Consolidated Vehicle Converters
Issue link: http://read.uberflip.com/i/1376224
CONSOLIDATED VEHICLE CONVERTERS QUALITY • SERVICE • SATISFACTION Expect the Best 120 GENERAL MOTORS 4T65-E 258mm Piston Deflection \In 4T65-E 258mm converters it is common to see the piston deflected so far forward that it makes metal-to-metal contact with the cover. In some cases the piston will be forced against the cover so severely that it actually takes the shape of the cover. The piston deflection results from high apply pressure and the root cause of the high pressure can be traced back to the TCC regulator valve. TCC apply oil starts as line pressure, and becomes regulated apply oil at the innermost spool of the TCC regulator valve. Bore wear in this area will allow full line pressure to cross leak into what should be regulated apply oil. High line pressure, in general, can also lead to high TCC apply pressure. High line pressure raises 2nd gear oil pressure, which can increase TCC solenoid output; forcing the TCC regulator valve to the full inboard position. This introduces full line pressure into what should be regulated apply. Elevated line pressure can be caused by many conditions including fail safe, or any of the system protect modes. One option for the torque converter rebuilder is to install a billet piston, but the best way to fix the problem is to educate the transmission rebuilder on how to restore the integrity of the TCC apply circuit. In the 4T65-E transmission, the actuator feed limit (AFL) valve bore wears first, followed by the TCC regulator valve bore and the TCC control valve bore. Some 4T65-E transmissions have a TCC apply blow-off ball, which presents another option. The OE relief point for this blow-off is higher than the pressure needed to bend the piston. An aftermarket solution is available to lower the relief point to a safe level. Article courtesy of TCRA 4T65E CONTINUED Please verify proper converter replacement by OEM STICKER / CODE BU21 (SERIES) DIA SPLINE PILOT HUB MTG CLUTCH 10" 27 .825" 1.787" NO DRIVE 3 PADS YES NO DRIVE ON HUB WITH INNER BUSHING 9 1/2" BOLT CIRCLE BU21C KEVLAR TYPE CLUTCH UNIT BU21W WOVEN TYPE CLUTCH UNIT BU29 (SERIES) DIA SPLINE PILOT HUB MTG CLUTCH 10" 27 .825" 1.787" NO DRIVE 3 PADS YES NO DRIVE ON HUB WITH INNER BUSHING 9 1/2" BOLT CIRCLE BU29C KEVLAR TYPE CLUTCH UNIT BU29W WOVEN TYPE CLUTCH UNIT BU30 (SERIES) DIA SPLINE PILOT HUB MTG CLUTCH 10" 27 .825" 1.787" NO DRIVE 3 PADS YES NO DRIVE ON HUB WITH INNER BUSHING 9 1/2" BOLT CIRCLE BU30C KEVLAR TYPE CLUTCH UNIT BU30W WOVEN TYPE CLUTCH UNIT