Faulty speedometer and loud indicators

[Palm9]

Hi all.

I recently got my first Beemer, a 1980 R65/7. I have a few issues that'll need doing, and I'll start with the following two.

My speedometer is a W978 from an R45 (not sure?) but it works perfectly and shows the speed as accurate as our car. The problem is in the trip counter and the odometer, which does not work at all. I have dismounted the speedometer unit from the bike, and I can see several screws on the back. Would it be possible to open it up and have a look and try to fix it? What could be wrong with it? Could the fault be in the cable connected to the speedometer?


Secondly, when I indicate right or left while driving (i.e. while clutch is left untouched) the bike makes a beeping sound. Is this  meant to be like that, or is there a way of getting rid of the sound, as I find it very annoying?


I hope you can help me solve this issues. Thanks!
- Frederik

[Bob_Roller]

To gain access to the interal workings of the speedometer, you must remove the crimped ring that holds the glass lens on the speedometer .

There is a buzzer, or horn located somewhere under the fuel tank / seat area should be easy to find with the tank removed  .

 Disconnect the wires from it secure them  .

[Barry]

My speedometer is a W978 from an R45 (not sure?) but it works perfectly and shows the speed as accurate as our car.  

That is a metric speedo from the lower powered 27 HP R45. It should be matched with a 8/34 or 4.25 final drive ratio. If it reads accurately on a different final drive it may have been re-calibrated.

The indicator warning buzzer was only fitted for a few years on the early models. My 79 has one and it is annoyingly loud.  It's a useful safety feature though so rather than disconnecting it I muffled it with a piece of duct tape. It's located under the left hand side of the tank at the front and there is a connector in the wiring harness close bye. I normally remove the tank but you might just be able to remove it by lifting the tank up at the rear without disconnecting the fuel hose. The buzzer has a rubber surround and slides on to a vertical metal tab on the frame.

[Palm9]

Thank you for your replies.

I decided to reconnect the speedo again, and I will look out for working replacement one instead. Do you know what type number it has for an early R65? It has to be metric as I'm from Denmark (We use km and kp/h here).
It concerns me slightly now, that you tell me it might have been re-calibrated, as I imagine that would be rather complicated. Is there any specific way I can tell if I have actually ended up with an R45 instead of an R65?

Barry, thanks for the tip, I'll try to go look at it tomorrow when the sun comes out. It's 8.20 pm here now

[Barry]

If you look at the final drive casting close to the drive shaft filler plug the drive ratio will stamped into the metal e.g. 35/9. From that we can calculate the correct speedo ratio.

I've updated my table to include Metric speedo ratios.

For interest the speedo ratio is the number of turns that the drive cable makes for one mile or one Km travelled.

BMW sure made life complicated by driving the speed from the gearbox. Most others used the front wheel and needed only one speedo whatever the gearing of the bike.

[Bob_Roller]

You can find out what bike you have, by going to the following link .

http://www.realoem.com/bmw/select.do

Put the last seven characters of the bikes serial number, in the search box .

[Palm9]

Wow, that is one clever search box! I put in the seven digits as seen close to the oil filler cap, which showed that it is a May 1979 R 65. I believe this is true, but I still fail to understand why I have two front discs and a 27hp R45 speedo on my 1979 R65. I have acomplished a 8 seconds 0-100 kph (0-60) time on my bike, (first timer!!!!) and this is after 34-35 years. So either I have a perfect and as new R45, or an R65. I believe an R65, what do you think is the most realistic?

I greatly appreciate your posts so far.

[Palm9]

I went downstairs to check the drive ratio, which turned out to be 31/9. Now, what exactly can I do when I know this number?

[Barry]

I don't think there is any doubt you have an R65. The serial number and final drive ratio confirm that. A 31/9 should have a speedo ratio of 793 if you are looking for a replacement.

Here is a table of what revs your bike should achieve at different speeds in KPH.

[Palm9]

Alright, I understand how it works. I even went and checked out the speeds with a GPS speedometer next to me, which showed that the speedometer is indeed very accurate. At 130 the GPS showed 123, and at 100 the GPS showed around 95, and finally at 55, the gps showed 53. So pretty much as usual. I'm convinced the gearing in my R45 speedo has been tampered with.

Thank you all for your help. I do appreciate it.