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1985 4 + 3 transmission

My transmission will not stay in overdrive. It has gotten more sensitive over time. Originally it would kick out of overdrive with fast acceleration or by using rocker switch. Is there an adjustment for this? Steve Meillier

Submitted by: Steve Meillier

 

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Wish I could help but I need a lot more information. I’m assuming it’s a Vette but what year? What engine? What transmission? Is it 2 speed, 3 speed, 4 speed, 6 speed, 8 speed? Depending on the year and transmission it could be a basic throttle valve adjust up to reprogramming a computer. But one thing is universal among all automatic transmissions --- hydraulic pressure. Every automatic transmission relies on hydraulic pressure to perform shifts and if that pressure is not right the transmission will not shift properly. So no matter year make model, etc. the first test is a line pressure test. Line pressure testing determines if the transmission is mechanically sound and can produce the right pressure for it to work right. I always start with line pressure so I don’t waste a lot of my client’s money trying to fix or diagnose a transmission that will never be right without internal repair. Posted by Administrator on 2/29/2016 4:27:28 PM
Thank you for the advice. Steve Meillier on 11/30/2014 2:20:24 PM
If the coolant temp gets below 185 degrees, the overdrive will drop out too. I had a failing thermostat, and after replacing it, everything was AOK....Hoping for the best Michael Bondi on 2/5/2014 5:14:31 PM
Sounds like worn synchro. No adjustment that I know of. Overhaul transmission, replace synchros. Master Certified Vehicle Inspector on 4/16/2013 9:32:50 AM
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