QuestionHello,
I have a 67 Mustang 289 eng C4 trans and Ford 8"(small)2.80 rear axle. Engine recently modified from a 2 to 4v edelbrock intake with an edelbrock mild camshaft and an Edelbrock 4v carb. I'll be doing mostly normal driving and no racing.
My question:
I was wondering about changing the rear axle from the 2.80 to a 3.0 gear ratio (also small 8" ford), as my mechanic said the 2.80 is lazy for a take off and the 3.0 would be much better. Is this true and would I notice a real difference? do you recommend this swap?
By the way I don't want to go up to say a 3.5 ratio since I heard that would rattle the car during highway driving.
Many Thanks
AnswerI'm sure you didn't notice in my intro on this site that I don't advise about modifications; I don't do them and I don't think they are anything but a waste of money, since the person doing them probably doesn't have either the engineering experience or the testing equipment, plus a durability test facility to wring the bugs out of a new design comparable to that of the staff and facilities of the manufacturer who originally designed and manufactured the car.
However, your 'modification' is pretty minor, so probably you don't have to worry about all that, but I doubt you will notice any long term improvement beyond what you would have gotten had you simply repaired whatever was wrong with the original equipment.
Having said that, I note that changing the rear axle ratio from 2.80 to 3.00 is only a 7% change - I doubt you would even feel the difference, and it would screw up your odometer and speedometer readings - the car would be going 7% slower than you think, and so you will get fewer traffic tickets and points on your license. You could also get the same result by putting on lower profile tires than the stock size.
But, of course it's your money, and your car, and since you have a "belly button" car (everyone has one!), you are not ruining a valuable example of a rare collectible, so have at it!
Good luck, and drive safely, whatever you decide.
Dick
