull up resistor is 'switched on' with a jumper or configuration setting. <BR>
I just installed the Rostra CC on my 2005 1200GS. It works perfectly. The "blue/green" wire in the accessory harness under the tank worked perfectly. I tapped it directly with no modification using the grey wire on the rostra servo. It works great. I have installed this cruise on several other bikes. None of my other bikes had a double throttle cable. They all worked perfectly. I've put over 50,000 miles on bikes using this CC with absolutely no problems. Currently have one on my R1150RT and it works flawlessly. The install of this unit on my 1200GS was much more straightforward. No modified Bowden box and a readily available VSS. Thanks to all who posted here regarding the VSS signal.
Yep...I used the stock CC cable wheel for a 1200RT, return spring, and lid. They all install perfectly to the 1200GS bowden box. I had to drill a 1/4' hole in the right side of the bowden bow where the RT cruise cable would normally go. Then I used a bicycle cable to a slack tube I built from 1" PVC. In the slack tube I attached the bicycle cable to the Rostra servo cable with a ball chain. I can post photo's if needed. The cool thing was no serious surgery require to the bowden box (since the RT Box is essentially identical) and a useable VSS signal is readily available on the GS since it is wired almost identically to the RT...that has a factory cruise.
Mounted the servo under the instruments on the Horn Bolt Moved horn above Switch Pad After adding the BMW OEM Cruise Control cable wheel and return spring you need to cut the spool retainer on the box lid down to accommodate the new cable wheel. If not then you must use the lid from a 1200RT bowden box. I used a standard copper tubing compression fitting to retain the cables. It was a 1/8" NPT to 1/4" compression fitting. The ferrel will fit the cable sheathing and hold it in the box and slack tube Slack tube for cable - 1 inch PVC with 1/8 to 1/4 compression fitting to retain cable to and fro. I used a bicycle cable to connect the BMW bowden box to the slack tube. The Rostra servo cable connects to the other end of the slack tube and a ball chain is used to connect the two. Not much slack is needed...just enough to allow the cable wheel in the Bowden box room to rotate easily. You may be able to interface the Rostra directly to the BMW cable wheel but I didn't try. I post these pics merely for reference. Also the way I mounted the switch pad was by drilling a hole through the handle bars :eek1:eek1:eek1 and using a 5MM bolt and nut to fasten it to the bar. This was pretty much the mechanical end of the install.
Interesting, so you did modify the Bowden Box just with stock parts, that's were I was confused. Evidently the VSS signal wire you tracked down is the same one that terminates as a three wire connector under the beak of my 09. Although it was much easier for me to mount my CC box were the ABS unit goes I had considered the same location you used but did not consider that orientation. I was trying to come up with a mount that would work on my brother's ESA, ABS model as well as mine. Nice job.
Well yes technically I "modified" it. But it was nothing like the mod I had to do to my R1150RT bowden box for same install. THAT was major surgery! But hey it worked. This GS install was much more straight forward. All ya have to do is add the OEM cruise cable wheel...return spring...and corresponding box lid (or just cut the spindle retainer off on YOUR lid). Very simple. The VSS signal on the GS makes it much easier. On my 1150RT I had to install a magnetic coil pickup and magnets in the bolt heads of the brake rotor. This GS is much "cleaner". Another option I've seen guys mount the Rostra servo in the void on the left side of the rear shock...IF the bike has had the venerable "canisterectomy". Mine has had the canister removed but we decided to mount the servo under the beak for several reasons. PS: I am soooo glad you found that little blue/green VSS wire. People that have never installed one of these on a bike don't understand how significant that is is. KUDOS for finding it!
Addendum: The bicycle brake cable I used was too stiff in the bowden box and created a problem when throttling off...the bike didn't quite return to idle. So I pulled the 1/16th inch bicycle cable and replaced it with 1/16 inch wire cable from a hardware store that was more supple. I had to solder a round end on it to fit the cable wheel. But it worked! The more supple cable created no drag in the box and the system works perfectly now.
OK I have the Rostra and I am about ready to start the install on my 2008 R1200GSA. Does anyone know the part numbers for the RT cable spool and return spring? I think there is also something else I need to order also. If you don't know the numbers do you have a source? Thanks
I am a little confused about the location of the blue green vss wire? One post says it is under the beak, another says under the tank. Is that wire run through both locations? Thanks
OK I ordered the parts from BikeBandit. A cruise control spool and return spring for a 2008 1200RT. All of 13.00 including shipping. When you connect the Rostra using the VSS signal only, not using the tach signal. Does the RPM over rev protection feature still work? Or is the tach wire required for that feature? Thanks
