Are 355's my best option - Page 2 - Ford Mustang Forum
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I hope it's okay if I chime in here, being a V6 owner. I experienced a loss of 2-3 MPG avg going from 2.73's to 3.55's.

Considering the fuel economy I'm reading about from 5.0 owners, and based upon the jump I made, I'd say you would likely lose about 1 MPG moving up from 3.31's to 3.55's.

I agree with those recommending the 3.73 upgrade. Expect minimal loss, if you can keep your foot out of it once it's done! :kooky:

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I drove all three ratios and the 3.73 (with mt and brembos) was the only car I was going to buy. Huge difference, car pulls and revs harder, just rips!

I drive 45 miles each way to DC for work and average 22mpg commuting, 24-26 hwy. Driving 3.73 with a manual may not be everyones cup of tea in heavy traffic. The gears are shorter and the car is twitchy moving at slow speeds, but I am very willing to trade this off for acceleration when the road is open. My suggestion if your going through the trouble of swapping gears (or anyone buying one as it is only $375 option) ? 3.73


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post #18 of 55 (permalink) Old 01-03-2012 Thread Starter
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Guys, thank you all for your input, some interesting comments for sure.

Before I swap out the gars I plan to get the FRPP tune, and as one of you said - it seemed to have greater effect on 331's than 355's. so I'll check the tune before swapping gears - but you've also convinced me to try 373's as it would be much more noticeable than just switching to 355's - I know where my money is going next

thanks again, I thought I was going to get flamed with this one, but you proved me wrong - in a good way
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post #19 of 55 (permalink) Old 01-03-2012 Thread Starter
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Quote:
Originally Posted by HEISMANHERSCHEL View Post
The truth is a few miles per gallon are not going to make much of a difference on your gas bill. Gas mileage is way overrated. I should know. I drive 50 miles to work, one way, four times a week. I used to have a Toyota Yaris because I thought it was saving me so much money. Well, one day I sat down and actually did the math. Here is how it pans out.

400 miles a week going to and from work. That equals roughly 20,000 miles a year.

At 30 mpg, you will spend somewhere around $2,200 in gas throughout the year.

At 20 mpg, you will spend somewhere around $3,300 in gas. So you save $1,100 during the year. Or $22 bucks a week. Now that seems like a lot, I know. But that is the difference in 10 mpg. Even going from 331's to 373's, you will not drop anywhere near 10 mpg. Maybe three or four.

Now, those numbers are found if you are driving approximately 20,000 miles a year just to work and back. Most people don't drive that much. And there was a 10 mpg drop in mileage, which you wont have. The less you drive, the smaller the price gap.

While saving approximately $90 a month on gas sounds great, you can easily cut that much out of your budget on other things and drive the car you want.

I went from my Yaris and getting 37 mpg to my Mustang getting 24 mpg (now 28 mpg with the cat back). It was a little cheaper to drive the Yaris. I guess you could say I would have an extra $100 a month in my pocket if I was still driving one. But I was driving a YARIS! I am much happier driving my Mustang. I can actually pass people on the highway now. And no one makes fun of my car anymore. The real savings was that the Yaris was cheaper to buy and cheaper to insure. That is where the savings are. But you already have a Mustang. The rear end change will not change your insurance.

So if you want more pep, I would get the 373's. I don't think it will make that much of a difference, either in mpg or performance. But the 373's will be faster than the 355's, and the change might be noticeable if you go from the 331's to the 373's. I bought the 355's to save gas, too. But now I doubt it saved me much at all. Next time I am getting the bigger rear end.

You got the car because it was the best performance bang for the buck on the market. It gets respectable mpg. You won't kill the MPG unless you drive fast and race around town.

If you want the lower rear end, don't pass on it because you will save $10 a month on gas. I say eat at home once more a week and get the hot set up. The only real savings you will have is not changing out the rear end. But you have to have a car you like driving.
This says it all, thanks HEISMANHERSCHEL
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I have a 3.55:1 gear set and cruising at 65 mph, the best mileage my Mustang delivers is 28 mpg. First gear is not useless, but you can start in 2nd gear easily.

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Quote:
Originally Posted by 5.0ben View Post
Great reply HEISMANHERSCHEL !
I went from 3.31's to 3.73's in my manual and wouldn't do it again. I got a humming sound and burning smell in the rear after the install. I was also ripped off by the dealer for the install $1000 P&L.
The worst part about 3.31's IMO is 6th gear on the highway.
That alone is worth the upgrade in gears maybe to 3.55's.
I noticed top end loss with the 3.73's which was very disappointing. The overall performance difference was noticeable but nothing major. 1st gear definitely pulled harder and it felt a little snappier in all of the gears in the low rpm's with a top end trade off. The extra shifting was annoying too on my daily traffic filled commute.
I could however see the 3.73's being good with a race tune allowing you to rev higher and having more top end power.

I think 3.55's are the optimal overall gear for this car for the manual.

In the end I got an auto which pulls harder after first gear than the manual with any of the gear choices and couldn't be happier:smilie
sounds to me like you just had a complete bad experience with 3:73's starting with the install. should be no noise or smell when installed correct... and yes a 1000.oo they got ya...

as far as top end loss very little if any at all just turning a few more rpms at the top...

in my opinion 3:55's would be a waste of money ...I would not even of bought mine without the 3;73'S that was a must for me..

best of luck with your choice...

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Quote:
Originally Posted by johnr2001 View Post
sounds to me like you just had a complete bad experience with 3:73's starting with the install. should be no noise or smell when installed correct... and yes a 1000.oo they got ya...

as far as top end loss very little if any at all just turning a few more rpms at the top...

in my opinion 3:55's would be a waste of money ...I would not even of bought mine without the 3;73'S that was a must for me..

best of luck with your choice...
For me my choice in the end was a winner. I have a 60 mile commute with crazy traffic and very little twisties. The automatic is so much easier to drive fast with very little effort and is a beast on the highway. I'm also more of a straight line racer kinda guy. On top of it my manual trans was giving me some issues the dealer was saying was "normal"
The auto pulls/feels stronger than the manual especially above 80
(yes I like to speed)


Anyone who's considering the gear swap to 3.73's should really just go to your local dealer and test drive one before pulling the trigger.
You may find the small difference isn't worth it.
When I said weaker up top I meant it felt weaker, especially 3rd and 4th gear above 4k rpms. I don't know if it's actually slower but something was missing from the top end.

I think my auto would slay a 3.73 5.0 from an 80-115 pull.


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Quote:
Originally Posted by 5.0ben View Post
I think my auto would slay a 3.73 5.0 from an 80-115 pull.
That's a bold claim. My '12 Brembo/3.73 300A is stock and I ran off and hid from the few A6s that have tried. Most of them had similar mods to you (tune and axlebacks). I've never started a race at 80mph though.

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excellent informantion and advice in this thread so far....but if I may, I'd like to put in a word for the 3.55s.

1.) 3.55 car felt noticably faster than the 3.31 car that I initially I test drove. Obviously, the 3.73s are a bigger jump and will feel even faster "seat o' the pants" but the 3.55s are no slouch and you will notice them. Regardless of how the gears feel, it's conceivable that the 3.55s are faster than the 3.73s in some situations.

2.) I have plans to campaign this car in Autocross. The 3.55s are supposedly more useful in this application since 1st and 2nd will take you up a little higher in the speed range. I have heard from a few road racers that this is their gear of choice as well but this will probably vary from track to track/driver to driver.

3.) Even with some power adders, you can finish the 1/4 mile in 4th gear rather than having to shift one more time into 5th. Early on, it was speculated that the 3.73s were chosen to optimize the 0-60 and the 3.55s were chosen to optimize the 1/4 mile...and so far, it's hard to tell if that's right since all the tests are done on 3.73 cars.

4.) More versatility by changing tire sizes- more gear- go a bit smaller, less gear, go a bit taller. The 3.55s put you right in the middle and give you a pick...but that's admittedly a stretch.
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Quote:
Originally Posted by 46Tbird View Post
That's a bold claim. My '12 Brembo/3.73 300A is stock and I ran off and hid from the few A6s that have tried. Most of them had similar mods to you (tune and axlebacks). I've never started a race at 80mph though.
You claiming that you ran off and hid from a tuned auto with you being stock is quite bold as well...
From a dig I could see maybe if your one hell of a driver. I could also see if there were turns involved but from a roll?


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Well you're right, there is no skill involved with racing from 80mph.

You can't really quantify how quick a car is 80-115. I've only been to the track once, and ran 7.98 at 88 in the 1/8 on my fourth pass ever. On that day it was the quickest of nine n/a 5.0s at the track and nearly all of them had tunes and exhaust. It was also quicker than the two supercharged 3-valve GTs there. I think I can back up my claim. What have you run?

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Quote:
Originally Posted by 46Tbird View Post
Well you're right, there is no skill involved with racing from 80mph.

You can't really quantify how quick a car is 80-115. I've only been to the track once, and ran 7.98 at 88 in the 1/8 on my fourth pass ever. On that day it was the quickest of nine n/a 5.0s at the track and nearly all of them had tunes and exhaust. It was also quicker than the two supercharged 3-valve GTs there. I think I can back up my claim. What have you run?
I've run quick times in other cars and bikes that I've owned but haven't been to the track with my auto yet.
If your stock from what your telling me, it's not your car that is more powerful/better geared than tuned auto 5.0's or other, it's that you know how to drive...
A roll race can give a good idea of power to weight taking out a lot of the skill part of the launch.


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Great thread and discussion going here.
I would like to add something that many may not have realized.
The effective gearing of the MT82 with 3.73's is like a T56/T6060 equipped car (GM LS's, Terminators, and GT500's) with a set of 4.88+ gears. Matter of fact 2nd gear in a MT82(2.84?) is still steeper then first in a T56(2.66). This gives these cars some brutal torque multiplication compared to other cars both old and new.
Also the difference in rpm per cruise speed for 3.31 to 3.55 is approx 200 rpm, from 3.55 to 3.73 approx 200 rpm. IMO this isn't enough difference to warrant not opting for the latter two. The minimal (if any) loss in mileage is more then made up for in the acceleration and fun factor.

As for the M6 3.73 vs tuned A6 from a 80 roll to 115.
I say it would be close since the auto will have to downshift, and the manual can stay in 4th for practically the whole race with a shift to fifth at the very end (unless the rev limiter has been bumped).
I would definetely like to try it some time though.

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Quote:
As for the M6 3.73 vs tuned A6 from a 80 roll to 115.
I say it would be close since the auto will have to downshift, and the manual can stay in 4th for practically the whole race with a shift to fifth at the very end
FYI,
The auto would be in 3rd gear from 80-115 (compared to 4th-5th in the 3.73 manual) and doesnt need to downshift since you can manually put it in 1st-3rd from any speed even from a stop without downshifting and start from there.

I know you should use the butt dyno but the auto feels much better than the 3.73 geared manual at these speeds or really anywhere above 60. Could be because you're in 3rd instead of 4th going from 60-115...
Even if I started with dowshifting I bet I'd pull:shiny:


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I think my auto would slay a 3.73 5.0 from an 80-115 pull.[/quote]


Sorry for your troubles and no a manual is not for everyone.
That would be 4th gear, slayed? Hmmm


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