When I bought my '68 a couple of months ago, the speedometer worked, but the odometer did not. Snow came for real this week in Iowa, so the interior is onits way out, and I pulled the driver's side instrument panel to address the odometer tonight.

The speedo/odo is dated 1969, so I assume it's not the original...mileage is utterly unknown. I disassembled the whole unit and found the problem (worm gear not meshing with the cog that turns the odometer), fixed it, and reassembled.

Now the problem:

In order to disassemble, it was necessary to remove the speedometer needle from the TINY pin that it rotates on. Now I'm having a devil of a time re-mounting the needle in the proper position, i.e. such that it sits at 0 mph, will move easily to 160 mph, and easily move back.

Has anyone who has done this before can steer me in the right direction? A speedy reply would be great, I'd like to get this finished tonight if possible.


-Roy

 

You may be S.O.L. It will have to be calibrated by driving the shaft at a given speed and adjusting the unit in order to get an accurate reading. It has a slight preload on the return spring, and there is little chance of getting it back exactly the way it was.

 

The '68 speedo cable screws on to the the back of the speedo. I believe later years the speedo cable clips on. Can't help with the loose needle. You might try Bob's speedometer shop in Farmington, MI. They advertise in Hemmings. He does all sorts of instrument restorations for vintage cars.

 

Maybe I can help...First of all if your speedo cable screws on instead of clipping on (1969 did this) the Speedo is correct ....The Gears if you fixed them yourself without buying new ones is a bit puzzleing to me but if it works ok ......now to your real problem........
The Speedo is calibrated using magnatism so you should be ok if the speedo was reading correctly before...there is a load arm in the back,its where the little cirle spring is...Don't slide it in any manner for this will mess with you calibration....The Needle is on a Taper Shaft ...its small so becaeful but Place the needle on firmly at lets say the 30 MPH mark and while pressing on it turn it counter clockwise down to the 0 mark then lightly tap it with the handle part of a screwdriver or whatever..this should get you there...take the needle with you hand and push it up and see where it stops if it doesn't stop right on the 0 mph mark do this again ....The proper way to remove and install these needles is to twist and pull off and twist and push on .

Hope this helps

Jason
Vetteinstruments@aol.com

 

Update: Clearly this is not the original speedometer, the cable clips on.

I'm a little pessimistic about the gear that meshes with the worm gear on the shaft that the cable turns, it appears to be worn, but at the moment turns as it should.

I took everything apart again and VERY carefully cleaned the "flywheel" and housing around the magnet, after which on reassembly the shaft turned freely and had a firm, correct positive stop (for 0mph) and unrestricted movement through 160mph, with no more catching or hanging up. The needle is correctly re-installed, and all that remains is to wait for spring, go for a ride with my friend's GPS unit, and see how well my speedometer agrees with the multibillion dollar satellites.

Question for JOliver: If that blasted little gear is in fact worn beyond functioning consistently, can a replacement be purchased? Even if it can, I'm not sure how it could be installed without stretching that delicate little spring unacceptably...I just hate to buy a whole new speedometer if I can avoid it.

Bottom line: it took a couple of hours of fiddling, but now I know exactly how the beast operates, and could do it in 20 minutes the next time, just like a hundred other things on this project. Have fun tinkering!

-Roy

 

Sent you an IM


Jason