GM 4T60 and 4T60-E units commonly display negative shift characteristics that can be traced to excess wear at the 1-2 and 2-3 accumulator piston pin bores. Slipping, flares, and soft or inconsistent shifts often result, followed by burnt 2nd and 3rd clutches. Extreme cases will cause a loss of 2nd, 3rd and/or 4th gears. Restore hydraulic control and banish sloppy shifting by reconditioning the pin bore and installing Sonnax oversized accumulator pin 84573-02K.
Contact a Sonnax Parts Distributor.