i have 1988 lincoln town car once i get up to 40 mph it wont shift gears, whats the problem

Check the transimmission fluid level. Use the owners manual as a guide.

check your trans fluid.

You probably need to have the fluid and filters changed in your transmission. There is probably some debris blocking a valve in the ''valve body''. There is also a governor that contols pressure in the valve body, that may need to be cleaned or replaced.

Either way you need to get it to the shop ASAP. Damage is getting worse every mile you drive it.

well at that speed its trying to shift into overdrive. For now you can select the drive that does not send the car into overdrive and drive it that way but you will burn a lot more gas. A car that old its not uncommon that the overdrive has failed if its a really nice low mileage lincoln its worth it to find a replacement in the salvage yard and some will install it and guarantee it.

Shift cable unhooked or broken = burnt transmission

144289 is correct. Check the ''TV'' bushing.it is a small plastic bushing on the throttle that connects the transmission cable to it. Common problem, and as he said, drive it with it disconnected=fried tranny.