Typically, just age. Each gear of an automatic transmission is operated by one of a set of clutches or bands. When a band or clutch wears out that gear is through and the transmission will need to be rebuilt. The Valve Body controls pressures to different pistons in the transmission. At specific events the valve body causes pressure to be applied to the 2nd gear clutch piston and if the pressure is not sufficient the clutch may "slip", causing additional and premature wear. Driving a vehicle with insufficient ATF can also cause slipping and wear.
A bad transmission gear can cause your 1999 Nissan frontier to shift hard. Low transmission fluid can also cause the transmission to shift hard.
could be a worn pinion gear or bad U joint or both
Check the transmission fluid on the 1995 Nissan Altima. Bad fluid can cause the transmission to shift harder on parts that are more worn.
a bad driver?? Seriously, i could be the ECU
In automatic transmissions the second to third syncronizers always seem to go bad first, the syncronizers are worn, bad or gone. This is common in these transmissions. Also you might check your trans fluid level, sometimes a low level will cause the transmission not to shift correctly.
Bad spark plug wires affect many areas of your vehicle. However, gear shifting in an automatic transmission is not one of them.
If would not be bad for a car engine to shift from third to second gear if you are traveling at 30mph.
You need to replace the trans or rebuilted it if it's a stick shift the u have a bad gear if it a automatic then check the fluids in the trans if it good on fluid the it a bad trans or torque converter
Bad universal joint
Poor driver or bad transmission.
a bad radiator -automatic portion of radiator not cooling off transmission
1st step would be to change fluid and filter and see if any improvement