4th gear lockup

[Guest jcc3inc]

I asked a similar question before about lockup; I looked at a '90 and we drove it at about 50 MPH. The car was warmed up, but the tach said 2500 RPM when we were doing 50. Today I drove another and when going 50, the tach said about 1500, but seemed to vary with the accelerator.

Where should we see lockup? And when the torque converter is locked up, if one increases pressure on the accelerator, will the tach remain steady, that is it appears to be in sync with the speedometer? And if one lets off on the accelerator, will the tach and speedometer ramain "synced" together?

I'd like to know what to expect: my Camaro does lockup and tach and speedometer seem to be "synced".

Thanks for your comments.

Jack C.

[2seater]

The lockup speed may vary a little, but around 50 mph for 4th gear is about right (at minimum throttle). It will drop the lockup if you release the throttle close to the idle position. The rpm may not change much when the throttle is released as the "coast" rpm in 4th gear is around 1500 rpm, even though the converter is unlocked. If you step on the throttle again, the rpm may flare a few hundred rpm until the converter relocks. When unlocked the rpm will change more rapidly that the speedo, when locked up, the two will be change pretty much together.

[manikmekanik]

Lockup should happen at precisely 48 mph, with load on, not coasting.

@seater is right, if you back off throttle @ 50mph it will release until you apply load over 48mph.