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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
If somebody gets a set of gears in could they measure the distance across the face of the gears (I think it is like 9 inches). I have seen photos and you can tell the size difference. I always wanted to see what they measured I know the regular C6 ones are like 8.25 inches or so.
If somebody gets a set of gears in could they measure the distance across the face of the gears (I think it is like 9 inches). I have seen photos and you can tell the size difference. I always wanted to see what they measured I know the regular C6 ones are like 8.25 inches or so.
Back in my days of muscle cars, my 1969 Z/28, 2.20 first gear, 3.73 rear end. When you tried to launch on street tires, the wheels just fried the tires because the were spinning so fast. After the install of 4.88's, drop the clutch at 3,500 RPM and nail it, no frying the tires and the car left, gone, see the USA from behind my Chevrolet, ate Road Runners and 440's alive.
I read an article where they had a 302 in a 69 Camaro race car. Testing to get the best times they had really low gears, 5.38's if I remember correctly. Then they swapped the 302 for a big block, both were race motors. The car slowed down. They ended up going to a taller gear because of the rotating mass of the BBC would launch the car better with a tall gear.
I think the lower gear will help E.T. times on the Vette race cars, but then I'm old and may be full of baloney.
I understand the theory behind that is that the car/tires will reach a speed when they wont spin - less tire speed shock to the system. I think also with the low gear in your example above there may have been more weight transfer to the back with the 4.88, thus helping traction. It will spin easier with the lower gear like the 3.90s as there is more torque to the tire.
My current acceleration plots with 3.42 read gear.....
All the parts to put the 3.90 rear gear in my diff have arrived, so I’m dropping the diff off this weekend, then the car goes back together. Then, I’ll be able to compare the numbers with the 3.42’s to see the impact on overall acceleration. For 1/2 mile races I’ll be shifting into 5th gear now, but I’ve got the .81 5th gear in my ZR1 transmission so this will be very interesting. Here’s some data from my last 1/2 mile run that I’ll be using as my baseline:
Standing start 1/2 mile 166.1 mph@ 18.50 seconds.
I hit 170 mph in 20 seconds, and hit 172 mph in 3005’ ....all in 4th gear at 7400 RPM.
This was on my 335/25/20 street tires in street trim
Standing start to top of 4th gear...172 mph in 3005’ ....all in 4th gear at 7400 RPM.
Standing start 1/2 mile 166.1 mph@ 18.50 seconds.
I hit 170 mph in 20 seconds,
Since switching to the MH3 ZR1 transmission (2.29 1st gear) my 0-60 Mph and 60’ launches have suffered big time, but I knew that as I had always had 3.90’s in mind. Check out my 1st gear acceleration plot with my 3.42’s and 335/25/20 street tires..... 73.47 MPH in 1st gear !!!!
Acceleration plot showing speed/distance/time for 1st gear pull shown above
Victor, you are a treasure of good technical information!
I timed from my GoPro at Mojave and was about 15.7 sec. to 150 with serious 1st gear tire spin and 1-2 shift spin on the runway. It was 38 second to the 1.5 mile trap, taching ~6400 RPM, stock size tires, rear gear and tranny gears.
04-26-2018, 08:42 AM
