so after finding out that my car has 4.56 gears in it (i just got it), i did some online research. i found out that those gears are mostly for big 4x4 trucks. having a 91 mustang gt 5.0 with 17 inch rims, is it monitarily worth it to buy the 3.73 gears i hear so much about? and what is the big difference? i am no expert on cars. the only thing that i have noticed is that it is slightly annoying to drive, as i have to switch gears often. Very often. what does this all mean for a normal joe?
You bought a car that turns 3600 rpm at 60 mph in direct and, at todays gas prices, you are wondering if 3.73s are worth the plunge? Your engine rpm will drop to 2900ish in direct (4th in a stick - 3rd in an auto) and your gas savings will likely pay for the gearset in the first year...
The 4.56 (revolutions of your driveshaft) to 1 (revolution of your rear axel) rear end gear ratio is low and in a Mustang are for short quick 1/8 or
1/4 mile drag racing type application. With these gears there will be few street cars that can beat you from zero to sixty, but they will have a higher top speed.
Basically the lower your final gear ratio (4.56 being a very low street gear ratio), the quicker your car will get up to (a lower) top speed. This also translates into higher engine RPM's at highway speeds, and generally a drop in fuel economy.
If you bought this car for a daily driver, it will be quick, but not too economical. :-)
If you are going to spend the $500-$2000 dollars to have the rear gears changed for fuel economy reasons, 3.73/1 gears aren't considered a very high (read economical) gear ratio. 3.50 and lower gears (4.11-4.56 the higher the number the lower the gear ratio) are generally thought of as low gears.
Something in the 3.00-3.08-3.25 range would make more sense if you are thinking of making kind of change for fuel economy reasons.
i was planning to take a long trip. from pensacola to missouri. having an average RPM of 3k(a guess) would that be a safe trip, or should i use another vehicle. overheating is not an issue as it runs at a cool
120 ' f. so i guess i am asking if it is rough on the gears to go that long that fast?
I would suggest considering 3.55's. I have them on my '89 LX and they are a good compromise between performance and economy. Also, 4.56 gears on a trip that long will drive you insane from the engine screaming and into the poor house due to low gas mileage.
Why would 3000 RPM be "not real good for a small block"??? That small block Ford V-8 engine should be able to run at 3000 RPM non stop, tank after tank of gas with absolutely zero negative results...
look gas shouldn't even be that bad. from here to missouri it is about
1.3k miles, going the long way. so you gotta think even at 20 miles to the gallon, i will only need 65 gallons. that would be less that 200 dollars in gas. and i would have a car there. so even worst possible situation, it wouldn't be that bad. i would think that the engine should run stronger than 3k. without problems, why shouldn't it?
Your car will have zero problems going to Missouri with the 4.56 gears. You will use more gas than with 3.27 gears or there abouts. Let us know what kind of mileage you get on the trip.
I have a Sunbeam Tiger that the previous owner replaced the stock rear end gears (2.88) with 3.36 gears. My car runs 3500 rpm at 70 mph. I don't have overdrive gears in the trans and the wheels are 205/60-13's (only 23 inches in diameter). I have driven on long trips (San Diego to San Francisco) with the tach sitting at 4000 rpm (80 mph). The engine is completely happy. It just sucks gas. 16 mpg tops.
i will post the gas mileage, but the trip is not until december. i don't think it will be a problem. i think that i will get better gas mileage than that. it gets about 190 miles for 27.50 at 2.98 per gallon. thats right at 21 mpg. i would hope i did better on the long run. i can have it in neutral some of the way. i am glad that it not bad on the gears.
My mistake....ours gets about 10mpg and we have 3:00-1 gears, 302, mild cam, carter 650, performer intake....the performance to mpg ratio sucks...should be MUCH quicker
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