It so happens I've been studying/working on/swearing at my BJ8's speedometer
extensively for the last few years (got
tired of dropping $200 at the speedo shop). I'm not a hexpert, but I've
learned a lot.
If the bounce is 'rhythmic;' that is, the needle is steady then pops at an even
period--particularly when the odometer
or tripmeter increments--it's probably a cracked or stripped odometer or
tripmeter drive gear, respectively.
If it's more or less random--and since you have a fresh cable and angle
drive--it's probably due to some resistance in
the mechanism. There is a surprising (to me) amount of resistance to the cable
even in a properly functioning speedo.
Anything that adds to that resistance will cause the cable to wind up slightly,
then when you're past the resistance the
cable snaps back and bingo--a bounce.
Remove the cable at the back of the speedo, insert a small screwdriver and turn
it (you can do this with the speedo in
the car if you're a contortionist). It should turn smoothly through 360deg--if
it binds at all you'll need to pull it
out and inspect the guts. There's no mystery--no 'jeweled bearings' etc.--just
a small shaft that looks like a
miniature camshaft that drives the magnet carrier. The magnet pulls the drag
cup, which turns the needle. The odometer
and tripmeter are driven by two gears off a large spiral gear on the shaft.
I don't want to start a debate on the best lube for the cable--I use silicone
oil; graphite is good but messy, and light
grease is OK but might gunk up over time. Dry is probably just fine, too.
I've attached a doc that might help.
Bob
On 5/1/2011 6:51 AM, Ron Ray wrote: ..
--
*******************************************************************
Bob Spidell San Jose, CA bspidell at comcast.net
*******************************************************************
[demime 1.01d removed an attachment of type application/pdf which had a name of
Repairing Speedo-2002.pdf]
|