BADSS70 Posted September 2, 2012 Share Posted September 2, 2012 I have an SS 454 with turbo 400 trany - all original. Lately, when I accelerate, the trany feels like it shifts to early and than will down shift and up shift again quickly. Any ideas of what this could be? Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted September 2, 2012 Share Posted September 2, 2012 How does the fluid look? burnt at all or cleam and red? you may want to drop the pan and see what lays in the bottom of the pan. Quote Link to comment Share on other sites More sharing options...
BADSS70 Posted September 3, 2012 Author Share Posted September 3, 2012 fluid looks clean and red. It seems like the trany is shifting from 1st to third and down shifting to second and back to third. this happens only when I am pushing the car a little hard. Otherwise it shifts in order but still it feels early. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted September 14, 2012 Share Posted September 14, 2012 I think I would look at the kick down switch located above the gas pedal. it has a slide switch that may not have continuity along its travel. Quote Link to comment Share on other sites More sharing options...
wallaby Posted September 14, 2012 Share Posted September 14, 2012 Or maybe a vacuum modulator issue? Quote Link to comment Share on other sites More sharing options...
iceman Posted September 15, 2012 Share Posted September 15, 2012 I'm thinking vacuum modulator as well. I had a similar problem with mine last summer that turned out to be a leaky vacuum line that ran to the modulator. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted September 15, 2012 Share Posted September 15, 2012 a vacuum leak at the modulator will cause higher shift points. Pull the vacuum line and the trans will not shift until it hits the governors shift points. Could that be what you are feeling? Quote Link to comment Share on other sites More sharing options...
BADSS70 Posted September 28, 2012 Author Share Posted September 28, 2012 Change the modulator and things got a little better but the problem still occurs. It happens less frequently. I am going to check the kick down switch near the gas pedal next. thanks Quote Link to comment Share on other sites More sharing options...
BIG E Posted October 4, 2012 Share Posted October 4, 2012 Governor Oil Pressure and Modulator Oil Pressure are used to control your upshifts. Strictly Governor Pressure is used to control downshifts. For a forced 3-2 downshift, there is an electric solenoid activated by a switch located either on your accelerator pedal, or it could even be on the carburetor. Since this circuit is only used to control a downshift under heavy load, I don't know if this is a primary area of concern. If the weights on the governor are sticking, it could raise the line pressure and force it to shift earlier regardless of engine vacuum (modulator pressure). Is is possible that the 2-3 shift valve is sticking? Quote Link to comment Share on other sites More sharing options...
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