R1200RT ABS Sensor air ap

[lindsaywest]

I sold my K after 20+ years and picked up a clean R1200RT 2005 with Issues. I have purchased:
GS911
New Battery
rear ABS sensor
Front ABS sensor
Gear potienometer (sp)
I am getting an error code of 25070 - Too much slip of the rear wheel. The air gap on the front ABS front Sensor is .8mm +. the speedo is a good 20MPH slow. any adjustment?
I can not see any way to move the wheel over. The front wheel has been off twice, inspected, and installed to all the proper torque settings.



David
K100RS
R100RT
R90s
R75/7

 

[henzilla]

Welcome to the Forum David

You have cleared the fault codes or it says "still present"? And have road tested with new sensors, not just on center stand?
Is there any damage to slotted ring on front wheel?

Unlike the Oilheads and early K's there are no spacers to allow adjustments of gap from my recall. One oddball thing I crossed paths with was a change in speed sensor rings between a K1200 and 1300 which showed up as a wheel swap was attempted and caused all sorts of bad read outs and no ABS .Just thinking outside the box as that sounds like a weird situation.

 

[lkraus]

I have not seen this problem, but the speed sensor driving the R1200RT speedometer is the one on the REAR wheel. It counts the teeth on the driven gear of the final drive. (run the bike in gear on the centerstand and the speed is shown on the speedo)

Is the rear tire the stock size - 180/55 17?

Has the final drive been swapped for one from a different model? The standard final drive ratio is 34/13, stamped on the bottom of the housing near the pivot. Police RTP models used a 33/12 FD for better acceleration, a GS used 31:11.

 

[jandhumphreyme]

Maybe a wanky connection, it would appear the ABS module is not recording consistent output from the wheel sensors. I'd be inclined to try unplugging any connectors between the abs sensors and computer and cleaning the contacts.

 

[lindsaywest]

I have cleared the error code and inspected and replaced the sensor ring. The shop manual does state that the ring should have 100 slots and it is correct. I have check all of the sensor connections. I have not looked at the ring in the rear end. Iwill check the tire size.

 

[lindsaywest]

The final drive is 33/? the second number looks like a double stamp. the first is definitely a 33. so now what? change out the rear end or?

 

[pappy35]

Do you have a dealer nearby? I ask because the shop computer they have is far more capable than the GS-911. I know that they can activate features that the bike didn't come with (in my case seat heating for example) which implies to me that all the software is there for the various models and can be turned on or off as needed. I would at least ask them if they can verify the ration and reprogram it as needed. I doubt BMW would have a different computer for the different models and so the FD ratio may be something they can change. It's possible that a previous owner replaced the final drive and they installed the wrong one.

The ABS system compares the speed input from the two wheels and if they off beyond a certain tolerance will assume one or both sensors are failed. This may render the ABS system non-functional and so I'd be very careful riding it.

 

[lindsaywest]

I have a dealer about 2 hrs away. I will give them a call. This is the first bike I have had with ABS so having it disabled feels normal. The bike runs and stops fine accept for the flashing lights. That also explains when I ride it in town and go slow everything is fine. when I speed up into 4th and higher is when things start to go wrong.

I will update after I contact the dealer. Thanks for the idea.

Called the dealer. His response was that the pickup and sensor ring are on the "axle" and are only looking at tire rotation. So in his mind that is not it. we also talked about other ideas. He was as baffled as I am. He was very helpful and open to discussion.

The dealer also stated there is no way to adjust the air gap on the ABS sensors so they do not worry about it.

Only thing I have not done is pull the connectors into the actual computer.

 

[lindsaywest]

Here is where I am today. The speedo is off (slow) by 10 MPH at 25 MPH (GPS) the speedo reads 15. At 60 MPH (GPS) the speedo is about 39MPH so at least 20MPH difference. I believe that the ABS is comparing the two wheels and the large air gap on the front is the issue causing the rear wheel slip fault. I guess I try and bend the bracket. any other ideas?

 

[pappy35]

...I believe that the ABS is comparing the two wheels and the large air gap on the front is the issue causing the rear wheel slip fault. I guess I try and bend the bracket. any other ideas?

The only way to know would be to use the GS 911 to observe the sensor readings for each wheel (it will report real-time speeds for each wheel). I don't know how to do it it since I've never needed to but the 911 can record data for later review. The data can be exported to excel and from there you can create graphs.

You'd need to dismount the data port from the fender so you can plug in the 911 and lay it flat to put the seat back on. Go out for a ride in the neighborhood and then look and see what the data says. This can help you determine whether either sensor is providing erratic data. This is the only way I'm aware of to test the sensors. If the data is solid, then I'd start thinking about the final drive ratio. If you have the wrong ratio drive that will cause all kinds of problems including the symptoms you are describing.

 

[drneo66]

If the data is solid, then I'd start thinking about the final drive ratio. If you have the wrong ratio drive that will cause all kinds of problems including the symptoms you are describing.

I'm not sure that the final drive ratios will change the speedometer output, it seems like there hasn't been a reliable source to back this up. Take a look at this thread on advrider. - specifically take a look at page 7 where the OP found that his rear pickup was damaged slightly.

 

[pglaves]

I'm not sure that the final drive ratios will change the speedometer output, it seems like there hasn't been a reliable source to back this up. Take a look at this thread on advrider. - specifically take a look at page 7 where the OP found that his rear pickup was damaged slightly.

The ring turns one revolution for each revolution of the wheel. Therefore, how many engine RPM there are is irrelevant to speed detection. Thus gear ratio is irrelevant too. Tire size may make a two or three mph difference. From new to worn out a tire can cause the reading to vary by 1.5 to 2 mph.

 

[pappy35]

The ring turns one revolution for each revolution of the wheel. Therefore, how many engine RPM there are is irrelevant to speed detection. Thus gear ratio is irrelevant too. Tire size may make a two or three mph difference. From new to worn out a tire can cause the reading to vary by 1.5 to 2 mph.

Disregard...

 

[jandhumphreyme]

Disregard...

Disregard what specifically?

 

[lindsaywest]

As suggested I have started playing with the data collection on the GS-911to see what the voltages are on the ABS sensors. I have not been successfully riding yet with the laptop however I have gotten some readings at rest. The front wheel sensor starts out at 1.52 Volts the rear sensors is at .51 Volts. The front is at .57 Volts and .1 MPH. The Rear is at 1.52 Volts at .1 MPH.

spinning wheels by hand. so are they different sensors? I assume (!) they should be the same voltage at rest.

 

[pappy35]

Disregard what specifically?

I crafted a very long reply with equations and stuff. Then realized I made an error and that it came across as a know-it-all who doesn't really. I'm an Aerospace engineer and tend to go full-on geek when I'm trying to work something out. In this case it was ABS math (as in I worked out the frequency of the sensor output signals and then realized that I didn't actually know that that's how they worked). I got waayyyy out in front of my skis there.


...move along...nothing to read here...

 

[lindsaywest]

I am a mechanical Engineer with a bunch of computer certifications so I played with the front wheel sensor. I manual change the distance with tape to under .7mm per the spec. The voltage dropped to .52 Volts.

need more experiments to try.

 

[pappy35]

I don't understand why you think voltage matters. What matters is signal quality. The voltage is going to be varying like an AC signal whose frequency is determined by the ring step (or gear tooth) passing frequency (for the rear wheel at 60 mph it should be in the neighborhood of 13 khz) so if you are measuring voltage it would be RMS not peak to peak. Systems like this don't care about the voltage, they look for frequency.

Why are you focusing on the front air gap? I have forgotten most of what I used to know about these kinds of sensors but intuitively, I believe that closer/farther away would affect peak to peak voltage not frequency. If you have a ratty signal from one of the sensors, or nice clean signals whose frequencies don't agree (scalar value, not phasing) then the system's going to freak out. I think you should be focusing on recording data on the 911 and then comparing that data front to rear. That is the key to rooting out what's going on here.

 

[lindsaywest]

I believe you are correct It will be next weekend before I can run a data collection while riding. I think I have the process figured out. thanks for the help. I will update in about a week.

 

[jandhumphreyme]

I crafted a very long reply with equations and stuff. Then realized I made an error and that it came across as a know-it-all who doesn't really. I'm an Aerospace engineer and tend to go full-on geek when I'm trying to work something out. In this case it was ABS math (as in I worked out the frequency of the sensor output signals and then realized that I didn't actually know that that's how they worked). I got waayyyy out in front of my skis there.


...move along...nothing to read here...

Thanks for posting that, too many people this day and age double down instead of fold.