* Governor Problems: The governor controls shift points. A malfunctioning governor (either mechanically sticking or electrically failing, depending on the transmission type) will cause late shifts and high RPMs before upshifting.
* TV Cable Adjustment (if applicable): Older Ford transmissions often used a throttle valve (TV) cable that links the throttle to the transmission. If this cable is improperly adjusted, it can cause incorrect shift points. It might be stretched, broken, or out of adjustment.
* Transmission Fluid Level and Condition: Low transmission fluid, or fluid that's old, dirty, or burnt, can cause improper shifting and high RPMs. Check the fluid level (with the engine running and warmed up) and inspect its color and smell. Dirty or burnt fluid requires a flush and filter change.
* Internal Transmission Problems: Worn-out clutches, bands, or other internal components within the transmission itself can cause slippage and delayed shifting. This is a more serious problem requiring professional attention. A low fluid level can exacerbate this.
* Vacuum Modulator (if applicable): Some transmissions use a vacuum modulator to adjust shift points based on engine load. A faulty modulator can cause erratic shifting.
* Computer Issues (less likely in an '87): While less probable in a 1987 model (which likely has a simpler transmission control system), a problem with the electronic control module (if equipped) could contribute. This is less likely than mechanical issues.
Troubleshooting Steps:
1. Check the transmission fluid: This is the easiest and first step. Low or bad fluid is a common cause.
2. Inspect the TV cable (if applicable): Check for damage, proper adjustment, and free movement.
3. Listen for unusual noises: Grinding, whining, or banging sounds from the transmission indicate internal problems.
If you're not comfortable working on the transmission yourself, take it to a qualified mechanic specializing in older vehicles. Ignoring the problem will likely lead to more extensive and expensive damage to the transmission.
