Hi Chuck, you need way more info to give you a useful answer. You will need the revolutions per mile of the donor car and the same for your car. The math [arithmetic actually] is very simple your speedometer is looking for 1000 rev's/mile, so tire rev's/mi. X rear gear = driveshaft r's/mi. divide by 1000 and that will be your trans gear ratio. I believe the G-Body come with something like P205/75 R15 So side wall is 205mm X 75% X [both top and bottom] 2 so 307.5 mm [divide by 25.4 to go to inches] or 12.106" add the wheel dia. 15" = 27.106" tire height, now X pi [3.14159] 85.156" divide by 12 to go to feet = 7.096 feet per revolution of the tire. One mile is 5280 feet divided by the circumference of the tire [7.096] = rev's per mile of the tire which is 744.046 X 2.73 = 2031.246 rev's per mile of the driveshaft so your tranny/speedo gear will need to be 2:1 [2031.246/1000] I had a link saved with all available trans gears but that link is now dead so no need to share it
this is just a sample work up you will need the actual numbers from the vehicles involved and my tire numbers are based on perfect tire geometry not likely accurate to any degree, some tire sites will list actual Rev's/mile that would be best course of action if available, if not my way will get you close enough to start. I hope this helps! Harry
Harry Finishes with: wrote:Sorry I had to "Fly" you will also have to figure this out for your 'bird as well as different height tires and a different gear(?) than the G-Body
I'm not a hoarder I'm a preservationist 78 Monza Spyder (Soon To Be 2+2 with Spoilers)