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Old 05-28-2014, 06:08 AM   #1
MotorcycleWriter OP
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BMW Speedo/Speedometer Disassembly Procedure

There've been some great posts here recently on speedometer repair. Getting it apart hasn't been covered in detail yet so I'll share my experiences.

Here's the problem on my speedometer from a 1989 R100GS. The rubber cover over the trip odometer reset plunger has LONG since disintegrated which lets in water.



To fix it, I found a guy that makes them. You can get them from Henderson Precision. They carry a few neat little BMW ditties including a really neat, packable, exhaust nut wrench. (I got one of those too.) The new cover is nice and pliable and appears to be of decent quality.



The speedometer is held together by that black metal ring that is crimped around the front lip of the unit. This metal ring is fairly soft and wasn't made to be removed, but it can be done fairly easily if one takes time. The trick is to pry the ring off without bending it. I decided it would be best if the ring was supported while I pried it off. While a large helical hose clamp might work I thought a ring compressor would work better.



I didn't want to scratch the finish off of the ring so I lined the metal band with masking tape like so.



I next clamped the ring around the speedo, setting the lip a few millimeters beneath the level of the band so it would be supported during the next step. This keeps it from getting warped or scratched and it worked like charm.



As a few people have recommended, I used one of those hardware store paint can openers for the next part. This started life with a squared off end but that wasn't working so I used a Dremel tool to grind it into a sharp edge that would get under the thin metal lip.



Now you just work your way around the edge, prying up the lip. It took me about three passes all the way around to get the lip lifted up nice and straight.



Once the lip it up it is still pretty tight. I used my fingers to push it up a little at a time, working my way around the edge until it popped off. Again, not hard, just be patient. I was surprised to find that metal ring is attached to the lens. For some reason I thought it would be separate, but it does make things easier.



You'll probably find the remains of the old plunger cover still around the plunger. It should consist of a short piece of plastic sleeve with a plastic nut around it. You'll need that nut. Assemble the two pieces of the plunger cover from Henderson precision...



... and insert into the speedo lens like so, screwing the nut down finger tight. I put a tiny extra torque on it with a pair of needle nose pliers. The compression of the rubber will keep it in place.



Slip the lens and ring back over the speedo body being careful to line up the hole with the plunger. I tried the plunger before I pressed things back together and found I was having trouble getting it pushed all the way in. So, I took it back apart and glued a thin (two or three millimeters) shim to the top of the plunger effectively making it a tiny bit longer. Worked perfectly. Once I got it back together I used a pin driver and a small hammer to fold the lip back over. Again... patience...



I went around it about three times.



Very pleased with the results! No warping. No scratching. Looks like it's not been fiddled with. The seal probably isn't as good as new, however, so it remains to be seen if I get any water infiltration around that lip.



Nice having that plunger hole nice and sealed up.



From the time I pulled the speedometer to the time I was stuffing it back into the hole was probably an hour and a half, and that included finding the right tools, going down a few blind alleys, grinding the paint can opener, etc. Fairly easy job if you're patient.

MotorcycleWriter screwed with this post 05-28-2014 at 07:59 AM
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Old 05-28-2014, 10:43 AM   #2
bpeckm
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...those last three words are the key to it all!

Nicely done. I tried it freehand, never thought about the clamp around the edge. I did end up using some sealant/spooge that I worked in with a fingertip, around the underside (where it isn't seen, anyway).

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Old 05-28-2014, 10:51 AM   #3
globalt38
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Another thread for my "Maintenance and Upgrades" folder!

Nicely done!

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Old 05-28-2014, 12:08 PM   #4
disston
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It is a nice looking tool but it will not work on the early style exhaust nuts because the fins are too large on those.
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Old 05-28-2014, 06:30 PM   #5
MotorcycleWriter OP
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Quote:
Originally Posted by disston View Post


It is a nice looking tool but it will not work on the early style exhaust nuts because the fins are too large on those.
I think they sent me the wrong one... Mine has MUCH larger spaces for the fins. It still fits but only engages about six fins - sort of skipping every other fin. Not sure that's enough to get the job done. I'll have to call them...
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