The motors will be used as wheels. I dont need speed control (although it would be nice) but I do need forward and backwards
can anyone post a schematic?
The simpler (but less elegant) solution is to make an H-bridge from two SPDT relays. See http://www.engg.uaeu.ac.ae/departments/units/gra/presentation/nd_05_06/Final%20Pres%20ss05.06/Final%20Pres-M/Mech/MEM2-1/website&poster/Website_template/projec15.jpg
for the schematic. This gives control of direction but not speed. You will probably need to use transistors to drive the relay coils, and don't forget to connect diodes across the relay coils to catch the back emf when they are turned off.
The problem with using an L298n in this application is that the 5A stall current is too much for the L298, so you would need to implement current limiting. Alternatively, connect both channels of the L298n in parallel (which gives you 4A maximum DC current rating) and connect a power resistor of 0.6 ohms or more in series with the motor, to limit the current to 4A. However, current limiting is still a good idea, otherwise you may burn out the motors if they are stalled for a long time (of course, this applies to the relay solution as well). One possibility is to use a 0.6 ohm or greater power resistor as the current sense resistor (instead of in series with the motor) and to monitor the voltage across it using an analog input.