My friend's rear end with a 3.23 gear just broke. I have a 3.27 rear that I am selling to him. He has an 85 IROC Camaro with the 16" rims. Will he need to switch speedometer gears? Or will it not be off by that much. Thanks in advance.

Probably not, it should be plenty close enough.

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"So many Mustangs, so little time..."
ICON Motorsports

X84,

There is a 1.2% difference in the gear ratios. At 60 MPH the indicated difference in the speedometer would be 0.74 mph less with the 3.27:1 gearing. this si sroughly the equivalent of the difference created when new tires wear down to the point of replacement. The diameter change is more significant than the differences in your gearing. If you really want it to be dead-accurate, get tires that are ¼" larger in diameter.

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Later,
Vader
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"Let the bodies hit the floor!"
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Don't even worry about it, its not enough to make a difference.

I thought the factory only had a very limited combination of drive/driven gears anyway, and thus 3.23 and 3.27 cars have the same set as you can't match it any closer. Same w/ 3.42 vs 3.45s. I could be wrong though, i've never really looked at the speedo gear selections.
...ed

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Ed Maher - Moderator @ The Carb Board
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Ed, you are right. The difference is smaller than the smallest change you can make with a speedo gear change.

Do as Vader said and get one size larger tires.