Thread: Can someone school me on this

The transmission vacuum modulator valve determines how much load is on the engine so the transmission can shift properly. It has a vacuum line that connects to the intake and measures the amount of vacuum in the engine.

High Load vs. Low Load

• In order to determine if whether transmission should shift, the modulator valve measures the load of the engine's vacuum. Engine load is the measurement of how hard an engine works at any given moment. For example, coasting down hill will create a low engine load, while driving uphill with two passengers and a trunk full of luggage will create a high load. Thus, shift points for the transmission are figured according to the valve's measurement.
  
  

How It Works Within the Transmission

• The modulator valve is a part of the transmission vacuum. Inside the canister of the vacuum modulator, the valve works with a diaphragm and a calibrated spring to measure load. When the diaphragm senses changes in engine vacuum because of load changes, the diaphragm pushes against the valve while the calibrated spring moves against the movement of the diaphragm.
  
  
  

Potential Problems

• If the modulator valve is not working properly, the transmission will not shift properly. These problems can arise when the hose connecting the transmission to the engine vacuum cracks or burns, or collapses onto itself.
  
  

I pulled that from a website.

The 4T60e is just very weak in general, its internal parts plus the fact that its vacuum assisted makes it hardly able to hold up to the 200 crank hp of the car. But thats if you hot rodding the car.

I've seen many of them go over 200k miles from being just a daily driver.

The 4T60 is nearly the same trans as the 4T65. The major differences were the change from a mechanical shift pressure mechanism (modulator) to an electronic soleniod (EPC which fails more than the vac ever did), a larger diff in the 4T65HD, a pump capable of higher rpms without cavitation, and a 4th clutch hub that was known to strip easier. Those were the 4T65 improvements in a nutshell.

Not sure where Cam gets the part that it's fragile, it's not.. it doesn't like high rpm though.

Its junk bill, trust me I'm a doctor.

LOL.. I trust ya Cam.. I trust ya.

I've seen the guts of both and also don't think that 97 was a bastard year either. Especially since the motor was in use for many years before hand..just not in a Giant Pile