gear ratio confusion
04-14-2006, 02:16 PM
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gear ratio confusion i recently swapped out the rear end from my 00 TA with 2.73's for a rear from a 30th anniv TA that as far as i know came with 3.23's.
when i bought the car it came with a hpp so i changed the gear ratio's in the ecm with the programer but the speedo was still off. then i changed the ratio with the hpp from 3.23 to 3.42 and the speedo calibration was correct.
the rear i swapped in was totally stock(under 10k) is it possible that the 30th anniversary cars came with 3.42's or maybe the car or hpp is malfunctioning?
when i bought the car it came with a hpp so i changed the gear ratio's in the ecm with the programer but the speedo was still off. then i changed the ratio with the hpp from 3.23 to 3.42 and the speedo calibration was correct.
the rear i swapped in was totally stock(under 10k) is it possible that the 30th anniversary cars came with 3.42's or maybe the car or hpp is malfunctioning?
04-14-2006, 02:18 PM
#2
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Originally Posted by 1999 SS
i recently swapped out the rear end from my 00 TA with 2.73's for a rear from a 30th anniv TA that as far as i know came with 3.23's.
when i bought the car it came with a hpp so i changed the gear ratio's in the ecm with the programer but the speedo was still off. then i changed the ratio with the hpp from 3.23 to 3.42 and the speedo calibration was correct.
the rear i swapped in was totally stock(under 10k) is it possible that the 30th anniversary cars came with 3.42's or maybe the car or hpp is malfunctioning?
when i bought the car it came with a hpp so i changed the gear ratio's in the ecm with the programer but the speedo was still off. then i changed the ratio with the hpp from 3.23 to 3.42 and the speedo calibration was correct.
the rear i swapped in was totally stock(under 10k) is it possible that the 30th anniversary cars came with 3.42's or maybe the car or hpp is malfunctioning?
04-16-2006, 02:29 PM
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Originally Posted by OOOJOHN
It is highly possible that it came with the 3.42 gears .
04-16-2006, 03:40 PM
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Originally Posted by 1999 SS
that would be cool. my understanding is that f-bodies never came with 3.42's.
If the donor was an automatic, then it's either 2.73 or 3.23 (given it's stock), but there's no telling if the guy put different gears in it. Your best bet is to open the rear and find out for sure
04-16-2006, 03:43 PM
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Automatics came with 3.23 gears if the car had the high speed rated tires and 2.73 gears if it didn't.
Manual transmission equiped cars all came with 3.42 gears.
It appears you have the rearend from a 6 speed car.
Manual transmission equiped cars all came with 3.42 gears.
It appears you have the rearend from a 6 speed car.
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04-16-2006, 05:30 PM
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the car was an automatic thats why i assumed it had 3.23's but the speedo didnt read correctly until a punched in 3.42's as the rear axle ratio.
could this ratio been an option for auto 30th anniv TA's?
i know the guy that i got the rear from real well and i know that its stock.
could this ratio been an option for auto 30th anniv TA's?
i know the guy that i got the rear from real well and i know that its stock.
04-16-2006, 05:39 PM
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What are you using to check the speedo? I always use www.f-body.org/gears/ to double-check mine against the RPM to make sure my 2.73/3.42 takes after tuning.
04-16-2006, 06:59 PM
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Originally Posted by 2001NBMZ28
What are you using to check the speedo? I always use www.f-body.org/gears/ to double-check mine against the RPM to make sure my 2.73/3.42 takes after tuning.
04-17-2006, 01:53 PM
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Originally Posted by 1999 SS
i drive next to my brother in his 05 Durango. he sets his cruise control and so do i till were at the same pace and he tells me what speed were going.
04-17-2006, 02:32 PM
#12
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According to that calculator there's not a lot of difference between 3.23/3.42's at speed, and cruise control can fluctuate RPM's:
3.23 @ 71 MPH = 2100 RPM
3.42 @ 70 MPH = 2200 RPM
3.23 @ 71 MPH = 2100 RPM
3.42 @ 70 MPH = 2200 RPM
04-17-2006, 03:18 PM
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Originally Posted by 2001NBMZ28
According to that calculator there's not a lot of difference between 3.23/3.42's at speed, and cruise control can fluctuate RPM's:
3.23 @ 71 MPH = 2100 RPM
3.42 @ 70 MPH = 2200 RPM
3.23 @ 71 MPH = 2100 RPM
3.42 @ 70 MPH = 2200 RPM
