Rear Gearing for my 440/727 upgraded '69 Coronet : LUSENET : MoPar Fun : One Thread

Just wanted to get an opinion on my situation... I've got a '69 Coronet which now has a mild 440 (Crane HMV 284, I believe, hyd. cam; Edelbrock 750 Performer carb and Performer 440 intake; and 1 3/4" headers with dual exhaust), rebuilt 727 with no mods and stock converter, and an 8 3/4 rear. I've got a 489 case with what was suppose to be 3.23's with Sure Grip. Now, when the car is off the ground and one rear tire is rotated in one direction, the other tire turns in the opposite direction... which last I heard means an open rear. Am I right on this? When I ran the car at the track, I didn't have someone lookin' out for me to let me know if both tire were spinnin' or if one was goin' to town while the other one was sleepin :) This brings me to the whole point of this post - the car was shifting into top gear just about the end of the 1/4 mile, which seems to me to mean the gearing is a little long. I'm running 325-50-15's on the rear (basically a N50). I haven't pulled the pinion carrier to confirm the gear ratio and I tried the "spin the driveshaft and count the tire revolution" trick, but it didn't seem to add up to me. If the car is shifting into top gear all most at the end of the track, do I really have 3.23's or are they taller than that? Cause as it is, I'm not getting any traction off the line (open rear?) which must be contributing to my problems. I was laying down 2.55 60 foot times (ack!!). So, what's your opinion? I don't want to pull the pinion carrier until I have to. Do I have 3.23's and no Sure Grip? If so, I don't plan on doing much street driving and would like to gear it for the track - what should I go with? It's my first Mopar and I love it!!! The Mopar family is like no other...

-- James Manifold (, November 28, 1997

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