BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down    K75 speedo down on Sat Jan 06, 2018 1:39 pm

BooG

avatar
Gold member
Gold member
It appears my speedo/odometer is not working. I removed the instrument cluster and took off the back. I checked the three pin connector which didn't show any corrosion, so put it back together. I unplugged and put back the connector next to the underseat tray. I removed the rear speed sensor from the final drive, cleaned it and replaced, but still no joy. I have noticed the indicators do not self cancel....does this point to a faulty sensor? Should I try the soldering iron trick?

    

2Back to top Go down    Re: K75 speedo down on Sat Jan 06, 2018 2:05 pm

Ringfad

avatar
Life time member
Life time member
The soldering iron trick will eliminate the sensor so well worth a try.


__________________________________________________


;BMW;K100RS Style Black 1987 105K Km ;BMW; K1 Black 1993 51KKm ;BMW;K1100RSRed 1993 70k miles ;BMW; K100 16V Black (ex ElectricMonk)
    

3Back to top Go down    Re: K75 speedo down on Sat Jan 06, 2018 3:05 pm

robmack

avatar
Life time member
Life time member
Either the soldering iron trick or try Kramba / KDiag.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

4Back to top Go down    Re: K75 speedo down on Sat Jan 06, 2018 4:34 pm

BooG

avatar
Gold member
Gold member
Thanks for the pointers. I'll try soldering iron first as the lower tech option...

    

5Back to top Go down    Re: K75 speedo down on Sat Jan 13, 2018 6:51 am

BooG

avatar
Gold member
Gold member
A run out on the A12 in London has thrown up a feature....the Speedo works once I get to about 40mph, and appears to be accurate. As my speed drops below this, it falls to zero once more Shocked
So... I'll display my logic for your assessments!

If the Speedo works at all, that means the connector at the tool tray isn't at fault as at least something is getting through.
The Speedo is reading, although not under 40mph, so this means the Speedo internals are functioning.
The sensor could be at fault, hence the faulty reading under 40mph. This can be tested by applying my original plan, which was the soldering iron trick, to verify this. I'll clean it up again (in daylight this time) and see if anything improves. If not....replace sensor.
How does that sound? Reasonable? Question

    

6Back to top Go down    Re: K75 speedo down on Sat Jan 13, 2018 11:33 am

charlie99

avatar
VIP
VIP
sort of sensible
if you have on going issues could it be that the vaned impeller inside the final drive has become loose and is now free wheeling ?
I believe we have seen this a couple of times , or heard about it at least

I'm thinking the impeller would resist turning as rate of acceleration is changing (and sitting in diff oil ), but once a more constant speed is achieved it then catches up sort of thing ?

just a thought

I guess you could test it out by probing - observing the speedo sensor hole whilst on the centre stand and selecting a gear and running the bike static ?
a good torch might help out ?


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

7Back to top Go down    Re: K75 speedo down on Sat Jan 13, 2018 11:36 am

BooG

avatar
Gold member
Gold member
Thanks C99.....good call on the impeller. Will try checking that as well.

    

8Back to top Go down    Re: K75 speedo down on Sat Jan 13, 2018 1:44 pm

robmack

avatar
Life time member
Life time member
I'm kind of siding with Charlie. I can't imagine what could be wrong with a sensor that can cause it to function above a set frequency. The problem sounds more mechanical in nature, and might be related to the motor driving the speedometer. Remove the guts of the cluster and inspect the speedometer region for interference from dust and debris or from mechanical damage. There is a dampening mechanism on the speedometer needle that dampens its return to zero that might be acting up.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

9Back to top Go down    Re: K75 speedo down on Sat Jan 13, 2018 4:48 pm

charlie99

avatar
VIP
VIP
hi rob , currently working on a faulty speedo issue on some new to me instruments

with Karumba only , I have to max out the volume output on the pc to get a good spread of speedo reading
which is different from this pc , than others that I have calibrated before , usually only need to get about 30 % volume for a good consistent drive

I have already fixed a burnt out track on the membrane circuit (an earth reference actually )
but think the input buffer of the op amp has been upset somewhat and I have a fair bit of dc on the input of the op amp

I have a replacement to hand (lm358 rather than lm2904 ) to install
so hope this may resolve the issue

but it could be a similar issue has happened to others ?

time will tell I guess


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum