[quote=ho428]I do it all the time on the race car, chock the front wheels fore and aft, both sides, don't get the rear to high.

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I've let mine run for 20 minutes forward and reverse to run in a new rear gear.

This will not break in new gears properly...just so you know. You need the weight of the vehicle to create the heat you need for breaking gears in. This heat and the cooling effect in the oil is what rockwells the gear set properly. To break in drag race gears IF the car is track only... take it down the strip 2 -3 times... first one soft hit and run it to the end (1/4 or 1/8). let it fully cool. 2nd run, little harder on the line run it down the track again ...let fully cool you should be good to go. If you can cut the trans brake do so if you have to use the trans have it hit at a lower rpm. Jim