A
Anonymous
Guest
I've been working on this problem and I'm starting to bug out and need someone else to take a look and tell me what you think.
My problem has to be one of three things. I recently start thinking about what I want to do for a rear end. To my knowledge the rear end is stock and according to my axle code (found on the panel attached to the drivers door) says the car is equiped with a 2.83 ratio (looked up axle code in my manual). However, at 60mph my tack is reading around 3200 rpm's. All the research I have done says the 3rd in my C4 is a 1:1 ratio. Problem is the math doesn't work out
60mph
tire diameter = 25"
axle ratio = 2.83
high gear ratio = 1 to 1
With the figures above the car should be pulling around 2200 rpm's. Best I can figure is either the axle is not stock or the final gear ratio in the 65 C4 is more like 1.46 or my tach is not reading correctly. Tach's are not rocket science in terms of hooking them up so I don't think that is the problem. Below is the web site I'm using to calculate the rpm's.
http://www.quiknet.com/~ke6vut/rpmcalc.html
Does anyone have any ideas? The Tach is a sunpro unit. Shifts occur around 5800 RPM's according to the Tach. I've checked the axle for a tag indicating the axle ratio but no dice. Everything on the car was stock when I bought it and I can't imagine the axle is anythign but the stocker 2.83.
Using the URL above I would have to have a 4.1 axle to turn the engine 3200 rpm's at 60mph with 25" tire diameter and a 1 to 1 3rd gear ratio. That better not be right cause even after the aussie head upgrade I'm not completly satisfied with the accelration of the car (it is way better then before but it was a gutless pig before) and was hoping to change rear end's for something like a 3.5 ratio.
Does anyone have any ideas?
My problem has to be one of three things. I recently start thinking about what I want to do for a rear end. To my knowledge the rear end is stock and according to my axle code (found on the panel attached to the drivers door) says the car is equiped with a 2.83 ratio (looked up axle code in my manual). However, at 60mph my tack is reading around 3200 rpm's. All the research I have done says the 3rd in my C4 is a 1:1 ratio. Problem is the math doesn't work out
60mph
tire diameter = 25"
axle ratio = 2.83
high gear ratio = 1 to 1
With the figures above the car should be pulling around 2200 rpm's. Best I can figure is either the axle is not stock or the final gear ratio in the 65 C4 is more like 1.46 or my tach is not reading correctly. Tach's are not rocket science in terms of hooking them up so I don't think that is the problem. Below is the web site I'm using to calculate the rpm's.
http://www.quiknet.com/~ke6vut/rpmcalc.html
Does anyone have any ideas? The Tach is a sunpro unit. Shifts occur around 5800 RPM's according to the Tach. I've checked the axle for a tag indicating the axle ratio but no dice. Everything on the car was stock when I bought it and I can't imagine the axle is anythign but the stocker 2.83.
Using the URL above I would have to have a 4.1 axle to turn the engine 3200 rpm's at 60mph with 25" tire diameter and a 1 to 1 3rd gear ratio. That better not be right cause even after the aussie head upgrade I'm not completly satisfied with the accelration of the car (it is way better then before but it was a gutless pig before) and was hoping to change rear end's for something like a 3.5 ratio.
Does anyone have any ideas?