63' Speedo Too Slow/ Trip Too High

[Larry T.]

I have a situation where I started out trying to lower a speedometer that was running 15% fast and also a odometer/trip meter also 15% too much. I have a 4:11 that I first changed out a black driven gear to the correct yellow. Speedo came down 2-3mph and trip came down a little bit. So I went to a 4:56 (Orange)driven gear and the result is now the speedo is 10% too Low and the Trip is about 10% still too High. I know the speedo can be calibrated, but what about the Odometer/trip? Pv's require a max of 5% error. What's my choices?

[George R.]

Re: 63' Speedo Too Slow/ Trip Too High

Larry do you know if your tail shaft assy. on the tranny is orignal. Mine is off a 64 that has a steel drive gear for 3.08 through 3.55 etc. I've tried every combination plastic gear I can find and I'm still reading to slow.

I have a 67 BB coupe w/4.11. It might help if you have your box and tailshaft numbers posted like I did unless you have the orignal rear end and tranny which I don't. Good luck,grr#33570

[Michael W.]

Re: 63' Speedo Too Slow/ Trip Too High

Larry,

There is no calibration per se in an odometer. It usually works perfectly or not at all due to a stripped gear. In your case it sounds like you have two problems, one being unable to find the correct drive gear combo for the cable, and the speedo head itself being out of calibration.

To start with basics, are your tires the same circumference as the originals? This could explain why the odo reading is off even with the correct drive gear installed.

Mike