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PKRWUD · 02-20-2002, 07:49 PM

Metaldude-

You picked up on that well. Good. I can never tell if I'm explaining something well enough when I can't see facial reactions! Any gears lower than 4:1 (ie: 4.10:1, 4.56:1. 5.56:1, etc.) are considered by most to be racing gears. Any gear higher than 3:1 (ie: 2.83:1, 2.53:1, etc.) are considered by most to be "highway gears". Most ring and pinion gear manufacturers offer a wide variety of gear ratio combinations in most sizes. The only thing that is significant about the ring gear size is it's strength. It's important to note that other components are not interchangeable, either. For example, a 7.5" ring gear will not fit in an 8.8" rear end, and will not work with a 9" pinion. The rings and pinions are always a matched set, and should remain that way, and a specific size (7.5", 8.8", etc.) can only be used in their respective housings. otherwise, like I said, the only real significane is the strength. Bigger is better, from a strength standpoint. The 7.5" sucks eggs, and I wouldn't recommend one for use with a driveline exceeding 150hp. The 8.8 is much stronger, and can comfortably handle up to 400hp, and a Ford 9" can take on levels above that. Installing a ring and pinion set can be cumbersome, and takes a while. The Ford 9" rear end is a different design, and has a third member design that allows the entire gear set to be removed and exchanged with others in a matter of minutes. Very handy for circle track racing, where changing track conditions often require changing the rear gears.

lastly, the only thing that determines the gear ratio is the number of teeth on the ring gear divided by the number of teeth on the pinion gear. If you want a different gear ratio, you substitute a ring and pinion with a different number of teeth on them. For example, the ring and pinions that Richmond makes for a Ford 8.8" rear end have the following tooth counts:

3.55:1 39-11 (that is 39 teeth on the ring gear, and 11 on the pinion)
3.73:1 41-11
4.10:1 41-10
4.56:1 41-9

Their Ford 9" selection is alot bigger, and ranges from 2.80:1 all the way to 6.50:1. Their tooth count, for example, of those two sets are:

2.80:1 42-15
6.50:1 39-6

If you ever run across a ring and pinion set, again, all you have to do to determine the ratio is to divide the ring teeth by the pinion teeth.

As for my personal recommendation for you, that's hard because I don't know you, or your car. It depends on alot of factors, like your current and planned mods, and what kind of driving you will do. if you spend alot of time on the freeway, I would not recommend anything smaller than 3.73:1. 3.55:1 might be even better.

The general rule of thumb, though, is in order to acheive similar results, a vehicle with an automatic transmission requires a lower ratio than a car with a manual transmission. As such, I wouldn't exceed 3.73:1 with a 5spd, or 4.10:1 with an automatic.

Take care,
-Chris

02-20-2002, 07:49 PM	#6
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Metaldude- You picked up on that well. Good. I can never tell if I'm explaining something well enough when I can't see facial reactions! Any gears lower than 4:1 (ie: 4.10:1, 4.56:1. 5.56:1, etc.) are considered by most to be racing gears. Any gear higher than 3:1 (ie: 2.83:1, 2.53:1, etc.) are considered by most to be "highway gears". Most ring and pinion gear manufacturers offer a wide variety of gear ratio combinations in most sizes. The only thing that is significant about the ring gear size is it's strength. It's important to note that other components are not interchangeable, either. For example, a 7.5" ring gear will not fit in an 8.8" rear end, and will not work with a 9" pinion. The rings and pinions are always a matched set, and should remain that way, and a specific size (7.5", 8.8", etc.) can only be used in their respective housings. otherwise, like I said, the only real significane is the strength. Bigger is better, from a strength standpoint. The 7.5" sucks eggs, and I wouldn't recommend one for use with a driveline exceeding 150hp. The 8.8 is much stronger, and can comfortably handle up to 400hp, and a Ford 9" can take on levels above that. Installing a ring and pinion set can be cumbersome, and takes a while. The Ford 9" rear end is a different design, and has a third member design that allows the entire gear set to be removed and exchanged with others in a matter of minutes. Very handy for circle track racing, where changing track conditions often require changing the rear gears. lastly, the only thing that determines the gear ratio is the number of teeth on the ring gear divided by the number of teeth on the pinion gear. If you want a different gear ratio, you substitute a ring and pinion with a different number of teeth on them. For example, the ring and pinions that Richmond makes for a Ford 8.8" rear end have the following tooth counts: 3.55:1 39-11 (that is 39 teeth on the ring gear, and 11 on the pinion) 3.73:1 41-11 4.10:1 41-10 4.56:1 41-9 Their Ford 9" selection is alot bigger, and ranges from 2.80:1 all the way to 6.50:1. Their tooth count, for example, of those two sets are: 2.80:1 42-15 6.50:1 39-6 If you ever run across a ring and pinion set, again, all you have to do to determine the ratio is to divide the ring teeth by the pinion teeth. As for my personal recommendation for you, that's hard because I don't know you, or your car. It depends on alot of factors, like your current and planned mods, and what kind of driving you will do. if you spend alot of time on the freeway, I would not recommend anything smaller than 3.73:1. 3.55:1 might be even better. The general rule of thumb, though, is in order to acheive similar results, a vehicle with an automatic transmission requires a lower ratio than a car with a manual transmission. As such, I wouldn't exceed 3.73:1 with a 5spd, or 4.10:1 with an automatic. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!