dascoupeguy
Well-Known Member
I am restoring a 72 3.0cs (referenced in this forum currently as 'the madness begins'.) At issue now is an odometer issue with the common problem of the numbered wheels apparently slipping. My speedo works fine and the trip reset works as well. The 1/10's wheel would work for about two-tenths and then quit.
I am familiar with 2002 speedos which are easy to get to the 'guts' but as we are all aware, coupes are a sealed unit. Accordingly many here on this forum have their units shipped out to a very reputable shop in North Hollywood. I called them and they stated a typical service/repair for this problem is @ $150.00.
Having a need for $150 elsewhere on my coupe, I decided to brave it out and attempt the reapir myself. The key issue is taking the mechanism out of the housing.
Somewhere in this forum a member indicate that he had wrestled successfully with the task and made reference to 'prying and twisting... and prying and twisting... and finally getting it apart.
So I grabbed a small flat tipped screwdriver and slowly began to pry back the small metal lip on the back of the chrome bezel. Be careful and patient, it is VERY soft metal. After about 15 minutes i was able to separate the bezel/inner black ring/glass assembly from the speedo housing. The large hex nut on the back was loosened and the whole mechanical assemble was easily removed.
On the side of the main assembly is a sub-assembly consisting of a worm-drive and gear and shaft housing that is attached by a machine screw. (big screw in center of the attached pic) This screw also allows for a simple adjustment for wear. This screw was loosened and allowed the worm drive to be separated from the brass gear.
To make sure that there was not an issue with the rotating numbered wheels the brass gear was easily rotated (this gear is attached directly to the white 1/10's wheel on the odo) and after lots of spinning by hand it was determioned that there were NO problems in the rotating numbered wheels (whew!)
Then that worm-drive shaft assembly was reset making proper contact with the brass gear and the machine screw tightened.
To be sure the problem was 'fixed' a DC motor was used to spin the speedo shaft (on the back side) counter clockwise. After about 5 min of 'driving 30 mph' the odo wheels were spinning and registering correctly. Problem solved!
Some light grease was applied to the worm gears and the main assembly refit into the metal housing (BTW, the flexible odo reset cable is a slip fit into the mechanism and remains on the round metal housing when taking it apart and easily refitted) and the large hex nut secured.
The glass was cleaned inside and out and the bezel, glass and black ring assembly was carefully refitted to the round metal housing.
Great care was take to slowly press back the chrome metal lip and the job completed.
Hope this can take some of the mysteries out of a speedo/odo issue you may be having.
Thanks
I am familiar with 2002 speedos which are easy to get to the 'guts' but as we are all aware, coupes are a sealed unit. Accordingly many here on this forum have their units shipped out to a very reputable shop in North Hollywood. I called them and they stated a typical service/repair for this problem is @ $150.00.
Having a need for $150 elsewhere on my coupe, I decided to brave it out and attempt the reapir myself. The key issue is taking the mechanism out of the housing.
Somewhere in this forum a member indicate that he had wrestled successfully with the task and made reference to 'prying and twisting... and prying and twisting... and finally getting it apart.
So I grabbed a small flat tipped screwdriver and slowly began to pry back the small metal lip on the back of the chrome bezel. Be careful and patient, it is VERY soft metal. After about 15 minutes i was able to separate the bezel/inner black ring/glass assembly from the speedo housing. The large hex nut on the back was loosened and the whole mechanical assemble was easily removed.
On the side of the main assembly is a sub-assembly consisting of a worm-drive and gear and shaft housing that is attached by a machine screw. (big screw in center of the attached pic) This screw also allows for a simple adjustment for wear. This screw was loosened and allowed the worm drive to be separated from the brass gear.
To make sure that there was not an issue with the rotating numbered wheels the brass gear was easily rotated (this gear is attached directly to the white 1/10's wheel on the odo) and after lots of spinning by hand it was determioned that there were NO problems in the rotating numbered wheels (whew!)
Then that worm-drive shaft assembly was reset making proper contact with the brass gear and the machine screw tightened.
To be sure the problem was 'fixed' a DC motor was used to spin the speedo shaft (on the back side) counter clockwise. After about 5 min of 'driving 30 mph' the odo wheels were spinning and registering correctly. Problem solved!
Some light grease was applied to the worm gears and the main assembly refit into the metal housing (BTW, the flexible odo reset cable is a slip fit into the mechanism and remains on the round metal housing when taking it apart and easily refitted) and the large hex nut secured.
The glass was cleaned inside and out and the bezel, glass and black ring assembly was carefully refitted to the round metal housing.
Great care was take to slowly press back the chrome metal lip and the job completed.
Hope this can take some of the mysteries out of a speedo/odo issue you may be having.
Thanks
