Saturday, August 23, 2014

A New (to her) Speedometer for Brigitta

Brigitta, my '87 BMW R80 Airhead, had issues with the odometer shortly after she went over 100,000 miles a few months ago.  It would accumulate 17 miles for every actual mile ridden!

Since then, I'd been tracking mileage with a cyclometer and had been putting up with a wonky reading on the odometer.  Then a couple of weeks ago I noticed the tripmeter was not reporting accumulated miles between gas fillups accurately.  Now it was getting annoying, since I need that to ensure I don't run out of gas!

I started half-heartedly searching around the usual spots online for a replacement speedometer, and soon found I would not be buying a new one from the BMW dealer: $440!  Tried craigslist, ebay and such to no avail, or the units I found were over $150 and I was unwilling to spend that much.

Then, I tried googling for W-1078.1 which is the speedometer ratio stamped on the speedometer that came with Brigitta.  Google found this webpage listing just the speedometer I needed and for $85!

Some emails later, I agreed to ride up to Longmont, where Jon the speedometer's owner lived.  I left the house today at 13:00 and was delayed due to construction on I-70, a car/truck accident on I-25 and one of the more violently windy rain storms I've ridden through in quite a while!

The wind was so strong, it threatened to blow me off the side of the road several times!  Couple the wind with driving rain, and the last few miles on I-25 before the exist for CO 119 were "interesting".

I gladly got to the exit and slowed my speeds which made the driving wind and rain much more manageable.

I headed west on CO119 and soon was in the city of Longmont.  I found Jon's house easily enough I got ready to swap out the speedometer right then and there.  Jon was kind enough to lend me the use of his workbench and advice as I took apart the instrument cluster and swapped out Jon's speedometer for my broken one.

I did a quick check of the lightbulbs and Jon generously gave me one he had on hand when I found the speedo's light bulb burned out.

I re-assembled the instrument cluster and plugged it onto the wire connector from the wiring harness.  I then geared up and took Brigitta out for a short tide to test the new speedo and to get some beers for Jon as payment for the light bulb and assistance he'd rendered.

I got back from the short run to the liquor store and was happy to report that the odometer/tripmeter and speedometer worked just fine!  Trouble was though, the turn signal indicator wasn't working!  Dammit.

Jon offered to help troubleshoot the issue and once again the instrume cluster came off Brigitta and was taken partly apart on Jon's workbench to expose the circuit board for the lights.

We first tried using a small air powered "sand blaster" using aluminum oxide powder to thoroughly clean all the connectors.  Pretty cool actually, and it sure did a better job than a wire brush or sand paper!  Took the re-assembled instrument cluster back to Brigitta, connected up the plug, turned on the ignition and started checking for turn signals.  I noted though, lots of smoke coming from somewhere and a burning smell!


The burning smell and smoke turned out to be the connectors for the switch that controls the heated grips.  It had grounded on the handlebar and with power applied, got really hot!

After that little scare, the turn signal light indicator still didn't work!  Off came the instrument cluster again and once again it's innards were exposed for examination.

Some checks with the multimeter later which gave us no real clues.  However it was then that Jon spotted a broken contact tab for the turn signal indicator light!  The turn signal light indicator had been a bit "sticky" to remove to check the bulb and I think it had probably broken a long time ago and only held in place by the light bulb socket.

Above is a view of the circuit board that hold the dash lights underneath. 
You're looking at the exposed back side of the instrument cluster.
The two rows of metal tubes connect to the motorcycle's wiring harness plug

 Here's the problem Jon found, the socket where the turn indicator bulb mounts.
As you can see, the portion of the metal tab had broken off and disappeared
so no circuit could be formed with the light bulb socket in place.

 Jon handed me an x-acto knife and had me cut/peel away
the blue insulator material and scrap lightly to remove
the oxidation on the copper tab.

 Jon then deftly placed a bit of copper tape that had an
adhesive side, heated up the bits with a soldering iron and 
put a drop of molten solder to hold the tape in place
and form an electrical connection.

Voila, a new tab for the light bulb socket to make 
contact with and form a circuit when the turn signals are operating.

Took the newly repaired instrument cluster and hooked it up to the connector plug, the turn signal indicator worked!  Smiles all around.

Here's Jon on Brigitta after the successful repair of the turn signal light indicator.

 Check out the Luftmeister saddle bag gas tanks on Jon's BMW RS
motorcycle, it gives him a total of 8 gallons of fuel for a range of
about 400 miles he says.

It was a little bit past 5:00 PM by now, skies were clear and temperatures had cooled off a bit from the warm weather that had followed the rainstorm.

I geared up, did one last check for the turn signal light and bid goodbye to Jon.  Truly a helpful and friendly fellow Airhead rider!

As I motored away from the city, I noticed though that my speedometer wasn't working!  Doh!  Then I realized I forgot to hook up the speedometer cable, pheew!  I got to I-25 and pulled into a gas station to fill up and to hook up the speedometer cable.

Pulling out onto the highway, I then noticed that while the speedometer was working again, now the tachometer wasn't working!  Doh!

I continued riding on home though, taking the super slabs all the way to the Quincy Avenue exit off the E-470 Tollway and was home without incident by 6:30 or so.  A quick check of the instrument cluster's connector revealed one of the plugs had gotten pushed in too far, so I pulled it forward so it would contact the corresponding connector on the instrument cluster and voila, I had a working tachometer again!  Yay.

For record.

The replacement odometer had 95,218 miles on it when I put it on today.  The cyclometer reports I have accumulated 4095 miles since the 100,000 mile mark on the previous speedometer.  The replacement odometer now reads 95273.5 miles. Brigitta's 5000 mile service is due when the odometer reads 96,178, 905 miles from now.

I am now debating whether to hook up an electric drill with suitable connector to the speedometer and move the odometer forward to 004095 so it "matches" the recorded mileage I have for Brigitta.  Or just write down the mileage on the odometer and allow for the differences in order to track service interval mileages and total mileage.  Any opinions out there on this idea?


SonjaM said...

Dom, I have heard about people manipulating odometers... but usually in the opposite direction to make a better sale ;-)

Now that the thing is set up and working, why bother with it?

Ken said...

I really like the detail, great job!!
Very well written blog:)

Charlie6 said...

Thanks SonjaM, I'm going to leave it alone and deal with notes/offsets to schedule service intervals....the risk of damaging the plastic gears in the "new" speedo are too great for the benefits involved.

Thanks Ken.