Background

When I got this '86 K75C the speedo and tacho were intermittent, a tap on the cluster would restore the tacho and sometimes the speedo. Research on BMWOUSA (this was 4 years ago) gave the solution so ripped into it and did the job and would have been sucessful except I used a product that even now am ashamed to reveal! Even to you guys!
Well it actually did improve the situation, the tacho has been good for 20k kms, great. the speedo has been working maybe 50%, typically nothing on the first part of the ride then rock steady accurate for the next, fill up with juice and back to square one. Heating up of the contacts?

Forum to the rescue.

Since then i've found Flying brick and K100 Forum and having read extensively many cases of the same problem I attacked the cluster for the second time, last January. Oh no ! Worse ! How can that be when I am a forum "Expert"? Now the needle was "I think I can, I think I can " struggling up there and sometimes making it but ohh soo tired and just as often sliding back. Damn!
I can cope with estimating my speed by the revs and haven't been booked for speeding but it's the odometer I miss, not being able to brag about the 1 thousand and something km day ride, or calculate the fuel consumpion or range.

Back to the Forum

More threads have come and gone in the last year and now i'm ready for the final fix. To tell the truth I love pulling the thing apart even tho i've only done it 3 times it's a nice clean challenge that rewards gentle handling and cleanliness, good fun.
This time I cleaned even more traces of the crap mentioned above, DeOxit of course (did that last time too) then looked very closely at the pins and sockets because Charlie and others mentioned corrosion. I noted that the female part of the socket had a side that was sprung to grip the pin, on the 4 in a row set below the speedo it was easy to push the "spring" in a bit to give them more bite but the 3 pins in a row that do the speedo this was'nt possible due to them being hidden on a circuit board with stuff in the way.
So... If I can't make the sockets tighter I decided to make the pins larger by soldering , very thinly like Charlie did, but maybe on something else? the multipin connectors on the outside showed some plating missing on 4 of the pins so they got tinned also.
DeOxit followed by the gold stuff again and slip her back together.
oOn the bike now and decided to use the test attributed to Rick G of soldering iron near the wheel sensor and hey bingo 60 and a bit ( hard to see crouched at the back wheel!) great!

On the road test

Honestly felt like a new bike, first time in 5 years with a rock steady speedo.
Thanks to all the real forum experts who made their knowledge so freely available

Part 2 tomorrow when I can get this real computer again, where i want to pose a question, and make a couple of suggestions.

see ya



Part 2 i'm back, got the computer for 5 more mins.


Question. Is there a definative, complete how to on the forum for the speedo fix? I google searched but only came up with threads that I'd already read which only give part answers or links to other threads. I was looking for two specific photos Inge's labelled multipin photo and another but only found one in the end. As it turned out I knew what to do but wondered if this common problem could be covered ( if not already, pardon) for others searching?
Being a bozo with a computer limits me ie photos and diagrams, anyone got the time and skill?


cheers GORDO

onya gordo ....!

no, no one has done a definative fix as far as i can see yet ....

but good to see you had a result

i do have a small diagrame of the wiring from the multi pin connectors to the first of the speedo terminals and then to the speedo motor ...which i can redo for here mate ....is this what you were asking ?

Is it this you have in mind, Gordo?

Thanks Inge but no not that one i, in fact i don'
t recognise that picture at all !
The one i was refering to is of the multipin plugs on the back of the instruments , maybe it was CF who posted it ?
Anyway all good for now , will get to a pc soon and post again
cheers guys G

Hmm...since this thread was about the speedo...previous picture shows the
connections at the multipin connector which is neceserry for speedo function.
(exept power supply, pin 6).

But if you have the multipin connectors in mind, it could be this one:

Yes Inge thats the pins but i recall a colour picture with the speedo imputs (only ) "pointed " and named .
Bear with me , i'm going to write it up and ask you and others to add the pics , ok?
Or is there already a complete "how to " on flying brick , BMWOCUSA , motobrick ? that we can steal or link to?

Cheers Gordon

ps i'm thinking of an all info in the one post without links to this or that .

i "get you" now ghosty

like put it in the "how to" section ?

all the things you need to do .....rear pickup clean etc ...joint under the right hand side cover ...then the multi pin at instruments ....

something like that ?

Yeah thats it Charlie , just making sure no one else has done it and opinions on whether it's needed ?

Gordo

I haven't seen a write up on that Gordy and we do get quite a few questions about speedos so I certainly would be worthwhile.

worth doing... if you have a mind to gordo

as rick says,, dont think the whole chain of complications and findings has been attempted before .

do you want to use some of my pics ...your welcome ...or should we create a colaboration in one single post ...in the how to section ?

personally i dont think some of my weird ideas .....especially on the soldering of the terminals etc, hold much cred . but i post the trials ...hoping to acheive some success with a fix acheived ...just hope it helps someone somewhere .

Great idea and good on you Gordo, go for it!
Regards,
K-BIKE