Q: transmission doesn't shift at higher speeds ~ 60mph on 1992 Volvo 940

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the transmission is shifting at lower speeds but when i am traveling at 60mph, it won't shift. sometimes it will begin to shift after i have been driving for 20-30 minutes. Shifting has been difficult for a while but i use to be able to get it to shift but letting off the gas and then accelerating.
(3) Answers
Have a shop check your transmission kick down cable and make sure it isn't sticking. These commonly fail on the Volvo 240, 740 and 940's. If it does need replacement, they will have to remove the transmission pan, so have them replace the Automatic Transmission Filter at the same time, this should take a few minutes extra to do, so little or no labor should be charged for replacing he filter.
ihave a 1992 buick roadmaster5.7l v8. the transmission wont shift after about 40 mph. what can i do to fix this?
I had this problem also. There could be several reasons but after consulting with a transmission specialist the best way of rectifying this was to do an overdrive bypass. It does not actually fix the problem but the car functions without the use of the overdrive disengage button on the gear changer, which is near useless anyway.