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hey guys me and my buddy just took a posi rear off a G.T.A. and put on my 89 camaro rs with a stock 305 in it. and i wnt to know what the gear ratio is for both the old rear and the posi rear,which by the way came off a 5.7. i have no clue and would really like to find out :confused:
 

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:D


All the GM vehicles I have seen have a build sheet...........or code with the engine/trans/rear and other equipment listed. It's in the glove box, on the door post on under the seat as a general rule.

If that fails..........:rolleyes: take the rear end cover off and count the teeth. Divide the little number into the BIG number......and there you have it.

Most GM rears have a code stamped on them.........which tells the original ratio. I am NOT a F car series person and do not have the codes .............

:D
 

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thanks i will count the teeth i already looked in the car but no dice and the only way i knew it was a posi someone said there would be a tag on it and there was its worn and unreadable though. i wanted to check the lube in it so now i have a motive to do it little# into big# sounds easy enough thanks for the info
 

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After the lube drains off, look at the edge of the ring gear & see if there are some numbers. Look for a pair of numbers one of which is between 9 & 16, & another which is between 35 & 45. If so, these are the tooth counts for the pinion & ring gears, respectively. Divide the big one by the small one & that's your gear ratio. For examble "41 10" would be 4.10, "37 9" would be 4.11, etc. Other numbers found may be a part number or a date code.
 

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You could also just rotate the driveshaft and see how many turns it takes to make the tires rotate one time.

On the off chance you just want to add some more oil to it and go without taking off any covers or what not.
 
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