4.10's vs 3.73's

[merc123]

Like I said before, look at the future of your car. If you're going to S/C then go 3.73's. If you're staying N/A go with 4.10's.

I didn't get 100% what I thought I would get with 3.73's when I bought them and probably would have enjoyed 4.10's, BUT I want to supercharge so I got the 3.73's. Even though I don't enjoy them as much as I probably would 4.10's, that will change shortly when I get the S/C. Plus, I'll be getting lower RPM's than 4.10's

tomustang: Wrong. It's 1 out of 43656562456710876435013450356014865056014561043651 03945610345164395649561056435134857349853495874398 57134957435843953496543956934593925932459435428047 56060836508650465046109865019650945609756045764305 6314095604395634591263405963405962315

 

[5spd GT]

the internals will be fine. you lose longevity, but if that's your goal, then buy a toyoya. numerical advantage is more than sotp. just try 0-100 with 2.73 against 4.56. me, i have used 3.73's with no overdrive and the 302 lasted for many years. drag racing twice a week, trips across the country. my next gear is 4.56. for what it is worth.

There is a simple explanation why I don't want a Toyota (or make of the like). Very simple...ready?

I don't want one.

I want to take care of a car and I want a mustang. Simple enough? That whole "get a honda" clause is and has no basis and isn't backed up.

They all last a very long time...they both can hit 200k...and you can get attainable mpg out of a car and make it worthwhile.

Let me ask you this to disprove your get a honda type posting.

Would you rather get 2mpg or 20mpg? Simple question.

For years huh? That doesn't say anything...for all I know you could have just drove it 5 miles a day if at all?(besides the drag strip trips where it doesn't matter in overdrive so I'm not sure why you brought that up )

Internals is piston rings as well. More up and down motion caused by the increased consistent and constant revs eats away at the piston ring composite. Very simple again.

 

[jstreet0204]

You guys need to read more: Many think the gears are to harsh, especially those that go on the highway frequently.

It is more than 3,000 rpm at 90mph. That is a marketing ploy to sway people to get 4:10's.

Just remember getting these high gears isn't all about sotp feel and drag racing. Think longterm here - mileage, more engine rpm's and revs, clutch/tranny components.

To many times there is the "sotp" feel info and not what is actually does mechanically.

The argument can just as easily go the other way. While steeper gears put the revs higher, it also eleviates load on the engine making it not have to work as hard during stop and go driving. So which is harder on the engine? Cruising at a slightly higher rpm, or pushing harder every time you are getting up to speed.

Also you are incorect about it being harder on the clutch and tranny since with steeper gears you have decreased the work load on components from the rearend forward (other than the fact that they have to spin a little faster), and increased the load on components from the rearend back. i.e. axles.

 

[Give Me TP]

i'm with u guys ""5spd gt""and ""give me tp"" the main reason, its rpm and mpg not really how long my engine will last.. i know it will last atleast 100kand + easy and getting spanked everyday.. but hey i already have a weekend warrior and i dont need a bad gasser for a every day drive car... not with the miles that i do every day... some gears pulleys and drive shaft i should be fine ...i just dont want to drop more than 4/6 miles per gallon...that lol and i am almost placing my order for 3.90s gonna wait a little more and see how things so...working on my home made intake first!!! custon made gt scoop cold air... that will be sweet.. stock looking

Unles you radically change your driving habits after a gear change your mileage will drop little if at all. Mine gets about 20 mpg on average, which though not great is good enough for me. After all, I bought a Mustang to use as a performance car.

 

[BrK02Gt]

Everyone on here has probably already covered all the topics relating to gears, but I'll throw in my suggestion for the 4.10s. If your going to run nitrous consider 3.90s. Just my opinion but 3.73s dont make enough of the difference for the money.

 

[5spd GT]

The argument can just as easily go the other way. While steeper gears put the revs higher, it also eleviates load on the engine making it not have to work as hard during stop and go driving. So which is harder on the engine? Cruising at a slightly higher rpm, or pushing harder every time you are getting up to speed.

It isn't a slightly higher rpm to the engine. Taking half the rpms at cruise increases the internals dynamic vibration and wears the piston rings down. Would you rather buy a car that has been cruised during it's life at 2,000rpm or 4,000rpm with a 5,800 rpm redline? It isn't pushing harder everything you get up to speed...there is a catch there because to much gear allows for to much "dead time" while your putting it in another gear where with a higher gear your still using the gas to get going instead of being in a "temporary neutral" 2-3x more often...

Also you are incorect about it being harder on the clutch and tranny since with steeper gears you have decreased the work load on components from the rearend forward (other than the fact that they have to spin a little faster), and increased the load on components from the rearend back. i.e. axles.

No, I'm not incorrect. The steeper gears wear out your tranny/clutch components quicker. You have to shift more (especially city driving) which uses your tranny more. To shift you have to depress the clutch pedal and release the pressure plate from the disc. The more you do that the more it wears out. It really is simple. Also under traction the steeper gears will "hit" harder therefore hitting the tranny/clutch disc material harder along with the rear and all. The spring up rate of the engine has progressed the clutch to try to keep up even that much harder and for example, if by chance your clutch is about to go...that might be the straw that breaks the camels back.

 

[jstreet0204]

It isn't a slightly higher rpm to the engine. Taking half the rpms at cruise increases the internals dynamic vibration and wears the piston rings down. Would you rather buy a car that has been cruised during it's life at 2,000rpm or 4,000rpm with a 5,800 rpm redline? It isn't pushing harder everything you get up to speed...there is a catch there because to much gear allows for to much "dead time" while your putting it in another gear where with a higher gear your still using the gas to get going instead of being in a "temporary neutral" 2-3x more often...

4.10's put the engine no where near 4000 rpm range at cruise unless you are regularly cruise at 90mph. Cruising at 75 puts you at 2600 rpm vs. 2400 rpm with 3.73's not that big a difference. You aren't in neutral more often unless you drive around in 3rd all the time. You still have to shift 4 times to get to cruising speed, lowers gears just cause you to shift sooner. Unless you do like I sometimes do, which is shift 1st to 3rd to 5th, which is easier with lower gears.

No, I'm not incorrect. The steeper gears wear out your tranny/clutch components quicker. You have to shift more (especially city driving) which uses your tranny more. To shift you have to depress the clutch pedal and release the pressure plate from the disc. The more you do that the more it wears out.

That might be a valid argument depending on how you drive. I shift no more often, just sooner, allowing me to cruise at lower speeds in 5th without bogging the engine down. In fact I may shift less due to the fact that I don't have to downshift to speed up.

It really is simple. Also under traction the steeper gears will "hit" harder therefore hitting the tranny/clutch disc material harder along with the rear and all. The spring up rate of the engine has progressed the clutch to try to keep up even that much harder and for example, if by chance your clutch is about to go...that might be the straw that breaks the camels back.

Still incorrect. The harder hitting is taking place after the rear end because of the multiplied torque. Dont beleive me, take a car with 3.27 gears and get the car rolling starting in third gear a few times. Then do it with a car with 4.10's and see which one the clutch burns out in first. Another example, on a ten speed bike, which feels harder on your legs, starting off in first or tenth?

I've got 80,000+ miles on my engine with 77,000 with 4.10's and the original clutch, and the last compression test I did a few months ago showed around 190 on all cylinders. So I would say I'm not seeing much in the lines of extra wear from the 4.10's

 

[forpit2000gt]

Changing the oil regularly will have a bigger difference on engine longevity than gears. The engines will go way over 150k and I would bet over 200k. I haven't put 200k on a mustang yet, but have had 2, F150 with 4.6 engines.( 1997 Still going 206k, 1997 264k until it was wrecked, They were loaded most of the time.
They have a pretty hard life. High rpms and loaded with more than they should be . The rpms will not make a noticable difference on the engine if oil and coolant is correct. ( I am not saying run at redline for 1000 miles. )

 

[Give Me TP]

I shift the same with 4.10s as I did with 3.55s, and typically run at about 2500 rpm cruising in fifth gear. The actual 90 mph/3000 rpm figure I posted was only intended to show that 4.10s really don't increase your rpm to extreme levels in normal highway driving as is often warned about. Real world use of 4.10s convinces me that most, but not all, naysayers either do not have them or should not have them. As for the drivetrain, any performance mod (not including gears in this category) that increases HP will presumably increase wear. Is that a good reason then to do no performance mods?

 

[billfisher]

Exactly

For those of you that are trying to decide what gears to get, and what difference it makes in the actual torque applied to your back tires... try this out for size.

So, I have been doing a little homework trying to figure out if I want to get 4.10s or 4.30s. One thing that I did to help me decide was to graph the actual torque to the wheels (dyno WTQ x gear ratio x diff. gear ratio) for a variety of different gears versus my car's speed.

For the dyno WTQ numbers I used this graph that I found for a stock 1999 Cobra (since I haven't dynoed my car...yet):

(I forget where I found this, but it seems kind of typical, and my car is sort of near stock... for now... )

I then mapped out the torque curve and input the data into a data processing program that I use. Once the data was acquired, I calculated the torque to the wheels (after gears, and differential ratios). For speed I used the info for the stock 245/45R17 tires.

Here's the chart for 3.90 differential gears:

and for 4.10 gears...

and for 4.30 gears...

and for 4.56 gears...

Since actual torque to the wheels is directly proportional to your acceleration, just think of the vertical axis as the kick in the pants that you feel for that gear at that particular speed.

As you can see, from a roll in second gear (say on the 4.10 graph) from anywhere between 20 and 50 mph, you have an extra 500 or so ft-lbs of torque to the back wheels! So, for 4.10 gears, second gear pretty much feels like second gear with 3.27s with a 100 or so shot of nitrous!

These graphs and data are rather useful for other things; for instance, thrust (forward force) is your torque to the wheels divided my the radius of your back tire. Since the stock 245/45R17 tires are close to a foot in radius (12.84") you can approximately think of the vertical axes as the forward thrust of your car. Then divide that number by your car's weight and you have your forward thrust in g's. (Of course this is all assuming that you don't break traction...) Also, where you see the curves for a given set of gears cross is your optimal shift point for maximum acceleration and 1/4 mile times.

My conclusions:
After playing around with the numbers, I am definitely going with 4.30 gears! With sticky tires, first gear will launch you out of the hole like a freaked out cat on carpet. Then for regular city driving on street tires, second and thrid gear would make it feel like I've got another 100 to 130 ft-lbs of torque to pin me back in the seat for sh1ts and giggles!

I had the "fun" of analyzing this data for my own info and gear decision, but I thought the info and graphs might be useful for the rest of the community.

Enjoy...

It is nice to see some actual physics applied to these discussions. I am giong with 4.56, mine is not an every day driver.

 

[jstreet0204]

The actual 90 mph/3000 rpm figure I posted was only intended to show that 4.10s really don't increase your rpm to extreme levels in normal highway driving as is often warned about.

Well according to 5spd GT it was a marketing ploy. You must own stock in a company that only produces 4.10 gears.

It is more than 3,000 rpm at 90mph. That is a marketing ploy to sway people to get 4:10's.

 

[billfisher]

Huh?

Sorry, but 162 mph with 4.30's and 26 inch tires would be 9100 rpm. 155 mph would be 8700 rpm.

4.40 x .67 = 2.88 I calulated 139 mph with my old stang without overdrive and

3.73 @6900 rpm. mph=(((15*+(245x.6x2)/25.4)*3.14)/12)*(rpmx60/(1x3.73))=

feet per rev = 26.57 in tire heigth*3.14 = 83.444 in/12 = 6.5937 ft/revolution

6900*60/3.73 = 110991.975 tire rotations per hour=

731847 ft/hour/5280 = 138.60 mph

so...

it is more than possible to go 155 mph with 4.30*.67 overdrive =2.88 final drive
much better than my 3.73/no overdrive

 

[Give Me TP]

Well according to 5spd GT it was a marketing ploy. You must own stock in a company that only produces 4.10 gears.

Shhhhhh.....they also produce 4.30s and much, much worse but don't let anyone know...

The marketing ploy is to get 4.10s (or 4.30s, etc.) in more cars so they will wear out faster and then more new cars will be sold to replace them and the cycle will repeat itself on and on

 

[merc123]

Anyone else notice that a simple question about gears that has been asked and answered 1000 times stirs up the same 1000 arguments that happened in the other gear threads?

 

[forpit2000gt]

3.73 or 4.10 ??? same old thing, Why don't we just discuss the chicken or the egg, probably get more people to agree.

 

[Give Me TP]

Anyone else notice that a simple question about gears that has been asked and answered 1000 times stirs up the same 1000 arguments that happened in the other gear threads?

Not arguments....just opinions and every so often a few facts

 

[forpit2000gt]

Fact, I am an experience racer.( more than 100 passes, does that make me experienced?)
00 GT with bolt ons, 3.27 gears, street radials, 1.95( best) -2.2 60 ft. , ETs13.9-14.5,
Installed 4.10s, ETs went to 14.2-14.7 for a bunch of passes.I wont even talk about the 60s I pulled then. ( damn those 4.10s)
Practice, practice, practice.
Ets started coming back down, then 13.6-13.7.
ET streets, 13.2.
I did pick up time with the 4.10s, maybe I would have done the same with 3.90 or 3.73???

 

[04gtdrop]

sounds like its all about how you handle the car and practice? its really about the driver right?

i wonder what i will pull at the track after these gears? hmm ohh any suggestions on luanching?

 

[Bulldog Stang]

I was launching at 1500 RPM's (Solid Dump Launch) on Nitto Extreme 555's and they seemed to hook up ok, but the tires were still screaching some. I am now purchasing a set of Nitto Drag Radials and have been told that I can luanch somewhere between 3500 - 4000 (Walking it out of the hole) and have an awesome launch.
With the .410's you have to walk the car out of the hole, let it hook up and then NAIL it all in a matter of a second or so.

 

[Mike97gt]

You guys need to read more: Many think the gears are to harsh, especially those that go on the highway frequently.

It is more than 3,000 rpm at 90mph. That is a marketing ploy to sway people to get 4:10's.

Just remember getting these high gears isn't all about sotp feel and drag racing. Think longterm here - mileage, more engine rpm's and revs, clutch/tranny components.

To many times there is the "sotp" feel info and not what is actually does mechanically.

what it does is make the car faster. the engine revs more but works less too move the car so the engine may last LONGER since it is at a lower percentage of load when you are not on it.