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Dirty instrument-glass on inside

3K views 25 replies 10 participants last post by  MickyP10 
#1 ·
I am having this urge to have a shiny bike. I have noticed that on the inside of both instrument glasses there are spots, and even a finger print. How do I get access to the inside of the glass without ruining anything? It´s a 95 TBird. Pic attached.
 

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#4 ·
There are people who have worked around the bottom of the chrome ring with a thin screw driver and gotten the glass off, but it's hard to do without doing some damage, and doubly hard to get it crimped back down again without it looking like it has been butchered.
 
#5 ·
There are a couple of old threads on here about successfully opening the cases. I did one and Arferbrick has done one using slightly different methods. It's no picnic, but I was OCD like you and did my tach just because it was foggy inside. It basically involves carefully cutting all around the plastic case, doing whatever is needed inside, and then rejoining the case halves. The other alternative is replacement new gauges which can be had for only about $300-$400.
 
#8 ·
What I want to know is how in the blazes bugs can get into these spaces - not on a bike but a couple of our older cars. there's a dead mosquito behind the clear plastic on one and a dead, dried-up spider in another. It's almost like they had to hatch in there or something.
 
#9 ·
Ssevy: your PM mailbox is full...

You said to cut the housing in the area where the grommet contacts it (close to the glass). Any reason not to cut it farther down, where the metal cover, which has more clearance, covers it?

(My problem is the tach reads about 1000 RPM high and doesn't return to zero.) I'm thinking the spring on the needle may have come loose. I seem to recall Hondas plagued with that problem.

Do you know if the meter is a stepper? If so, maybe it's just not stepped back to zero, for whatever reason...
 
#10 ·
Sorry John,


Just emptied my inbox.


If you look at the picture of the inside of the white plastic housing in my thread, you'll see there are some other things just below the spot I cut that would be affected if you cut it lower. Maybe no issue, but if you follow my lucky guess first cut, you know it's a proven thing. No reason you can't try whatever you want though.
 
#13 ·
Here's JRobyn's pics -

http://repo.duckdns.org/pub/adventurer/tacho-repair-jrobyn/



(Images held on my server by previous permission of JRobyn - thanks again J :D)

...and here's my take on his idea -



I made it out of junk laying around the workshop and did the cutting upside down to avoid getting white plastic bits jammed between the glass and that black baffle ring thingy because J had problems with that. It worked very well, good clean cut and no horrid white bits in sight :).

The rubber band applies enough pressure, and I just rotated the whole assembly by hand till the top popped off - easy as.

To rejoin the two halves I simply used a wide packing tape instead of screws & plate - it's still holding up and when I need to rip it apart again it will be dead easy.

Make a permanent vertical mark on the outside of the housing before you cut so you can re-align it on reassembly - saves a ton of time!
 
#14 ·
OK, I cut mine open today. Made a tool much like JRobyn's. I cut 11/16" from the face and it was just about perfect; just below the face and above all the bits molded into the case.

An aside: the needle was stuck at 800 RPM. (I know it was not stuck the other day when I ran it, but it was off by 800 - 1000 RPM.) Anyhow, when I pushed on it it "snapped" free. I had to reposition the needle on the shaft to get it to read zero. Now it seems to work fine. I have not been able to get it to stick again. I'm always leery of things that "fix" themselves.

The only explanation I can come up with is it somehow got knocked out of place with all the banging I did trying to free the top triple clamp a few weeks back.
 
#18 ·
Cutting it open wasn't an issue. Did the needle itself break or the shaft? I've heard of people making a new needle from the plastic in a CD case and gluing it on, but the shaft and the part of the needle that attaches to it have to be intact.
 
#20 ·
I tackled this project yesterday and much easier than expected. My speedo needle broke off so getting that fixed was my main goal. But since it went so well, I opened up my tach as well since mine had smudges on the inside like yours.

Unlike some others that set up a jig to get a precise cut, I freehanded with the cutting wheel on my Dremel and it was literally like a hot knife thru butter.

Because the cut was not going to seen, I didn't see the need for perfection. And like another suggested, I used tape (black electrical) to join the pieces back together to allow access in the future if needed.

Beginning to end, not counting the time for the glue on the speedo to dry, I'd say it took me an hour to do both.
 
#22 ·
My concern with the tape is, when you tighten the nuts on the bottom of the case it puts tension on the tape. If the tape eventually fails the black cover and bottom half of the instrument case will fall off. I used Loctite plastic epoxy on mine. If I have to cut it open again, so be it...
 
#23 ·
Certainly a good point but there was not much torque put on those bottom nuts so I don't see much chance of separation but if it happens, I'll certainly let everyone know. I'm just thrilled to now be able to look at my tach thru crystal clear glass (yeah, I know that there is OCD therapy available).
 
#24 ·
I should have done some step by step photos but it really was so simple (really, if I can do it anyone can) that I didn't see the need.

But, here is the finished product. Only thing that bothers me a bit (OCD remember) is that the glue I used (Gorilla glue) mushroomed a bit so you can see the blob under the splice.

And just to explain how the fix was done, I glued a small piece of wire to the underside of the broken off needle. Then drilled a very small hole in the "hub" just below the still intact needle stub. Inserted the wire into the hole with a dab of glue and mission accomplished.
 

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#25 ·
Thanks to All who have pioneered and shared such good information on this method of repair. Because of it I was able to fix my tacho after an unfortunate failure. I used a hot blade to cut it open and then epoxy to stick it back together.

Noting mine’s failure as ‘unfortunate’ because it has always worked fine (the needle does flutter a little but I think it kind’ve adds to the bike’s charm) however the two tiny screws which hold the clock face (the piece with the numbers printed on it) in place vibrated themselves loose. When both screws eventually dropped out they left the clock face free to swivel around which pretty much rendered the tacho useless - will attempt to include a picture of it prior to being repaired.

Thanks again
 
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