grinding noise please help

[scheffler]

ok got new motor in runing all goodbut on the way home little affter got on freeway noticed grindingstoped to check to look for any thing nothingit sounds like if you had bad brakes that were just grindingonly does it when i move forward and backward rpm doesn't matterwhen rolling slow it feels like i am rolling on a circle with a flat spot thinking it could be diff just put in 300zx with j30 axles or maybe drive shaft hiting something going to look at it today just wanted to see if anyone had some advice thanks

[sensibleS13driver]

sounds like something is rubbing where its not supposed to be rubbing. check all the brake/wheel clearances. take off all the wheels (separately) and make sure the rotor turns freely in the hub, could hint at a bad bearing. i know theres something about abs diffs having longer output shafts which could maybe lead to some rubbing or grinding.check the whole driveline and make sure its all smooth.good luck

[scheffler]

well i had the diff in for like a week and a half before this happend would it take that long to present a problem? yea i plan to just jack it up and check everthing just was looking for some remarks from other people any one else have any let me know

[sensibleS13driver]

the ring gear on the diff could have become damaged within the last week which would make a noise each time the damaged part of the gear passes

[scheffler]

that would suck but would that cause it to alwasys make a griding noise?