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I bought used "3.55's", but am starting to think they may actually be 3.73's.

My car: Stock 16's, 245/50/16 tire, 5 speed ... and I just went to the track for the first time and finished at ~102mph at about 4900 rpms in 4th gear.

What do you guys think?

According to the corral tech calc., w/ 3.55's I should be around 4750 rpms and w/ 3.73's I should be around 5000 rpms. Is there any other way to tell?

Thanks,
Andy
 

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hey hey

pop the cover off the diff, count teeth and do the math. Divide the number of ring gear teeth by the pinion teeth. Then you'll know for sure.
 

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put you car in the 1:1 gear. i'm not sure, but i think it's 4th for 5 speeds. then go 80MPH and what ever RPM you are at is what gear ratio you have. if it is closer to 3550 then it's a 3.55 and if it's closer to 3730 then they are 3.73.
 

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EASIEST WAY!!!

jack up the back end.

spin the drive shaft until the tires make on complete rotation.

if you have to spin the drive shaft 3 and a half times = 3.55
if you have to spin the drive shaft 3 and 3/4 times = 3.73
 

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same here

Yeah I had the same kind of question because I thought I had 3.73's but the corral tech calculator said 4.5's. That seemed slightly extreme. I've yet to procure a jack to do the wheel spin trick, though.
 
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