My '89 740 16 valve jerks abruptly when I shift into reverse or drive from park. ' Just wondering why it does this. The car's idle speed is fine as well. The driveshaft support bearing is bad, but would that cause the jerking?

Thanks,
Dave

Have a '90 740 B230 that started engaging harshly in Drive but not so much reverse. After checking the throttle pressure cable adjustment about three times, I took the valve body down, replaced the accumulator piston o-rings, and replaced the valve body gaskets and check balls (some are plastic). I found some wear on the separator plate between two holes that restrict pressure under certain conditions. I put it all back together and it was smoother for about two minutes. I wish I had used Mobil synthetic ATF but I added BG Products trans conditioner (was not previously a believer in additives). After a little while it made a difference. Some say synthetic makes a huge difference. Did not solve the problem completely but it improved greatly. Would love to be able to buy a new separator plate and selector piston just to try, but the hesitation engaging Drive is almost gone and the harshness is at acceptable level. And I have no idea where to get new valve body parts. Got used one from junker but it was corroded and plates were etched and unusable. The cheap way is to change the fluid by one way or the other and try either synthetic fluid($5 qt.) or use the additive.

I'm guessing those valves are on the tranny somewhere?Did you refer to a shop manual to do this? If I could get these parts new, I'd be tempted to go that way. None of the local auto parts stores around here sell synthetic ATF, but I noticed that IPD sells Redline synthetic. Where can I find Mobil ATF?

Thanks for your help.

Dave

By the way have you been able to look at the center support bearing when it's shifted. Don't forget that it may amplifying the problem. I still recommend the synthetic. It's compatible with conventional as you make the change. My 850 loves it.

You just wanna make sure the kickdown cable (throttle pressure) is adjusted. You can disconnect the cable at the engin end and make sure that it is free and not binding when you pull it and then release it (hold the cable and don't let it snap back. You will hear the bellcrank in the trans click as it contacts the stop. It's possible the cable is frayed and binding in the housing. If you're sure it's OK, then change the fluid. You can do that by taking the return line off at the radiator and putting a clear tube on it to a container. Crank it and run till bubbles come out and shut down. Put in three quarts and repeat until it looks clean. Caution! Some people say they experience problems after a flush. I drained it all when I took the valve body down. Fluid drains for a long time and then fill it with about 7 quarts. The easiest is to just start draining the 3 quarts out thru the plug and refill. It will eventually be clean. Everything else is definitely inside the transmission. The throttle pressure cable is the only easy thing that will cause the symptoms besides the fluid.
Autozone carries the Mobil I.