Torque Convertor Lockup

[Doutdoor]

I recently had the 700R4 trans. rebuilt in my 92 with a new 2500 stall torque convertor installed. After I got the car back from the shop I was experiencing a problem that I thought was slipping but actually was the torque convertor engaging into lockup at about 48 mph. The rear gears had been changed out in the car to 3.54's from 2.59's prior to the trans. rebuild. What I finally discovered after discussing with Jeff from the forum here, is the custom PROM could be recalibrated to change the convertor lockup to a higher speed. So the convertor lockup was raised to 52 mph so it wouldn't engage during most normal city cruising. The problem is I just don't like it at all. Has anyone experienced the same thing from doing the same mods and is there a way to lessen the effect? It makes sense to me that you'd want the convertor to lockup, but I didn't notice this lockup effect when the car had the stock gears & convertor. Any ideas and/or feedback would be appreciated.


Thanks

 

[Eagle85C4]

On the drivers side of the tranny is a 4 wire plug. Two of the wires control the lockup soleniod in the tranny. Mid-America and Ecklers sell a switch you can install to keep the ECM from turning the soleniod on and sticking the converter in lockup.

 

[grapeknutz]

I too have a 92 LT1 and I have a chatter which I narrowed down to the converter clutch thats chattering just before it kicks down and disengages the converter clutch. It seems to be a problem on this type of trans.

 

[drags1998]

While I am not a transmission expert,Iwill try to explain whats going on.When you raise the stall speed of the converter,you introduce slippage into the drivetrain.When the car is at 40-55 MPH(depending on rear gears,throttle pos,and a few other factors) with a stock converter this slippage is minamal,with a high stall converter, it is slipping a little more,When the converter goes into lock-up, the RPM's drop a little more harshly. I would recommend if this really bugs you,leave the shift lever in 3rd. gear until your at or above the rated stall speed of the torque converter.Then shift into overdrive.This should take of your problem!I suspect the only other way to take care of this is to re-install the stock converter. Good Luck,Paul t

 

[jpanek]

grapeknutz,

I had the exact same chatter when I bought the car. After changing out to mobil 1 synthetic ATF, it hasn't happened since.

 

[grapeknutz]

Thats good to know! Thanks