Engine Speed at Road Speed - Rear End Identification Help
07-17-2016, 09:32 AM
#1
Staging Lane
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Join Date: May 2006
Location: Upstate NY
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Engine Speed at Road Speed - Rear End Identification Help I was hoping someone out there with a similar car could help me out. My car:
97 Formula
T56 Tranny
245/50 r16 Tires
Totally Stock
A little while back I had the rear end rebuilt. At the time, I asked to keep the stock ratio, but I've been wondering ever since if the builder might have used the wrong ratio differential.
My understanding is that the Autos were either 2.73 or 3.23, while my manual should've had a 3.42. It just seems slightly different, so I wonder if I have a 3.23 in my car now.
I was hoping someone with a totally stock set up could do a little driving and watch the tach and speedometer at a few speeds and gears and let me know what you see? For example, in 6th, it looks like I'm going 53mph at 1500RPM, and turning about 1650 at 60MPH.
I realize I could do the formulas with all the known ratios and tire sizes, but I've had inconsistent results with that. Thanks so much for any help you can offer!
97 Formula
T56 Tranny
245/50 r16 Tires
Totally Stock
A little while back I had the rear end rebuilt. At the time, I asked to keep the stock ratio, but I've been wondering ever since if the builder might have used the wrong ratio differential.
My understanding is that the Autos were either 2.73 or 3.23, while my manual should've had a 3.42. It just seems slightly different, so I wonder if I have a 3.23 in my car now.
I was hoping someone with a totally stock set up could do a little driving and watch the tach and speedometer at a few speeds and gears and let me know what you see? For example, in 6th, it looks like I'm going 53mph at 1500RPM, and turning about 1650 at 60MPH.
I realize I could do the formulas with all the known ratios and tire sizes, but I've had inconsistent results with that. Thanks so much for any help you can offer!
07-17-2016, 01:50 PM
#2
stock dashboard tachs typically indicate higher than true by 100-150rpm. speedos can be in error too. most GPS unit will show true MPH.
http://fitbodyshop.net/gear/index.php
http://fitbodyshop.net/gear/index.php
