Dismantling a stock R65 speedometer

[MatthewH]

Hi all.  I'm new to the board, just finding my feet with BMW bikes generally.

I picked up a used but intermittently working stock Motometer R65 speedo for my R65 project.  It's the 110 mph variety - odometer and tripmeter both function fine but the speedo needle itself works in an upwards-only direction and doesn't come back to rest at zero upon deceleration.  I've not had it fitted to a bike yet, only a power drill to turn the mechanism.

I conclude from this that it must be sticky or dirty somewhere inside, but I need to get into the casing to investigate.  From what I can see, I am going to have to prize off the metal bezel/surround to get the glass off the front and then, having undone three scews in the back, lift the mechanism out, face-first.   Am I right?  Seems to be the only way.   I did this once to a Porsche 924 speedo to replace the odometer gear, I seem to remember it being a total pain in the arse.  If there's an easier way I'd love to hear it, or any general tips from someone who's done this before.
Thanks all!

[montmil]

Ain't no easier way, Matthew. Go slowly and carefully, taking tiny bites. Other inmates may have thoughts about your internal issues.

Welcome the the R65 Asylum. Lots of your fellow countrymen are sequestered here. Post up a photo of your Airhead when you get a chance.

Monte

[tvrla]

Welcome, Matt! Anyone into Porsches and beemers has good taste!

And to work on them himself - you sound like one of us!

I've made a little pry bar out of a small screw driver, otherwise it can be difficult getting under the metal. It's a good idea to support the outer surface of the bezel when prying, otherwise the whole thing will splay out, rather than the lip move upward. Consider this - when metal is folded it becomes work hardened. It doesn't want to straighten out. Prying on an edge to straighten it out only warps it out of shape in other areas that weren't work hardened. So, the solution is to support it in the areas you don't want it to move (around the outer rim and especially at the bend).

And you're right, removing the screws on the back allows the mechanism to then come out the front. You'll want to dismantle the input drive from the housing, then the magnet with its housing. Clean everything very well, especially the bushing in the center of the magnet. Apply a drop of clock oil or high viscosity gun oil. Also clean and lube the needle shaft bushing just below the coiled brass spring.

When re-assembling, be very careful about getting the needle shaft end into the magnet bushing. Be gentle. I've never broken or damaged one, but sure wouldn't want to take the chance! Those things are really thin - about the size of a pin.

And be careful of the needle - it's very delicate and made of aluminum the thickness of a beer can.

[bruce_launceston]

First try and get some lube onto the white nylon bevel gear that you can see in the back of the speedo after you remove the cable. I think there may be a tiny screw and a fitting that comes out for better access. Give it a spin with the drill and see if it improves the operation.
It worked for me and stopped the needle flicking around like a mad thing.

If that doesn't work wirespokes seems to have the hard bit covered!

[tvrla]

For sure - if you're in there, take it all apart, clean and apply fresh lube! I only mentioned the high points.

[Barry]

This topic came up on the airheads list recently and there are some good photos courtesy of Rob Kleinschmidt which may give an insight


https://picasaweb.google.com/rob.kleinschmidt/BmwSpeedo

[Julio A.]

I used this page as a guide when I did my speedometer

http://www.airheads.org/content/view/160/98/

When it comes to the speedometer assembly itself, the ones on our R65's are the same.

Just a word of warning, use a grease with good long term qualities like super lube or white lithium.

My Speedometer clonked out because the PO rebuilt it before and used a very thick grease which hardened in time, making the main odometer gear slip on it's shaft.

[tvrla]

Those are excellent references!

I will comment on the first picture Barry linked from Rob Kleinschmidt. He's using the screwdriver to lever the crimped-over metal away, which causes the bezel to expand in diameter. If a new bezel will be used to close it all back up, then there's no problem. However, to reuse this one after 'expanding' it that way it'll never bear close inspection as there's no way to reduce it's diameter again. It'll probably work fine and hold everything together, but will show signs of having been opened.

I'm not a fan of epoxying that drive gear. Never tried it, but it just doesn't seem epoxy is that strong in shear. Perhaps in this application it's over the top, I don't know. Any of you tried it? How long has it held so far?

[MatthewH]

Well I am inside the casing successfully and have the mechanism out of its tin can. So that's progress.  The problem seems to be that the speedo needle is able to move backward and forward as well as rotate round its dial, so if you grab it (gently) between two fingers you can pull it in and out about 1 - 1.5mm, and you can see the shaft doing the same.  When it's pulled outwards, the needle settles nicely back to its stop post in a smooth linear motion.  If the needle is pushed in, it sticks and stops or fails to move at all when the drill is used to turn the drive mechanism.  It's a weird fault.  It feels as though something on the needle shaft is not fully in position, or worn, or maybe just very dirty.

I don't think I'm going to fix this without completely taking apart the vital organs, so I'm going in!  The pictures you linked me to are a great help thank you.  I'll report back...

[Julio A.]

Have you already removed the magnetic drive at the back of the speedometer needle? I noticed that the play perpendicular to the needle shaft does seem to increase when that part was removed.

[tvrla]

Julio - no, he didn't have the speedo apart as of the last posting.

The play is normal, though maybe not quite that much. The problem is the needle shaft has worn down where it bottoms in the magnet bushing. Because of this, the speed cup now hits the magnet - or, after re-reading your post, it's quite possible the lower part of the needle shaft may be missing.

Not much else it can be.

[Julio A.]

Julio - no, he didn't have the speedo apart as of the last posting.

Oh, sorry. My Bad.

The is no other reasons for the needle to have excessive play other than the one wirespokes specified.

[tvrla]

I think the normal play is probably a millimeter or two - that's only .040 to .080". Not very much!

And then consider that the shaft can wear .020" and cause all these troubles. You won't be able to feel the difference - it has to be measured with a caliper.

Even once you've deterimined the shaft has worn short it's not easy adjusting the distance. I've got a special press for that particular purpose - how do you apply force to a shaft that's only2mm in diameter? I guess you could clamp it in a vise and attempt to move the speed cup .020". That's about the only way I can see doing it.