1500rpm in 6th = 58mph?
09-19-2003, 04:21 PM
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1500rpm in 6th = 58mph? I just got a 98 Z28 6speed for my wife. I'm used to 1500rpm in 6th gear being about 70mph in my C5, and AFAIK the t56 in the vette and fbody have the same gears (6th=0.50:1), and both cars come with a 3.42 rear end stock.
1500 rpm in the camaro is only 58mph, which according to my calculations, would imply a 3.95 rear gear.
Is there a 3.95 for the fbody, or are my numbers off? Also, how do I know if just the ring and pinion was changed, or if it's got a 8.8, 9", 12 bolt, 10 bolt, etc? I'll count the bolts on the differential cover tonight, but how many would there be if it's stock?
Thanks.
1500 rpm in the camaro is only 58mph, which according to my calculations, would imply a 3.95 rear gear.
Is there a 3.95 for the fbody, or are my numbers off? Also, how do I know if just the ring and pinion was changed, or if it's got a 8.8, 9", 12 bolt, 10 bolt, etc? I'll count the bolts on the differential cover tonight, but how many would there be if it's stock?
Thanks.
09-19-2003, 07:33 PM
#2
Re: 1500rpm in 6th = 58mph? I come up with a 4.10 being 56 and like you said a 3.95 being ~58.
Stock 10 bolt has 10 bolts on the cover, 9" has none, 12bolt has 12, I doubt the car has an 8.8 but I forget how many bolts on the cover (I think its 10), the giveaway there would be the torque arm mount..
3.90s come for 9" and 12 bolts, not sure about an 8.8.
Most likely someone had a larger gear in the car and didnt change the speedo calibration when they traded it in/sold it and put the stock rear or gear back in. Also the tach and or speedo may be way off (1300rpm in 6th = 58mph). You can jack the car up and see how many times the pinion turns for one revolution of the tire. If its ~3.5 turns you can have someone who has LS1edit read your PCM and see what gear its programmed for. A dealer can see on a tech II also...
Stock 10 bolt has 10 bolts on the cover, 9" has none, 12bolt has 12, I doubt the car has an 8.8 but I forget how many bolts on the cover (I think its 10), the giveaway there would be the torque arm mount..
3.90s come for 9" and 12 bolts, not sure about an 8.8.
Most likely someone had a larger gear in the car and didnt change the speedo calibration when they traded it in/sold it and put the stock rear or gear back in. Also the tach and or speedo may be way off (1300rpm in 6th = 58mph). You can jack the car up and see how many times the pinion turns for one revolution of the tire. If its ~3.5 turns you can have someone who has LS1edit read your PCM and see what gear its programmed for. A dealer can see on a tech II also...