Earlier I started information on the Motometer instruments used on BMW motorcycles, and this is to be continued, as I have yet to cover the BMW K100 and K75 series and the BMW/6 and /7 series.
But this blog deals a bit more technically with problems that arise with the BMWR80GS and a start on the BMW/6 and /7.
Left click on the images to enlarge.....
I had a comment from a chap, "Peter G" who looked at the R80GS blog and I recalled then a common problem that occured with this instrument.
The area where the cable attaches to, and this thread is 18mm x 1.5mm metric, is what we call the lower frame and originally it was supplied as a plastic item..who knows why, but cost is a likely consideration.
With time and heat, the material seemes to change and as the section where the threaded part changes into the main top part of this frame is thin, vibration and road shock would snap it off.
A "quick fix" was to use Araldite or and adhesive, but it seems to not be a permanant repair.
I knew that the frame on the previous BMW/5 models used a diecast metal frame and it was identical, so I used them, but soon ran out of used items.
On a visit to Motometer I enquired as to parts for the BMW/5 intending to purchase these metal frames.
Parts for this model were no longer available, although Motometer admitted to making small batches of the complete instrument for BMW as a spare part.
During the inevitable tour of the factory I noted a pile of these diecast frames and observed the Motometer part number which I quickly wrote down.
Later in Sydney, assembling an order of parts for the later BMW speedos, I included this diecast frame number with a quantity of 100...
I was pleasantly surprised when 6 months later the order arrived and those diecast frames were supplied...Eureka!
I did this a second time before they ceased supply and I note, although I sold all my Motometer parts when I sort of retired to Lionel Otto Instruments in Salisbury, Brisbane, Queensland, I kept three and still have them.
Yes I'll sell them ...email me.
The mainshaft like most of the steel parts in speedometers are unplated metal and thus rust. The rust on the mainshaft causes a squealing noise in operation and cleaning off the rust and regreasing it cures this problem.
The later /7 instruments had a damping bridge and cup arrangement with silicon damping fluid as the medium and reduced the tremor of the pointer in operation.
However pointer trembling or oscillation can also be as a result of an inner drive cable fault....another blog for the future, the care of speedometer cables...or wear in the top and bottom speedcup bushes as well as no damping medium.
Detail of the speedcup shaft bottom pivot length. This wears on the end stone in the bush at the top of the mainshaft and the inside of the aluminium speedcup "poles" on the magnet, eventually destroying it.
You can lightly stone the worn end of the shaft and then tap it though the brass piece in the speedcup to the correct setting...0.140" protruding.
From DQs notebooks...electronic tacho calibration information.