nuztome Posted May 27, 2010 Share Posted May 27, 2010 '83 w / 141000 on the clock. this is whats going on with it. when the car is cold, it shifts onto reverse smooth & quiet ... but after warmup, boy does it thump hard into reverse. any ideas ? Quote Link to comment Share on other sites More sharing options...
jasper Posted May 27, 2010 Share Posted May 27, 2010 What is your warm idle speed? Quote Link to comment Share on other sites More sharing options...
nuztome Posted May 27, 2010 Author Share Posted May 27, 2010 What is your warm idle speed? right on target @ 750 +/- Quote Link to comment Share on other sites More sharing options...
19762802+2 Posted May 28, 2010 Share Posted May 28, 2010 Is it an auto or Manual? Quote Link to comment Share on other sites More sharing options...
nuztome Posted May 28, 2010 Author Share Posted May 28, 2010 Is it an auto or Manual? automatic Quote Link to comment Share on other sites More sharing options...
19762802+2 Posted May 28, 2010 Share Posted May 28, 2010 Well in that case me thinks you have a vacuum problem somewhere. There should be a hardline from the intake manifold to the transmission that might be disconnected at the intake manifold. It could be the Vacuum modulator here is what a Vacuum Modulator does. It is located on the left side of the Auto trans on a Z. "The Vacuum Modulator monitors engine vacuum by a rubber vacuum hose which is connected to the engine. Engine vacuum reacts very accurately to engine load with high vacuum produced when the engine is under light load and diminishing down to zero vacuum when the engine is under a heavy load. The modulator is attached to the outside of the transmission case and has a shaft which passes through the case and attaches to the throttle valve in the valve body. When an engine is under a light load or no load, high vacuum acts on the modulator which moves the throttle valve in one direction to allow the transmission to shift early and soft. As the engine load increases, vacuum is diminished which moves the valve in the other direction causing the transmission to shift later and more firmly." Quote Link to comment Share on other sites More sharing options...
nuztome Posted May 28, 2010 Author Share Posted May 28, 2010 Well in that case me thinks you have a vacuum problem somewhere. There should be a hardline from the intake manifold to the transmission that might be disconnected at the intake manifold. It could be the Vacuum modulator here is what a Vacuum Modulator does. It is located on the left side of the Auto trans on a Z. "The Vacuum Modulator monitors engine vacuum by a rubber vacuum hose which is connected to the engine. Engine vacuum reacts very accurately to engine load with high vacuum produced when the engine is under light load and diminishing down to zero vacuum when the engine is under a heavy load. The modulator is attached to the outside of the transmission case and has a shaft which passes through the case and attaches to the throttle valve in the valve body. When an engine is under a light load or no load, high vacuum acts on the modulator which moves the throttle valve in one direction to allow the transmission to shift early and soft. As the engine load increases, vacuum is diminished which moves the valve in the other direction causing the transmission to shift later and more firmly." well thank you much. will check it out, & let you know my findings Quote Link to comment Share on other sites More sharing options...
nuztome Posted May 28, 2010 Author Share Posted May 28, 2010 well thank you much. will check it out, & let you know my findings i did find a disconnected rubber line along the front crossmember with the two metal power steering lines. any ideas on this one. havent checked under-carriage to trace the module line yet. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.