1967 DeVille Speedometer Drive

[ccd3]

I'm in the process of buying parts for the speedometer drive of my 1967 DeVille. Anyone remember how many teeth and/or the color of the speedometer drive gear? Just trying to front-load the part order before I begin the job.

Thanks,
Carey

[savemy67]

Hello Carey,

According to the '67 Shop Manual, your car would have been originally equipped with an AA TH400 transmission.which would have used either a 38 tooth/blue gear, or a 41 tooth/yellow gear.  Each gear uses a different sized sleeve (into which the gear is inserted, and which in turn is inserted into the transmission case).

If your car was originally equipped with Automatic Climate Control, then the transmission would have used the 41 tooth/yellow gear.  If not equipped with ACC, then the 38 tooth/blue gear would have been used.

Christopher Winter

[bcroe]

I'm in the process of buying parts for the speedometer drive
of my 1967 DeVille. Anyone remember how many teeth and/or the color of the
speedometer drive gear? Just trying to front-load the part order before I begin the job.
Thanks, Carey

What happened to your original gears?  The frequent speedo drive gear is 17 tooth;
the driven might be as Christopher said. However it will depend on the axle ratio as
well as the pair to be used in the trans, not to mention the tires.  Even tires with the
same rim size can have a different "rolling circumference", esp if going from bias to
radials. 

The most accurate way to set up the speedo, is first measure very accurately the
error now.  Then pull the trans gears, note the ratio, and set up a pair with a ratio
that will just cancel the error.  good luck, Bruce Roe

[ccd3]

Thanks for your advice. It was the yellow gear as advised. Thanks to your help, I was able to pre-order a new gear (the old gear was worn and letting ATF through the seal) and get the everything buttoned up properly. I just couldn't remember what color gear I had... it's been a few months since I opened it up.

As a side note- I twice replaced seals in the drive only to have the the drive continue to leak. The only part I never replaced was the plastic drive gear, itself. Apparently 50 years of use finally wore it down.

Carey

[bcroe]

I twice replaced seals in the drive only to have the the drive continue to leak. The only part I never replaced was the plastic drive gear, itself. Apparently 50 years of use finally wore it down.
Carey 

As I drive them past 200,000 miles, I see a groove worn in the plastic gear shaft
which prevents the seal from doing its job.  Maybe a second seal farther out on
the shaft would work, haven't proved that yet.  Bruce Roe