Hi guys

so I recently picked up a 94 Ford Thunderbird and I notice after a few days of driving it that the speedo is off by 5-10 mph, it’s not really a big deal to me except when I slow down to turn it stays in drive at 20 on the gauge and it Luggs in that gear

should I be concerned or is it ok for it to do that? And how would you go about calibrateting it?

 

There could be more than one problem.
Check the speedo drive gear where the cable attaches to the trans.

If trans downshift linkage is not adjusted correctly it will not downshift like it is supposed to.

 

Check the vehicle speed sensor.Not sure but if your Bird only has one,it will affect both the speedo and the way the transmission shifts.It is either mounted on the differential or on the transmission tailshaft(or both).You didn't mention what engine you had.
https://www.rockauto.com/en/catalog/...d+sensor,10634

 

Looks like another first time post, run and hide.