hey guys i have a 76 pontiac firebird esprit and want to upgrade the gear ratio but dont know much about it... i was told that doing so would increase acceleration and what not and was just wondering if someone can tell me about what it is, how it works, and whether or not its good. Thanks for any help that can be given  

Addacore, gear ratio, as it relates to the rear axle is basically the number of turns the driveshaft makes for one turn of the wheels (ie: 3.08:1=three turns,plus a little bit of the driveshaft for one of the wheels). In general, the higher or larger the number (4.11 as opposed to 2.73), the quicker the acceleration and the higher the rpm on the highway at cruise speed (assuming tire diameter and trans top gear ratio stays the same). Typically low performance models such as the Esprit came with ratios such as 2.41, 2.56, 2.73 or 3.08:1. Higher perf models (Formula,TA) come with ratios in the 3.23, 3.42, 3.55, 3.90, 4.11 or even 4.33 in the highest perf versions. Crane Cams website and Wallace Racing (I believe) have charts which show your cruise rpm at 60mph for various gear and tire diameter combos. These charts assume that you have a 1:1 top gear in the trans (TH350,400 or T10,Muncie M20,21,22 4-speeds) if you have an overdrive trans the 3rd gear (auto) or 4th gear (5spd manual) is 1:1. What gears you choose depends on how you use your car and how the engine is built. Highway cruisers taken on long trips benefit from numerically lower gears, while big cammed, high hp racers that seldom see the highway work better with high numerical gears. Adding to the confusion is the fact that we refer to high numerical gears as "low" gears or deep gears and low numerical gears as "high" gears or highway gears. Have I helped? Are you totally confused yet? Any questions, just ask, I'll try to help.
Steve  

barney you havent let me down yet its been awhile since i have been on but thank you again i have found a tremendous amount of help from ya... when i got back into the coutry the orginal 79 ta i wanted had sold and i settled for a 76 firebird in emaculate condition... only problem is she has a v6 231 and thats where my next question comes in... i wanted to do a 4:10 gear ratio would this destroy the engine i have and if not will it still be okay when i drop the chevy 403 olds i want in it  

o and i forgot to metion it has a turbo 400 tranny  

Addacore, go to Wallace racing's site and scroll down the left side of the page to Automotive Calculators, click on it then click on Gear-Speed calculator. Enter the numbers they ask for and it will list the rpm and speed on a chart. I used 26" as a typical tire diameter, that's about the height of a P225/70r15 or P245/60r15, and 1.00 as the trans ratio for a th400. That works out to 3000rpm at 56mph with 4.10 gears, so you can see what effect that gear has on your engine rpm at highway speed. Yes that will rapidly affect the wear of an older engine that already has lots of mileage on it and is likely way more than you need. Try inputting different gear combos to see what rpm you are comfortable with. For example, switching the 2.73's for 3.42's in my Formula with a 350/th400 and 25" p235/60r15 tires, raises my rpm at 55mph from 2000 to 2500 rpm. Not a huge increase but it will affect mileage and make it a bit of a pain in the ear for longer trips (2 hours @60-65mph to get to the dragstrip). However, since it rarely gets outside the city limits, I will live with it for the increase in low-end grunt off the line. In the future I may swap the th400 for a 200r4 overdrive when the budget allows.
Steve
http://www.wallaceracing.com/index.html  

Okay now i got it thanks again for the help and im gonna check the web site now to see what stats i get for the different ratios, i dont really leave the city and she needs quite a bit more work before i can even think of taking her to the drag strip lol like a new engine for starters... not that i would never try to make a grand national but i think a chevy 350 will be much cheaper building on thanks again barney... or is it steve? :-)  

I answer to both, Barney is a nickname I picked up at work a long time ago!