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rotorwrench · 10-09-2020, 06:21 PM

For most cars with large diameter tires something in the low to mid 3s would generally be fine but with small diameter tires the taller gears like 3.0:1 or 3.25:1 would be OK with an automatic transmission.

If it's built and you want to get off the line quick then the higher ratio numbers would apply but it won't do much for top end or gas mileage. If you don't care about getting off the line but still want freeway speeds then don't go for higher ratios.

You might try to find a mustang forum to ask your question just to see if anyone has experience with changing the 8" type ratios. With 14" tires & wheels you may want to try a 3.25. It should be a good all around ratio with that wheel size. If you tires are 15" or just really high aspect ratio then you would be OK with 3.55:1.

10-09-2020, 06:21 PM	#11
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: 1967 Mustang rear end gear ratio For most cars with large diameter tires something in the low to mid 3s would generally be fine but with small diameter tires the taller gears like 3.0:1 or 3.25:1 would be OK with an automatic transmission. If it's built and you want to get off the line quick then the higher ratio numbers would apply but it won't do much for top end or gas mileage. If you don't care about getting off the line but still want freeway speeds then don't go for higher ratios. You might try to find a mustang forum to ask your question just to see if anyone has experience with changing the 8" type ratios. With 14" tires & wheels you may want to try a 3.25. It should be a good all around ratio with that wheel size. If you tires are 15" or just really high aspect ratio then you would be OK with 3.55:1.