As you all know, if we want the best performance out of a Stang, gear ratios are a must.

I've ran across several conflicting statements, and was wondering what's y'alls thoughts. I'd like to hear more fact than opinion, but all input is welcome.

Before I bought my Mustang, I thought I'd do research on all parts needed to make the car go faster. One day I was watching Horsepower TV, and they did a gear swap...forgot if it was a Stang or not. When installing the new ratio Chuck(the host....aka the Chevy guy) mentioned that the new ratio was 15% more efficient, but would cause the engine to work 15% harder. This would cause the engine to wear out 15% faster.

After hearing that, I thought....well I guess ratios will be one of the last steps of my project. It was slightly discouraging news.

This month I'm reading my MM&FF and in the "Yo Ken"(What happened to Bernie?) section a guy writes(paraphrased):

I am looking to upgrade my gear ratios, your mag recommends 3.73s, but my local shop insists on 4.10s. A mechanic I know suggested 3.55s, because the car will rev too high, and shorten the engine life. I can only image what 4.10s would do to my engine. Please advise.

Ken responds with(paraphrased):

3.73s are best for daily drivers, it'll raise your rev about 400rpm at highway speeds. The effect on engine life with lower gear ratios is negligible---definately not something to worry about.

Thoughts? Who's right? Will the engine wear out faster?

 

I think Ken's response is sensible. I would think if you're visiting the track 4.10's would be a must. But daily driving?

I think the 3.73's are for auto trans and I recall hearing there's a 3.90 set for manuals. Someone else chime in; I'm no super rear gear expert!

 

Keep in mind the smaller wheel diameter of the 2004 and earlier mustangs. 3.73's on a 2005 5-speed will be the equivalent of about 3.60's (not an available ratio, but you get the point). Not worth changing 3.55's for 3.73's.

4.10's in a 2005 5-speed are the equivalent of about 4.00's (again, not an available ratio...) in 2004 and earlier cars. This is why the 4.10's are so popular for 2005's.

If you *really* want the equivalent of 3.73's in a 2004 for your 2005, you could put in 3.90's. I think most with 4.10's will chime in and tell you to just get the 4.10's. FWIW, I'm trying to decide between 4.10's and 4.30's for mine (when it gets here)--and mine is a daily driver that will see minimal track time.

 

My 05 is a daily driver and I just had 4.10s installed. It does NOT rev too quickly and at 75 mph I am at 2625 RPMs. I got 22.2 mpg during my last 4 hour highway trip. As most 4.10 owers will tell you, they are a great mod.

 

I love my 4.10s The car could of come with them with no downsides.3,73s would definately be a waste of time and money.I am now going to have 4.30s installed.Puting carbon fiber shaft in wich requires pinion change so I am going to bump up to 4.30s.I am going to run 11,s with no power adder.

 

I wasn't challenging Ken's judgment on the ratios, but more so on if the engine wears out quicker. I edited my first post to clarify.

 

I am keeping my stock gears for awhile but will eventually go to 4;10's. IMO if an engine is properly running and properly maintained, it will not be an issue. Your looking at minimal increased rpm's unless your red-lining the thing all the time.

 

I run 4.10's in my fox, and I will run 4.30's in the new car as they are equivalent due to differences in tire height. Also, the 07 will have another 1000 usable RPM.

Don't listen to HP TV. LMAO "work 15% harder wear out 15% faster.." You think you're going to live forever?!? Drive the darn car!

 

My auto Stallion has 4:10s cause its a fun car and when I ask him to getty--up -- go he does. RIDE ON

 

He is right!

 

I originally purchased 3.73s to replace my stock 3.31s. Prior to installing the 3.73s I exchanged them for 4.10s and have never looked back. As someone else put it very well:
"Don't fear the gear!!"

 

I agree 100%.

 

i have a set of 4.10 for my automatic,just waiting for my ex2 so i can set the computer for the gears.

 

If you are going to the track occasionally, I would stick with the 4.10's. They will wake up the car on the street and will get you some good times at the track (with good driving). In these cars, without make some other changes in the car, the 4.30's are not going to benefit you much at the track. I, personally, wouldn't put in 4.30's unless you were running drag radials or slicks at the track.

 

Don't change out the gears. My FFRP gears whine like you wouldn't believe even with a good install, and While the car feels more alive, the actual acceleration didn't improve. If you change the ring and pinion, you'll wish you hadn't, just like me. Doc

 

You must have an automatic.Because with the 5spd the gear change is night and day.Pulls hard even in fourth on the highway.First is now a creeper gear and this change got me from 13.0,s to 12.7,s.I also can do 80 down the highway at 2,800rpm.

 

He's right on the money about the tire diameter. If you plan on swapping out the wheels & tires, take a look at the new tire diameter, then make a call whether or not you need gears. I will be putting on a set of 18x9.5 rims with 285/30ZR18 tires, which will be roughly the equivalent of 3.90 gears with the stock rims/tires.

 

Thanks for the info. A few months ago I was dead set on 4.30's, last month I was 50/50, and now that the car should be arriving any week I'm leaning towards 4.10's. Decisions, decisions. :scratch:

 

What is a creeper gear?

 

I left my gears stock, I plan on adding a S/C so I need a taller gear to pull better under boost. Nitrous also loves the load of a taller gear. If you want a little ratio witout the bucks of a gear change then as the others have said look at shorter tires. I put on a set of Fuzion (true radial tires) 275/40/17's and the car runs 12.90's all day long with the factory gearing. I could be in the mid to low 12's with slicks and shorter gears but for me the gearing is perfect for the street with short tires.

BTW: A "creeper" gear is what a lot of heavy duty trucks have as a 1st gear ratio just to get a heavy load moving easily without a lot of wear and tear on the clutch assembly. Most people don't even start in 1st gear when it is that low, especially if you are not racing.