In Reply to: HOW DOES ONE KNOW WHAT KIND OF TRANNY HE HAS? posted by SIMPLETON on December 11, 2000 at 16:37:18:
The four speed box was a top gear overdrive model, third one-to-one with several first and second gear ratios depending on model and year. The four speed boxes are geared to have no first gear and a low second, this results in poorer 0-60 times but good mid range performance. The last cars to use it were made in '93.
These gearboxes could fail if revved hard in neutral or parked, such as during emissions testing. Pressure would build up and kill the A clutch pack. After mid '87 a pressure relief hole was added in the A clutch to help prevent this. I'd advise an oil change with Dexron II or III ATF every 15-20,000 miles using good quality oil. There is also a filter screen which should be replaced every second oil change, it's under the oil pan. You'll need a new O-ring, oil pan rubber gasket and Torx socket. Clean the two magnets in the oil pan while you're at it. Caution - the oil level needs to be checked when the engine is running!
Later GM five speeds can't be refilled at home, you need special equipment. These units have a learning facility to suit the driver's mood.
All auto boxes should shift and kick down smoothly. At the first sign of slipping change the oil and filter screen. Most older units will creep forwards in Drive, live with it. Auto cars have a relay to prevent the engine starter running except in parked or neutral.
2nd and fifth gear are slipping and the pump is cavitating noticably. My local tech and Heishman are quoting $5000 to $7000 for a reman trans from BMW (out of Illinois, BTW). Does anybody know of a TRUSTWORTHY transmission shop in the DC metro area that can handle the ZF 5HP30 automatics? I'd rather rebuild my own for less $$$$ than spend $5000.
Any help really would be appreciated...