Shifting problem-auto

When you first start out the transmission will not shift to a higher gear and you can not exceed 35 mph(high rpms).After 10 minutes or so the car starts shifting correctly.3 mechanics have evaluated and can not correct.I noticed that sometimes the speedometer does not work but starts working when the proper shifting starts.However,usually the speedometer works from a dead stop and the tachometer works fine and when the car feels it is ready it will start shifting correctly.It is not shifting at the 10 minute range- it is now taking longer.

You have a failing automatic transmission. The problem is internal to the transmission. IF 3 mechanics independently of one another could not pin point the problem, then it is not low transmission fluid, or just a bad donut. IF this car is in warranty they owe you, if not you are looking at most likely a new tranny. You dont say how old it is, what model it is, or how many miles are on it, or what kind of driving city or road? Have you had the filter changed, is it old enough to have adjustable bands, does it have a vacume valve on it? If it is that old, you could get away with a regular servicing, but I doubt it.

Thank you for your input.1996 Riviera 3.8 supercharged.Fluid level is fine. I pointrd the vacuum possibility to the mechanics.I do not know if it has vacuum.They checked it over but had no suggestions.I hate having my young daughter get into a major tranny job.I was just hoping that maybe someone had simple fix.

What kind of mechanics are we talking about? Jiffy lube guys? General purpose repair shops?

What you need is an actual transmission shop - not a national chain shop like AAMCO or Cottman - a local person.

Is the check engine light on?

Given the erratic speedo I’m not so sure the whole transmission is doomed - it sounds like you could just have a failing speed sensor.

Find a reputable, local transmission shop and have them evaluate it, including a scan of the computer for error codes.