Gear questions

[4wheelfurry]

First post here guys, I'm on Ford-Trucks Forums as well as several others. I currently own several rides, 2 Fords, a Dodge, a Chevy and a Honda car. I have spent years working on all makes but I really speciallize in Fords and GMs and I've owned several 4.6 cars.

Little history; my wife had a 06 Chevy Trailblazer and a guy pulled out in front of us and totalled it so I picked up a 03 Mountaineer on the cheap while waiting on insurance settlement. It is really nice and has turnes out my wife really likes it so we'll just keep it. I gave $1800 and put about another $500 in the engine. I had to do timing chains, rods and main bearings, head job, gaskets, intake mani, ect. Some work was needed and some of it just because I was there... Anyway the body is perfect and the interior is great too so all in all the car is set for many more miles EXCEPT the rear end is singing so I am going to rebuild it.

It currently has an open diff 3.55:1. My question is what would I benefit by going to a 3.73 gear? The car is a 4.6L 2WD Auto with the 17" wheels. Fuel mileage is currently 17 city and 21 highway (by the computer). I certainly don't mind the fuel mileage, would dropping to a 3.73 effect me? We do much more town/back road driving than highway traveling so I'm thinking more gear will equil less stress on the trans stop/go driving.

I like to regear most everything I drive just because IMO they are always geared to hight anyway lol.. Has anyone out there compared these two ratios?? Thanks!

 

[Ronin8002]

Not much of a change in ratio but since you need to rebuild it anyway it might be worthwhile, especially since it sounds like you can set the gears up yourself. On stock sized tires it would probably impact your fuel economy a bit due to the higher RPMs, but if you upgraded to a 265/70/17 (31.6") tire then 3.73 gearing would put the effective gear ratio back to about 3.55. Fuel economy might be better than stock for the type of driving you mentioned.

Here's a cool calculator that lets you do a side by side comparison of gears, tire sizes, RPMs and MPH. It will let you select a transmission so pick the 5r55w from the drop down. I know you're a 2wd but the calculator needs a transfer case so just pick whatever you want there (I always use BW1354 since it's the same gearing as the BW 4411/12):

http://www.grimmjeeper.com/gears.html

If you do this one thing you should think about is getting a tuner like an SCT XCal 3 to correct the speedometer and transmission shifting since the truck will still think it has 3.55 gears otherwise.

If you need a set of used gears I know Wills05XLT4x4 on this forum is regearing his 2005 to a 4.56 ratio and his 3.73s are coming out. They are the same 8.8 IFS gears that are in your truck so you might try sending him a PM.

First post here guys, I'm on Ford-Trucks Forums as well as several others. I currently own several rides, 2 Fords, a Dodge, a Chevy and a Honda car. I have spent years working on all makes but I really speciallize in Fords and GMs and I've owned several 4.6 cars.

Little history; my wife had a 06 Chevy Trailblazer and a guy pulled out in front of us and totalled it so I picked up a 03 Mountaineer on the cheap while waiting on insurance settlement. It is really nice and has turnes out my wife really likes it so we'll just keep it. I gave $1800 and put about another $500 in the engine. I had to do timing chains, rods and main bearings, head job, gaskets, intake mani, ect. Some work was needed and some of it just because I was there... Anyway the body is perfect and the interior is great too so all in all the car is set for many more miles EXCEPT the rear end is singing so I am going to rebuild it.

It currently has an open diff 3.55:1. My question is what would I benefit by going to a 3.73 gear? The car is a 4.6L 2WD Auto with the 17" wheels. Fuel mileage is currently 17 city and 21 highway (by the computer). I certainly don't mind the fuel mileage, would dropping to a 3.73 effect me? We do much more town/back road driving than highway traveling so I'm thinking more gear will equil less stress on the trans stop/go driving.

I like to regear most everything I drive just because IMO they are always geared to hight anyway lol.. Has anyone out there compared these two ratios?? Thanks!

 

[willied]

Not much of a change in ratio but since you need to rebuild it anyway it might be worthwhile, especially since it sounds like you can set the gears up yourself. With the 4.6 you've got the sturdy 6 speed transmission which has a pretty low first gear but I guess it can't hurt. On stock sized tires it would probably impact your fuel economy a bit due to the higher RPMs, but if you upgraded to a 265/70/17 (31.6") tire then 3.73 gearing would put the effective gear ratio back to about 3.55. Fuel economy might be better than stock for the type of driving you mentioned.

Here's a cool calculator that lets you do a side by side comparison of gears, tire sizes, RPMs and MPH. It will let you select a transmission so pick the 6r60 from the drop down. I know you're a 2wd but the calculator needs a transfer case so just pick whatever you want there (I always use BW1354 since it's the same gearing as the BW 4411/12):

http://www.grimmjeeper.com/gears.html

If you do this one thing you should think about is getting a tuner like an SCT XCal 3 to correct the speedometer and transmission shifting since the truck will still think it has 3.55 gears otherwise.

If you need a set of used gears I know Wills05XLT4x4 on this forum is regearing his 2005 to a 4.56 ratio and his 3.73s are coming out. They are the same 8.8 IFS gears that are in your truck so you might try sending him a PM.

He says he has a 2003, which I believe has the 5R55W 5 speed.

This is in the wrong part of the forum, maybe someone could move it.

 

[Ronin8002]

He says he has a 2003, which I believe has the 5R55W 5 speed.

This is in the wrong part of the forum, maybe someone could move it.

Good catch, I saw the "06" where he was talking about the trailblazer and missed the "03" explorer. Edited my post.

 

[4wheelfurry]

I accidentally posted in the wrong year section. I didn't catch it. Mod please move to the correct year forum. Thanks