Anyone out there knows of a good shop to get my 67 speedo calibrated in the Houston, TX area. Appreciate any feed back.

 

Are you certain the speedometer head needs work? If you have changed rear end gears or transmission you could have the incorrect driven gear.

 

I have changed the tranny but the rear end is the same ratio as before. I install a new speedo cable and see the following problems.
1) The speedo needle shimmies and rattles at low speed.
2) my speed is not accurate. I find out I am running 15mph in a 30 mph school zone and keeping up with everyone else.
3) When I installed the speedo back in the dash, I ended up advancing the mileage by about 20K. Need to set that back to where it was.

I thought a speedo caliberation shop might be able to set these straight. I am not an expert on speedo issues.

 

If the speed is about 1/2 of what it should be chances are you have the wrong driven gear.
Go here: http://www.transmissioncenter.net/sp...n_______va.htm
You can figure out which gear you need, they are color coded and easy to change. Also the gears are still available from GM. Even though you have a new cable make a final check of the routing. Any sharp bends can produce an unsteady speedometer needle.

The mileage problem could be sticky. In most states it is against the law to roll back the miles no matter what the reason is.

 

Do I keep swapping gears and driving it until the speed matches or is there an easier way to get the speed calibrated. It seems like a lot of work to keep swapping out gears until I get the speed right on.

 

If you go to the link that JR posted (good one by the way), there is a chart a short way down on the right. You need to know your rear gear ratio, and tire diameter, then you can figure what speedo gears you'll need.
A jumpy speedo needle is usually from a sticky cable. You can pull the cable from the housing, clean it, and lube it up with a graphite based cable lubricant. Using oil can cause the cable to stick, and that could be your problem right there.
Pulling the odometer from the speedo is simple, it's only held in with a clip. And rolling back the odometer is just as easy, and as long as you're just wanting to put it back where it belongs, then I don't see a problem. I'm just curious how you rolled it forward, your fingers must have been in the wrong place at the right time? You can accidentally roll the numbers forward without removing it, just not backwards.

 

Guys Thanks a lot for all the good info. Sounds like I have to tear open the pumpkin to find the gear ratio as I have no idea what it is.

 

You don't need to tear it open, unless you planned on changing the oil anyway.
Jack up and support the rear of the car. Make a reference chalk line on the tire (either straight up or down). Also make a mark on the pinion yoke/u-joint on the rearend. Now turn the rear tire one full revolution while counting how many times the yoke turns. For instance, if the yoke spins approx. 3.5 times to the tires one turn, you have a 3.55 (nearest ratio) gear.

 

Thank you all for the tips. Looks like I have me a project for the Thanksgiving break.

Mark